Publikationen

% % This file was created by the TYPO3 extension % publications % --- Timezone: CEST % Creation date: 2024-04-14 % Creation time: 13:05:42 % --- Number of references % 632 % @Article { NGUYEN2024111375, author = {Nguyen, Huu Thien and Nguyen, Ngoc Thinh and Prodan, Ionela}, title = {Notes on the terminal region enlargement of a stabilizing NMPC design for a multicopter}, abstract = {This work proposes an NMPC scheme for stabilizing multicopter dynamics with semi-globally asymptotic stability guarantees. Recurrent issues in the state of the art, such as the existence of a terminal invariant set and a decreasing terminal cost under a local controller are analyzed. Within this context, the novelty resides in the use of a nonlinear local controller with feedback linearization properties which allows for arbitrary enlargement of the ellipsoidal terminal region with respect to the initial conditions. The framework is completed through a detailed analysis of the NMPC parameters. Comparisons and simulations for a nanodrone system show the benefits of the approach.}, year = {2024}, issn = {0005-1098}, DOI = {https://doi.org/10.1016/j.automatica.2023.111375}, journal = {Automatica}, volume = {159}, pages = {111375}, keywords = {Multicopters, NMPC (Nonlinear Model Predictive Control), Terminal invariant set, Semi-globally asymptotic stability}, file_url = {https://www.sciencedirect.com/science/article/pii/S0005109823005411} } @Article { Krusen2024, author = {Krusen, Marius and Ernst, Floris}, title = {Very fast digital 2D rigid motion estimation directly on continuous k-space data using an RNN}, abstract = {Objective: Motion of the target during radiotherapy negatively impacts the effectiveness and can cause damage to nearby tissue. MRI offers great soft-tissue contrast to visualize the target but its long acquisition time requires high undersampling of k-space to monitor this motion in real time. This typically limits the achievable latency even though every saved millisecond can increase the effectiveness of the treatment. Methods: In this study, a recurrent neural network (RNN) is used to continuously estimate motion directly from incoming k-space data. A golden-angle radial k-space trajectory continuously scans the target region and feeds the acquired data spoke-by-spoke into the RNN. Skipping image reconstruction and focusing only on the motion in the data allows for very fast motion monitoring in the order of milliseconds. To improve network training and generalization, different amounts of peripheral values are removed from the k-space spokes during preprocessing. To train and evaluate the network, 2D MRI motion datasets with different motion characteristics were generated by synthetically transforming slices of 25 MRI head scans. Results: The RNN takes less than a millisecond to accurately estimate motion. By keeping only the inner 10% of each spoke, a mean rotational error of 0.37° and a mean translational error of 0.26 mm are achieved. No patient-specific preparation or retraining is necessary. Conclusion and significance: The network gives very fast motion estimations with sub-millimeter accuracy. The results demonstrate the feasibility of this approach and provide the groundwork to further reduce latency in real-time motion monitoring systems for radiotherapy without sacrificing accuracy.}, year = {2024}, DOI = {10.1016/j.bspc.2023.105413}, journal = {Biomedical Signal Processing and Control}, volume = {87}, number = {Part B}, keywords = {Deep Learning; motion estimation; MR-guided radiotherapy; MR-linac; Real-time MRI; Undersampling}, file_url = {https://doi.org/10.1016/j.bspc.2023.105413} } @Article { Janorschke2023, author = {Janorschke, Christian and Xie, Jingyang and Lu, Xinyu and Grehn, Melanie and Blanck, Oliver and Schweikard, Achim}, title = {Landmark-Based Generation of Common Ultrasound Views and 17-Segment Model from Cardiac Computed Tomography}, year = {2023}, DOI = {10.1515/cdbme-2023-1016}, journal = {Current Directions in Biomedical Engineering}, volume = {9}, pages = {61-64}, number = {1}, file_url = {https://doi.org/10.1515/cdbme-2023-1016} } @Inproceedings { Hohmann2023a, author = {Hohmann, Stephan and Xie, Jingyang and Grehn, Melanie and Karfoul, N. and Janorschke, Christian and Mehrhof, Felix and Merten, Roland and Rudic, Boris and Krug, David and Boldt, Leif‐Hendrik and Lyan, Evgeny and Buergy, Daniel and Fanslau, Hanna and Kaestner, Lena and Zaman, Adrian and Duncker, David and Dunst, J{\{\dq}u}rgen and Tilz, Roland and Schweikard, Achim and Blanck, Oliver and Boda-Heggemann, Judit}, title = {Ziel{\{\dq}u}bertragung vom elektroanatomischen Mapping auf Strahlentherapie-Planungssysteme f{\{\dq}u}r die kardiale Radioablation -- Kreuzvalidierung zweier Ans{\{\dq}a}tze f{\{\dq}u}r die RAVENTA-Studie}, year = {2023} } @Inproceedings { Hohmann2023b, author = {Hohmann, Stephan and Xie, Jingyang and Grehn, Melanie and Karfoul, N. and Janorschke, Christian and Mehrhof, Felix and Merten, Roland and Rudic, Boris and Krug, David and Boldt, Leif‐Hendrik and Lyan, Evgeny and Buergy, Daniel and Fanslau, Hanna and Kaestner, Lena and Giordano, Frank A. and Zaman, Adrian and Duncker, David and Dunst, J{\{\dq}u}rgen and Tilz, Roland and Schweikard, Achim and Blanck, Oliver and Boda-Heggemann, Judit}, title = {Ziel{\{\dq}u}bertragung vom elektroanatomischen Mapping auf das Planungs-CT f{\{\dq}u}r die kardiale stereotaktische Strahlentherapie -- Kreuzvalidierung zweier Software-Ans{\{\dq}a}tze f{\{\dq}u}r die RAVENTA-Studie}, year = {2023} } @Article { Wulff2023b, author = {Wulff, Daniel and Dohnke, Timon and Nguyen, Ngoc Thinh and Ernst, Floris}, title = {Towards Realistic 3D Ultrasound Synthesis: Deformable Augmentation using Conditional Variational Autoencoders}, year = {2023}, DOI = {10.1109/CBMS58004.2023.00326}, journal = {IEEE 36th International Symposium on Computer-Based Medical Systems (CBMS)}, pages = {821-826}, file_url = {https://doi.org/10.1109/CBMS58004.2023.00326} } @Article { Hohmann2023c, author = {Hohmann, Stephan and Xie, Jingyang and Grehn, Melanie and Karfoul, N. and Mehrhof, Felix and Merten, Roland and Rudic, Boris and Krug, David and Lyan, Evgeny and Duncker, David and Dunst, J{\{\dq}u}rgen and Tilz, Roland and Schweikard, Achim and Blanck, Oliver and Boda‐Heggemann, Judit}, title = {Reproducible target transfer from electroanatomic mapping to radiotherapy planning systems for cardiac radioablation - cross-validation for the RAVENTA trial}, year = {2023}, DOI = {10.1093/europace/euad122.303}, journal = {EP Europace}, volume = {25}, file_url = {https://doi.org/10.1093/europace/euad122.303} } @Article { Mayinger2023, author = {Mayinger, Michael and Boda‐Heggemann, Judit and Mehrhof, Felix and Krug, David and Hohmann, Stephan and Xie, Jingyang and Ehrbar, Stefanie and Kovacs, Boldizsar and Merten, Roland and Grehn, Melanie and Zaman, Adrian and Fleckenstein, Jens and Kaestner, Lena and Buergy, Daniel and Rudic, Boris and Kluge, Anne and Boldt, Leif‐Hendrik and Dunst, J{\{\dq}u}rgen and Bonnemeier, Hendrik and Saguner, Ardan M. and Andratschke, Nicolaus and Blanck, Oliver and Schweikard, Achim}, title = {Quality Assurance Process for the Fusion of Electroanatomical Mapping and Radiotherapy Planning Imaging Data in Cardiac Radioablation}, year = {2023}, DOI = {10.1016/j.phro.2022.12.003}, journal = {Physics and Imaging in Radiation Oncology}, volume = {25}, file_url = {https://doi.org/10.1016/j.phro.2022.12.003} } @Article { ngks_23, author = {Nguyen, Ngoc Thinh and Gangavarapu, Pranav Tej and Kompe, Niklas Fin and Schildbach, Georg and Ernst, Floris}, title = {Navigation with Polytopes: A Toolbox for Optimal Path Planning with Polytope Maps and B-spline Curves}, abstract = {To deal with the problem of optimal path planning in 2D space, this paper introduces a new toolbox named {\dq}Navigation with Polytopes{\dq} and explains the algorithms behind it. The toolbox allows one to create a polytopic map from a standard grid map, search for an optimal corridor, and plan a safe B-spline reference path used for mobile robot navigation. Specifically, the B-spline path is converted into its equivalent B{\'e}zier representation via a novel calculation method in order to reduce the conservativeness of the constrained path planning problem. The conversion can handle the differences between the curve intervals and allows for efficient computation. Furthermore, two different constraint formulations used for enforcing a B-spline path to stay within the sequence of connected polytopes are proposed, one with a guaranteed solution. The toolbox was extensively validated through simulations and experiments.}, year = {2023}, DOI = {10.3390/s23073532}, journal = {Sensors}, volume = {23}, pages = {3532}, number = {7}, file_url = {https://doi.org/10.3390/s23073532} } @Inproceedings { glhb_23, author = {G{\{\dq}o}b, Madita and Lotz, Simon and Ha-Wissel, Linh and Burhan, Sazgar and B{\{\dq}o}ttger, Sven and Ernst, Floris and Hundt, Jennifer and Huber, Robert}, title = {Large area robotically assisted optical coherence tomography (LARA-OCT) for skin imaging with MHz-OCT surface tracking}, year = {2023}, DOI = {10.1117/12.2652616}, volume = {12367}, publisher = {SPIE}, address = {San Francisco, USA}, series = {Proceedings of SPIE}, pages = {123670C}, file_url = {https://doi.org/10.1117/12.2652616} } @Inproceedings { 10160561, author = {Nguyen, Ngoc Thinh and Gangavarapu, Pranav Tej and Sahrhage, Arne and Schildbach, Georg and Ernst, Floris}, title = {Navigation with polytopes and B-spline path planner}, year = {2023}, DOI = {10.1109/ICRA48891.2023.10160561}, booktitle = {2023 IEEE International Conference on Robotics and Automation (ICRA)}, pages = {5695-5701}, keywords = {Automation;Navigation;Path planning;Planning;Splines (mathematics);Standards;Path planner;B-spline;B{\'e}zier;Polytopes} } @Article { Wulff2023a, author = {Wulff, Daniel and Hagenah, Jannis and Ernst, Floris}, title = {Landmark tracking in 4D ultrasound using generalized representation learning}, year = {2023}, journal = {Int J CARS}, volume = {18}, pages = {493-500}, note = {doi: https://doi.org/10.1007/s11548-022-02768-z} } @Inproceedings { 10308456, author = {Yadav, Harsh and Xue, Honghu and Rudall, Yan and Bakr, Mohamed and Hein, Benedikt and Rueckert, Elmar and Nguyen, Ngoc Thinh}, title = {Deep Reinforcement Learning for Mapless Navigation of Autonomous Mobile Robot}, year = {2023}, DOI = {10.1109/ICSTCC59206.2023.10308456}, booktitle = {2023 27th International Conference on System Theory, Control and Computing (ICSTCC)}, pages = {283-288}, keywords = {Deep learning;Training;Visualization;Laser radar;Navigation;Reinforcement learning;Cameras;Autonomous Navigation;Deep Reinforcement Learning;Warehouses;Mapless Navigation} } @Article { hrsk_23, author = {Haxthausen, Felix and R{\{\dq}u}ger, Christoph and Sieren, Malte Maria and Kloeckner, Roman and Ernst, Floris}, title = {Augmenting Image-Guided Procedures through In Situ Visualization of 3D Ultrasound via a Head-Mounted Display}, abstract = {Medical ultrasound (US) is a commonly used modality for image-guided procedures. Recent research systems providing an in situ visualization of 2D US images via an augmented reality (AR) head-mounted display (HMD) were shown to be advantageous over conventional imaging through reduced task completion times and improved accuracy. In this work, we continue in the direction of recent developments by describing the first AR HMD application visualizing real-time volumetric (3D) US in situ for guiding vascular punctures. We evaluated the application on a technical level as well as in a mixed-methods user study with a qualitative prestudy and a quantitative main study, simulating a vascular puncture. Participants completed the puncture task significantly faster when using 3D US AR mode compared to 2D US AR, with a decrease of 28.4% in time. However, no significant differences were observed regarding the success rate of vascular puncture (2D US AR---50% vs. 3D US AR---72%). On the technical side, the system offers a low latency of 49.90 ± 12.92 ms and a satisfactory frame rate of 60 Hz. Our work shows the feasibility of a system that visualizes real-time 3D US data via an AR HMD, and our experiments show, furthermore, that this may offer additional benefits in US-guided tasks (i.e., reduced task completion time) over 2D US images viewed in AR by offering a vividly volumetric visualization.}, year = {2023}, DOI = {10.3390/s23042168}, journal = {Sensors}, volume = {23}, pages = {2168}, number = {4}, file_url = {t3://file?uid=4155} } @Inproceedings { Budig2023, author = {Budig, Hauke and Kiefer, Bernd and Ernst, Floris and Bruder, Ralf and Schwegmann, Holger}, title = {Automatic Glasgow Coma Score Determination for Mobile Robots}, year = {2023}, publisher = {De Gruyter} } @Article { Krug2023, author = {Krug, David and Blanck, Oliver and Dunst, J{\{\dq}u}rgen and Zaman, Adrian and Tilz, Roland and Grehn, Melanie and Rades, Dirk and Both, Markus and Rogge, Annette and Siebert, Frank-Andre and Boda-Heggemann, Judit and Rudic, Boris and Mehrhof, Felix and Boldt, Leif‐Hendrik and Hohmann, Stephan and Merten, Roland and Buergy, Daniel and Fleckenstein, Jens and Kluge, Anne and Olbrich, Denise and Koenig, Inke and Schweikard, Achim and Vonthein, R. and Bonnemeier, Hendrik}, title = {Interim analysis of a multi-center multi-platform feasibility trial}, year = {2023}, journal = {Strahlentherapie und Onkologie} } @Inproceedings { 10284439, author = {Nguyen, Ngoc Thinh and Gangavarapu, Pranav Tej and Ernst, Floris}, title = {B-Spline-to-B{\'e}zier Conversion and Applications on Path Planning}, year = {2023}, DOI = {10.1109/CoDIT58514.2023.10284439}, booktitle = {2023 9th International Conference on Control, Decision and Information Technologies (CoDIT)}, pages = {2643-2648}, keywords = {Navigation;Path planning;Splines (mathematics);Matrix converters;Information technology;B-spline-to-B{\'e}zier conversion;obstacle avoidance;way-points;path planner} } @Book { din91477-1, author = {Eichmann, Jens and Grobelny, Stefan and Lel, Alexander and Bruder, Ralf and Miller, Alexander and Henke, Maria and R{\{\dq}o}hrig, Christoph and Surmann, Hartmut}, title = {DIN SPEC 91477-1 Robotersysteme f{\{\dq}u}r den Einsatz in Schadenslagen -- Teil 1: Allgemeine Anforderungen}, abstract = {Dieses Dokument bietet den Anbietern von Robotersystemen und unterst{\{\dq}u}tzender Technologie, wie dem Einsatzleitwagen, eine Hilfestellung bei der Entwicklung von Systemen, die im Einsatzfall parallel und kooperierend mit anderen Systemen BOS-Einheiten unterst{\{\dq}u}tzen. Im Detail werden Anleitungen zu Kategorisierung eines Systems gegeben, wie teleoperiert, teil-autonom oder autonom agierende Systeme, und entsprechende Anforderungen werden je nach Kategorie festgelegt. Die zu erf{\{\dq}u}llenden Merkmale k{\{\dq}o}nnen z.B.im Bereich Kommunikation (Redundanz, St{\{\dq}o}rsicherheit, usw.), Bedienfunktionen und -schnittstellen oder in Sicherheitsaspekten (Tampering, Notfallsteuerung, usw.) liegen.}, year = {2023}, publisher = {Beuth Verlag} } @Book { din91477-2, author = {Eichmann, Jens and Bruder, Ralf and Miller, Alexander and Henke, Maria and Lel, Alexander and Grobelny, Stefan and R{\{\dq}o}hrig, Christoph and Daun, Kevin}, title = {DIN SPEC 91477-2 Robotersysteme f{\{\dq}u}r den Einsatz in Schadenslagen -- Teil 2: Anforderungen an Roboter in der Brandbek{\{\dq}a}mpfung}, abstract = {Ziel dieses Dokuments ist es, Rahmenbedingungen zu schaffen, die erfolgreiche und sichere Produkte f{\{\dq}u}r die robotergest{\{\dq}u}tzte L{\{\dq}o}schung sicherstellen, w{\{\dq}a}hrend gleichzeitig unterschiedlichste Ans{\{\dq}a}tze f{\{\dq}u}r L{\{\dq}o}schroboter unterst{\{\dq}u}tzt werden. Teleoperierte, teilautonome oder vollautonome Systeme m{\{\dq}u}ssen {\{\dq}a}hnliche Voraussetzungen erf{\{\dq}u}llen, je h{\{\dq}o}her der Grad der Autonomie in einem System ist, desto wichtiger werden z.B. die Anforderungen an die Navigation oder Sensorik im Brandszenario. Daher sollen diese speziellen Funktionen ebenfalls Rahmenbedingungen bekommen, die gew{\{\dq}a}hrleisten, dass die Ger{\{\dq}a}te zur Gefahrenabwehr bef{\{\dq}a}higt sind, einen Einsatz erfolgreich abarbeiten zu k{\{\dq}o}nnen. Interne Abl{\{\dq}a}ufe, Schnittstellen, Hard- oder Software sowie Sensorik und Kommunikation sollen nicht explizit vorgegeben werden, nur essentielle F{\{\dq}a}higkeiten und Anforderungen an die genannten Systeme sollen formuliert werden, damit Systeme in der Gefahrenabwehr eine vergleichbare Sicherheit erm{\{\dq}o}glichen.}, year = {2023}, publisher = {Beuth Verlag} } @Article { Kaestner2023, author = {Kaestner, Lena and Boda‐Heggemann, Judit and Fanslau, Hanna and Xie, Jingyang and Schweikard, Achim and Giordano, Frank A. and Blanck, Oliver and Rudic, Boris}, title = {Electroanatomical mapping after cardiac radioablation for treatment of incessant electrical storm: a case report within the RAVENTA trial}, year = {2023}, DOI = {10.1007/s00066-023-02136-z}, journal = {Strahlentherapie und Onkologie}, file_url = {https://doi.org/10.1007/s00066-023-02136-z} } @Inproceedings { Kriebisch2023b, author = {Kriebisch, Susann and Bruder, Ralf and Ernst, Floris}, title = {Generation of 3D models of victims within their surroundings at rescue sites}, year = {2023}, publisher = {De Gruyter} } @Inproceedings { Bockelmann2022b, author = {Bockelmann, Niclas and Schetelig, Daniel and Bonsanto, M. and Buschschl{\{\dq}u}ter, Steffen and Ernst, Floris}, title = {Intelligent ultrasonic-aspirator for CNS/ tumor tissue differentiation -- a feasibility study using machine learning}, year = {2022}, DOI = {10.3205/22dgnc188}, address = {K{\{\dq}o}ln}, file_url = {https://doi.org/10.3205/22dgnc188} } @Article { Xue2022a, author = {Xue, Honghu and Hein, Benedikt and Mohamed, Bakr and Schildbach, Georg and Abel, Bengt and Rueckert, Elmar}, title = {Using Deep Reinforcement Learning with Automatic Curriculum Learning for Mapless Navigation in Intralogistics}, abstract = {We propose a deep reinforcement learning approach for solving a mapless navigation problem in warehouse scenarios. In our approach, an automatic guided vehicle is equipped with two LiDAR sensors and one frontal RGB camera and learns to perform a targeted navigation task. The challenges reside in the sparseness of positive samples for learning, multi-modal sensor perception with partial observability, the demand for accurate steering maneuvers together with long training cycles. To address these points, we propose NavACL-Q as an automatic curriculum learning method in combination with a distributed version of the soft actor-critic algorithm. The performance of the learning algorithm is evaluated exhaustively in a different warehouse environment to validate both robustness and generalizability of the learned policy. Results in NVIDIA Isaac Sim demonstrates that our trained agent significantly outperforms the map-based navigation pipeline provided by NVIDIA Isaac Sim with an increased agent-goal distance of 3 m and a wider initial relative agent-goal rotation of approximately 45∘. The ablation studies also suggest that NavACL-Q greatly facilitates the whole learning process with a performance gain of roughly 40% compared to training with random starts and a pre-trained feature extractor manifestly boosts the performance by approximately 60%.}, year = {2022}, journal = {Applied Sciences special issue {\dq}Intelligent Robotics{\dq}}, volume = {12}, editor = {Bonciu, Yasmine}, pages = {3153}, number = {6}, keywords = {automatic curriculum learning; autonomous navigation; deep reinforcement learning; multi-modal sensor perception}, note = {doi: https://doi.org/10.3390/app12063153} } @Article { Osburg2022a, author = {Osburg, Jonas and Ivo, Kuhlemann and Hagenah, Jannis and Ernst, Floris}, title = {Using Deep Neural Networks to Improve Contact Wrench Estimation of Serial Robotic Manipulators in Static Tasks}, abstract = {Reliable force-driven robot-interaction requires precise contact wrench measurements. In most robot systems these measurements are severely incorrect and in most manipulation tasks expensive additional force sensors are installed. We follow a learning approach to train the dependencies between joint torques and end-effector contact wrenches. We used a redundant serial light-weight manipulator (KUKA iiwa 7 R800) with integrated force estimation based on the joint torques measured in each of the robot's seven axes. Firstly, a simulated dataset is created to let a feed-forward net learn the relationship between end-effector contact wrenches and joint torques for a static case. Secondly, an extensive real training dataset was acquired with 330,000 randomized robot positions and end-effector contact wrenches and used for retraining the simulated trained feed-forward net. We can show that the wrench prediction error could be reduced by around 57% for the forces compared to the manufacturer's proprietary force estimation model. In addition, we show that the number of high outliers can be reduced substantially. Furthermore we prove that the approach could be also transferred to another robot (KUKA iiwa 14 R820) with reasonable prediction accuracy and without the need of acquiring new robot specific data.}, year = {2022}, journal = {Frontiers in Robotics and AI}, volume = {9}, keywords = {artificial neural network; Deep Learning; force estimation; robotic manipulator; wrench estimation}, file_url = {https://www.frontiersin.org/articles/10.3389/frobt.2022.892916/full?{\\&}utm_source=Email_to_authors_{\\&}utm_medium=Email{\\&}utm_content=T1_11.5e1_author{\\&}utm_campaign=Email_publication{\\&}field={\\&}journalName=Frontiers_in_Robotics_and_AI{\\&}id=892916}, note = {doi: https://doi.org/10.3389/frobt.2022.892916} } @Article { hpmp_22, author = {Haxthausen, Felix and Pose-D{\'i}ez-de-la-Lastra, Alicia and Moreta-Martinez, Rafael and Pascau, Javier and Ernst, Floris}, title = {UltrARsound: In-situ visualisation of live ultrasound images using HoloLens 2}, year = {2022}, DOI = {10.1007/s11548-022-02695-z}, journal = {International Journal of Computer Assisted Radiology and Surgery}, tags = {UGRT}, file_url = {https://doi.org/10.1007/s11548-022-02695-z} } @Article { Ehrbar2022, author = {Ehrbar, Stefanie and Grehn, Melanie and Fleckenstein, Jens and Baus, Wolfgang W. and Siebert, Frank-Andre and Schweikard, Achim and Mayinger, Michael C. and Andratschke, N. and Boda-Heggemann, Judit and Buergy, Daniel and Celik, Eren and Krug, David and Saguner, Ardan M. and Rudic, Boris and Boldt, Leif‐Hendrik and Stauber, Annina and Zaman, Adrian and Bonnemeier, Hendrik and Dunst, J{\{\dq}u}rgen and Budach, Volker and Blanck, Oliver}, title = {Treatment Planning for Cardiac Radioablation: Multicenter Multiplatform Benchmarking for the XXX Trial (to appear)}, year = {2022}, journal = {International Journal of Radiation Oncology*Biology*Physics} } @Article { Bockelmann2022a, author = {Bockelmann, Niclas and Schetelig, Daniel and Kesslau, Denise and Buschschl{\{\dq}u}ter, Steffen and Ernst, Floris and Bonsanto, M.}, title = {Toward intraoperative tissue classification: exploiting signal feedback from an ultrasonic aspirator for brain tissue differentiation}, year = {2022}, DOI = {10.1007/s11548-022-02713-0}, journal = {International Journal of Computer Assisted Radiology and Surgery}, file_url = {https://doi.org/10.1007/s11548-022-02713-0} } @Article { NEZAMI2022103, author = {Nezami, Maryam and Abbas, Hossam Seddik and Nguyen, Ngoc Thinh and Schildbach, Georg}, title = {Robust tube-based LPV-MPC for autonomous lane keeping}, abstract = {This paper proposes a control architecture for autonomous lane keeping by a vehicle. In this paper, the vehicle dynamics consist of two parts: lateral and longitudinal dynamics. Therefore, the control architecture comprises two subsequent controllers. A longitudinal model predictive control (MPC) makes the vehicle track the desired longitudinal speeds that are assumed to be generated by a speed planner. The longitudinal speeds are then passed to a lateral MPC for lane keeping. Due to the dependence of the lateral dynamics on the longitudinal speed, they are represented in a linear parameter-varying (LPV) form, where its scheduling parameter is the longitudinal speed of the vehicle. In order to deal with the imprecise information of the future longitudinal speed (the scheduling parameter), a bound of uncertainty is considered around the nominal trajectory of the future longitudinal velocities. Then, a tube-based LPV-MPC is adopted to control the lateral dynamics for attaining the lane keeping goal. In the end, the effectiveness of the proposed methods is illustrated by carrying out simulation tests.}, year = {2022}, issn = {2405-8963}, DOI = {https://doi.org/10.1016/j.ifacol.2022.11.297}, journal = {IFAC-PapersOnLine}, volume = {55}, pages = {103-108}, number = {35}, keywords = {Automotive Dynamic, Uncertain Systems, LPVS, Predictive Control, Optimal Control, Robustness Issues}, file_url = {https://www.sciencedirect.com/science/article/pii/S2405896322029408}, note = {5th IFAC Workshop on Linear Parameter Varying Systems LPVS 2022} } @Inproceedings { Xue2022b, author = {Xue, Honghu and Song, Rui and Petzold, Julian and Hein, Benedikt and Hamann, Heiko and Rueckert, Elmar}, title = {End-To-End Deep Reinforcement Learning for First-Person Pedestrian Visual Navigation in Urban Environments}, abstract = {We solve a pedestrian visual navigation problem with a first-person view in an urban setting via deep reinforcement learning in an end-to-end manner. The major challenges lie in severe partial observability and sparse positive experiences of reaching the goal. To address partial observability, we propose a novel 3D-temporal convolutional network to encode sequential historical visual observations, its effectiveness is verified by comparing to a commonly-used Frame-Stacking approach. For sparse positive samples, we propose an improved automatic curriculum learning algorithm NavACL , which proposes meaningful curricula starting from easy tasks and gradually generalizing to challenging ones. NavACL is shown to facilitate the learning process with 21% earlier convergence, to improve the task success rate on difficult tasks by 40% compared to the original NavACL algorithm and to offer enhanced generalization to different initial poses compared to training from a fixed initial pose.}, year = {2022}, publisher = {The 2022 IEEE-RAS International Conference on Humanoid Robots}, keywords = {automatic curriculum learning; deep reinforcement learning; Visual Navigation} } @Article { Çallar2022, author = {Çallar, Tolga-Can and B{\{\dq}o}ttger, Sven}, title = {Hybrid Learning of Time-Series Inverse Dynamics Models for Locally Isotropic Robot Motion}, abstract = {Applications of force control and motion planning often rely on an inverse dynamics model to represent the high- dimensional dynamic behavior of robots during motion. The widespread occurrence of low-velocity, small-scale, locally isotropic motion (LIMO) typically complicates the identification of appropriate models due to the exaggeration of dynamic effects and sensory perturbation caused by complex friction and phenomena of hysteresis, e.g., pertaining to joint elasticity. We propose a hybrid model learning base architectures combining a rigid body dynamics model identified by parametric regression and time-series neural network architectures based on multilayer-perceptron, LSTM, and Transformer topologies. Further, we introduce a novel joint-wise rotational history encoding, reinforcing temporal information to effectively model dynamic hysteresis. The models are evaluated on a KUKA iiwa 14 during algorithmically generated locally isotropic movements. Together with the rotational encoding, the proposed architectures outperform state-of-the-art baselines by a magnitude of 10^3 yielding an RMSE of 0.14 Nm. Leveraging the hybrid structure and time-series encoding capabilities, our approach allows for accurate torque estimation, indicating its applicability in critically force-sensitive applications during motion sequences exceeding the capacity of conventional inverse dynamics models while retaining trainability in face of scarce data and explainability due to the employed physics model prior.}, year = {2022}, DOI = {10.1109/LRA.2022.3222951}, journal = {IEEE Robotics and Automation Letters}, editor = {Asfour, Tamim and Gosselin, Cl{\'e}ment}, keywords = {Deep Learning Methods; Dynamics; Force and Tactile Sensing; force control; Model Learning for Control}, file_url = {https://doi.org/10.1109/LRA.2022.3222951} } @Inproceedings { Osburg2022b, author = {Osburg, Jonas and Wulff, Daniel and Ernst, Floris}, title = {Generalized Automatic Probe Alignment based on 3D Ultrasound}, year = {2022}, DOI = {10.1515/cdbme-2022-0015}, volume = {8}, pages = {58-61}, number = {1}, file_url = {https://doi.org/10.1515/cdbme-2022-0015} } @Article { Kluge2022, author = {Kluge, Anne K. and Ehrbar, Stefanie and Grehn, Melanie and Fleckenstein, Jens and Baus, Wolfgang W. and Siebert, Frank-Andre and Schweikard, Achim and Andratschke, Nicolaus and Mayinger, Michael C. and Boda‐Heggemann, Judit and Buergy, Daniel and Celik, Eren and Krug, David and Kovacs, Boldizsar and Saguner, Ardan M. and Rudic, Boris and Bergengruen, Paula and Boldt, Leif‐Hendrik and Stauber, Annina and Zaman, Adrian and Bonnemeier, Hendrik and Dunst, J{\{\dq}u}rgen and Budach, Volker and Blanck, Oliver and Mehrhof, Felix}, title = {CLINICAL INVESTIGATION Treatment Planning for Cardiac Radioablation: Multicenter Multiplatform Benchmarking for the RAdiosurgery for VENtricular TAchycardia (RAVENTA) Trial}, year = {2022}, journal = {International Journal of Radiation Oncology Biology Physics} } @Article { Herzog2022, author = {Herzog, Rebecca and M Berger, Till and Pauly, Martje Gesine and Xue, Honghu and Rueckert, Elmar and M{\{\dq}u}nchau, Alexander and B{\{\dq}a}umer, Tobias and Weissbach, Anne}, title = {Cerebellar transcranial current stimulation-an intraindividual comparison of different techniques}, abstract = {Transcranial current stimulation (tCS) techniques have been shown to induce cortical plasticity. As an important relay in the motor system, the cerebellum is an interesting target for plasticity induction using tCS, aiming to modulate its excitability and connectivity. However, until now it remains unclear, which is the most effective tCS method for inducing plasticity in the cerebellum. Thus, in this study, the effects of anodal transcranial direct current stimulation (tDCS), 50 Hz transcranial alternating current stimulation (50 Hz tACS), and high frequency transcranial random noise stimulation (tRNS) were compared with sham stimulation in 20 healthy subjects in a within-subject design. tCS was applied targeting the cerebellar lobe VIIIA using neuronavigation. We measured corticospinal excitability, short-interval intracortical inhibition (SICI), short-latency afferent inhibition (SAI), and cerebellar brain inhibition (CBI) and performed a sensor-based movement analysis at baseline and three times after the intervention (post1 = 15 min; post2 = 55 min; post3 = 95 min). Corticospinal excitability increased following cerebellar tACS and tRNS compared to sham stimulation. This effect was most pronounced directly after stimulation but lasted for at least 55 min after tACS. Cortico-cortical and cerebello-cortical conditioning protocols, as well as sensor-based movement analyses, did not change. Our findings suggest that cerebellar 50 Hz tACS is the most effective protocol to change corticospinal excitability.}, year = {2022}, journal = {Frontiers Neuroscience}, file_url = {https://www.frontiersin.org/articles/10.3389/fnins.2022.987472/full?{\\&}utm_source=Email_to_authors_{\\&}utm_medium=Email{\\&}utm_content=T1_11.5e1_author{\\&}utm_campaign=Email_publication{\\&}field={\\&}journalName=Frontiers_in_Neuroscience{\\&}id=987472}, note = {doi: https://doi.org/10.3389/fnins.2022.987472} } @Article { hse_22, author = {Hagenah, Jannis and Scharfschwerdt, Michael and Ernst, Floris}, title = {Aortic Valve Leaflet Shape Synthesis With Geometric Prior From Surrounding Tissue}, abstract = {Even though the field of medical imaging advances, there are structures in the human body that are barely assessible with classical image acquisition modalities. One example are the three leaflets of the aortic valve due to their thin structure and high movement. However, with an increasing accuracy of biomechanical simulation, for example of the heart function, and extense computing capabilities available, concise knowledge of the individual morphology of these structures could have a high impact on personalized therapy and intervention planning as well as on clinical research. Thus, there is a high demand to estimate the individual shape of inassessible structures given only information on the geometry of the surrounding tissue. This leads to a domain adaptation problem, where the domain gap could be very large while typically only small datasets are available. Hence, classical approaches for domain adaptation are not capable of providing sufficient predictions. In this work, we present a new framework for bridging this domain gap in the scope of estimating anatomical shapes based on the surrounding tissue's morphology. Thus, we propose deep representation learning to not map from one image to another but to predict a latent shape representation. We formalize this framework and present two different approaches to solve the given problem. Furthermore, we perform a proof-of-concept study for estimating the individual shape of the aortic valve leaflets based on a volumetric ultrasound image of the aortic root. Therefore, we collect an ex-vivo porcine data set consisting of both, ultrasound volume images as well as highresolution leaflet images, evaluate both approaches on it and perform an analysis of the model's hyperparameters. Our results show that using deep representation learning and domain mapping between the identified latent spaces, a robust prediction of the unknown leaflet shape only based on surrounding tissue information is possible, even in limited data scenarios. The concept can be applied to a wide range of modeling tasks, not only in the scope of heart modeling but also for all kinds of inassessible structures within the human body.}, year = {2022}, DOI = {10.3389/fcvm.2022.772222}, journal = {Frontiers in Cardiovascular Medicine}, volume = {9}, pages = {772222}, file_url = {https://doi.org/10.3389/fcvm.2022.772222} } @Inproceedings { 9867578, author = {Nezami, Maryam and Nguyen, Ngoc Thinh and M{\{\dq}a}nnel, Georg and Abbas, Hossam Seddik and Schildbach, Georg}, title = {A Safe Control Architecture Based on Robust Model Predictive Control for Autonomous Driving}, year = {2022}, DOI = {10.23919/ACC53348.2022.9867578}, booktitle = {2022 American Control Conference (ACC)}, pages = {914-919}, keywords = {Roads;Computer architecture;Control systems;Safety;Electron tubes;Collision avoidance;Autonomous vehicles} } @Article { s22134915, author = {Pose-D{\'i}ez-de-la-Lastra, Alicia and Moreta-Martinez, Rafael and Garc{\'i}a-Sevilla, M{\'o}nica and Garc{\'i}a-Mato, David and Calvo-Haro, Jos{\'e} Antonio and Mediavilla-Santos, Lydia and P{\'e}rez-Ma{\~n}anes, Rub{\'e}n and Haxthausen, Felix and Pascau, Javier}, title = {HoloLens 1 vs. HoloLens 2: Improvements in the New Model for Orthopedic Oncological Interventions}, abstract = {This work analyzed the use of Microsoft HoloLens 2 in orthopedic oncological surgeries and compares it to its predecessor (Microsoft HoloLens 1). Specifically, we developed two equivalent applications, one for each device, and evaluated the augmented reality (AR) projection accuracy in an experimental scenario using phantoms based on two patients. We achieved automatic registration between virtual and real worlds using patient-specific surgical guides on each phantom. They contained a small adaptor for a 3D-printed AR marker, the characteristic patterns of which were easily recognized using both Microsoft HoloLens devices. The newest model improved the AR projection accuracy by almost 25%, and both of them yielded an RMSE below 3 mm. After ascertaining the enhancement of the second model in this aspect, we went a step further with Microsoft HoloLens 2 and tested it during the surgical intervention of one of the patients. During this experience, we collected the surgeonsrsquo; feedback in terms of comfortability, usability, and ergonomics. Our goal was to estimate whether the improved technical features of the newest model facilitate its implementation in actual surgical scenarios. All of the results point to Microsoft HoloLens 2 being better in all the aspects affecting surgical interventions and support its use in future experiences.}, year = {2022}, issn = {1424-8220}, DOI = {10.3390/s22134915}, journal = {Sensors}, volume = {22}, number = {13}, file_url = {https://doi.org/10.3390/s22134915}, note = {article-number=4915} } @Article { hce_21, author = {Haxthausen, Felix and Chen, Yenjung and Ernst, Floris}, title = {Superimposing holograms on real world objects using HoloLens 2 and its depth camera}, year = {2021}, DOI = {10.1515/cdbme-2021-1024}, journal = {Current Directions in Biomedical Engineering}, volume = {7}, publisher = {De Gruyter}, pages = {111-115}, number = {1}, file_url = {https://doi.org/10.1515/cdbme-2021-1024} } @Article { EstradaLugo2021b, author = {Estrada Lugo, Ana and Bockelmann, Niclas and Haxthausen, Felix}, title = {Sequential U-Net Architecture for Automatic Femoral Artery Segmentation in Ultrasound Images}, year = {2021}, DOI = {10.1515/cdbme-2021-1034}, journal = {Current Directions in Biomedical Engineering}, volume = {7}, pages = {158-161}, number = {1}, file_url = {https://doi.org/10.1515/cdbme-2021-1034} } @Article { Tanneberg2021, author = {Tanneberg, Daniel and Ploeger, Kai and Rueckert, Elmar and Peters, Jan}, title = {SKID RAW: Skill Discovery from Raw Trajectories}, year = {2021}, journal = {IEEE Robotics and Automation Letters (RA-L)}, pages = {1-8}, keywords = {Manipulation; movement primitives; Probabilistic Inference}, file_url = {https://ai-lab.science/wp/RAL2021Tanneberg.pdf, Article File}, note = {tppubtype=article} } @Article { 9011746, author = {Nguyen, Ngoc Thinh and Prodan, Ionela and Lef{\'e}vre, Laurent}, title = {Stability Guarantees for Translational Thrust-Propelled Vehicles Dynamics Through NMPC Designs}, year = {2021}, DOI = {10.1109/tcst.2020.2974146}, journal = {IEEE Transactions on Control Systems Technology}, volume = {29}, pages = {207-219}, number = {1}, file_url = {https://doi.org/10.1109/tcst.2020.2974146} } @Article { NGUYEN2021126, author = {Nguyen, Ngoc Thinh and Prodan, Ionela}, title = {Stabilizing a multicopter using an NMPC design with a relaxed terminal region}, abstract = {This paper highlights the benefits of a feedback linearization local controller and the associated terminal bound constraints (box-type inequalities) in an NMPC (Nonlinear Model Predictive Control) design for a multicopter system. We replace the standard invariant construction for the terminal region of the NMPC design with two sets: i) a $\delta$-invariant set (with $\delta$ the sampling time) which constrains the trajectories to re-enter it periodically, at pre-defined moments of time; ii) a constraint admissible safe set in which the trajectories lie in the remaining time instants. We show that this alternative construction verifies the recursive feasibility and asymptotic stability. Moreover, the additional degrees of freedom and simpler construction show advantages over similar NMPC designs with standard ellipsoidal terminal region.}, year = {2021}, issn = {2405-8963}, journal = {IFAC-PapersOnLine}, volume = {54}, pages = {126-132}, number = {6}, keywords = {feedback linearization; Multicopter; NMPC; terminal constraint; $\delta$-invariant set}, file_url = {https://www.sciencedirect.com/science/article/pii/S2405896321013094}, note = {doi: https://doi.org/10.1016/j.ifacol.2021.08.534} } @Article { Xie2021, author = {Xie, Jingyang and Liu, Xidong and Tang, Jianhua and Li, Xi and Li, Wei}, title = {Study on friction behavior at the interface between prosthetic socket and liner}, year = {2021}, journal = {Acta of Bioengineering and Biomechanics}, volume = {23}, pages = {83-93}, number = {1}, note = {doi: 10.37190/ABB-01751-2020-04} } @Article { wcac_21, author = {Wilhelm, Maria-Lisa and Chan, Mark K. H. and Abel, Benedikt and Cremers, Florian and Siebert, Frank-Andre and Wurster, Stefan and Krug, David and Wolff, Robert and Dunst, J{\{\dq}u}rgen and Hildebrandt, Guido and Schweikard, Achim and Rades, Dirk and Ernst, Floris and Blanck, Oliver}, title = {Tumor-dose-rate variations during robotic radiosurgery of oligo and multiple brain metastases}, year = {2021}, DOI = {10.1007/s00066-020-01652-6}, journal = {Springer}, volume = {197}, pages = {581-591}, file_url = {https://doi.org/10.1007/s00066-020-01652-6} } @Inproceedings { 9607209, author = {Nguyen, Ngoc Thinh and Schildbach, Georg}, title = {Tightening polytopic constraint in MPC designs for mobile robot navigation}, year = {2021}, DOI = {10.1109/icstcc52150.2021.9607209}, pages = {407-412}, file_url = {https://doi.org/10.1109/icstcc52150.2021.9607209} } @Article { iwks_21, author = {Ipsen, Svenja and Wulff, Daniel and Kuhlemann, Ivo and Schweikard, Achim and Ernst, Floris}, title = {Towards automated ultrasound imaging -- robotic image acquisition in liver and prostate for long-term motion monitoring}, year = {2021}, DOI = {10.1088/1361-6560/abf277}, journal = {Physics in Medicine Biology}, volume = {66}, pages = {094002}, number = {9}, file_url = {https://doi.org/10.1088/1361-6560/abf277} } @Inproceedings { Bockelmann2021, author = {Bockelmann, Niclas and Kesslau, Denise and Bonsanto, M. and Buschschl{\{\dq}u}ter, Steffen and Ernst, Floris}, title = {Towards machine learning-based tissue differentiation using an ultrasonic aspirator: computer assisted radiology and surgery proceedings of the 35th international Congress and exhibition Munich, Germany, June 21--25, 2021}, year = {2021}, DOI = {10.1007/s11548-021-02375-4}, pages = {107-108}, file_url = {https://doi.org/10.1007/s11548-021-02375-4} } @Inproceedings { Barua2021, author = {Barua, Timir and Haxthausen, Felix and Garc{\'i}a-V{\'a}zquez, Ver{\'o}nica}, title = {Ultrasound Medical Imaging: Comparison of Methods for Adjusting Speed of Sound of Human Tissue in Water}, year = {2021}, isbn = {9783945954652}, publisher = {Infinite Science Publishing GmbH} } @Article { Xue2021, author = {Xue, Honghu and Herzog, Rebecca and M Berger, Till and B{\{\dq}a}umer, Tobias and Weissbach, Anne and Rueckert, Elmar}, title = {Using Probabilistic Movement Primitives in analyzing human motion differences under Transcranial Current Stimulation}, abstract = {In medical tasks such as human motion analysis, computer-aided auxiliary systems have become preferred choice for human experts for its high efficiency. However, conventional approaches are typically based on user-defined features such as movement onset times, peak velocities, motion vectors or frequency domain analyses. Such approaches entail careful data post-processing or specific domain knowledge to achieve a meaningful feature extraction. Besides, they are prone to noise and the manual-defined features could hardly be re-used for other analyses. In this paper, we proposed probabilistic movement primitives(ProMPs), a widely-used approach in robot skill learning, to model human motions. The benefit of ProMPs is that the features are directly learned from the data and ProMPs can capture important features describing the trajectory shape, which can easily be extended to other tasks. Distinct from previous research, where classification tasks are mostly investigated, we applied ProMPs together with a variant of Kullback-Leibler (KL)divergence to quantify the effect of different transcranial current stimulation methods on human motions. We presented an initial result with 10 participants. The results validate ProMPs as a robust and effective feature extractor for human motions.}, year = {2021}, journal = {Frontiers Robot. AI - Humanoid Robotics}, keywords = {Finger-tapping Motion; Human Motion Analysis; machine learning; Probabilistic Movement Primitives; Transcranial Current Stimulation}, note = {doi: https://doi.org/10.3389/frobt.2021.721890} } @Inbook { ies_21, author = {Ipsen, Svenja and Ernst, Floris and Schlaefer, Alexander}, title = {Modern Applications of 3D/4D Ultrasound Imaging in Radiotherapy}, year = {2021}, DOI = {10.1088/978-0-7503-2552-3ch9}, publisher = {IOP Publishing}, editor = {Harris, Emma and Fontanarosa, Davide}, pages = {9.1-9.27}, file_url = {https://doi.org/10.1088/978-0-7503-2552-3ch9} } @Article { Jamsek2021, author = {Jamsek, Marko and Kunavar, Tjasa and Bobek, Urban and Rueckert, Elmar and Babic, Jan}, title = {Predictive exoskeleton control for arm-motion augmentation based on probabilistic movement primitives combined with a flow controller}, year = {2021}, journal = {IEEE Robotics and Automation Letters (RA-L)}, pages = {1-8}, keywords = {human motor control; movement primitives}, file_url = {https://ai-lab.science/wp/RAL2021Jamsek.pdf, Article File}, note = {tppubtype=article} } @Inproceedings { wmeh_21, author = {Wulff, Daniel and Mehdi, Mohamad and Ernst, Floris and Hagenah, Jannis}, title = {Cross Data Set Generalization of Ultrasound Image Augmentation using Representation Learning: A Case Study}, year = {2021}, DOI = {10.1515/cdbme-2021-2193}, volume = {7}, pages = {755-758}, number = {2}, file_url = {https://doi.org/10.1515/cdbme-2021-2193} } @Misc { Hofmann2021b, author = {Hofmann, Klaus and B{\{\dq}o}ke, Joachim and Jauer, Philipp and Derksen, Alexander and Bruder, Ralf}, title = {Method of Configuring a Fire Locator Device and Method of Operating a Fire Fighting System}, year = {2021} } @Misc { Hofmann2021a, author = {Hofmann, Klaus and B{\{\dq}o}ke, Joachim and Derksen, Alexander and Jauer, Philipp and Bruder, Ralf}, title = {Fire Locator Device, Fire Fighting System and Corresponding Operating Method}, year = {2021} } @Article { vonHaxthausen2021, author = {Haxthausen, Felix and B{\{\dq}o}ttger, Sven and Wulff, Daniel and Hagenah, Jannis and Garc{\'i}a-V{\'a}zquez, Ver{\'o}nica and Ipsen, Svenja}, title = {Medical Robotics for Ultrasound Imaging: Current Systems and Future Trends}, year = {2021}, journal = {Current Robotics Reports}, volume = {2}, pages = {55-71}, note = {doi: https://doi.org/10.1007/s43154-020-00037-y} } @Inproceedings { EstradaLugo2021a, author = {Estrada Lugo, Ana and Haxthausen, Felix and Bockelmann, Niclas and Ernst, Floris}, title = {Automatic Segmentation of the Femoral Artery from 2D Ultrasound Images}, year = {2021}, isbn = {9783945954652}, publisher = {Infinite Science Publishing GmbH} } @Inproceedings { 9636612, author = {Nguyen, Ngoc Thinh and Schilling, Lars and Angern, Michael Sebastian and Hamann, Heiko and Ernst, Floris and Schildbach, Georg}, title = {B-spline path planner for safe navigation of mobile robots}, year = {2021}, DOI = {10.1109/IROS51168.2021.9636612}, booktitle = {2021 IEEE/RSJ International Conference on Intelligent Robots and Systems (IROS)}, pages = {339-345}, keywords = {Navigation;Lasers;Path planning;Data models;Mobile robots;Splines (mathematics);Optimization;Path planner;B-spline;B{\'e}zier;Convexity} } @Inproceedings { whe_21, author = {Wulff, Daniel and Hagenah, Jannis and Ernst, Floris}, title = {Comparison of Representation Learning Techniques for Tracking in time resolved 3D Ultrasound}, year = {2021}, file_url = {https://arxiv.org/abs/2201.03319}, note = {doi: 10.48550/arXiv.2201.03319} } @Inproceedings { he_21, author = {Hagenah, Jannis and Ernst, Floris}, title = {Discrete Pseudohealthy Synthesis: Aortic Root Shape Typification and Type Classification with Pathological Prior}, year = {2021}, volume = {143}, series = {Proceedings of Machine Learning Research}, pages = {252-267} } @Inbook { jgem_21, author = {J{\{\dq}a}ckle, Sonja and Garc{\'i}a-V{\'a}zquez, Ver{\'o}nica and Eixmann, Tim and Matysiak, Florian and Haxthausen, Felix and Sieren, Malte and Schulz-Hildebrandt, Hinnerk and H{\{\dq}u}ttmann, Gereon and Ernst, Floris and Kleemann, Markus and {others}}, title = {3D Guidance Including Shape Sensing of a Stentgraft System}, year = {2021}, publisher = {Springer Vieweg, Wiesbaden}, pages = {34-34} } @Article { Lin2021, author = {Lin, Chengxiong and Liu, Wei and Xie, Jingyang and Li, Wei}, title = {Hardness properties of pig esophagus at nanoscale using atomic force microscopy}, year = {2021}, journal = {Journal of Medical Biomechanics}, volume = {36}, pages = {68-72}, number = {1} } @Article { Cansev2021, author = {Cansev, Mehmet and Xue, Honghu and Rottmann, Nils and Bliek, Adna and Miller, Luke E. and Rueckert, Elmar and Beckerle, Philipp}, title = {Interactive Human-Robot Skill Transfer: A Review of Learning Methods and User Experience}, year = {2021}, DOI = {10.1002/aisy.202000247}, journal = {Advanced Intelligent Systems}, file_url = {https://doi.org/10.1002/aisy.202000247} } @Article { bbme_21, author = {Boda-Heggemann, Judit and Blanck, Oliver and Mehrhof, Felix and Ernst, Floris and Buergy, Daniel and Fleckenstein, Jens and T{\{\dq}u}l{\{\dq}u}men, Erol and Krug, David and Siebert, Frank-Andre and Zaman, Adrian and Kluge, Anne K. and Parwani, Abdul Shokor and Andratschke, Nicolaus and Mayinger, Michael C. and Ehrbar, Stefanie and Saguner, Ardan M. and Celik, Eren and Baus, Wolfgang W. and Stauber, Annina and Vogel, Lena and Schweikard, Achim and Budach, Volker and Dunst, J{\{\dq}u}rgen and Boldt, Leif‐Hendrik and Bonnemeier, Hendrik and Rudic, Boris}, title = {Interdisciplinary clinical target volume generation for cardiac radioablation: Multi-center benchmarking for the RAdiosurgery for VENtricular TAchycardia (RAVENTA) trial}, year = {2021}, DOI = {10.1016/j.ijrobp.2021.01.028}, journal = {International Journal of Radiation Oncology Biology Physics}, volume = {110}, pages = {745-756}, number = {3}, file_url = {https://doi.org/10.1016/j.ijrobp.2021.01.028} } @Inproceedings { Henke2021BMT, author = {Henke, Maria}, title = {Is there a loss in quality between a whole-day face-to-face instructor-led seminar with group work and an instructor-led distance-learning alterna-tive? 55th Annual Conference}, year = {2021}, DOI = {10.1515/bmt-2021-6038}, booktitle = {Deutsche Gesellschaft f{\{\dq}u}r Biomedizinische Technik: 55th Annual Conference}, address = {Hannover}, pages = {262} } @Article { dplb_21, author = {Dimitri, Paul and Pignataro, Valeria and Lupo, Mariangela and Bonifazi, Donato and Henke, Maria and Musazzi, Umberto M. and Ernst, Floris and Minghetti, Paola and Redaelli, Davide F. and Antimisiaris, Sophia G. and Migliaccio, Giovanni and Bonifazi, Fedele and Marciani, Luca and Courtenay, Aaron J. and Denora, Nunzio and Lopedota, Angela}, title = {Medical Device Development for Children and Young People: Reviewing the Challenges and Opportunities}, abstract = {Development of specific medical devices (MDs) is required to meet the healthcare needs of children and young people (CYP). In this context, MD development should address changes in growth and psychosocial maturation, physiology, and pathophysiology, and avoid inappropriate repurposing of adult technologies. Underpinning the development of MD for CYP is the need to ensure MD safety and effectiveness through pediatric MD-specific regulations. Contrary to current perceptions of limited market potential, the global pediatric healthcare market is expected to generate around USD 15,984 million by 2025. There are 1.8 billion young people in the world today; 40% of the global population is under 24, creating significant future healthcare market opportunities. This review highlights a number of technology areas that have led to successful pediatric MD, including 3D printing, advanced materials, drug delivery, and diagnostic imaging. To ensure the targeted development of MD for CYP, collaboration across multiple professional disciplines is required, facilitated by a platform to foster collaboration and drive innovation. The European Pediatric Translational Research Infrastructure (EPTRI) will be established as the European platform to support collaboration, including the life sciences industrial sector, to identify unmet needs in child health and support the development, adoption, and commercialization of pediatric MDs.}, year = {2021}, issn = {1999-4923}, DOI = {10.3390/pharmaceutics13122178}, journal = {Pharmaceutics}, volume = {13}, pages = {2178}, number = {12}, file_url = {https://doi.org/10.3390/pharmaceutics13122178}, note = {pubmedid=34959459} } @Article { jlge_21, author = {J{\{\dq}a}ckle, Sonja and Lange, Annkristin and Garc{\'i}a-V{\'a}zquez, Ver{\'o}nica and Eixmann, Tim and Matysiak, Florian and Sieren, Malte Maria and Horn, Marco and Schulz-Hildebrandt, Hinnerk and H{\{\dq}u}ttmann, Gereon and Ernst, Floris and {others}}, title = {Instrument localisation for endovascular aneurysm repair: Comparison of two methods based on tracking systems or using imaging}, year = {2021}, DOI = {10.1002/rcs.2327}, journal = {The International Journal of Medical Robotics and Computer Assisted Surgery}, volume = {17}, pages = {e2327}, number = {6}, file_url = {https://doi.org/10.1002/rcs.2327} } @Inproceedings { vonHaxthausen2020c, author = {Haxthausen, Felix and Hagenah, Jannis and Kaschwich, Mark and Kleemann, Markus and Garc{\'i}a-V{\'a}zquez, Ver{\'o}nica and Ernst, Floris}, title = {Robotized ultrasound imaging of the peripheral arteries -- a phantom study}, year = {2020}, volume = {6}, publisher = {De Gruyter}, pages = {20200033}, number = {1}, tags = {UGRT}, note = {doi: https://doi.org/10.1515/cdbme-2020-0033} } @Article { NGUYEN20206101, author = {Nguyen, Ngoc Thinh and Prodan, Ionela and Lef{\'e}vre, Laurent}, title = {Multicopter Attitude Control through NMPC Design with Guaranteed Stability}, abstract = {This paper presents an original NMPC (Nonlinear Model Predictive Control) design with guaranteed stability for the attitude set-point angle tracking of multicopters. The design is an extension of our previous work on stabilizing the NMPC scheme for {\dq}computed-torque like{\dq} systems by using terminal invariant set constructed under the CTC (Computed-Torque Control) controller. The novelty resides in the complexity reduction for the design process which is done by reducing the dependence of the required elements (e.g., the terminal region's radius, the Lipschitz constant) on the desired angle set-points which change fast and are not known in advance. The contributions are validated in simulation over a quadcopter model.}, year = {2020}, issn = {2405-8963}, journal = {IFAC-PapersOnLine}, volume = {53}, pages = {6101-6106}, number = {2}, keywords = {Attitude control; CTC (Computed-Torque Control); Multicopter; NMPC (Nonlinear Model Predictive Control); set-point tracking}, file_url = {https://www.sciencedirect.com/science/article/pii/S2405896320322886}, note = {doi: https://doi.org/10.1016/j.ifacol.2020.12.1685} } @Article { Rottmann2020c, author = {Rottmann, Nils and Bruder, Ralf and Xue, Honghu and Schweikard, Achim and Rueckert, Elmar}, title = {Parameter Optimization for Loop Closure Detection in Closed Environments}, abstract = {Tuning parameters is crucial for the performance of localization and mapping algorithms. In general, the tuning of the parameters requires expert knowledge and is sensitive to information about the structure of the environment. In order to design truly autonomous systems the robot has to learn the parameters automatically. Therefore, we propose a parameter optimization approach for loop closure detection in closed environments which requires neither any prior information, e.g. robot model parameters, nor expert knowledge. It relies on several path traversals along the boundary line of the closed environment. We demonstrate the performance of our method in challenging real world scenarios with limited sensing capabilities. These scenarios are exemplary for a wide range of practical applications including lawn mowers and household robots.}, year = {2020}, journal = {Workshop Paper at the International Conference on Intelligent Robots and Systems (IROS)}, pages = {8}, file_url = {https://ai-lab.science/wp/IROSWS2020Rottmann.pdf} } @Article { Blanck2020, author = {Blanck, Oliver and Buergy, Daniel and Vens, Maren and Eidinger, Lina and Zaman, Adrian and Krug, David and Rudic, Boris and Boda‐Heggemann, Judit and Giordano, Frank A. and Boldt, Leif‐Hendrik and Mehrhof, Felix and Budach, Volker and Schweikard, Achim and Olbrich, Denise and K{\{\dq}o}nig, Inke R. and Siebert, Frank-Andre and Vonthein, R. and Dunst, J{\{\dq}u}rgen and Bonnemeier, Hendrik}, title = {Radiosurgery for ventricular tachycardia: preclinical and clinical evidence and study design for a German multi‐center multi‐platform feasibility trial (RAVENTA)}, year = {2020}, journal = {Clinical Research in Cardiology}, note = {doi: https://doi.org/10.1007/s00392-020-01650-9} } @Article { Cartoni2020, author = {Cartoni, Emilio and Mannella, Franscesco and Santucci, Vieri Giuliano and Triesch, Jochen and Rueckert, Elmar and Baldassarre, Gianluca}, title = {REAL-2019: Robot open-Ended Autonomous Learning competition}, year = {2020}, journal = {Proceedings of Machine Learning Research}, pages = {142-152}, file_url = {https://ai-lab.science/wp/PMLR2020Cartoni.pdf} } @Techreport { Khiosapjaroen2020, author = {Khiosapjaroen, Wimonsiri}, title = {Rendering of ultrasound volumes on augmented reality glasses}, year = {2020}, series = {L{\{\dq}u}beck University of Applied Sciences and Universit{\{\dq}a}t zu L{\{\dq}u}beck}, tags = {UGRT} } @Article { Jäckle2020a, author = {J{\{\dq}a}ckle, Sonja and Garc{\'i}a-V{\'a}zquez, Ver{\'o}nica and Eixmann, Tim and Matysiak, Florian and Haxthausen, Felix and Sieren, Malte Maria and Schulz-Hildebrandt, Hinnerk and H{\{\dq}u}ttmann, Gereon and Ernst, Floris and Kleemann, Markus and P{\{\dq}a}tz, Torben}, title = {Three-dimensional guidance including shape sensing of a stentgraft system for endovascular aneurysm repair}, year = {2020}, journal = {International Journal of Computer Assisted Radiology and Surgery}, volume = {15}, pages = {1033-1042}, note = {Oral presentation at {\dq}34th International Congress and Exhibition of Computer Assisted Radiology and Surgery{\dq}, Munich (Germany)} } @Inproceedings { Xue2020, author = {Xue, Honghu and B{\{\dq}o}ttger, Sven and Rottmann, Nils and Pandya, Harit and Bruder, Ralf and Neumann, Gerdhard and Rueckert, Elmar}, title = {Sample-Efficient Covariance Matrix Adaptation Evolutional Strategy via Simulated Rollouts in Neural Networks}, abstract = {Gradient-free reinforcement learning algorithms often fail to scale to high dimensions and require a large number of rollouts. In this paper, we propose learning a predictor model that allows simulated rollouts in a rank-based black-box optimizer Covariance Matrix Adaptation Evolutional Strategy (CMA-ES) to achieve higher sample-efficiency. We validated the performance of our new approach on different benchmark functions where our algorithm shows a faster convergence compared to the standard CMA-ES. As a next step, we will evaluate our new algorithm in a robot cup flipping task.}, year = {2020}, publisher = {Proceedings of International Conference on Advances in Signal Processing and Artificial Intelligence (ASPAI)}, address = {Berlin, Germany}, file_url = {https://cps.unileoben.ac.at/wp/ASPAI2020Xue.pdf}, note = {doi: https://cps.unileoben.ac.at/wp/ASPAI2020Xue.pdf} } @Article { Ipsen2020, author = {Ipsen, Svenja and B{\{\dq}o}ttger, Sven and Schwegmann, Holger and Ernst, Floris}, title = {Target tracking accuracy and latency with different 4D ultrasound systems -- a robotic phantom study}, abstract = {Ultrasound (US) imaging, in contrast to other image guidance techniques, offers the distinct advantage of providing volumetric image data in real-time (4D) without using ionizing radiation. The goal of this study was to perform the first quantitative comparison of three different 4D US systems with fast matrix array probes and real-time data streaming regarding their target tracking accuracy and system latency. Sinusoidal motion of varying amplitudes and frequencies was used to simulate breathing motion with a robotic arm and a static US phantom. US volumes and robot positions were acquired online and stored for retrospective analysis. A template matching approach was used for target localization in the US data. Target motion measured in US was compared to the reference trajectory performed by the robot to determine localization accuracy and system latency. Using the robotic setup, all investigated 4D US systems could detect a moving target with sub-millimeter accuracy. However, especially high system latency increased tracking errors substantially and should be compensated with prediction algorithms for respiratory motion compensation.}, year = {2020}, journal = {Current Directions in Biomedical Engineering}, volume = {6}, number = {1}, keywords = {Image guidance; motion compensation; Radiation therapy; real-time imaging}, tags = {UGRT}, file_url = {https://www.degruyter.com/view/journals/cdbme/6/1/article-20200038.xml?rskey=iFKwiD{\\&}result=2}, note = {doi: https://doi.org/10.1515/cdbme-2020-0038} } @Article { Lin2020a, author = {Lin, Chengxiong and Liu, Wei and Xie, Jingyang and Li, Wei and Zhou, Zhongrong}, title = {The Lubricating Function of Mucin at the Gastroscope Device-Esophagus Interface}, year = {2020}, DOI = {10.1007/s11249-020-01322-9}, journal = {Tribology Letters}, volume = {68}, pages = {1-10}, number = {3}, file_url = {https://doi.org/10.1007/s11249-020-01322-9} } @Inproceedings { ibse20, author = {Ipsen, Svenja and B{\{\dq}o}ttger, Sven and Schwegmann, Holger and Ernst, Floris}, title = {Tracking Performance of 4D Ultrasound Systems with Real-Time Streaming Interfaces - A Robotic Phantom Study}, year = {2020}, series = {Annual Meeting of the American Association of Physicists in Medicine (AAPM)}, tags = {UGRT} } @Article { NGUYEN20205731, author = {Nguyen, Huu Thien and Nguyen, Ngoc Thinh and Prodan, Ionela and Pereira, Fernando Lobo}, title = {Trajectory Tracking for a Multicopter under a Quaternion Representation}, abstract = {This paper proposes a two-layer hierarchical control scheme for trajectory tracking of a multicopter system using attitude quaternion. We first present the differential flatness properties of the system and then, exploit them to design the feedback linearization laws for the position controller at the high control level. Next, the computed-torque control method is employed for stabilizing the attitude quaternion. The whole control scheme is illustrated through simulations while the position controller is further tested under experiments over a nano-drone quadcopter platform.}, year = {2020}, issn = {2405-8963}, journal = {IFAC-PapersOnLine}, volume = {53}, pages = {5731-5736}, number = {2}, keywords = {computed torque control; Differential flatness; feedback linearization; Multicopter unmanned vehicle; Quaternion; Trajectory tracking}, file_url = {https://www.sciencedirect.com/science/article/pii/S2405896320321984}, note = {doi: https://doi.org/10.1016/j.ifacol.2020.12.1602} } @Inproceedings { vonHaxthausen2020a, author = {Haxthausen, Felix and Aust, Till and Schwegmann, Holger and B{\{\dq}o}ttger, Sven and Ernst, Floris and Garc{\'i}a-V{\'a}zquez, Ver{\'o}nica and Kleemann, Markus and Kaschwich, Mark}, title = {Visual servoing for semi-automated 2D ultrasound scanning of peripheral arteries}, year = {2020}, volume = {1}, publisher = {Infinite Science Publishing GmbH}, number = {1}, tags = {UGRT}, note = {doi: https://doi.org/10.18416/AUTOMED.2020} } @Inproceedings { Chen2020b, author = {Chen, Yenjung and Shah, Nilay Yatinkumar and Goswami, Subhra Sundar and Lange, Annkristin and Haxthausen, Felix and Sieren, Malte Maria and Hagenah, Jannis and Ernst, Floris and Garc{\'i}a-V{\'a}zquez, Ver{\'o}nica}, title = {Localization of endovascular tools in X-ray images using a motorized C-arm: visualization on HoloLens}, year = {2020}, volume = {6}, publisher = {De Gruyter}, pages = {20200029}, number = {1}, note = {doi: https://doi.org/10.1515/cdbme-2020-0029} } @Article { Lin2020b, author = {Lin, Chengxiong and Xie, Jingyang and Li, Wei}, title = {Measuring the micromechanical properties of esophageal mucosa with atomic force microscopy}, year = {2020}, DOI = {10.1049/bsbt.2020.0015}, journal = {Biosurface and Biotribology}, volume = {6}, pages = {97-103}, number = {4}, file_url = {https://doi.org/10.1049/bsbt.2020.0015} } @Article { Tanneberg2020, author = {Tanneberg, Daniel and Rueckert, Elmar and Peters, Jan}, title = {Evolutionary training and abstraction yields algorithmic generalization of neural computers}, year = {2020}, journal = {Nature Machine Intelligence}, note = {doi: https://dx.doi.org/10.1038/s42256-020-00255-1} } @Techreport { Chen2020a, author = {Chen, Yenjung}, title = {Localization of endovascular tools in X-ray images from a motorized C-arm. Visualization on HoloLens}, year = {2020}, series = {L{\{\dq}u}beck University of Applied Sciences and Universit{\{\dq}a}t zu L{\{\dq}u}beck} } @Article { Çallar2020, author = {Çallar, Tolga-Can and Rueckert, Elmar and B{\{\dq}o}ttger, Sven}, title = {Efficient Body Registration Using Single-View Range Imaging and Generic Shape Templates}, abstract = {Computer-aided medical systems, e.g. in the fields of medical robotics or image-based assistance, are continuously investigated to overcome human limitations concerning perception, memory or dexterity. A common requirement of such systems is the availability of a digital model describing the patient's position and morphology during a procedure. Operational complexity and technical limitations of established 3D imaging methods leave clinical settings in need of a method for the fast acquisition of a three-dimensional body surface representation. For this purpose, we propose an unsupervised and efficient body registration pipeline based on the markerless elastic registration and completion of single-view stereo range images of the body surface with statistical para-metric body shape templates. Initial results show a promising representative quality of the models generated through the registration process with submillimetric fitting accuracy and realistic surface morphology, indicating the general feasibility of our approach as an instant body registration method for automated medical and biometric applications.}, year = {2020}, journal = {54th Annual Conference of the German Society for Biomedical Engineering (BMT 2020)}, volume = {6}, editor = {D{\{\dq}o}ssel, O.}, pages = {119-122}, number = {3}, keywords = {3D modeling; Automation; body registration; Computer Vision; medical robotics; range imaging}, file_url = {https://www.degruyter.com/document/doi/10.1515/cdbme-2020-3031/html}, note = {doi: https://doi.org/10.1515/cdbme-2020-3031} } @Inproceedings { Wulff2020, author = {Wulff, Daniel and Hagenah, Jannis and Ipsen, Svenja and Ernst, Floris}, title = {Learning Local Feature Descriptions in 3D Ultrasound}, year = {2020}, DOI = {10.1109/BIBE50027.2020.00059}, series = {IEEE Computer Society}, pages = {323-330}, tags = {UGRT}, file_url = {https://doi.org/10.1109/BIBE50027.2020.00059} } @Inproceedings { vonHaxthausen2020b, author = {Haxthausen, Felix and Ipsen, Svenja and Schwegmann, Holger and Bruder, Ralf and Ernst, Floris and Garc{\'i}a-V{\'a}zquez, Ver{\'o}nica}, title = {A 3D Slicer module for calibration of spatially tracked 3D ultrasound probes}, year = {2020}, volume = {15}, address = {Munich}, pages = {S14-S16}, number = {1}, tags = {UGRT}, note = {doi: https://doi.org/10.1007/s11548-020-02171-6} } @Article { Rottmann2020d, author = {Rottmann, Nils and Bruder, Ralf and Schweikard, Achim and Rueckert, Elmar}, title = {A novel Chlorophyll Fluorescence based approach for Mowing Area Classification}, abstract = {Detecting cost-effectively and accurately the working area for autonomous lawn mowers is key for widespread automation of garden care. At present this is realized by means of perimeter wire, which leads to high setup and maintenance costs. Here, we propose an active low-cost sensor approach for detecting chlorophyll fluorescence response. Our novel and innovative sensing concept allows for a robust working area detection. The classification is thereby based on the averaging of multiple measurements using LED pulses and sensed fluorescence responses. By selecting only low-cost consumer components for the sensor design, we allow for high-volume production under low-cost aspects. We evaluated our novel sensor system by analyzing theoretically the signal path. Among other we investigated sampling frequencies, sensed surface areas and environmental influences. In real world experiments, we evaluated the performance of our sensor in an exemplary garden and on collected grass samples. Our theoretical and practical evaluations show that the sensor classification result is robust under different environmental conditions, such as changes in lawn quality.}, year = {2020}, DOI = {10.1109/JSEN.2020.3032722}, journal = {IEEE Sensors Journal}, keywords = {Mobile Navigation; smart sensors}, file_url = {https://doi.org/10.1109/JSEN.2020.3032722} } @Inproceedings { Jäckle2020c, author = {J{\{\dq}a}ckle, Sonja and Garc{\'i}a-V{\'a}zquez, Ver{\'o}nica and Haxthausen, Felix and Eixmann, Tim and Sieren, Malte Maria and Schulz-Hildebrandt, Hinnerk and H{\{\dq}u}ttmann, Gereon and Ernst, Floris and Kleemann, Markus and P{\{\dq}a}tz, Torben}, title = {Abstract: 3D catheter guidance including shape sensing for endovascular navigation}, year = {2020}, DOI = {10.1007/978-3-658-29267-6_58}, file_url = {https://doi.org/10.1007/978-3-658-29267-6_58} } @Techreport { Krusen2020, author = {Krusen, Marius}, title = {Automatic Attention-based Class Hierarchy Construction for Deep Image Classification}, year = {2020}, series = {Universit{\{\dq}a}t zu L{\{\dq}u}beck} } @Inproceedings { García-Vázquez2020, author = {Garc{\'i}a-V{\'a}zquez, Ver{\'o}nica and Matysiak, Florian and J{\{\dq}a}ckle, Sonja and Eixmann, Tim and Sieren, Malte Maria and Haxthausen, Felix and Ernst, Floris}, title = {Catheter pose-dependent virtual angioscopy images for endovascular aortic repair: validation with a video graphics array (VGA) camera}, year = {2020}, volume = {6}, publisher = {De Gruyter}, pages = {20200010}, number = {1}, note = {doi: https://doi.org/10.1515/cdbme-2020-0010} } @Inproceedings { Akbulut2020, author = {Akbulut, Mete Tuluhan and Oztop, Erhan and Seker, M. Yunus and Xue, Honghu and Tekden, ‪Ahmet Ercan and Ugur, Emre}, title = {ACNMP: Flexible Skill Formation with Learning from Demonstration and Reinforcement Learning via Representation Sharing}, abstract = {To equip robots with dexterous skills, an effective approach is to first transfer the desired skill via Learning from Demonstration (LfD), then let the robot improve it by self-exploration via Reinforcement Learning (RL). In this paper, we propose a novel LfD RL framework, namely Adaptive Conditional Neural Movement Primitives (ACNMP), that allows efficient policy improvement in novel environments and effective skill transfer between different agents. This is achieved through exploiting the latent representation learned by the underlying Conditional Neural Process (CNP) model, and simultaneous training of the model with supervised learning (SL) for acquiring the demonstrated trajectories and via RL for new trajectory discovery. Through simulation experiments, we show that (i) ACNMP enables the system to extrapolate to situations where pure LfD fails; (ii) Simultaneous training of the system through SL and RL preserves the shape of demonstrations while adapting to novel situations due to the shared representations used by both learners; (iii) ACNMP enables order-of-magnitude sample-efficient RL in extrapolation of reaching tasks compared to the existing approaches; (iv) ACNMPs can be used to implement skill transfer between robots having different morphology, with competitive learning speeds and importantly with less number of assumptions compared to the state-of-the-art approaches. Finally, we show the real-world suitability of ACNMPs through real robot experiments that involve obstacle avoidance, pick and place and pouring actions.}, year = {2020}, publisher = {Conference on Robot Learning (CoRL)}, address = {Virtual Conference}, keywords = {Deep Learning; Learning from Demonstration; Reinforcement Learning; Representation Learning}, file_url = {https://arxiv.org/pdf/2003.11334.pdf} } @Inproceedings { Jäckle2020b, author = {J{\{\dq}a}ckle, Sonja and Garc{\'i}a-V{\'a}zquez, Ver{\'o}nica and Haxthausen, Felix and Eixmann, Tim and Sieren, Malte Maria and Schulz-Hildebrandt, Hinnerk and H{\{\dq}u}ttmann, Gereon and Ernst, Floris and Kleemann, Markus and P{\{\dq}a}tz, Torben}, title = {3D catheter guidance including shape sensing for endovascular navigation: Image-Guided Procedures, Robotic Interventions, and Modeling}, year = {2020}, pages = {1131504}, file_url = {https://www.spiedigitallibrary.org/conference-proceedings-of-spie/11315/2548094/3D-catheter-guidance-including-shape-sensing-for-endovascular-navigation/10.1117/12.2548094.full} } @Article { Rottmann2020b, author = {Rottmann, Nils and Bruder, Ralf and Schweikard, Achim and Rueckert, Elmar}, title = {Exploiting Chlorophyll Fluorescense for Building Robust low-Cost Mowing Area Detectors}, abstract = {Detecting cost-effectively and accurately the working area for autonomous lawn mowers is key for widespread automation of garden care. Therefore, we propose an active low-cost sensor approach for detecting fluorescence response. The area to be detected is illuminated by an LED and the chlorophyll fluorescence response is observed by a phototransistor. The signal from the phototransistor is further processed by a transimpedance amplifier, an amplifier and a band pass filter and forwarded to a microprocessor. By choosing only low-cost consumer products for construction, high-volume lowest cost sensors can be built. We demonstrate the feasibility of our low-cost approach by evaluating the sensor mounted on an autonomous lawn mower in a garden environment.}, year = {2020}, journal = {IEEE SENSORS Conference}, pages = {4}, file_url = {https://ai-lab.science/wp/IEEESensors2020Rottmann.pdf} } @Article { doi:10.1080/00207179.2018.1502474, author = {Nguyen, Ngoc Thinh and Prodan, Ionela and Lef{\'e}vre, Laurent}, title = {Flat trajectory design and tracking with saturation guarantees: a nano-drone application}, year = {2020}, DOI = {10.1080/00207179.2018.1502474}, journal = {International Journal of Control}, volume = {93}, publisher = {Taylor {\\&} Francis}, pages = {1266-1279}, number = {6}, file_url = {https://doi.org/10.1080/00207179.2018.1502474}, note = {eprint=https://doi.org/10.1080/00207179.2018.1502474} } @Inproceedings { Henke2020BMT, author = {Henke, Maria}, title = {From whole-day face-to-face instructor-led seminars with group work to successful instructor-led distance-learning alternatives: 54th Annual Conference}, year = {2020}, booktitle = {Deutsche Gesellschaft f{\{\dq}u}r Biomedizinische Technik: 54th Annual Conference}, address = {Leipzig} } @Article { Hagenah2020, author = {Hagenah, Jannis and Mehdi, Mohamad and Ernst, Floris}, title = {Fully Data-Driven Pseudohealthy Synthesis for Planning Valve-Sparing Aortic Root Reconstruction using Conditional Variational Autoencoders}, year = {2020}, journal = {Current Directions in Biomedical Engineering}, volume = {6}, pages = {284-287}, number = {3}, note = {doi: https://doi.org/10.1515/cdbme-2020-3072} } @Article { NGUYEN20204258, author = {Nguyen, Ngoc Thinh and Prodan, Ionela and Petzke, Felix and Streif, Stefan and Lef{\'e}vre, Laurent}, title = {Hierarchical Control of a Quadcopter under Stuck Actuator Fault}, abstract = {We propose a hierarchical FTC (Fault Tolerant Control) scheme for trajectory tracking by a quadcopter system under stuck actuator fault and actuator saturation. Both the FDI (Fault Detection and Isolation) and control reconfiguration modules are implemented at the low-level associated with the rotation dynamics through a NMPC (Nonlinear Model Predictive Control) strategy. The uncontrolled (when under fault) yaw torque is predicted and compensated by the NMPC. It is shown that the overall control scheme succeeds in maintaining trajectory tracking for various fault events (both in the sense of having various stuck values and in the sense of changing the actuator under fault).}, year = {2020}, issn = {2405-8963}, journal = {IFAC-PapersOnLine}, volume = {53}, pages = {4258-4263}, number = {2}, keywords = {feedback linearization; FTC; Hierarchical control; NMPC; Quadcopter; Stuck actuator fault; Trajectory tracking}, file_url = {https://www.sciencedirect.com/science/article/pii/S2405896320331852}, note = {doi: https://doi.org/10.1016/j.ifacol.2020.12.2479} } @Inproceedings { Rottmann2020a, author = {Rottmann, Nils and Kunavar, Tjasa and Babic, Jan and Peters, Jan and Rueckert, Elmar}, title = {Learning Hierarchical Acquisition Functions for Bayesian Optimization}, abstract = {Learning control policies in robotic tasks requires a large number of interactions due to small learning rates, bounds on the updates or unknown constraints. In contrast humans can infer protective and safe solutions after a single failure or unexpected observation. In order to reach similar performance, we developed a hierarchical Bayesian optimization algorithm that replicates the cognitive inference and memorization process for avoiding failures in motor control tasks. A Gaussian Process implements the modeling and the sampling of the acquisition function. This enables rapid learning with large learning rates while a mental replay phase ensures that policy regions that led to failures are inhibited during the sampling process. The features of the hierarchical Bayesian optimization method are evaluated in a simulated and physiological humanoid postural balancing task. The method outperforms standard optimization techniques, such as Bayesian Optimization, in the number of interactions to solve the task, in the computational demands and in the frequency of observed failures. Further, we show that our method performs similar to humans for learning the postural balancing task by comparing our simulation results with real human data.}, year = {2020}, booktitle = {International Conference on Intelligent Robots and Systems}, publisher = {Proceedings of International Conference on Intelligent Robots and Systems (IROS)}, address = {Las Vegas, USA}, keywords = {Reinforcement Learning}, file_url = {https://rob.ai-lab.science/wp/IROS2020Rottmann.pdf} } @Article { Binder2019, author = {Binder, Sonja and M{\{\dq}o}lle, Matthias and Lippert, Michael and Bruder, Ralf and Aksamaz, Sonat and Ohl, Frank and Wiegert, J. Simon and Marshall, Lisa}, title = {Monosynaptic Hippocampal-Prefrontal Projections Contribute to Spatial Memory Consolidation in Mice}, year = {2019}, DOI = {10.1523/JNEUROSCI.2158-18.2019}, journal = {The Journal of Neuroscience}, volume = {39}, pages = {2158-18}, tags = {TES}, file_url = {https://doi.org/10.1523/JNEUROSCI.2158-18.2019} } @Article { Boda-HegemannJahnkeChanErnst2019, author = {Boda‐Heggemann, Judit and Jahnke, Anika and Chan, Mark K. H. and Ernst, Floris and Ghaderi, Ardekani Leila and Attenberger, Ulrike and Hunold, Peter and Sch{\{\dq}a}fer, Jost Philipp and Wurster, Stefan and Rades, Dirk and Hildebrandt, Guido and Lohr, Frank and Dunst, J{\{\dq}u}rgen and Wenz, Frederik and Blanck, Oliver}, title = {In-vivo treatment accuracy analysis of active motion-compensated liver SBRT through registration of plan dose to post-therapeutic MRI-morphologic alterations}, year = {2019}, journal = {Radiotherapy and Oncology}, volume = {134}, pages = {158-165}, tags = {MCRT}, file_url = {https://www.sciencedirect.com/science/article/pii/S0167814019300283?dgcid=coauthor} } @Inproceedings { 8899514, author = {Stoican, Florin and Prodan, Ionela and Gr{\o}tli, Esten Ingar and Nguyen, Ngoc Thinh}, title = {Inspection Trajectory Planning for 3D Structures under a Mixed-Integer Framework}, year = {2019}, DOI = {10.1109/icca.2019.8899514}, pages = {1349-1354}, file_url = {https://doi.org/10.1109/icca.2019.8899514} } @Article { Hagenah2019b, author = {Hagenah, Jannis and Leymann, Sascha and Ernst, Floris}, title = {Integrating Label Uncertainty in Ultrasound Image Classification using Weighted Support Vector Machines}, year = {2019}, DOI = {10.1515/cdbme-2019-0072}, journal = {Current Directions in Biomedical Engineering}, volume = {5}, pages = {285-287}, number = {1}, file_url = {https://doi.org/10.1515/cdbme-2019-0072} } @Article { Tanneberg2019, author = {Tanneberg, Daniel and Peters, Jan and Rueckert, Elmar}, title = {Intrinsic Motivation and Mental Replay enable Efficient Online Adaptation in Stochastic Recurrent Networks}, abstract = {Autonomous robots need to interact with unknown, unstructured and changing environments, constantly facing novel challenges. Therefore, continuous online adaptation for lifelong-learning and the need of sample-efficient mechanisms to adapt to changes in the environment, the constraints, the tasks, or the robot itself are crucial. In this work, we propose a novel framework for probabilistic online motion planning with online adaptation based on a bio-inspired stochastic recurrent neural network. By using learning signals which mimic the intrinsic motivation signal cognitive dissonance in addition with a mental replay strategy to intensify experiences, the stochastic recurrent network can learn from few physical interactions and adapts to novel environments in seconds. We evaluate our online planning and adaptation framework on an anthropomorphic KUKA LWR arm. The rapid online adaptation is shown by learning unknown workspace constraints sample-efficiently from few physical interactions while following given way points.}, year = {2019}, issn = {0893-6080}, DOI = {10.1016/j.neunet.2018.10.005}, journal = {Neural Networks - Elsevier}, volume = {109}, pages = {67-80}, keywords = {Autonomous robots; Experience replay; Intrinsic motivation; Neural sampling; Online learning; Spiking recurrent networks}, file_url = {https://doi.org/10.1016/j.neunet.2018.10.005}, note = {Impact Factor of 7.197 (2017)} } @Inproceedings { Rottmann2019b, author = {Rottmann, Nils and Bruder, Ralf and Schweikard, Achim and Rueckert, Elmar}, title = {Loop Closure Detection in Closed Environments}, year = {2019}, series = {European Conference on Mobile Robots (ECMR 2019)} } @Article { Böttger2019c, author = {B{\{\dq}o}ttger, Sven and Çallar, Tolga-Can and Rueckert, Elmar and Schweikard, Achim}, title = {Medical robotics simulation framework for application-specific optimal kinematics}, abstract = {Most kinematic structures in robot architectures for medical tasks are not optimal. Further, the workspace and payloads are often oversized which results in high product prices that are not suitable for a clinical technology transfer. To investigate optimal kinematic structures and configurations, we have developed an adaptive simulation framework with an associated workflow for requirement analyses, modelling and simulation of specific robot kinematics. The framework is used to build simple and cost effective medical robot designs and was evaluated in a tool manipulation task where medical instruments had to be positioned precisely and oriented on the patient's body. The model quality is measured based on the maximum workspace coverage according to a configurable scoring metric. The metric generalizes among different human body shapes that are based on anthropometric data from UMTRI Human Shape. This dexterity measure is used to analyze different kinematic structures in simulations using the open source simulation tool V-REP. Therefor we developed simulation and visualization procedures for medical tasks based on a patchwork of size-variant anatomical target regions that can be configured and selectively activated in a motion planning controller. In our evaluations we compared the dexterity scores of a commercial lightweight robot arm with 7 joints to optimized kinematic structures with 6, 7 and 8 joints. Compared to the commercial hardware, we achieved improvements of 59% when using an optimized 6-dimensional robot arm, 64% with the 7-dimensional arm and 96% with an 8-dimensional robot arm. Our results show that simpler robot designs can outperform the typically used commercial robot arms in medical applications where the maximum workspace coverage is essential. Our framework provides the basis for a fully automatic optimization tool of the robot parameters that can be applied to a large variety of problems.}, year = {2019}, issn = {2364-5504}, DOI = {10.1515/cdbme-2019-0037}, journal = {Current Directions in Biomedical Engineering}, volume = {5}, pages = {145-148}, number = {1}, keywords = {anthropometric body shape data; medical robotics; optimization; robot kinematics}, file_url = {https://doi.org/10.1515/cdbme-2019-0037} } @Inproceedings { iks19, author = {Ipsen, Svenja and Kuhlemann, Ivo and Schweikard, Achim and Ernst, Floris}, title = {MO-K-303-3: Continuous long-term imaging with robotic 4D ultrasound for motion compensation in radiotherapy and beyond}, year = {2019}, volume = {46}, series = {Annual Meeting of the American Association of Physicists in Medicine (AAPM)}, pages = {E287-E288}, number = {6}, tags = {UGRT} } @Article { Bockelmann2019a, author = {Bockelmann, Niclas and Kr{\{\dq}u}ger, Diana and Wieland, D.C. Florian and Zeller-Plumhoff, Berit and Peruzzi, Niccol{\'o} and Galli, Silvia and Willumeit-R{\{\dq}o}mer, Regine and Wilde, Fabian and Beckmann, Felix and Hammel, J{\{\dq}o}rg and Moosmann, Julian and Heinrich, Mattias}, title = {Sparse Annotations with Random Walks for U-Net Segmentation of Biodegradable Bone Implants in Synchrotron Microtomograms}, year = {2019}, journal = {arXiv preprint arXiv:1908.04173} } @Inproceedings { Bouchagiar2019, author = {Bouchagiar, Juljan and Haxthausen, Felix and J{\{\dq}a}ckle, Sonja and Matysiak, Florian and Kaschwich, Mark and Goltz, Jan Peter and Horn, Marco and Stahlberg, Erik and Garc{\'i}a-V{\'a}zquez, Ver{\'o}nica and Ernst, Floris and Kleemann, Markus}, title = {NAV EVAR Auf dem Weg zur strahlungsfreien Stentgraft Implantation}, year = {2019}, address = {W{\{\dq}u}rzburg (Germany)} } @Inproceedings { 8814763, author = {Nguyen, Ngoc Thinh and Prodan, Ionela and Lef{\'e}vre, Laurent}, title = {On the use of a computed-torque control law for the terminal region of an NMPC scheme}, year = {2019}, DOI = {10.23919/ACC.2019.8814763}, booktitle = {2019 American Control Conference (ACC)}, pages = {1008-1013}, keywords = {NMPC (Nonlinear Model Predictive Control);CTC (Computed-Torque Control);Ellipsoidal invariant set;Taylor's approximation;Inverted pendulum} } @Phdthesis { nguyen:tel-02526853, author = {Nguyen, Ngoc Thinh}, title = {Reliable hierarchical control for multicopter systems}, abstract = {The goal of this thesis is to propose reliable control laws for the motion planning of a multicopter system under constraints and unexpected events (e.g., actuator faults). A hierarchical control architecture which decouples the scheme into position and attitude control is proposed. At the high level the position controller calculates the position error and provides the desired thrust and angles to the attitude controller at the low level to stabilize the system around the desired angles. The scheme's reliability (i.e., ensuring feasibility, stability and constraint validation) is done through a coherent merging of differential flatness, feedback linearization and Nonlinear Model Predictive Control (NMPC). Hence, the main thesis contributions lie in:i) The analysis and design of bounds which characterize the various inputs and states of the system (angle position and velocity, torques, etc.). These are subsequently applied for constrained trajectory design (which combines differential flatness and feedback linearization through the use of B-spline parametrizations).ii) Designs which exploit the {\dq}computed-torque control law{\dq} as local control within an NMPC with recursive feasibility guarantees. We show that avoiding the standard linearizations employed for nonlinear dynamics improves performance (in the sense of reducing the prediction horizon, enlarging the terminal region and reducing the problem's complexity). Further advances relax the requirement of set invariance and even discard the need for terminal stabilizing constraints. Generalizations for similar feedback linearizable systems are discussed.iii) A hierarchical optimization-based FTC (Fault Tolerant Control) scheme to counteract a stuck rotor fault. This is done through control reconfiguration at both high and low levels, coupled with a fault diagnosis mechanism capable of handling fault detection, isolation and estimation.The results are validated over extensive simulations and laboratory experiments involving a nano-quadcopter.}, year = {2019}, school = {Universit{\'e} Grenoble Alpes}, institute = {Laboratory of Conception and Integration of Systems}, series = {Universit{\'e} Grenoble Alpes}, number = {2019GREAT061}, keywords = {Commande hi{\'e}rarchique; Commande predictive non lin{\'e}aire; Differential flatness; Feedback Linearization Control; Hierarchical control; Lin{\'e}arisation de r{\'e}troaction de commande; Motion planning; Multicopters; Multicopt{\'e}res; Nonlinear Model Predictive Control; Planification de mouvement; Platitude diff{\'e}rentielle}, file_url = {https://tel.archives-ouvertes.fr/tel-02526853}, note = {PhD thesis} } @Inproceedings { Böttger2019a, author = {B{\{\dq}o}ttger, Sven and Haxthausen, Felix and Kleemann, Markus and Ernst, Floris and Schweikard, Achim}, title = {Robotics from the bench -- Research for ultrasound automation with augmented reality visualization}, abstract = {Ultrasound imaging commonly used for diagnostics may also be used for radiation-free catheter and needle navigation. Due to the considerable skill and expertise it requires, ultrasound image acquisition and diagnostics are difficult to be done. Automated ultrasound image acquisition could potentially overcome this operator dependency. For the automation and standardization of the diagnostic ultrasound imaging process as well as for the operator-free automated catheter and needle navigation, we are currently developing a medical robotic device platform. A prototype of this robot-supported ultrasound platform was produced, on which various medical examination procedures can be developed. Three core technologies were applied therefor: - A force-sensitive 7-DoF robot arm (KUKA LBR iiwa), which can position both automatically and manually over a certain target area on the body surface. The arm has collision avoidance and ensures the dynamic force-controlled posture of the transducer to the patient. - 3D ultrasound is realized by a matrix probe and appropriate calculation algorithms on a modified ultrasound station (GE Vivid 7). It enables recording of large areas at high frame rates. Thus the target, its surrounding areas and nearby navigation points can be recorded simultaneously. - 3D ultrasound data streaming from ultrasound system to Microsoft HoloLens glasses and visualization at a certain distance from the ultrasound probe by tracking augmented reality markers. The functionality was verified using an ultrasound phantom (BluePhantom FAST ultrasound training model). The result is a 4D volume data set for the physician-assisted diagnostic evaluation. The process delivered reproducible real-time visualization results on a workstation where the volumes were simultaneously visualized and stored. Ultrasound volume data of the training model (matrix size 103x74x134) were sent from the ultrasound system to HoloLens in order to display them, showing a latency of 259 ± 86 ms. Automated ultrasound diagnostics and navigation should help to reduce the binding of clinical resources in the future, thereby enabling better reproducibility of imaging and reducing side effects from radiation exposure. The device platform will serve as the basis for further automated ultrasound diagnostics and therapy procedures.}, year = {2019}, tags = {MCRT UGRT}, file_url = {https://www.mic2019.org/fileadmin/Files/Projects/08_MIC/2019/Flyer/MIC_2019_Program.pdf} } @Article { Kleemann2019, author = {Kleemann, Markus and B{\{\dq}o}ttger, Sven and Haxthausen, Felix}, title = {Robotik: automatisierte Verfahren in der Gef{\{\dq}a}{\{\dq}s}medizin}, year = {2019}, DOI = {10.1007/s00772-019-00581-8}, journal = {Gef{\{\dq}a}{\{\dq}s}chirurgie}, volume = {24}, pages = {557-563}, keywords = {Endovaskularchirurgie; Laparoskopie; Maschinenlernen; Strahlenbelastung; Ultraschalluntersuchung}, file_url = {https://doi.org/10.1007/s00772-019-00581-8} } @Inproceedings { Wulff2019, author = {Wulff, Daniel and Kuhlemann, Ivo and Ernst, Floris and Schweikard, Achim and Ipsen, Svenja}, title = {Robust motion tracking of deformable targets in the liver using binary feature libraries in 4D ultrasound}, year = {2019}, DOI = {10.1515/cdbme-2019-0151}, volume = {5}, series = {German Society for Biomedical Engineering}, pages = {601-604}, number = {1}, tags = {UGRT}, file_url = {https://doi.org/10.1515/cdbme-2019-0151} } @Phdthesis { ip19d, author = {Ipsen, Svenja}, title = {See what you treat -- 4D ultrasound imaging for real-time motion compensation in the liver}, year = {2019}, series = {Universit{\{\dq}a}t zu L{\{\dq}u}beck}, tags = {UGRT} } @Inproceedings { Chen2019, author = {Chen, Yenjung and Risto, Stamatis and Haxthausen, Felix and Ernst, Floris and Garc{\'i}a-V{\'a}zquez, Ver{\'o}nica}, title = {HoloLens: Third-person Perspective}, year = {2019}, isbn = {978-3-945954-57-7}, publisher = {Infinite Science Publishing GmbH}, address = {L{\{\dq}u}beck (Germany)}, pages = {51-54} } @Inproceedings { ieg19, author = {Ipsen, Svenja and Ernst, Floris and Garc{\'i}a-V{\'a}zquez, Ver{\'o}nica and Schweikard, Achim}, title = {SU-F-303-3: Assessment of CT artefacts caused by matrix array transducers for intra-modality registration in 4D ultrasound-guided radiotherapy}, year = {2019}, volume = {46}, series = {Annual Meeting of the American Association of Physicists in Medicine (AAPM)}, pages = {E132-E133}, number = {6}, tags = {UGRT} } @Article { mpse_19, author = {Manit, Jirapong and Preusse, Luise and Schweikard, Achim and Ernst, Floris}, title = {Human Forehead Recognition: A Novel Biometric Modality based on NIR Laser Backscattering Feature Image using Deep Transfer Learning}, year = {2019}, issn = {2047-4938}, DOI = {10.1049/iet-bmt.2019.0015}, journal = {IET Biometrics}, volume = {online first}, publisher = {Institution of Engineering and Technology}, tags = {HPHT}, file_url = {https://doi.org/10.1049/iet-bmt.2019.0015} } @Inproceedings { Horn2019a, author = {Horn, Marco and J{\{\dq}a}ckle, Sonja and Haxthausen, Felix and Eixmann, Tim and Schulz-Hildebrandt, Hinnerk and H{\{\dq}u}ttmann, Gereon and Bouchagiar, Juljan and Matysiak, Florian and Kaschwich, Mark and Kleemann, Markus and Ernst, Floris and Garc{\'i}a-V{\'a}zquez, Ver{\'o}nica and P{\{\dq}a}tz, Torben}, title = {First steps into catheter guidance including shape sensing for endovascular aneurysm repair procedures}, year = {2019}, address = {Hamburg (Germany)}, pages = {e610-e611}, number = {6, Supplement 3}, note = {doi: https://doi.org/10.1016/j.ejvs.2019.09.091} } @Article { whse_19, author = {Wattenberg, Maximilian and Hagenah, Jannis and Schareck, Constantin and Ernst, Floris and Koch, Martin A.}, title = {Head Movement Detection from Radial k-Space Lines using Convolutional Neural Networks - A Digital Phantom Study}, year = {2019}, journal = {Annual Meeting of the International Society of Magnetic Resonance in Medicine} } @Article { Hippmann2019, author = {Hippmann, Bernadette and Kuhlemann, Ivo and B{\{\dq}a}umer, Tobias and Bahlmann, J{\{\dq}o}rg and M{\{\dq}u}nte, Thomas F. and Jessen, Sarah}, title = {Boosting the effect of reward on cognitive control using TMS over the left IFJ}, abstract = {Although an enhancing effect of reward on cognitive performance has been observed consistently, its neural underpinnings remain elusive. Recent evidence suggests that the inferior frontal junction (IFJ) may be a key player underlying such an enhancement by integrating motivational processes and cognitive control. However, its exact role and in particular a potential causality of IFJ activation is still unclear. In the present study, we therefore investigated the causal contributions of the left IFJ in motivated task switching by temporarily disrupting its activity using continuous theta burst stimulation (cTBS, Exp.1) or 1 Hz repetitive transcranial magnetic stimulation (rTMS, Exp.2). After TMS application over the left IFJ or a control site (vertex), participants performed a switch task in which numbers had to be judged by magnitude or parity. Different amounts of monetary rewards (high vs low) were used to manipulate the participants' motivational states. We measured reaction times and error rates. Irrespective of TMS stimulation, participants exhibited slower responses following task switches compared to task repeats. This effect was reduced in high reward trials. Importantly, we found that disrupting the IFJ improved participants' behavioral performance in the high reward condition. For high reward trials exclusively, error rates decreased when the IFJ was modulated with cTBS or 1 Hz rTMS but not after vertex stimulation. Our results suggest that the left IFJ is causally related to the increase in cognitive performance through reward.}, year = {2019}, issn = {0028-3932}, journal = {Neuropsychologia}, volume = {125}, pages = {109-115}, file_url = {http://www.sciencedirect.com/science/article/pii/S0028393218305633}, note = {doi: https://doi.org/10.1016/j.neuropsychologia.2019.01.016} } @Inproceedings { Kraft2019, author = {Kraft, Valentin and Strehlow, Jan and J{\{\dq}a}ckle, Sonja and Garc{\'i}a-V{\'a}zquez, Ver{\'o}nica and Link, Florian and Haxthausen, Felix and Schenk, Andrea and Schumann, Christian}, title = {A comparison of streaming methods for the Microsoft HoloLens}, year = {2019}, isbn = {978-3-00-063717-9}, publisher = {Oliver Burgert, Hochschule Reutlingen, Bernhard Hirt, Universit{\{\dq}a}t T{\{\dq}u}bingen}, address = {Reutlingen (Germany)}, pages = {212-216} } @Inproceedings { 8814321, author = {Nguyen, Ngoc Thinh and Prodan, Ionela and Lef{\'e}vre, Laurent}, title = {A stabilizing NMPC design for thrust-propelled vehicles dynamics via feedback linearization}, year = {2019}, DOI = {10.23919/ACC.2019.8814321}, booktitle = {2019 American Control Conference (ACC)}, pages = {2909-2914}, keywords = {Feedback linearization;Vehicle dynamics;Stability analysis;Linear systems;Asymptotic stability;Optimization;Drones;NMPC;terminal constraint;feedback linearization;ellipsoidal invariant set;asymptotic stability;thrust-propelled vehicles} } @Inproceedings { vonHaxthausen2019d, author = {Haxthausen, Felix and Ernst, Floris and Bruder, Ralf and Kaschwich, Mark and Garc{\'i}a-V{\'a}zquez, Ver{\'o}nica}, title = {Abstract: HoloLens Streaming of 3D Data from Ultrasound Systems to Augmented Reality Glasses}, year = {2019}, pages = {231}, file_url = {https://link.springer.com/chapter/10.1007/978-3-658-25326-4_51} } @Article { Hagenah2019c, author = {Hagenah, Jannis and Mehdi, Mohamad and Ernst, Floris}, title = {Generating Healthy Aortic Root Geometries from Ultrasound Images of the Individual Pathological Morphology Using Deep Convolutional Autoencoders}, year = {2019}, journal = {Computing in Cardiology} } @Inproceedings { ibg19, author = {Ipsen, Svenja and Bruder, Ralf and Garc{\'i}a-V{\'a}zquez, Ver{\'o}nica and Schweikard, Achim and Ernst, Floris}, title = {Assessment of 4D Ultrasound Systems for Image-guided Radiation Therapy -- Image Quality, Framerates and CT Artifacts}, year = {2019}, series = {BMT 2019 - 53rd Annual Biomedical Engineering Congress}, number = {Supplement}, tags = {UGRT} } @Inproceedings { Kaschwich2019, author = {Kaschwich, Mark and Matysiak, Florian and Bouchagiar, Juljan and Horn, Marco and Garc{\'i}a-V{\'a}zquez, Ver{\'o}nica and Haxthausen, Felix and J{\{\dq}a}ckle, Sonja and Eixmann, Tim and Goltz, Jan Peter and Ernst, Floris and Kleemann, Markus}, title = {Augmented Reality navigierte endovaskul{\{\dq}a}re Chirurgie -- das NavEVAR-Projekt}, year = {2019} } @Unpublished { ip19, author = {Ipsen, Svenja}, title = {Bewegungsmuster und Tracking im Herzen -- ICD-Elektroden, Ultraschall und MRT (Presentation)}, year = {2019}, note = {1. Deutscher Interdisziplin{\{\dq}a}rer Herz-Radiochirurgie Workshop} } @Misc { García-Vázquez2019, author = {Garc{\'i}a-V{\'a}zquez, Ver{\'o}nica}, title = {An augmented reality guidance system for endovascular aortic repair: first steps in reducing radiation exposure}, year = {2019}, note = {Invited talk. Santiago Aortic Meeting 2019} } @Inproceedings { Rottmann2019a, author = {Rottmann, Nils and Bruder, Ralf and Schweikard, Achim and Rueckert, Elmar}, title = {Cataglyphis ant navigation strategies solve the global localization problem in robots with binary sensors}, year = {2019}, publisher = {Proceedings of International Conference on Bio-inspired Systems and Signal Processing (BIOSIGNALS)}, address = {Prague, Czech Republic}, keywords = {Constraint optimization; Mobile Navigation; simulation}, file_url = {https://rob.ai-lab.science/wp/Biosignals2018Rottmann.pdf} } @Article { vonHaxthausen2019b, author = {Haxthausen, Felix and J{\{\dq}a}ckle, Sonja and Strehlow, Jan and Ernst, Floris and Garc{\'i}a-V{\'a}zquez, Ver{\'o}nica}, title = {Catheter pose-dependent virtual angioscopy images visualized on augmented reality glasses}, year = {2019}, journal = {Current Directions in Biomedical Engineering}, volume = {5}, pages = {289-292}, number = {1}, note = {doi: from doi:10.1515/cdbme-2019-0073} } @Article { Hagenah2019a, author = {Hagenah, Jannis and K{\{\dq}u}hl, Kenneth and Scharfschwerdt, Michael and Ernst, Floris}, title = {Cluster Analysis in Latent Space: Identifying Personalized Aortic Valve Prosthesis Shapes using Deep Representations}, year = {2019}, journal = {Proceedings of Machine Learning Research}, volume = {102}, pages = {236-249} } @Article { Bockelmann2019b, author = {Bockelmann, Niclas and Gra{\{\dq}s}hoff, Jan and Hansen, Lasse and Bellani, Giacomo and Heinrich, Mattias and Rostalski, Philipp}, title = {Deep Learning for Prediction of Diaphragm Activity from the Surface Electromyogram}, year = {2019}, journal = {Current Directions in Biomedical Engineering}, volume = {5}, publisher = {De Gruyter}, pages = {17-20}, number = {1}, note = {doi: https://doi.org/10.1515/cdbme-2019-0005} } @Inproceedings { Risto2019, author = {Risto, Stamatis and Chen, Yenjung and Haxthausen, Felix and Matysiak, Florian and Ernst, Floris and Garc{\'i}a-V{\'a}zquez, Ver{\'o}nica}, title = {Development of HoloLens Mount for Third-Person Perspective and Augmented Reality Application for Endovascular Aortic Repair Procedures}, year = {2019}, isbn = {978-3-945954-57-7}, publisher = {Infinite Science Publishing GmbH}, address = {L{\{\dq}u}beck (Germany)}, pages = {47-50}, file_url = {https://www.youtube.com/watch?v=YQodwOsihhY} } @Inproceedings { Rueckert2019, author = {Rueckert, Elmar and Jauer, Philipp and Derksen, Alexander and Schweikard, Achim}, title = {Dynamic Control Strategies for Cable-Driven Master Slave Robots}, year = {2019}, address = {Luebeck, Germany}, editor = {Keck, Tobias}, note = {doi: 10.18416/MIC.2019.1901007} } @Inproceedings { Böttger2019b, author = {B{\{\dq}o}ttger, Sven and Kleemann, Markus and Ernst, Floris}, title = {Ergebnisse einer Akzeptanzumfrage zur Roboter-assistierten Ultraschalldiagnostik unter Gef{\{\dq}a}{\{\dq}s}medizinern}, year = {2019}, booktitle = {136. Kongress Deutsche Gesellschaft f{\{\dq}u}r Chirurgie}, series = {Deutsche Gesellschaft f{\{\dq}u}r Chirurgie}, number = {211}, tags = {UGRT} } @Inproceedings { Horn2019b, author = {Horn, Marco and Ernst, Floris and Ivo, Kuhlemann and Stahlberg, Erik and Goltz, Jan Peter and Wiedner, Marcus and Kleemann, Markus}, title = {Experimental visualization of vascular structures with Microsoft Hololens -- Set-up for navigated contrast agent and radiation-sparing endovascular procedures (NAV-CARS EVAR)}, year = {2019}, volume = {58}, pages = {e104}, number = {6} } @Misc { vonHaxthausen2019c, author = {Haxthausen, Felix and J{\{\dq}a}ckle, Sonja and Eixmann, Tim and Strehlow, Jan and Schumann, Christian and Bouchagiar, Juljan and Matysiak, Florian and Schulz-Hildebrandt, Hinnerk and H{\{\dq}u}ttmann, Gereon and Kaschwich, Mark and Kleemann, Markus and Ernst, Floris and P{\{\dq}a}tz, Torben and Garc{\'i}a-V{\'a}zquez, Ver{\'o}nica}, title = {Catheter navigation and augmented reality visualisation for endovascular aneurysm repair procedures}, year = {2019}, note = {Invited poster. 2019 Hamlyn Symposium Workshop on Endovascular Intervention} } @Article { BöttgerKleemannAl-BadriIpsenErnst2018, author = {B{\{\dq}o}ttger, Sven and Kleemann, Markus and Al-Badri, Mohammed and Ipsen, Svenja and Kuhlemann, Ivo and Bruder, Ralf and Ernst, Floris}, title = {Robotergest{\{\dq}u}tzte Ultraschall-Plattform f{\{\dq}u}r die Automatisierung und Standardisierung von Screening-Verfahren}, abstract = {Einleitung Die medizinischen Anwendungsbereiche der US-Bildgebung verbinden sowohl in der Diagnostik als auch in der Therapie gemeinsam deren gr{\{\dq}o}{\{\dq}s}te Nachteile: Zeit-, Raum- und Benutzerabh{\{\dq}a}ngigkeit. Obwohl dieses Bildgebungsverfahren wegen seiner Vorteile das meistverwendete ist, erfordern Aufnahme und Interpretation der US-Daten erhebliche Erfahrung und k{\{\dq}o}nnen weder in Echtzeit noch retrospektiv auf mehrere Ressourcen aufgeteilt werden. F{\{\dq}u}r die Automatisierung und Standardisierung des Ultraschall-Bildgebungsprozesses entwickeln wir derzeit eine robotergest{\{\dq}u}tzte, medizintechnische Ger{\{\dq}a}teplattform. Material und Methoden Es wurde ein Prototyp dieser robotergest{\{\dq}u}tzten US-Plattform hergestellt, auf der nachfolgend eine geeignete Untersuchungsprozedur f{\{\dq}u}r das BAA-Screening der Deutschen Gesellschaft f{\{\dq}u}r Gef{\{\dq}a}{\{\dq}s}chirurgie und Gef{\{\dq}a}{\{\dq}s}medizin e.V. (DGG) entwickelt werden soll. Ma{\{\dq}s}gebliche Ziele sind die Automatisierung und Standardisierung des US-Vorganges in der Klinik. Das System besteht aus einem 7-DoF Roboterarm (KUKA LBR iiwa), der einen realtime-3D Matrixschallkopf sowohl automatisch als auch handgef{\{\dq}u}hrt positionieren kann. Der Arm verf{\{\dq}u}gt {\{\dq}u}ber Kollisionsvermeidung und Kraftsensitivit{\{\dq}a}t, um die kraftgesteuerte Haltung des US-Schallkopfes an den Patienten zu gew{\{\dq}a}hrleisten. Zudem haben wir die eingesetzte US-Station (GE Vivid 7) modifiziert, um Echtzeit-Volumendaten auf einer externen Workstation zu visualisieren und zu speichern. Die Registrierung der K{\{\dq}o}rperoberfl{\{\dq}a}che erfolgt durch Laserscanning, wobei zus{\{\dq}a}tzlich die Bewegungsverfolgung mit einem optischen Trackingsystem durchgef{\{\dq}u}hrt werden kann. Mittels eines US-Phantoms (BluePhantom FAST Trauma) mit verschiedenen simulierten Organen wurde das System getestet und verifiziert. Ergebnisse Der Befund erfolgt als 4D-Volumendatensatz f{\{\dq}u}r die zweiseitige, {\{\dq}a}rztlich begleitete diagnostische Auswertung. Das Verfahren hat reproduzierbare Ergebnisse bei der Echtzeit-Visualisierung auf einer Workstation geliefert, auf der die Volumen gleichzeitig visualisiert und gespeichert wurden. Durch Anwendung von Verfahren zur optimalen Schallkopfpositionierung (OTP) sowie dem Wiederauffinden von gespeicherten Positionen, Fernsteuerung und Handf{\{\dq}u}hrung konnten verschiedene definierte Zielregionen sowohl semiautomatisch als auch manuell lokalisiert und mittels kraftsensitiver Bewegungskompensation dauerhaft beobachtet werden. Schlussfolgerung Die automatisierte US-Diagnostik soll zuk{\{\dq}u}nftig die zeitliche und r{\{\dq}a}umliche Bindung von klinischen Ressourcen reduzieren helfen und dabei eine bessere Reproduzierbarkeit der Bildgebung erm{\{\dq}o}glichen. Die Ger{\{\dq}a}teplattform soll als Basis f{\{\dq}u}r weiterf{\{\dq}u}hrende automatisierte US-Diagnostik und -Therapieverfahren dienen.}, year = {2018}, journal = {135. Kongress der Deutschen Gesellschaft f{\{\dq}u}r Chirurgie}, pages = {161}, keywords = {Roboter Ultrashall Automatisierung Standardisierung Screening}, tags = {UGRT}, file_url = {http://h2041619.stratoserver.net/chirurgie2018/timetable/abstract.php?id=553} } @Phdthesis { Jauer2018, author = {Jauer, Philipp}, title = {Physikalisch motivierte Punktwolkenregistrierung: Entwurf und Evaluierung eines neuen Konzepts zur effizienten Registrierung von Punktwolken}, year = {2018}, series = {University of L{\{\dq}u}beck}, keywords = {point cloud registration} } @Inproceedings { vonHaxthausen2018a, author = {Haxthausen, Felix and Ernst, Floris and Bruder, Ralf and Garc{\'i}a-V{\'a}zquez, Ver{\'o}nica}, title = {Real-Time Streaming of 3D Ultrasound Data to HoloLens}, year = {2018}, address = {Aachen (Germany)}, pages = {S344}, tags = {UGRT} } @Inproceedings { manit2018, author = {Manit, Jirapong and Ernst, Floris and Schweikard, Achim}, title = {Relationship between NIR laser power and the human forehead tissue backscattering image features: Photonic Solutions for Better Health Care VI}, abstract = {A novel markerless near infrared (NIR) laser-based head tracking system was recently proposed to resolve patient's head motion problem during cranial radiotherapy. Although previous research showed that we could track the patient's head position with the sub-millimetre range accuracy, the tracking performance strongly relied on the accuracy of the tissue thickness estimation. We noticed the factors that inuence the ROI features extracted from the backscattering images were the NIR laser power fluctuation and inconsistency. Therefore, the propose of this paper was to investigate the relationship between these parameters and determine a laser power independent feature transformation. We set up our head tracking system to project the pulsed NIR laser beam onto a single point on subject's forehead and observed the changes of the 5-ROI feature values on the different laser power level. The scatter plots between each ROI feature values and the laser power showed distinctive straight lines with similar slopes while applying linear regression to each scatter plot indicated that the slope of each ROI feature was also in the same range. According to the results, we could transform the data by subtracting the feature value of each ROI from their average slope value and the laser power. This new feature is laser power noise tolerance and could be used to enhance the tissue thickness estimation accuracy.}, year = {2018}, isbn = {9781510618961}, DOI = {10.1117/12.2306827}, volume = {10685}, publisher = {SPIE}, address = {Strasbourg (France)}, editor = {Popp, J{\{\dq}u}rgen and Tuchin, Valery V. and Pavone, Francesco S.}, pages = {136}, keywords = {Backscattering; Feature normalisation; Forehead tissue thickness; Head tracking system; NIR laser power; Region-of-interest feature; Thickness estimation}, tags = {HPHT}, file_url = {https://doi.org/10.1117/12.2306827} } @Inproceedings { Jäckle2018, author = {J{\{\dq}a}ckle, Sonja and Haxthausen, Felix and Garc{\'i}a-V{\'a}zquez, Ver{\'o}nica and Schumann, Christian and Kleemann, Markus and Ernst, Floris and Papenberg, Nils}, title = {Visuelle Unterst{\{\dq}u}tzung bei endovaskul{\{\dq}a}ren Eingriffen durch Darstellung einer virtuellen Angioskopie auf der HoloLens}, year = {2018}, address = {Bonn (Germany)} } @Inproceedings { Böttger2018, author = {B{\{\dq}o}ttger, Sven and Kleemann, Markus and Ipsen, Svenja and Kuhlemann, Ivo and Bruder, Ralf and Ernst, Floris}, title = {Robotic ultrasound platform for automation and standardization of the screening process}, abstract = {Due to the considerable skill and expertise it requires, ultrasound image acquisition and diagnostics are difficult to be done separately, neither in real time nor retrospectively. Automated ultrasound image ac-quisition could potentially overcome this operator dependency. For the automation and standardization of the ultrasound imaging process, we are currently developing a medical robotic device platform. A prototype of this robot-supported US platform was produced, on which a suitable examination procedure for the abdominal aortic aneurysm screening is to be developed. Two core technologies were combined therefor: - A force-sensitive 7-DoF robot arm (KUKA LBR iiwa), which can position both automatically and manual-ly over a certain target area on the body surface. The arm has collision avoidance and ensures the dynam-ic force-controlled posture of the transducer to the patient. - Three-dimensional ultrasound is realized by matrix transducers and appropriate calculation algorithms on a modified the US station (GE Vivid 7). It enables recording of large areas at high frame rates. Thus the target as well as surrounding areas and nearby navigation points can be recorded simultaneously. The registration of the body surface is carried out by laser scanning, wherein additionally the movement tracking can be performed with an optical tracking system. Using a US phantom (BluePhantom FAST Trauma) the system was tested and verified. The result is a 4D volume data set for the physician-assisted diagnostic evaluation. The process delivered reproducible real-time visualization results on a workstation where the volumes were simultaneously visualized and stored. Automated US diagnostics should help to reduce the temporal and spatial binding of clinical resources in the future, thereby enabling better reproducibility of imaging. The device platform will serve as the basis for further automated US diagnostics and therapy procedures.}, year = {2018}, series = {6th Spring Meeting on basic science of the European Society for Vascular Surgery} } @Inproceedings { vonHaxthausen2018b, author = {Haxthausen, Felix and Ernst, Floris and Bruder, Ralf and Garc{\'i}a-V{\'a}zquez, Ver{\'o}nica}, title = {Streaming of 3D Data from Ultrasound Systems to Augmented Reality Glasses (HoloLens)}, year = {2018}, isbn = {978-3-00-060786-8}, publisher = {Thomas Neumuth, Andreas Melzer, Claire Chalopin}, address = {Leipzig (Germany)}, pages = {2-3}, tags = {UGRT} } @Article { Hagenah2018a, author = {Hagenah, Jannis and Scharfschwerdt, Michael and Ernst, Floris}, title = {Towards personalized aortic valve prostheses - A sparse representation of the individual leaflet shape}, abstract = {Aim: Promising results in the field of tissue engineering move the goal of the fabrication of personalized aortic valve prostheses within reach. However, there is no study on the degree of personalization that is needed to find a trade-off between the patient's outcome and economical and logistical issues. A pattern analysis study could reveil generic valve types using clustering techniques. One problem in performing such a study is the lack of a sparse, unified representation of the individual aortic valve shape to perform clustering without facing the curse of dimensionality. We present such a description which is derived model-free and directly from experimental data. Methods: We set up a suitable data base, consiting of photographs of the leaflets of 10 porcine aortic valves (i.e. 30 leaflet images). We segmented the leaflets and used principal component analysis on these images for dimensionality reduction. Furthermore, we analyzed the minimal number of values in the representation preserving all relevant information to reconstruct the leaflet shape. The Jaccard coefficient and the Hausdorff distance served as evaluation metrics to compare the reconstructed images with their ground truth. Results: The shape reconstruction accuracy saturates at 13 incorporated principal components with acceptable error values (Jaccard above 0.94, Hausdorff below 1 mm). Hence, we could show that an accurate representation of the shape of one aortic valve leaflet is possible with no more than 13 values, resulting in 39 parameters for one complete valve. This relatively lowdimensional representation makes the search for geometrical patterns possible and has the potential to present the basis for economical valve prostheses personalization.}, year = {2018}, issn = {ISSN 0276-6574}, journal = {Computing in Cardiology}, volume = {45} } @Article { Moustakis2018, author = {Moustakis, Christos and Chan, Mark K. H. and Kim, Jinkoo and Nilsson, Joakim and Bergman, Alanah and Bichay, Tewfik J. and Palazon Cano, Isabel and Cilla, Savino and Deodato, Francesco and Doro, Raffaela and Dunst, J{\{\dq}u}rgen and Eich, Hans Theodor and Fau, Pierre and Fong, Ming and Haverkamp, Uwe and Heinze, Simon and Hildebrandt, Guido and Imhoff, Detlef and Klerck, Erik and K{\{\dq}o}hn, Janett and Lambrecht, Ulrike and Loutfi-Krauss, Britta and Ebrahimi, Fatemeh and Masi, Laura and Mayville, Alan H. and Mestrovic, Ante and Milder, Maaike and Morganti, Alessio G. and Rades, Dirk and Ramm, Ulla and R{\{\dq}o}del, Claus and Siebert, Frank-Andre and Toom, Wilhelm and Wang, Lei and Wurster, Stefan and Schweikard, Achim and Soltys, Scott G. and Ryu, Samuel and Blanck, Oliver}, title = {Treatment planning for spinal radiosurgery}, year = {2018}, issn = {1439-099X}, DOI = {10.1007/s00066-018-1314-2}, journal = {Strahlentherapie und Onkologie}, file_url = {https://doi.org/10.1007/s00066-018-1314-2}, note = {=2018/05/25} } @Article { García-Vázquez2018, author = {Garc{\'i}a-V{\'a}zquez, Ver{\'o}nica and Haxthausen, Felix and J{\{\dq}a}ckle, Sonja and Schumann, Christian and Kuhlemann, Ivo and Bouchagiar, Juljan and H{\{\dq}o}fer, Anna-Catharina and Matysiak, Florian and H{\{\dq}u}ttmann, Gereon and Goltz, Jan Peter and Kleemann, Markus and Ernst, Floris and Horn, Marco}, title = {Navigation and visualisation with HoloLens in endovascular aortic repair}, year = {2018}, journal = {Innovative Surgical Sciences}, file_url = {https://www.degruyter.com/view/j/iss.ahead-of-print/iss-2018-2001/iss-2018-2001.xml} } @Inproceedings { Matysiak2018, author = {Matysiak, Florian and Bouchagiar, Juljan and H{\{\dq}o}fer, Anna-Catharina and Ernst, Floris and Goltz, Jan Peter and Stahlberg, Erik and Kleemann, Markus and Horn, Marco}, title = {New navigation method for the treatment of aneurysms: Navigated endovascular aortic repair (Nav EVAR)}, year = {2018}, volume = {56}, pages = {e18}, number = {5} } @Inproceedings { ibes_18, author = {Ipsen, Svenja and Bruder, Ralf and Ernst, Floris and Schweikard, Achim}, title = {WE-HI-KDBRB1-02: Characterization of 4D ultrasound systems with streaming interfaces for real-time motion compensation in radiotherapy}, abstract = {Purpose: Real-time target localization using fast volumetric ultrasound (4D-US) is being increasingly investigated for motion compensation. New 4D-US systems with matrix arrays can achieve much higher framerates than mechanical 3D probes. In this study, three current systems with streaming capabilities were assessed regarding their suitability for real-time tracking tasks. Methods: Maximum volume sizes, volumetric framerates and image quality metrics were compared for a GE Vivid7 dimension (3V probe), a GE Vivid E95 (4V) and a Philips Epiq7 (X6-1) at similar settings. As an indicator for spatial resolution, the mean full width at half maximum (FWHM) was measured in a commercial wire phantom in each direction (0.2mm wire diameter). The speckle signal-to-noise ratio (SSNR) and the contrast-to-noise ratio (CNR) were measured in a calibration phantom with a spherical target and in an abdominal phantom. Results: At 150mm depth, the Vivid7 covered a maximum area of 122x84mm2 (azimuth, elevation) at 13.8Hz. For a similar size, E95 acquired at 20.9Hz and Epiq7 at 8Hz. Set to maximum, the area increased to 266x266mm2 at 3Hz for E95 and to 294x290mm at 2Hz for Epiq7. The mean FWHM in the smaller volumes was 2.8mm (E95), 3.0mm (Epiq7) and 3.1mm (Vivid7), which increased to 3.1mm (E95) and 3.4mm (Epiq7) for maximum volume sizes. The Epiq7 had superior SSNR values throughout all experiments, leading to smoother homogenous regions compared to E95 or Vivid7 volumes. In contrast, CNR was target-dependent. In the kidney tumor, CNR was higher for E95 and Vivid7 while Epiq7 had higher CNR in the spherical target. Conclusion: All three 4D-US systems achieved higher framerates than the currently available commercial solution, with newer systems (E95, Epiq7) covering larger volumes. While the E95 showed the highest temporal resolution, the Epiq7 had superior SSNR. Their individual strengths will be further investigated in tracking experiments and in-vivo.}, year = {2018}, booktitle = {Medical Physics}, volume = {45}, series = {Annual Meeting of the American Association of Physicists in Medicine (AAPM)}, pages = {E644}, number = {6}, tags = {MCRT UGRT} } @Inproceedings { GondaliyaPetersRueckert, author = {Rueckert, Elmar}, title = {Learning to Categorize Bug Reports with LSTM Networks}, year = {2018}, isbn = {978-1-61208-671-2}, publisher = {XPS (Xpert Publishing Services)}, address = {Nice, France}, pages = {6}, file_url = {https://rob.ai-lab.science/wp/VALID2018Gondaliya.pdf}, note = {October 14-18, 2018} } @Inproceedings { 8550134, author = {Nguyen, Ngoc Thinh and Prodan, Ionela and Lef{\'e}vre, Laurent}, title = {Effective angular constrained trajectory generation for thrust-propelled vehicles}, year = {2018}, DOI = {10.23919/ECC.2018.8550134}, booktitle = {2018 European Control Conference (ECC)}, pages = {1833-1838}, keywords = {Trajectory;Angular velocity;Vehicle dynamics;Aerodynamics;Propulsion;Acceleration;Constrained trajectory generation;Thrust-propelled underactuated vehicles;Angular constraints} } @Article { khwe_18, author = {Koch, Martin A. and Hagenah, Jannis and Wattenberg, Maximilian and Ernst, Floris}, title = {Learning motion artefacts in non - Cartesian magnetic resonance imaging}, abstract = {As magnetic resonance imaging is a relatively slow imaging method, motion artefacts are a major problem in many clinical applications. Motion sensitivity and appearance of image artefacts can vary considerably between imaging sequences and experimental conditions. If the raw data collection is performed in a radial fashion or using a stripe in kspace that is subsequently rotated about the origin (PROPELLER sequence), the sensitivity to motion is low. Although these sequences proved to be relatively insensitive to motion, the motion-correcting techniques built into the image reconstruction are not always robust: they fail in some situations. In addition, motion during this type of acquisition can lead to artefacts that are less easy to recognize in the final images when compared to the so-called Cartesian order of acquisition in k-space. Here, learning algorithms are used to detect motion degrading image quality. The detection algorithm can be used to inform motion correction approaches or to trigger data rejection and re-acquisition. The algorithm is trained and tested using a home-built phantom with MR-visible parts that can perform computer-controlled, reproducible movements in a clinical MR system. The motion is induced with an MR-compatible setup. The motion traces are known exactly and can be repeated accurately. These traces -- together with the corresponding motioncorrupted k-space sequences as well as their non-corrupted counterparts -- are used to train a deep convolutional neural network.}, year = {2018}, DOI = {10.1515/bmt-2018-6051}, journal = {Biomedical Technology/Biomedizinische Technik}, volume = {63}, pages = {S280}, number = {S1}, file_url = {https://doi.org/10.1515/bmt-2018-6051} } @Inproceedings { ips18, author = {Ipsen, Svenja}, title = {[I094] Ultrasound guidance in radiotherapy - Renaissance through innovation}, abstract = {Ultrasound has been used for motion compensation in radiotherapy since the late 1990s. It does not utilize ionizing radiation and can provide real-time imaging at a low cost. Early systems relied on freehand 2D imaging and facilitated soft-tissue image guidance for the first time. However, they suffered from strong user dependency and limited positioning accuracy, slowing their widespread utilization. Many of their drawbacks were overcome when 3D ultrasound was introduced. Innovations in hard- and software have led to the latest generation of ultrasound systems which can provide high volumetric framerates with superior image quality by using matrix array transducers. Due to the large field-of-view and the high spatiotemporal resolution, these new systems are ideally suited for real-time motion compensation tasks. By accessing the volume data directly, it is possible to interface with dynamic MLC tracking to follow tumor motion with low latency and good dosimetric results. To aid unexperienced users with the setup, tools were developed to calculate the ideal probe position and guide the user through the anatomy with real-time visual feedback or the use of augmented reality applications. Furthermore, robotic solutions for probe positioning and stabilization are currently being investigated in order to eliminate user dependency, one of the biggest challenges in ultrasound imaging. Recent developments in technology have facilitated such new approaches and helped overcome some of the previous drawbacks. The evident benefits of ultrasound imaging make it a promising modality for real-time motion compensation in radiotherapy of soft tissues.}, year = {2018}, DOI = {10.1016/j.ejmp.2018.06.166}, booktitle = {Physica Medica}, volume = {52}, publisher = {Elsevier}, series = {European Federation of Organisations For Medical Physics (EFOMP)}, pages = {57}, number = {Suppl 1 - Abstracts from the 2nd European Congress of Medical Physics (ECMP)}, tags = {MCRT UGRT}, file_url = {https://doi.org/10.1016/j.ejmp.2018.06.166} } @Article { Hagenah2018b, author = {Hagenah, Jannis and Evers, Tizian and Scharfschwerdt, Michael and Schweikard, Achim and Ernst, Floris}, title = {An SVR-based Data-driven Leaflet Modeling Approach for Personalized Aortic Valve Prosthesis Development}, abstract = {Aim: While the aortic valve geometry is highly patient-specific, state-of-the-art prostheses cannot reproduce this individual geometry. One challenge in manufacturing personalized prostheses is the mapping from the curved 3D shape extracted from imaging modalities to the planar 2D leaflet contour that is cut out of the fabrication material. We propose the use of machine learning to estimate this mapping completely data-driven. Methods: We set up a database to derive and evaluate leaflet shape models. First, 3D ultrasound images of ex-vivo porcine valves were acquired under realistic pressure to extract geometric key parameters describing the individual geometry. In a second step, the valves' leaflets were cut out, spread on an illuminated plate and photographed in this state. From these images, the leaflet shape was extracted using segmentation and edge detection. The resulting database (10 heart valves, i.e. 30 leaflet images) allows the derivation of a data-driven leaflet shape model using Support Vector Regression. This method was evaluated using 10-fold cross validation by calculating the average symmetric contour distance (ascd). Additionally, an existing geometric leaflet shape model from Sievers et al. was evaluated on the dataset. Results: The data-driven approach provided an acceptable leaflet shape estimation error of 0.58 mm mean ascd and clearly outperformed the existing model (2.79 mm mean ascd). Our study indicates that planar leaflet shape estimation based on 3D image data is possible and presents an important step towards personalized aortic valve prostheses.}, year = {2018}, issn = {ISSN 0276-6574}, journal = {Computing in Cardiology}, volume = {45} } @Article { Hagenah2018d, author = {Hagenah, Jannis and Heinrich, Mattias and Ernst, Floris}, title = {Deep transfer learning for aortic root dilation identification in 3D ultrasound images}, year = {2018}, journal = {Current Directions in Biomedical Engineering}, volume = {4}, pages = {71-74}, number = {1} } @Inproceedings { ibk18, author = {Ipsen, Svenja and Bruder, Ralf and Kuhlemann, Ivo and Jauer, Philipp and Motisi, Laura and Cremers, Florian and Ernst, Floris and Schweikard, Achim}, title = {A visual probe positioning tool for 4D ultrasound-guided radiotherapy}, abstract = {Ultrasound (US) guidance is a rapidly growing area in image-guided radiotherapy. For motion compensation, the therapy target needs to be visualized with the US probe to continuously determine its position and adapt for shifts. While US has obvious benefits such as real-time capability and proven safety, one of the main drawbacks to date is its user dependency - high quality results require long years of clinical experience. To provide positioning assistance for the setup of US equipment by non-experts, we developed a visual guidance tool combining real-time US volume and CT visualization in a geometrically calibrated setup. By using a 4D US station with real-time data access and an optical tracking system, we achieved a calibration accuracy of 1.2 mm and a mean 2D contour distance of 1.7 mm between organ boundaries identified in US and CT. With this low calibration error as well as the good visual alignment of the structures, the developed probe positioning tool could be a valuable aid for ultrasound-guided radiotherapy and other interventions by guiding the user to a suitable acoustic window while potentially improving setup reproducibility.}, year = {2018}, issn = {1558-4615}, DOI = {10.1109/EMBC.2018.8512390}, series = {IEEE Engineering in Medicine and Biology Society (EMBS)}, pages = {883-886}, tags = {MCRT UGRT}, file_url = {https://doi.org/10.1109/EMBC.2018.8512390} } @Article { jauer2018, author = {Jauer, Philipp and Kuhlemann, Ivo and Bruder, Ralf and Schweikard, Achim and Ernst, Floris}, title = {Efficient Registration of High-Resolution Feature Enhanced Point Clouds}, abstract = {We present a novel framework for rigid point cloud registration. Our approach is based on the principles of mechanics and thermodynamics. We solve the registration problem by assuming point clouds as rigid bodies consisting of particles. Forces can be applied between both particle systems so that they attract or repel each other. These forces are used to cause rigid-body motion of one particle system toward the other, until both are aligned. The framework supports physics-based registration processes with arbitrary driving forces, depending on the desired behaviour. Additionally, the approach handles feature-enhanced point clouds, e.g. by colours or intensity values. Our framework is freely accessible for download. In contrast to already existing algorithms, our contribution is to precisely register high-resolution point clouds with nearly constant computational effort and without the need for pre-processing, subsampling or pre-alignment. At the same time, the quality is up to 28% higher than for state-of-the-art algorithms and up to 49% higher when considering feature-enhanced point clouds. Even in the presence of noise, our registration approach is one of the most robust, on par with state-of-the-art implementations.}, year = {2018}, issn = {0162-8828}, DOI = {10.1109/tpami.2018.2831670}, journal = {IEEE Transactions on Pattern Analysis and Machine Intelligence}, volume = {41}, pages = {1102-1115}, number = {5}, keywords = {Cameras; Cloud computing; Color; Coulomb's law; CUDA; efficiency; Features; Graphics processors; High-Resolution; Iterative closest point algorithm; Many-Particle systems; Monte Carlo; Newton's law; point cloud; registration; Rigid; Rigid-Body dynamics; Robustness; Sensors; Simulated Annealing; Three-dimensional displays}, file_url = {https://doi.org/10.1109/tpami.2018.2831670} } @Article { Hagenah2018c, author = {Hagenah, Jannis and Hillemanns, Maximilian and H{\{\dq}u}ttmann, Gereon and Ernst, Floris and Schweikard, Achim}, title = {Image-based analysis of individual movement patterns of C. elegans}, year = {2018}, journal = {International Conference on Systems Biology 2018} } @Article { SosicRueckertPetersZoubirKoeppl2018, author = {Sosic, Adrian and Rueckert, Elmar and Peters, Jan and Zoubir, Abdelhak M.}, title = {Inverse Reinforcement Learning via Nonparametric Spatio-Temporal Subgoal Modeling}, year = {2018}, journal = {Journal of Machine Learning Research (JMLR)} } @Article { lci18, author = {Lydiard, Suzanne and Caillet, Vincent and Ipsen, Svenja and O'Brien, Ricky T. and Blanck, Oliver and Poulsen, Per Rugaard and Booth, Jeremy and Keall, Paul J.}, title = {Investigating MLC tracking in stereotactic arrhythmic radioablation (STAR) treatments for atrial fibrillation}, abstract = {Stereotactic arrhythmia radioablation (STAR) is an emerging treatment option for atrial fibrillation (AF). However, it faces possibly the most challenging motion compensation scenario: both respiratory and cardiac motion. Multi-leaf collimator (MLC) tracking is clinically used for lung cancer treatments but its capabilities with intracardiac targets is unknown. We report the first experimental results of MLC tracking for intracardiac targets. Five AF STAR plans of varying complexity were created. All delivered 5^10 Gy to both pulmonary vein antra. Three healthy human target motion trajectories were acquired with ultrasound and programmed into a motion platform. Plans were delivered with a linac to a dosimeter placed on the motion platform. For each motion trace, each plan was delivered with no MLC tracking and with MLC tracking with and without motion prediction. Dosimetric accuracy was assessed with $\gamma$-tests and dose metrics. MLC tracking improved the dosimetric accuracy in all measurements compared to non-tracking experiments. The average 2%/2mm $\gamma$-failure rate was improved from 13.1% with no MLC tracking to 5.9% with MLC tracking (p<0.001) and 7.2% with MLC tracking and no motion prediction (p<0.001). MLC tracking significantly improved the consistency between planned and delivered target dose coverage. The 95% target coverage with the prescription dose (V100) was improved from 60% of deliveries with no MLC tracking to 80% of deliveries with MLC tracking (p=0.03). MLC tracking was successfully implemented for the first time for intracardiac motion compensation. MLC tracking provided significant dosimetric accuracy improvements in AF STAR experiments, even with challenging cardiac and respiratory-induced target motion and complex treatment plans. These results warrant further investigation and optimisation of MLC tracking for intracardiac target motion compensation.}, year = {2018}, DOI = {10.1088/1361-6560/aadf7c}, journal = {Physics in Medicine and Biology}, volume = {63}, pages = {195008}, number = {19}, tags = {MCRT}, file_url = {https://doi.org/10.1088/1361-6560/aadf7c} } @Article { lim18, author = {Lowther, Nicholas and Ipsen, Svenja and Marsh, Steven and Blanck, Oliver and Keall, Paul J.}, title = {Investigation of the XCAT phantom as a validation tool in cardiac MRI tracking algorithms}, abstract = {Purpose: To describe our magnetic resonance imaging (MRI) simulated implementation of the 4D digital extended cardio torso (XCAT) phantom to validate our previously developed cardiac tracking techniques. Real-time tracking will play an important role in the non-invasive treatment of atrial fibrillation with MRI-guided radiosurgery. In addition, to show how quantifiable measures of tracking accuracy and patient-specific physiology could influence MRI tracking algorithm design. Methods: Twenty virtual patients were subjected to simulated MRI scans that closely model the proposed real-world scenario to allow verification of the tracking technique's algorithm. The generated phantoms provide ground-truth motions which were compared to the target motions output from our tracking algorithm. The patient-specific tracking error, ep, was the 3D difference (vector length) between the ground-truth and algorithm trajectories. The tracking errors of two combinations of new tracking algorithm functions that were anticipated to improve tracking accuracy were studied. Additionally, the correlation of key physiological parameters with tracking accuracy was investigated. Results: Our original cardiac tracking algorithm resulted in a mean tracking error of 3.7 ± 0.6 mm over all virtual patients. The two combinations of tracking functions demonstrated comparable mean tracking errors however indicating that the optimal tracking algorithm may be patient-specific. Conclusions: Current and future MRI tracking strategies are likely to benefit from this virtual validation method since no time-resolved 4D ground-truth signal can currently be derived from purely image-based studies.}, year = {2018}, DOI = {10.1016/j.ejmp.2017.12.003}, journal = {Physica Medica}, volume = {45}, pages = {44-51}, number = {1}, keywords = {Cardiac tracking; Digital phantom; MRI-guided radiotherapy; Tracking evaluation}, tags = {MCRT}, file_url = {https://doi.org/10.1016/j.ejmp.2017.12.003} } @Inproceedings { ibw17, author = {Ipsen, Svenja and Bruder, Ralf and Worm, Esben Schj{\o}dt and Hansen, Rune and Poulsen, Per Rugaard and H{\o}yer, Morten and Schweikard, Achim}, title = {MO-DE-708-6: In-vivo comparison of real-time 4D ultrasound tracking with electromagnetic transponders in the liver during free breathing}, abstract = {Purpose: The feasibility of ultrasound-guided MLC tracking has recently been shown in phantom experiments but in-vivo validation remains a challenging task since a reliable ground truth is difficult to obtain. Manual annotations in ultrasound show high variability while comparisons with other target localization modalities to date were limited to static setup scenarios. The aim of this study is to enable in-vivo accuracy assessments of ultrasound tracking by simultaneous acquisition of real-time electromagnetic (EM) transponder signals. Methods: 4D ultrasound was acquired during free breathing over 8 minutes post-treatment in an SBRT patient with EM transponders implanted in the liver. The ultrasound probe was fixed with a metal holder, visualizing the transponders inside the patient with a framerate of 12Hz. EM tracking was simultaneously acquired at 8Hz per transponder. Ultrasound tracking was performed offline using fast template matching to localize the transponders. Spatial alignment of the different coordinate systems was obtained by calculating the rigid transform between the 3D tracking trajectories. The 3D root-mean-square error (RMSE) was calculated to evaluate the resulting alignment. Results: Strong interference from the EM system caused varying high-intensity streaks in the ultrasound volumes. An online filter iterating over the previous volumes was developed to facilitate stable tracking. The EM signal acquisition was highly disturbed due to the probe holder position close to the antenna, resulting in only one sparsely tracked transponder. However, six synchronized breathing cycles over 25.7s were obtained. The calculated rigid alignment of the tracking signals was close to expected values from the physical setup and the low RMSE of 0.55mm demonstrates good agreement between ultrasound tracking and the EM reference signal. Conclusion: An approach for in-vivo comparison between real-time ultrasound and EM tracking was developed. Having identified and minimized the mutual disturbance factors, this could provide a valuable tool for future ultrasound tracking validation.}, year = {2017}, booktitle = {Medical Physics}, volume = {44}, series = {Annual Meeting fo the American Association of Physicists in Medicine (AAPM)}, pages = {3069}, number = {6}, tags = {MCRT UGRT} } @Article { kuhlemann2017b, author = {Kuhlemann, Ivo and Kleemann, Markus and Jauer, Philipp and Schweikard, Achim and Ernst, Floris}, title = {Towards X-ray free endovascular interventions - using HoloLens for on-line holographic visualisation}, abstract = {A major challenge during endovascular interventions is visualising the position and orientation of the catheter being inserted. This is typically achieved by intermittent X-ray imaging. Since the radiation exposure to the surgeon is considerable, it is desirable to reduce X-ray exposure to the bare minimum needed. Additionally, transferring two-dimensional (2D) X-ray images to 3D locations is challenging. The authors present the development of a real-time navigation framework, which allows a 3D holographic view of the vascular system without any need of radiation. They extract the patient's surface and vascular tree from pre-operative computed tomography data and register it to the patient using a magnetic tracking system. The system was evaluated on an anthropomorphic full-body phantom by experienced clinicians using a four-point questionnaire. The average score of the system (maximum of 20) was found to be 17.5. The authors' approach shows great potential to improve the workflow for endovascular procedures, by simultaneously reducing X-ray exposure. It will also improve the learning curve and help novices to more quickly master the required skills.}, year = {2017}, issn = {2053-3713}, DOI = {10.1049/htl.2017.0061}, journal = {Healthcare Technology Letters}, volume = {4}, publisher = {Institution of Engineering and Technology}, pages = {184-187}, number = {5}, file_url = {https://doi.org/10.1049/htl.2017.0061} } @Article { Ipsen2017, author = {Ipsen, Svenja and Bruder, Ralf and Worm, Esben Schj{\o}dt and Hansen, Rune and Poulsen, Per Rugaard and H{\o}yer, Morten and Schweikard, Achim}, title = {Simultaneous acquisition of 4D ultrasound and wireless electromagnetic tracking for in-vivo accuracy validation}, abstract = {Ultrasound is being increasingly investigated for real-time target localization in image-guided interventions. Yet, in-vivo validation remains challenging due to the difficulty to obtain a reliable ground truth. For this purpose, real-time volumetric (4D) ultrasound imaging was performed simultaneously with electromagnetic localization of three wireless transponders implanted in the liver of a radiotherapy patient. 4D ultrasound and electromagnetic tracking were acquired at framerates of 12Hz and 8Hz, respectively, during free breathing over 8 min following treatment. The electromagnetic antenna was placed directly above and the ultrasound probe on the right side of the patient to visualize the liver transponders. It was possible to record 25.7 s of overlapping ultrasound and electromagnetic position data of one transponder. Good spatial alignment with 0.6 mm 3D root-mean-square error between both traces was achieved using a rigid landmark transform. However, data acquisition was impaired since the electromagnetic tracking highly influenced the ultrasound equipment and vice versa. High intensity noise streaks appeared in the ultrasound scan lines irrespective of the chosen frequency (1.7-3.3 MHz, 2/4 MHz harmonic). To allow for target visualization and tracking in the ultrasound volumes despite the artefacts, an online filter was designed where corrupted pixels in the newest ultrasound frame were replaced with non-corrupted pixels from preceding frames. Aside from these artefacts, the recorded electromagnetic tracking data was fragmented and only the transponder closest to the antenna could be detected over a limited period of six consecutive breathing cycles. This problem was most likely caused by interference from the metal holder of the ultrasound probe and was solved in a subsequent experiment using a 3D-printed non-metal probe fixation. Real-time wireless electromagnetic tracking was compared with 4D ultrasound imaging in-vivo for the first time. For stable tracking, large metal components need to be avoided during data acquisition and ultrasound filtering is required.}, year = {2017}, DOI = {10.1515/cdbme-2017-0016}, journal = {Current Directions in Biomedical Engineering}, volume = {3}, pages = {75-78}, number = {2}, keywords = {4D ultrasound tracking; Image guidance; liver SBRT; motion compensation; Radiotherapy}, tags = {MCRT UGRT}, file_url = {https://doi.org/10.1515/cdbme-2017-0016} } @Article { Hagenah2017c, author = {Hagenah, Jannis and Schweikard, Achim and Metzner, Christoph}, title = {Simplified deformation models for personalization of valve-sparing aortic root reconstruction}, year = {2017}, journal = {10. Jahrestagung der Deutschen Gesellschaft fuer Biomechanik}, pages = {120} } @Article { aibe_17, author = {Al-Badri, Mohammed and Ipsen, Svenja and B{\{\dq}o}ttger, Sven and Ernst, Floris}, title = {Robotic 4D ultrasound solution for real-time visualization and teleoperation}, abstract = {Automation of the image acquisition process via robotic solutions offer a large leap towards resolving ultrasound's user-dependency. This paper, as part of a larger project aimed to develop a multipurpose 4d-ultrasonic force-sensitive robot for medical applications, focuses on achieving real-time remote visualisation for 4d ultrasound image transfer. This was possible through implementing our software modification on a GE Vivid 7 Dimension workstation, which operates a matrix array probe controlled by a KUKA LBR iiwa 7 7-DOF robotic arm. With the help of robotic positioning and the matrix array probe, fast volumetric imaging of target regions was feasible. By testing ultrasound volumes, which were roughly 880 kB in size, while using gigabit Ethernet connection, a latency of ∼57 ms was achievable for volume transfer between the ultrasound station and a remote client application, which as a result allows a frame count of 17.4 fps. Our modification thus offers for the first time real-time remote visualization, recording and control of 4d ultrasound data, which can be implemented in teleoperation.}, year = {2017}, issn = {2364-5504}, journal = {Current Directions in Biomedical Engineering}, volume = {3}, publisher = {De Gruyter}, pages = {559-561}, number = {2}, keywords = {4d; Real-Time; robotic; ultrasound}, tags = {UGRT}, note = {doi: https://doi.org/10.1515/cdbme-2017-0116} } @Article { NGUYEN20176971, author = {Nguyen, Ngoc Thinh and Prodan, Ionela and Stoican, Florin and Lef{\'e}vre, Laurent}, title = {Reliable nonlinear control for quadcopter trajectory tracking through differential flatness}, abstract = {This paper addresses the trajectory tracking problem for a quadcopter system under nominal and fault-affected scenarios (in the latter case, due to stuck actuator(s)). Differential flatness is employed for trajectory generation and control design. The particularity resides in that a full parametrization of the states and inputs is given without any assumptions or simplifications on the quadcopter dynamics. Furthermore, using the properties of flatness and a combination between computed torque control and feedback linearization, a two-layer control design is proposed. The tracking performances and stability gurantees are analyzed for nominal and faulty functioning under extensive simulations.}, year = {2017}, issn = {2405-8963}, journal = {IFAC-PapersOnLine}, volume = {50}, pages = {6971-6976}, number = {1}, keywords = {computed torque control; Differential flatness; Fault events; feedback linearization; Quadcopter unmanned vehicle; Trajectory tracking}, file_url = {https://www.sciencedirect.com/science/article/pii/S2405896317318712}, note = {doi: https://doi.org/10.1016/j.ifacol.2017.08.1338} } @Inproceedings { mbse_17, author = {Manit, Jirapong and Bremer, Christina and Schweikard, Achim and Ernst, Floris}, title = {Patient identification using a near-infrared laser scanner: Image-Guided Procedures, Robotic Interventions, and Modeling}, year = {2017}, DOI = {10.1117/12.2254963}, volume = {10135}, publisher = {SPIE}, address = {Orlando, FL}, series = {Proceedings of SPIE}, pages = {101352L}, tags = {HPHT}, file_url = {https://doi.org/10.1117/12.2254963} } @Inproceedings { 7984183, author = {Nguyen, Ngoc Thinh and Prodan, Ionela and Lef{\'e}vre, Laurent}, title = {Multi-layer optimization-based control design for quadcopter trajectory tracking}, year = {2017}, DOI = {10.1109/med.2017.7984183}, pages = {601-606}, file_url = {https://doi.org/10.1109/med.2017.7984183} } @Article { gerlach2017, author = {Gerlach, Stefan and Kuhlemann, Ivo and Ernst, Floris and F{\{\dq}u}rweger, Christoph and Schlaefer, Alexander}, title = {Impact of robotic ultrasound image guidance on plan quality in SBRT of the prostate}, abstract = {Objective: Ultrasound provides good image quality, fast volumetric imaging and is established for abdominal image guidance. Robotic transducer placement may facilitate intrafractional motion compensation in radiation therapy. We consider integration with the CyberKnife and study whether the kinematic redundancy of a seven-degrees-of-freedom robot allows for acceptable plan quality for prostate treatments. Methods: Reference treatment plans were generated for 10 prostate cancer cases previously treated with the CyberKnife. Considering transducer and prostate motion by different safety margins, 10 different robot poses, and 3 different elbow configurations, we removed all beams colliding with robot or transducer. For each combination, plans were generated using the same strict dose constraints and the objective to maximize the target coverage. Additionally, plans for the union of all unblocked beams were generated. Results: In 9 cases the planning target coverage with the ultrasound robot was within 1.1 percentage points of the reference coverage. It was 1.7 percentage points for one large prostate. For one preferable robot position, kinematic redundancy decreased the average number of blocked beam directions from 23.1 to 14.5. Conclusion: The impact of beam blocking can largely be offset by treatment planning and using a kinematically redundant robot. Plan quality can be maintained by carefully choosing the ultrasound robot position and pose. For smaller planning target volumes the difference in coverage is negligible for safety margins of up to 35 mm. Advances in knowledge: Integrating a robot for online intrafractional image guidance based on ultrasound can be realized while maintaining acceptable plan quality for prostate cancer treatments with the CyberKnife.}, year = {2017}, DOI = {10.1259/bjr.20160926}, journal = {The British Journal of Radiology}, volume = {90}, pages = {20160926}, number = {1078}, tags = {UGRT}, file_url = {https://doi.org/10.1259/bjr.20160926}, note = {PMID: 28749165} } @Inproceedings { lci17, author = {Lydiard, Suzanne and Caillet, Vincent and Ipsen, Svenja and O'Brien, Ricky T. and Bruder, Ralf and Blanck, Oliver and Booth, Jeremy and Keall, Paul J.}, title = {MO-AB-FS4-10: First Cardiac Radiosurgery MLC Tracking Results}, abstract = {Purpose: Cardiac Radiosurgery has recently been proposed as a treatment option for Atrial Fibrillation (AF). However, it faces possibly the most challenging target tracking scenario: both respiratory and cardiac motion. MLC tracking is clinically used for respiratory motion compensation in lung cancer treatments but its capabilities with cardiac motion is unknown. We report the first results of MLC tracking for cardiac targets. Methods: The following steps were followed: i) Four dual arc AF Radiosurgery plans of varying complexity were created; three VMAT with target expansions of 0mm, 3mm and 5mm respectively, and one Dynamic Conformal Arc (DCA). All delivered 5x10Gy to both pulmonary vein antra. ii) Human target motion trajectories were acquired with ultrasound from three healthy volunteers and programmed into a motion platform. iii) Plans were delivered with a standard linac to a biplanar diode array dosimeter placed on the motion platform. For each motion trace, each plan was delivered without MLC tracking, with MLC tracking, and with MLC tracking and motion prediction. Real-time target position was acquired from Calypso beacons attached to the dosimeter. Static dosimetric measurements with no motion platform movement were also acquired for each plan. iv) Dosimetric accuracy was assessed with I³-tests using the static measurement as reference. Results: MLC tracking improved dosimetric accuracy in all measurements. The average 2%/2mm³-fail rate was improved from 15% without MLC tracking to 7.5% with MLC tracking (p=0.06) and 6.4% with MLC tracking and motion prediction (p=0.05). The average 3%/3mm³-fail rate was improved from 4.6% without tracking to 2.8% with MLC tracking (p=0.06) and 2.7% with MLC tracking and motion prediction (p=0.05). Conclusion: MLC tracking was successfully applied to compensate for cardiac target motion during AF Radiosurgery. Significant dosimetric accuracy improvements were seen despite challenging target motion and complex treatment plans, warranting further development of this technique.}, year = {2017}, booktitle = {Medical Physics}, volume = {44}, series = {Annual Meeting fo the American Association of Physicists in Medicine (AAPM)}, pages = {3034}, number = {6}, tags = {MCRT} } @Article { Hagenah2017b, author = {Hagenah, Jannis and Evers, Tizian and Scharfschwerdt, Michael and Schweikard, Achim}, title = {Data-driven leaflet modeling for personalized aortic valve prostheses development}, year = {2017}, journal = {Biomedical Engineering / Biomedizinische Technik}, volume = {62}, pages = {403-411} } @Article { Hagenah2017d, author = {Hagenah, Jannis and Evers, Tizian and Scharfschwerdt, Michael and Schweikard, Achim}, title = {An experimental method for evaluation of aortic leaflet shape models for personalized aortic valve prostheses development}, year = {2017}, journal = {10. Jahrestagung der Deutschen Gesellschaft fuer Biomechanik}, pages = {114} } @Article { Hagenah2017a, author = {Hagenah, Jannis and Scharfschwerdt, Michael and Schweikard, Achim and Metzner, Christoph}, title = {Combining Deformation Modeling and Machine Learning for Personalized Prosthesis Size Prediction in Valve-Sparing Aortic Root Reconstruction}, year = {2017}, journal = {Lecture Notes in Computer Science}, volume = {10263}, pages = {461-470}, note = {Pop M., Wright G. (eds) Functional Imaging and Modelling of the Heart. FIMH 2017.} } @Inproceedings { kuhlemann2017, author = {Kuhlemann, Ivo and Ernst, Floris}, title = {A safety module for active joint limit avoidance and intuitive hand guidance of a robotic ultrasound system}, year = {2017}, volume = {12}, publisher = {Springer}, series = {CARS 2017}, pages = {38-39}, number = {1}, keywords = {IGRT; medical robotics; Robotized ultrasound imaging; Ultrasound tracking}, tags = {UGRT} } @Inproceedings { mse_17, author = {Manit, Jirapong and Schweikard, Achim and Ernst, Floris}, title = {Deep Convolutional Neural Network Approach for Forehead Tissue Thickness Estimation from NIR Laser Backscattering Images}, year = {2017}, volume = {62}, address = {Dresden, Germany; Dresden}, series = {Biomedical Engineering}, pages = {submitted}, number = {S1}, tags = {HPHT}, file_url = {http://www.dgbmt-dgmp.de} } @Inproceedings { Horn2017b, author = {Horn, Marco and Goltz, Jan Peter and Stahlberg, Erik and Papenberg, Nils and Ernst, Floris and Kleemann, Markus}, title = {Endovascular interventions proceeded under contrast agent and radiation sparing using navigation and imaging techniques for holographic visualisation}, abstract = {This review provides an overview to current endovascular techniques which may reduce the amount of contrast agents and radiation exposure to patient and staff. One integral part for the success of endo - vas cular procedures is innovative and improved vascular imaging. A major challenge during these interventions is visualizing the position and orientation of the catheter being inserted. This is typically achieved by intermittent X-ray imaging and contrast agent application. While endovascular techniques are improving, imaging during the procedure is still dependent on contrast agents and X-Rays with their known disadvantages. Looking at current developments towards radiation-free localization of endo vascular tools, the visualization and proper integration of this spatial information will become a key technology. After an extensive literature review of pathophysiology and clinical side effects of contrast agents and radiation exposure, we describe established procedures added with current experimental work to reduce these well known side effects in endovascular procedures. Based on the ALARA-principles modern angiography systems show optimized technical settings to deliver the best image quality at low radiation levels, such as optimal collimation, flat panel detector technology, pulse mode, auto exposure settings, low-dose modes and anti-scatter grids. Carbon dioxide (CO2) angiography, contrast-enhanced ultrasound (CEUS) imaging, appropriate C-arm angulation for optimal visualization have become standard procedures in large vascular centers. Optical fiber technologies combined with navigation techniques, augmented reality and holographic visualization techniques are under current experimental development. These techniques seem to have the potential as a disruptive technology in future endovascular therapy. Advanced image application and upcoming techniques focus contrast agent and radiation exposure and even some show a disruptive character. The navigated visualization of vessels and spatial position and endovascular tools during interventional procedures will probably become a key technology in future.}, year = {2017}, isbn = {978-2-9544771-2-1}, address = {Strasbourg (France)}, series = {European Symposium on Vascular Biomaterials}, pages = {173-180}, file_url = {https://www.uksh.de/uksh_media/Dateien_Fachzentren_Netzwerke/Gefaesszentrum_HL/Publikationen/ESVB 2017_KLEEMANN.pdf} } @Inproceedings { Horn2017a, author = {Horn, Marco and Ernst, Floris and Stahlberg, Erik and Goltz, Jan Peter and Wiedner, Marcus and Kleemann, Markus}, title = {Experimental visualization of vascular structures using Microsoft HoloLens}, year = {2017}, pages = {33} } @Inproceedings { biae_17, author = {B{\{\dq}o}ttger, Sven and Ipsen, Svenja and Al-Badri, Mohammed and Ernst, Floris and Schweikard, Achim}, title = {Force sensitive robotics for automated ultrasonic diagnostics and therapy}, abstract = {Ultrasound imaging, while being widely used due to its low risks and low costs, is highly user dependent and time-consuming to perform. Robotic automation has the potential to make the image acquisition process more reproducible and facilitate retrospective diagnosis. However, special safety precautions for robot-assisted ultrasound imaging are mandatory to prevent patient and staff injury. When using conventional industrial robots, entry into the robot's working space is prohibited for reasons of safety. In this project, we use the KUKA LBR iiwa 7 featuring a high degree of freedom, a workspace diameter of 1.6 m and the necessary force sensitivity for human collaboration. Each of its seven revolute joints contains a torque sensor, which is constantly monitored by our application software. The goal for robotic ultrasound is to maintain a defined contact force (5 N) in all spatial directions, especially during movement. When the maximum contact force is exceeded, the robot stops its forward motion. Consequently, the robot arm is able to dynamically adapt to physiological motion like respiration. Additionally, an adapted hand guiding mode was implemented, allowing for manual position corrections and enabling the patient to push the robot arm away in case of hazard or discomfort. The high articulation of this robot allows free positioning of the probe on the patient's body and makes this system universally usable. For remote control, a 3D input device (3DConnexion SpaceNavigator) is used. Its control signals are transmitted to the robot in real-time with latencies < 1 ms. In a next step, the use of haptic input devices will be investigated to also provide tactile feedback to the operator. This force-sensitive collaborative robot motion control prototype was implemented within a larger project. It is an important building block for the development of a universal automatic robotic 4D ultrasound platform for diagnostics and therapy.}, year = {2017}, volume = {62}, publisher = {De Gruyter}, address = {Dresden}, series = {Biomedical Engineering / Biomedizinische Technik}, pages = {s103-s108}, number = {s1}, keywords = {force; force control; force feedback; robotic; ultrasound}, tags = {UGRT}, note = {doi: https://doi.org/10.1515/bmt-2017-5025} } @Article { Hagenah2016b, author = {Hagenah, Jannis and Scharfschwerdt, Michael and Schweikard, Achim and Metzner, Christoph}, title = {Prediction of individual aortic root prosthesis size: Deformation modeling as an alternative to direct estimation}, year = {2016}, journal = {Dreil{\{\dq}a}ndertagung BMT 2016} } @Article { Blanck2016, author = {Blanck, Oliver and Ipsen, Svenja and Chan, Mark K. H. and Kerl, Matthias and Hunold, P. and Jacobi, Volkmar and Bruder, Ralf and Schweikard, Achim and Rades, Dirk and Vogl, Thomas J. and Kleine, Peter and Bode, F. and Dunst, J{\{\dq}u}rgen}, title = {Treatment Planning Considerations for Robotic Guided Cardiac Radiosurgery for Atrial Fibrillation}, abstract = {Purpose Robotic guided stereotactic radiosurgery has recently been investigated for the treatment of atrial fibrillation (AF). Before moving into human treatments, multiple implications for treatment planning given a potential target tracking approach have to be considered. Materials {\\&} Methods Theoretical AF radiosurgery treatment plans for twenty-four patients were generated for baseline comparison. Eighteen patients were investigated under ideal tracking conditions, twelve patients under regional dose rate (RDR = applied dose over a certain time window) optimized conditions (beam delivery sequence sorting according to regional beam targeting), four patients under ultrasound tracking conditions (beam block of the ultrasound probe) and four patients with temporary single fiducial tracking conditions (differential surrogate-to-target respiratory and cardiac motion). Results With currently known guidelines on dose limitations of critical structures, treatment planning for AF radiosurgery with 25 Gy under ideal tracking conditions with a 3 mm safety margin may only be feasible in less than 40% of the patients due to the unfavorable esophagus and bronchial tree location relative to the left atrial antrum (target area). Beam delivery sequence sorting showed a large increase in RDR coverage (% of voxels having a larger dose rate for a given time window) of 10.8-92.4% (median, 38.0%) for a 40-50 min time window, which may be significant for non-malignant targets. For ultrasound tracking, blocking beams through the ultrasound probe was found to have no visible impact on plan quality given previous optimal ultrasound window estimation for the planning CT. For fiducial tracking in the right atrial septum, the differential motion may reduce target coverage by up to -24.9% which could be reduced to a median of -0.8% (maximum, -12.0%) by using 4D dose optimization. The cardiac motion was also found to have an impact on the dose distribution, at the anterior left atrial wall; however, the results need to be verified. Conclusion Robotic AF radiosurgery with 25 Gy may be feasible in a subgroup of patients under ideal tracking conditions. Ultrasound tracking was found to have the lowest impact on treatment planning and given its real-time imaging capability should be considered for AF robotic radiosurgery. Nevertheless, advanced treatment planning using RDR or 4D respiratory and cardiac dose optimization may be still advised despite using ideal tracking methods.}, year = {2016}, DOI = {10.7759/cureus.705}, journal = {Cureus}, volume = {8}, pages = {e705}, number = {7}, keywords = {4D dose calculation; Atrial fibrillation; cyberknife cardiac radiosurgery; dose rate optimization; Pulmonary vein isolation; stereotactic body radiation therapy; Treatment planning}, tags = {MCRT}, file_url = {https://doi.org/10.7759/cureus.705} } @Article { ibl16, author = {Ipsen, Svenja and Blanck, Oliver and Lowther, Nicholas and Liney, Gary and Rai, Robba and Bode, F. and Dunst, J{\{\dq}u}rgen and Schweikard, Achim and Keall, Paul J.}, title = {Towards real-time MRI-guided 3D localization of deforming targets for non-invasive cardiac radiosurgery}, abstract = {Radiosurgery to the pulmonary vein antrum in the left atrium (LA) has recently been proposed for non-invasive treatment of atrial fibrillation (AF). Precise real-time target localization during treatment is necessary due to complex respiratory and cardiac motion and high radiation doses. To determine the 3D position of the LA for motion compensation during radiosurgery, a tracking method based on orthogonal real-time MRI planes was developed for AF treatments with an MRI-guided radiotherapy system. Four healthy volunteers underwent cardiac MRI of the LA. Contractile motion was quantified on 3D LA models derived from 4D scans with 10 phases acquired in end-exhalation. Three localization strategies were developed and tested retrospectively on 2D real-time scans (sagittal, temporalresolution 100 ms, free breathing). The best-performing method was then used to measure 3D target positions in 2D--2D orthogonal planes (sagittal-coronal, temporal resolution 200--252 ms, free breathing) in 20 configurations of a digital phantom and in the volunteer data. The 3D target localization accuracy was quantified in the phantom and qualitatively assessed in the real data. Mean cardiac contraction was ⩽ 3.9 mm between maximum dilation and contraction but anisotropic. A template matching approach with two distinct template phases and ECG-based selection yielded the highest 2D accuracy of 1.2 mm. 3D target localization showed a mean error of 3.2 mm in the customized digital phantoms. Our algorithms were successfully applied to the 2D--2D volunteer data in which we measured a mean 3D LA motion extent of 16.5 mm (SI), 5.8 mm (AP) and 3.1 mm (LR). Real-time target localization on orthogonal MRI planes was successfully implemented for highly deformable targets treated in cardiac radiosurgery. The developed method measures target shifts caused by respiration and cardiac contraction. If the detected motion can be compensated accordingly, an MRI-guided radiotherapy system could potentially enable completely non- invasive treatment of AF.}, year = {2016}, issn = {0031-9155}, DOI = {10.1088/0031-9155/61/22/7848}, journal = {Physics in Medicine and Biology}, volume = {61}, pages = {7848-63}, number = {22}, keywords = {Atrial fibrillation; deformation; Image guidance; MRI-Linac; real-time motion compensation}, tags = {MCRT}, file_url = {https://doi.org/10.1088/0031-9155/61/22/7848} } @Inproceedings { ibok_16-1, author = {Ipsen, Svenja and Bruder, Ralf and O'Brien, Ricky T. and Keall, Paul J. and Schweikard, Achim and Poulsen, Per Rugaard}, title = {TH-AB-202-05: BEST IN PHYSICS (JOINT IMAGING-THERAPY): First Online Ultrasound-Guided MLC Tracking for Real-Time Motion Compensation in Radiotherapy}, abstract = {Purpose:While MLC tracking has been successfully used for motion compensation of moving targets, current real-time target localization methods rely on correlation models with x-ray imaging or implanted electromagnetic transponders rather than direct target visualization. In contrast, ultrasound imaging yields volumetric data in real-time (4D) without ionizing radiation. We report the first results of online 4D ultrasound-guided MLC tracking in a phantom. Methods:A real-time tracking framework was installed on a 4D ultrasound station (Vivid7 dimension, GE) and used to detect a 2mm spherical lead marker inside a water tank. The volumetric frame rate was 21.3Hz (47ms). The marker was rigidly attached to a motion stage programmed to reproduce nine tumor trajectories (five prostate, four lung). The 3D marker position from ultrasound was used for real-time MLC aperture adaption. The tracking system latency was measured and compensated by prediction for lung trajectories. To measure geometric accuracy, anterior and lateral conformal fields with 10cm circular aperture were delivered for each trajectory. The tracking error was measured as the difference between marker position and MLC aperture in continuous portal imaging. For dosimetric evaluation, 358° VMAT fields were delivered to a biplanar diode array dosimeter using the same trajectories. Dose measurements with and without MLC tracking were compared to a static reference dose using a 3%/3 mm $\gamma$-test. Results:The tracking system latency was 170ms. The mean root-mean-square tracking error was 1.01mm (0.75mm prostate, 1.33mm lung). Tracking reduced the mean $\gamma$-failure rate from 13.9% to 4.6% for prostate and from 21.8% to 0.6% for lung with high-modulation VMAT plans and from 5% (prostate) and 18% (lung) to 0% with low modulation. Conclusion:Real-time ultrasound tracking was successfully integrated with MLC tracking for the first time and showed similar accuracy and latency as other methods while holding the potential to measure target motion non-invasively. SI was supported by the Graduate School for Computing in Medicine and Life Science, German Excellence Initiative [grant DFG GSC 235/1].}, year = {2016}, DOI = {10.1118/1.4958069}, booktitle = {Medical Physics}, volume = {43}, series = {Annual Meeting of the American Association of Physicists in Medicine (AAPM)}, pages = {3857-3857}, number = {6}, tags = {MCRT UGRT}, file_url = {https://doi.org/10.1118/1.4958069} } @Article { Gerlach2016ab, author = {Gerlach, S. and Kuhlemann, Ivo and Ernst, Floris and Fuerweger, C. and Schlaefer, A.}, title = {SU-G-JeP3-03: Effect of Robot Pose On Beam Blocking for Ultrasound Guided SBRT of the Prostate}, abstract = {Purpose: Ultrasound presents a fast, volumetric image modality for real-time tracking of abdominal organ motion. How-ever, ultrasound transducer placement during radiation therapy is challenging. Recently, approaches using robotic arms for intra-treatment ultrasound imaging have been proposed. Good and reliable imaging requires placing the transducer close to the PTV. We studied the effect of a seven degrees of freedom robot on the fea-sible beam directions. Methods: For five CyberKnife prostate treatment plans we established viewports for the transducer, i.e., points on the patient surface with a soft tissue view towards the PTV. Choosing a feasible transducer pose and using the kinematic redundancy of the KUKA LBR iiwa robot, we considered three robot poses. Poses 1 to 3 had the elbow point anterior, superior, and inferior, respectively. For each pose and each beam starting point, the pro-jections of robot and PTV were computed. We added a 20 mm margin accounting for organ / beam motion. The number of nodes for which the PTV was partially of fully blocked were established. Moreover, the cumula-tive overlap for each of the poses and the minimum overlap over all poses were computed. Results: The fully and partially blocked nodes ranged from 12% to 20% and 13% to 27%, respectively. Typically, pose 3 caused the fewest blocked nodes. The cumulative overlap ranged from 19% to 29%. Taking the minimum overlap, i.e., considering moving the robot's elbow while maintaining the transducer pose, the cumulative over-lap was reduced to 16% to 18% and was 3% to 6% lower than for the best individual pose. Conclusion: Our results indicate that it is possible to identify feasible ultrasound transducer poses and to use the kinematic redundancy of a 7 DOF robot to minimize the impact of the imaging subsystem on the feasible beam directions for ultrasound guided and motion compensated SBRT.}, year = {2016}, DOI = {10.1118/1.4957068}, journal = {Medical Physics}, volume = {43}, pages = {3670-3671}, number = {6}, file_url = {https://doi.org/10.1118/1.4957068} } @Inproceedings { Kuhlemann2016, author = {Kuhlemann, Ivo and Schweikard, Achim and Jauer, Philipp and Ernst, Floris}, title = {Robust inverse kinematics by configuration control for redundant manipulators with seven DoF}, abstract = {This paper presents an optimized, robust inverse kinematics solution in a closed form for redundant manipulators with seven degrees of freedom and zero link offsets like the KUKA LBR iiwa lightweight robot. The computation allows for full range elbow self-motion manifold control, defined by an intuitive angle parameter. Furthermore, by using common configuration parameters, all possible solutions for a single effector pose are taken into account and full arm configuration control is realized. The algorithm was evaluated looking at configuration reliability and continuity for an exemplary, challenging path. The results show that commanded arm configurations are not changing spontaneously inside a trajectory. Even for varying elbow self-motion manifold angles, the joint trajectories stay continuous and the presented algorithm provides consistent solutions. In a second evaluation, the algorithm was implemented in three programming languages and analyzed with respect to computing times. The tests demonstrate short runtimes and overall real-time capability.}, year = {2016}, DOI = {10.1109/iccar.2016.7486697}, pages = {49-55}, keywords = {Aerospace electronics; arm configuration control; closed-form solution; Elbow; Inverse kinematics; kinematics; LBR iiwa; Manifolds; manipulators; redundant 7-DoF robot; Wrist}, file_url = {https://doi.org/10.1109/iccar.2016.7486697} } @Inproceedings { Kuhlemann2016a, author = {Kuhlemann, Ivo and Jauer, Philipp and Ernst, Floris and Schweikard, Achim}, title = {Robots with seven degrees of freedom: Is the additional DoF worth it?}, abstract = {This paper presents a detailed dexterity analysis of three different kinematics, comparing six-{}DoF}, year = {2016}, pages = {80-84}, keywords = {Dexterity map; Elbow; kinematics; KR 10; LBR iiwa; Manifolds; manipulators; reachability map; robot kinematics; Service robots; seven-DoF} } @Article { Gerlach2016b, author = {Gerlach, Stefan and Kuhlemann, Ivo and Jauer, Philipp and Bruder, Ralf and Ernst, Floris and F{\{\dq}u}rweger, Christoph and Schlaefer, Alexander}, title = {Robotic ultrasound-guided SBRT of the prostate: feasibility with respect to plan quality}, abstract = {Advances in radiation therapy delivery systems have enabled motion compensated SBRT of the prostate. A remaining challenge is the integration of fast, non-ionizing volumetric imaging. Recently, robotic ultrasound has been proposed as an intra-fraction image modality. We study the impact of integrating a light-weight robotic arm carrying an ultrasound probe with the CyberKnife system. Particularly, we analyze the effect of different robot poses on the plan quality.}, year = {2016}, issn = {1861-6429}, DOI = {10.1007/s11548-016-1455-7}, journal = {International Journal of Computer Assisted Radiology and Surgery}, pages = {1-11}, tags = {UGRT}, file_url = {https://doi.org/10.1007/s11548-016-1455-7} } @Article { Schlosser2016, author = {Schlosser, Jeffrey and Gong, Renhui and Bruder, Ralf and Schweikard, Achim and Jang, Sungjune and Henrie, John and Kamaya, Aya and Koong, Albert and Chang, Daniel and Hristov, Dimitre}, title = {Robotic intra-fractional US guidance for liver SABR: system design, beam avoidance, and clinical imaging}, year = {2016}, journal = {Medical Physics}, pages = {5951-5963}, tags = {UGRT} } @Inproceedings { hwse_16, author = {Hagenah, Jannis and Werrmann, Erik and Scharfschwerdt, Michael and Ernst, Floris and Metzner, Christoph}, title = {Prediction of Individual Prosthesis Size for Valve-Sparing Aortic Root Reconstruction Based on Geometric Features}, year = {2016}, DOI = {10.1109/EMBC.2016.7591427}, publisher = {IEEE}, address = {Orlando, FL, USA}, series = {EMBS}, pages = {3273-3276}, file_url = {https://doi.org/10.1109/EMBC.2016.7591427} } @Article { Kuhlemann2016b, author = {Kuhlemann, Ivo and Jauer, P. and Schweikard, Achim and Ernst, Floris}, title = {SU-G-JeP3-08: Robotic System for Ultrasound Tracking in Radiation Therapy}, abstract = {Purpose: For safe and accurate real-time tracking of tumors for IGRT using 4D ultrasound, it is necessary to make use of novel, high-end force-sensitive lightweight robots designed for human-machine interaction. Such a robot will be integrated into an existing robotized ultrasound system for non-invasive 4D live tracking, using a newly developed real-time control and communication framework. Methods: The new KUKA LWR iiwa robot is used for robotized ultrasound real-time tumor tracking. Besides more precise probe contact pressure detection, this robot provides an additional 7th link, enhancing the dexterity of the kinematic and the mounted transducer. Several integrated, certified safety features create a safe environment for the patients during treatment. However, to remotely control the robot for the ultrasound application, a real-time control and communication framework has to be developed. Based on a client/server concept, client-side control commands are received and processed by a central server unit and are implemented by a client module running directly on the robot's controller. Several special functionalities for robotized ultrasound applications are integrated and the robot can now be used for real-time control of the image quality by adjusting the transducer position, and contact pressure. The framework was evaluated looking at overall real-time capability for communication and processing of three different standard commands. Results: Due to inherent, certified safety modules, the new robot ensures a safe environment for patients during tumor tracking. Furthermore, the developed framework shows overall real-time capability with a maximum average latency of 3.6 ms (Minimum 2.5 ms; 5000 trials). Conclusion: The novel KUKA LBR iiwa robot will advance the current robotized ultrasound tracking system with important features. With the developed framework, it is now possible to remotely control this robot and use it for robotized ultrasound tracking applications, including image quality control and target tracking.}, year = {2016}, DOI = {10.1118/1.4957073}, journal = {Medical Physics}, volume = {43}, pages = {3672-3672}, number = {6}, file_url = {https://doi.org/10.1118/1.4957073} } @Inproceedings { ibs_16, author = {Ipsen, Svenja and Bruder, Ralf and Schweikard, Achim}, title = {P28: Towards 6dof tracking of deformable objects for 4D ultrasound-guided radiation therapy}, year = {2016}, DOI = {10.1007/s13246-016-0494-2}, volume = {39}, publisher = {Springer Netherlands}, address = {Sydney, Australia}, series = {EPSM 2016, Engineering and Physical Sciences in Medicine}, number = {4}, tags = {MCRT UGRT}, file_url = {https://doi.org/10.1007/s13246-016-0494-2} } @Inproceedings { ill16, author = {Ipsen, Svenja and Lowther, Nicholas and Liney, Gary and Rades, Dirk and Dunst, J{\{\dq}u}rgen and Schweikard, Achim and Keall, Paul J. and Blanck, Oliver}, title = {Echtzeit-Lokalisation in simulierten und realen MRT-Daten f{\{\dq}u}r nicht invasive Radiochirurgie des Herzens in einem MR-Linac}, year = {2016}, volume = {47. Jahrestagung}, series = {Jahrestagung Deutsche Gesellschaft f{\{\dq}u}r Medizinische Physik (DGMP)}, tags = {MCRT} } @Inproceedings { lmk15, author = {Lowther, Nicholas and Marsh, Steven and Keall, Paul J. and Ipsen, Svenja}, title = {A ground truth for volumetric MRI cardiac tracking using the XCAT phantom}, abstract = {Introduction A real-time cardiac MRI tracking technique based on template matching has been developed centred on the findings of a cardiac target localisation in real-time MRI investigations [1]. Real-time volumetric tracking of cardiac structures that undergo respiratory and cardiac motion with MRI is required if the novel method of treating atrial fibrillation with radiosurgery is to be realised. MR imaging currently lacks the required spatial and temporal resolution to provide a ground truth for comparison with the real-time cardiac MRI tracking technique. Aim Utilisation of the XCAT digital phantom software [2] to provide a ground truth for cardiac motion to provide verification of the accuracy of the template matching real-time cardiac tracking technique. Method The XCAT digital phantom software allows respiratory and cardiac motion to be simulated, in addition to user defined voxel values for cardiac structures. The left atrium is isolated through thresholding and the volumetric centroid is tracked over a period of multiple respiratory and cardiac cycles. The left atrium 3D centroid position from the XCAT phantom and template matching software are compared. XCAT phantom simulations with varying cardiac and respiratory motion traces are utilised to test the robustness of the real-time cardiac tracking MRI template matching approach. Results Sub-voxel accuracy has been demonstrated in phantoms with small cardiac LR respiratory motion and single voxel accuracy has been demonstrated in phantoms with larger cardiac LR respiratory motion. The presence of a ground truth has allowed optimisation of the template matching approach with dynamic search and absolute motion functions. Conclusion The XCAT digital phantom software has provided verification and identified areas of improvement with the real-time cardiac tracking MRI template matching method.}, year = {2016}, issn = {0158-9938}, DOI = {10.1007/s13246-015-0410-1}, volume = {39}, series = {Abstracts}, pages = {303}, number = {1}, file_url = {https://doi.org/10.1007/s13246-015-0410-1} } @Article { ibje_16, author = {Ipsen, Svenja and Bruder, Ralf and Jauer, Philipp and Ernst, Floris and Blanck, Oliver and Schweikard, Achim}, title = {An improved tracking framework for ultrasound probe localization in image-guided radiosurgery}, abstract = {Real-time target localization with ultrasound holds high potential for image guidance and motion compensation in radiosurgery due to its non-invasive image acquisition free from ionizing radiation. However, a twostep localization has to be performed when integrating ultrasound into the existing radiosurgery workflow. In addition to target localization inside the ultrasound volume, the probe itself has to be localized in order to transform the target position into treatment room coordinates. By adapting existing camera calibration tools, we have developed a method to extend the stereoscopic X-ray tracking system of a radiosurgery platform in order to locate objects such as marker geometries with six degrees of freedom. The calibration was performed with 0.1 mm reprojection error. By using the full area of the flat-panel detectors without pre-processing the extended software increased the tracking volume and resolution by up to 80%, substantially improving patient localization and marker detectability. Furthermore, marker-tracking showed submillimeter accuracy and rotational errors below 0.1°. This demonstrates that the developed extension framework can accurately localize marker geometries using an integrated X-ray system, establishing the link for the integration of real-time ultrasound image guidance into the existing system.}, year = {2016}, DOI = {10.1515/cdbme-2016-0091}, journal = {Current Directions in Biomedical Engineering}, volume = {2}, address = {Basel, Switzerland}, pages = {409-413}, number = {1}, keywords = {4D ultrasound tracking; Image guidance; real-time motion compensation; Robotic radiosurgery}, tags = {MCRT UGRT}, file_url = {https://doi.org/10.1515/cdbme-2016-0091} } @Article { cgcs_16, author = {Chan, Mark and Grehn, Melanie and Cremers, Florian and Siebert, Frank-Andre and Wurster, Stefan and Huttenlocher, Stefan and Dunst, J{\{\dq}u}rgen and Hildebrandt, Guido and Schweikard, Achim and Rades, Dirk and Ernst, Floris and Blanck, Oliver}, title = {Dosimetric Implications of Residual Tracking Errors during Robotic SBRT of Liver Metastases}, abstract = {Purpose While the metric precision of robotic stereotactic body radiation therapy (SBRT) in the presence of breathing motion is widely known, we investigated the dosimetric implications of breathing phase-related residual tracking errors. Methods and Material: From 24 patients (28 liver metastases) treated with the CyberKnife we recorded the residual correlation, prediction, and rotational tracking errors from 90 fractions and binned them into ten breathing-phases. The average breathing phase errors were used to shift and rotate the CTV/PTV for each phase to calculate a pseudo 4D error dose distribution for comparison with the original planned dose distribution. Results The median systematic directional correlation, prediction, and absolute aggregate rotation errors were 0.3mm (0.1--1.3mm), 0.01mm (0.00--0.05mm), and 1.5° (0.4°--2.7°). Dosimetrically, 44%, 81%, and 92% of all voxels differed less than 1%, 3%, and 5% of the planned local dose. Median coverage reduction for the PTV was 1.1% (-7.8%-- 0.8%), significantly depending on correlation (p=0.026) and rotational (p=0.005) error. With a 3mm PTV margin, the median coverage change for the CTV was 0.0% (-1.0%-- 5.4%), not significantly depending on any investigated parameter. In 42% of patients, the 3mm margin did not fully compensate for the residual tracking errors, resulting in a CTV coverage reduction of 0.1%--1.0%. Conclusions For liver tumors treated with robotic SBRT, a safety margin of 3mm is not always sufficient to cover all residual tracking errors. Dosimetrically, this translates only into small CTV coverage reductions.}, year = {2016}, issn = {0360-3016}, DOI = {10.1016/j.ijrobp.2016.11.041}, journal = {International Journal of Radiation Oncology textbullet Biology Physics}, publisher = {Elsevier}, pages = {accepted}, file_url = {https://doi.org/10.1016/j.ijrobp.2016.11.041} } @Inproceedings { Grasshoff2016, author = {Gra{\{\dq}s}hoff, J. and Hansen, L. and Kuhlemann, Ivo and Ehlers, K.}, title = {7DoF Hand and Arm Tracking for Teleoperation of Anthropomorphic Robots}, year = {2016}, address = {Munich, Germany}, pages = {555-562} } @Article { AntoniRinastMaSchlaefer2016, author = {Antoni, S. T. and Rinast, J. and Ma, X. and Schupp, S. and Schlaefer, A.}, title = {Online model checking for monitoring surrogate-based respiratory motion tracking in radiation therapy}, year = {2016}, journal = {Int J Comput Assist Radiol Surg}, volume = {11(11)}, pages = {2085-2096} } @Article { wswb_16, author = {Wissel, Tobias and St{\{\dq}u}ber, Patrick and Wagner, Benjamin and Bruder, Ralf and Erdmann, Christian and Deutz, Christin-Sophie and Sack, Benjamin and Manit, Jirapong and Schweikard, Achim and Ernst, Floris}, title = {Enhanced Optical Head Tracking for Cranial Radiotherapy: Supporting Surface Registration by Cutaneous Structures}, abstract = {Purpose Precise tumor localization is vital in cranial radiotherapy. Optical marker-less surface imaging is capable of rapidly and non-invasively locating the patient's head. However, to some extent any required registration is a non-convex optimization problem: Identifying correct correspondences between online scans and a reference can be prone to local minima due to deformation of the triangulated surface and spatial ambiguities. We propose to predict variations of tissue thickness across the forehead from backscattered near-infrared (NIR) light. Registration can then be supported by this structural information to minimize the risk for these ambiguities. Methods and Materials In a pilot study we recorded NIR surface scans by laser triangulation from 30 volunteers of different skin type. A ground truth for the soft tissue thickness was segmented from MR scans. After initially matching the NIR scans to the MR reference, Gaussian Processes were trained to predict tissue thicknesses from NIR backscatter. Moreover, motion starting from this initial registration was simulated by 5,000 random transformations of the NIR scan away from the MR reference. Re-registration to the MR scan was compared with and without tissue thickness support. Results By adding prior knowledge to the backscatter features, such as incident angle and neighborhood information in the scanning grid, we showed that tissue thickness can be predicted with mean errors of less than 0.2mm, irrespective of the skin type. With this additional information, the average registration error improved from 3.4mm to 0.48mm by factor 7. Misalignments of more than 1mm were almost thoroughly (98.9%) pushed below 1mm. Conclusions For almost all cases, tissue enhanced matching achieved better results than purely spatial registration. Ambiguities can be minimized if the cutaneous structures do not agree. This valuable support for surface registration increases tracking robustness and avoids misalignment of tumor targets far from the registration site. Disclosure conflict of interest statement: The study and the research reported in this article were funded by Varian Medical Systems, Inc. (Palo Alto, CA, USA) and supported by the Graduate School for Computing in Medicine and Life Science, German Excellence Initiative [grant DFG GSC 235/1].}, year = {2016}, DOI = {10.1016/j.ijrobp.2016.01.041}, journal = {International Journal of Radiation Oncology, Biology, Physics}, volume = {95}, pages = {810-817}, number = {2}, tags = {HPHT}, file_url = {https://doi.org/10.1016/j.ijrobp.2016.01.041} } @Inproceedings { Jauer2016, author = {Jauer, Philipp and Kuhlemann, Ivo and Ernst, Floris and Schweikard, Achim}, title = {GPU-based real-time 3D workspace generation of arbitrary serial manipulators}, abstract = {This paper presents a method to solve - in real time - the three dimensional workspace generation problem for arbitrary serial manipulators. Our approach is based on Monte Carlo simulation, to process a high number of forward kinematics with randomly chosen joint values. This results in an asymptotic coverage of the reachable workspace. Additionally, collision detection is integrated to consider obstacles within the manipulator's environment. The method is implemented on the graphics processing unit (GPU), such that an extremely high number of workspace points can be processed in parallel. Tests have shown that this approach is capable to generate acceptable workspace coverage within milliseconds. Furthermore, the workspace is held as a three dimensional texture volume on the graphics memory, allowing for instant visualisation of the workspace during the generation process without the need for further time-intensive data exchange.}, year = {2016}, DOI = {10.1109/iccar.2016.7486698}, pages = {56-61}, keywords = {Collision-Free; Computer architecture; GPU; Graphics processing units; Instruction sets; kinematics; manipulator; manipulators; Pseudo Random Numbers; Reachability; Real-Time; real-time systems; robot; Workspace}, file_url = {https://doi.org/10.1109/iccar.2016.7486698} } @Article { Metzner2016, author = {Metzner, Christoph and Schweikard, Achim and Zurowski, B.}, title = {Multifactorial Modeling of Impairment of Evoked Gamma Range Oscillations in Schizophrenia}, abstract = {Despite a significant increase in efforts to identify biomarkers and endophenotypic measures of psychiatric illnesses, only a very limited amount of computational models of these markers and measures has been implemented so far. Moreover, existing computational models dealing with biomarkers typically only examine one possible mechanism in isolation, disregarding the possibility that other combinations of model parameters might produce the same network behavior (what has been termed {\dq}multifactoriality{\dq}). In this study we describe a step toward a computational instantiation of an endophenotypic finding for schizophrenia, namely the impairment of evoked auditory gamma and beta oscillations in schizophrenia. We explore the multifactorial nature of this impairment using an established model of primary auditory cortex, by performing an extensive search of the parameter space. We find that single network parameters contain only little information about whether the network will show impaired gamma entrainment and that different regions in the parameter space yield similar network level oscillation abnormalities. These regions in the parameter space, however, show strong differences in the underlying network dynamics. To sum up, we present a first step toward an in silico instantiation of an important biomarker of schizophrenia, which has great potential for the identification and study of disease mechanisms and for understanding of existing treatments and development of novel ones.}, year = {2016}, DOI = {10.3389/fncom.2016.00089}, journal = {Frontiers}, file_url = {https://doi.org/10.3389/fncom.2016.00089} } @Article { ibok_16, author = {Ipsen, Svenja and Bruder, Ralf and O'Brian, Rick and Keall, Paul J. and Schweikard, Achim and Poulsen, Per Rugaard}, title = {Online 4D ultrasound guidance for real-time motion compensation by MLC tracking}, year = {2016}, DOI = {10.1118/1.4962932}, journal = {Medical Physics}, pages = {5695-5704}, tags = {MCRT UGRT}, file_url = {https://doi.org/10.1118/1.4962932} } @Inproceedings { Gerlach2016aa, author = {Gerlach, Stefan and Kuhlemann, Ivo and Jauer, Philipp and Bruder, Ralf and Ernst, Floris and F{\{\dq}u}rweger, Christoph and Schlaefer, Alexander}, title = {Feasibility of robotic ultrasound guided SBRT of the prostate}, year = {2016}, address = {Heidelberg}, tags = {MCRT UGRT} } @Inproceedings { Wilde2015, author = {Wilde, Christian and Bruder, Ralf and Trillenberg, Peter and Binder, Sonja and Marshall, Lisa and Schweikard, Achim}, title = {Modeling Electric Fields for Focal Transcranial Electrical Stimulation}, year = {2015}, address = {Duesseldorf, Germany}, series = {Deutsche Gesellschaft f{\{\dq}u}r Neurologie (DGN)}, tags = {TES} } @Article { wswb_15c, author = {Wissel, Tobias and St{\{\dq}u}ber, Patrick and Wagner, Benjamin and Bruder, Ralf and Schweikard, Achim and Ernst, Floris}, title = {Enriching 3D optical surface scans with prior knowledge: tissue thickness computation by exploiting local neighborhoods}, year = {2015}, issn = {1861-6410}, DOI = {10.1007/s11548-015-1246-6}, journal = {International Journal of Computer Assisted Radiology and Surgery}, volume = {11}, publisher = {Springer Berlin Heidelberg}, pages = {569-579}, number = {4}, keywords = {Head tracking; Laser scanning; Statistical learning; Tissue thickness}, tags = {HPHT}, file_url = {https://doi.org/10.1007/s11548-015-1246-6}, note = {language=English} } @Article { phe_15b, author = {Jauer, Philipp and Hainer, Franziska and Ernst, Floris}, title = {GPU-based real-time generation of large ultrasound volumes from freehand 3D sweeps}, abstract = {In the recent past, 3D ultrasound has been gaining relevance in many biomedical applications. One main limitation, however, is that typical ultrasound volumes are either very poorly resolved or only cover small areas. We have developed a GPU-accelerated method for live fusion of freehand 3D ultrasound sweeps to create one large volume. The method has been implemented in CUDA and is capable of generating an output volume with 0.5 mm resolution in real time while processing more than 45 volumes per second, with more than 300.000 voxels per volume. First experiments indicate that large structures like a whole forearm or high-resolution volumes of smaller structures like the hand can be combined eciently. It is anticipated that this technology will be helpful in pediatric surgery where X-ray or CT imaging is not always possible.}, year = {2015}, issn = {2364-5504}, DOI = {10.1515/cdbme-2015-0071}, journal = {Current Directions in Biomedical Engineering}, volume = {1}, address = {L{\{\dq}u}beck, Germany}, series = {Biomedical Engineering}, pages = {286-289}, number = {1}, file_url = {https://doi.org/10.1515/cdbme-2015-0071} } @Article { Gong2015, author = {Gong, Renhui and Bruder, Ralf and Schweikard, Achim and Hristov, Dimitre}, title = {Investigation of Treatment Interferences of a Novel Robotic Ultrasound Radiotherapy Guidance System with Clinical VMAT Plans for Liver SBRT Patients}, abstract = {To evaluate the proportion of liver SBRT cases in which robotic ultrasound image guidance concurrent with beam delivery can be deployed without interfering with clinically used VMAT beam configurations. A simulation environment incorporating LINAC, couch, planning CT, and robotic ultrasound guidance hardware was developed. Virtual placement of the robotic ultrasound hardware was guided by a target visibility map rendered on the CT surface. The map was computed on GPU by using the planning CT to simulate ultrasound propagation and attenuation along rays connecting skin surface points to a rasterized imaging target. The visibility map was validated in a prostate phantom experiment by capturing live ultrasound images of the prostate from different phantom locations. In 20 liver SBRT patients treated with VMAT, the simulation environment was used to place the robotic hardware and ultrasound probe at imaging locations indicated on the visibility map. Imaging targets were either entire PTV (range 5.9-679.5 ml) or entire GTV (range 0.9-343.4 ml). Presence or absence of mechanical collisions with LINAC, couch, and patient body as well as interferences with treated beams were recorded. For PTV targets, robotic ultrasound guidance without mechanical collision was possible in 80% of the cases and guidance without beam interference was possible in 60% of the cases. For the smaller GTV targets, these proportions were 95% and 85% correspondingly. GTV size (1/20), elongated shape (1/20), and depth (1/20) were the main factors limiting the availability of non-interfering imaging positions. This study indicates that for VMAT liver SBRT, robotic ultrasound tracking of a relevant internal target would be possible in 85% of cases while using treatment plans currently deployed in the clinic. With beam re-planning in accordance with the presence of robotic ultrasound guidance, intra-fractional ultrasound guidance may be an option for 95% of the liver SBRT cases. This project was funded by NIH Grant R41CA174089.}, year = {2015}, DOI = {10.1118/1.4925372}, journal = {Medical Physics}, pages = {3561}, tags = {UGRT}, file_url = {https://doi.org/10.1118/1.4925372} } @Book { Schweikard2015, author = {Schweikard, Achim and Ernst, Floris}, title = {Medical Robotics}, year = {2015}, isbn = {978-3-319-22891-4}, publisher = {Springer}, file_url = {https://www.springer.com/us/book/9783319228907} } @Article { Rodriguez-Herreros2015, author = {Rodriguez-Herreros, Borja and Amengual, Juli{\'a} L. and Gurtubay, Ane and Richter, Lars and Jauer, Philipp and Erdmann, Christian and Schweikard, Achim and L{\'o}pez-Moliner, Juan and Rodriguez-Fornells, Antoni and M{\{\dq}u}nte, Thomas F.}, title = {Microstructure of the superior longitudinal fasciculus predicts stimulation-induced interference with on-line motor control}, abstract = {A cortical visuomotor reaching network, comprising the medial intraparietal sulcus (mIPS) and the dorsal premotor area (PMd), encodes the sensorimotor transformations required for the on-line control of reaching movements. How information is transmitted between these two regions and which pathways are involved, is less clear. Here, we use a multimodal approach combining repetitive transcranial magnetic stimulation (rTMS) and diffusion tensor imaging (DTI) to investigate whether structural connectivity in the `reaching' circuit is associated to variations in the ability to control and update a movement. We induced a transient disruption of the neural processes underlying on-line motor adjustments by applying 1 Hz rTMS over the mIPS. After the stimulation protocol, participants globally showed a reduction of the number of corrective trajectories during a reaching task that included unexpected visual perturbations. A voxel-based analysis revealed that participants exhibiting higher fractional anisotropy (FA) in the second branch of the superior longitudinal fasciculus (SLF II) suffered less rTMS-induced behavioral impact. These results indicate that the microstructural features of the white matter bundles within the parieto-frontal `reaching' circuit play a prominent role when action reprogramming is interfered. Moreover, our study suggests that the structural alignment and cohesion of the white matter tracts might be used as a predictor to characterize the extent of motor impairments.}, year = {2015}, journal = {Neuroimage}, volume = {accepted for publication}, tags = {TMS} } @Techreport { s_15, author = {Ipsen, Svenja}, title = {Radiotherapy beyond cancer: Motion analysis, treatment planning and real-time target localization for non-invasive cardiac radiosurgery with MRI guidance}, abstract = {Atrial fibrillation (AF) is the most common cardiac arrhythmia that affects millions of patients world-wide. It is usually treated with minimally invasive, time consuming catheter ablation techniques. While recently non-invasive radiosurgery to the pulmonary vein antrum in the left atrium has been proposed for AF treatment, precise target location during treatment is challenging due to complex respiratory and cardiac motion. A MRI linear accelerator (MRI-Linac) could solve the problems of motion tracking and compensation using real-time image guidance. In this study, the motion range of the target is quantified on cardiac magnetic resonance imaging (MRI), its position is determined in real-time images and the dosimetric impact of different motion compensation strategies and related margin sizes is analyzed. Five human subjects received cardiac MRI of the left atrium. A 3D scan was acquired in inhale and exhale breath-holds, respectively, to measure the left atrial respiratory shift between the extreme breathing phases. Time-resolved 4D scans acquired in exhale showing the left atrium in multiple cardiac phases were used to quantify the extent of cardiac contraction from diastole (max. volume) to systole (min. volume). Both motion components need to be compensated during treatment and were considered in the planning stage. 30 Gy single fraction treatment plans for five different motion compensation scenarios were generated on a CT of an AF patient with a centrally located esophagus undergoing catheter ablation, representing an ideal case for cardiac radiosurgery. The target definition was similar to the ablation lesions created during catheter treatment. Safety margins from 0 mm (perfect compensation) to 8 mm (uncompensated respiratory motion and contraction) were added to the target. The target localization accuracy in an MRI-Linac was retrospectively optimized on 2D real-time MRI during free breathing by employing different template matching techniques. The technique with the highest accuracy was used to determine the 3D position of the left atrium from two orthogonal interleaved real-time MRI planes. The results indicate that real-time target localization and motion compensation are mandatory for high-dose cardiac radiosurgery to treat AF. MRI-guidance on orthogonal real-time planes could successfully be implemented and, as safety margins will likely be below 5 mm, treatment could be delivered with an MRI- Linac if the measured motion can be compensated with high accuracy. The findings of this work open the possibility of treating cardiac arrhythmia patients completely non-invasively.}, year = {2015}, series = {Universit{\{\dq}a}t zu L{\{\dq}u}beck}, note = {Master's thesis} } @Inproceedings { Ernst2015, author = {Ernst, Floris and Wissel, Tobias and St{\{\dq}u}ber, Patrick and Wagner, Benjamin and Bruder, Ralf and Schweikard, Achim}, title = {Optical localization of the human skull for cranial radiation therapy}, year = {2015}, address = {Atlanta, GA, USA}, series = {Varian Medical}, tags = {HPHT}, note = {timestamp=2015.07.19} } @Inproceedings { kjse_15, author = {Kuhlemann, Ivo and Jauer, Philipp and Schweikard, Achim and Ernst, Floris}, title = {Patient localization for robotized ultrasound-guided radiation therapy}, abstract = {Accurate localization and tracking of moving targets is one of the major challenges faced today during high-precision radiotherapy. Typically, the position of the treatment target is either determined using infrequent X-ray images or cone-beam CT scans. A totally different approach currently under active development makes use of ultrasound imaging to continuously track the target region. We have evaluated a robotized setup where Microsoft's Kinect v2 sensor is used to localize the patient and specific ultrasonic view ports previously defined in the planning CT. The setup is validated using an anthropomorphic torso phantom and four predefined view ports (apical and parasternal echocardiography, liver sonography, suprapubic prostate sonography). The Kinect sensor and an optical tracking system (used to determine the position of the torso phantom) were calibrated to the robot using the QR24 hand-eye calibration algorithm. Then each view port was approached fifteen times from different directions, showing that the accuracy achievable is, on average, approximately 2.1 cm. This number can mostly be attributed to the difficulty of obtaining accurate calibration of the geometric relationship between the robot and the Kinect sensor. It was observed that the Kinect sensor system suffers from substantial distortion in the centimeter range, severely compromising the accuracy of the whole setup.}, year = {2015}, pages = {105-112}, tags = {MCRT UGRT} } @Inproceedings { wswb_15a, author = {Wagner, Benjamin and St{\{\dq}u}ber, Patrick and Wissel, Tobias and Bruder, Ralf and Schweikard, Achim and Ernst, Floris}, title = {Ray Interpolation for Generic Triangulation Based on a Galvanometric Laser Scanning System}, abstract = {Our research group is currently developing a new optical head tracking system for intracranial radiosurgery. The system uses infrared laser light to measure features of the soft tissue on the patients forehead which correlate with the thickness of the soft tissue. For future registration purposes, the system also acquires accurate pointwise reconstructions of the corresponding surface of the forehead by using triangulation. This paper proposes a method for the interpolation of laser rays based on a galvanometric laser scanning system. The advantage of the ray interpolation is that an alternative time consuming recalibration of the laser rays can be avoided. Experiments revealed a triangulation accuracy of around 0.1192 mm using ray interpolation.}, year = {2015}, DOI = {10.1109/ISBI.2015.7164142}, volume = {12}, publisher = {IEEE}, address = {New York}, pages = {1419-1422}, tags = {HPHT}, file_url = {https://doi.org/10.1109/ISBI.2015.7164142}, note = {High-Accuracy Head Tracking} } @Article { es_15b, author = {Ernst, Floris and Sa{\{\dq}s}, Philipp}, title = {Respiratory motion tracking using Microsoft's Kinect v2 camera}, abstract = {In image-guided radiotherapy, monitoring and compensating for respiratory motion is of high importance. We have analysed the possibility to use Microsoft's Kinect v2 sensor as a low-cost tracking camera. In our experiment, eleven circular markers were printed onto a Lycra shirt and were tracked in the camera's color image using cross correlation-based template matching. The 3D position of the markerwas determined using this information and the mean distance of all template pixels from the sensor. In an experiment with four volunteers (male and female) we could demonstrate that real time position tracking is possible in 3D. By averaging over the depth values inside the template, itwas possible to increase the Kinect's depth resolution from 1mmto 0.1 mm. The noise level was reduced to a standard deviation of 0.4 mm. Temperature sensitivity of the measured depth values was observed for about 10-15 minutes after system start.}, year = {2015}, issn = {2364-5504}, DOI = {10.1515/cdbme-2015-0048}, journal = {Current Directions in Biomedical Engineering}, volume = {1}, address = {L{\{\dq}u}beck, Germany}, series = {Biomedical Engineering}, pages = {192-195}, number = {1}, tags = {MCRT}, file_url = {https://doi.org/10.1515/cdbme-2015-0048}, note = {Motion Compensation in Radiosurgery} } @Inproceedings { wsws_15c, author = {Wissel, Tobias and St{\{\dq}u}ber, Patrick and Wagner, Benjamin and Schweikard, Achim and Ernst, Floris}, title = {Tissue Segmentation from Head MRI: A Ground Truth Validation for Feature-Enhanced Tracking}, abstract = {Accuracy is essential for optical head-tracking in cranial radiotherapy. Recently, the exploitation of local patterns of tissue information was proposed to achieve a more robust registration. Here, we validate a ground truth for this information obtained from high resolution MRI scans. In ve subjects we compared the segmentation accuracy of a semi-automatic algorithm with ve human experts. While the algorithm segments the skin and bone surface with an average accuracy of less than 0.1mm and 0.2 mm, respectively, the mean error on the tissue thickness was 0.17 mm.We conclude that this accuracy is a reasonable basis for extracting reliable cutaneous structures to support surface registration.}, year = {2015}, issn = {2364-5504}, DOI = {10.1515/bmt-2015-5008}, journal = {Current Directions in Biomedical Engineering}, volume = {60}, address = {L{\{\dq}u}beck, Germany}, series = {Biomedical Engineering}, pages = {S184}, number = {S1}, tags = {HPHT}, file_url = {https://doi.org/10.1515/bmt-2015-5008}, note = {timestamp=2015.06.28} } @Article { Horn2015, author = {Horn, Marco and Nolde, Jan and Goltz, Jan Peter and Barkhausen, J{\{\dq}o}rg and Schade, Wolfgang and Waltermann, Christian and Modersitzki, Jan and Olesch, Janine and Papenberg, Nils and Keck, Tobias and Kleemann, Markus}, title = {Ein Prototyp f{\{\dq}u}r die navigierte Implantation von Aortenstentprothesen zur Reduzierung der Kontrastmittel- und Strahlenbelastung: Das Nav-CARS-EVAR-Konzept (Navigated-Contrast-Agent and Radiation Sparing Endovascular Aortic Repair)}, abstract = {Introduction: Over the last decade endovascular stenting of aortic aneurysm (EVAR) has been developed from single centre experiences to a standard procedure. With increasing clinical expertise and medical technology advances treatment of even complex aneurysms are feasible by endovascular methods. One integral part for the success of this minimally invasive procedure is innovative and improved vascular imaging to generate exact measurements and correct placement of stent prosthesis. One of the greatest difficulty in learning and performing this endovascular therapy is the fact that the three-dimensional vascular tree has to be overlaid with the two-dimensional angiographic scene by the vascular surgeon. Material and Methods: We report the development of real-time navigation software, which allows a three-dimensional endoluminal view of the vascular system during an EVAR procedure in patients with infrarenal aortic aneurysm. We used the preoperative planning CT angiography for three-dimensional reconstruction of aortic anatomy by volume-rendered segmentation. At the beginning of the intervention the relevant landmarks are matched in real-time with the two-dimensional angiographic scene. During the intervention the software continously registers the position of the guide-wire or the stent. An additional 3D-screen shows the generated endoluminal view during the whole intervention in real-time. Results: We examined the combination of hardware and software components including complex image registration and fibre optic sensor technology (fibre-bragg navigation) with integration in stent graft introducer sheaths using patient-specific vascular phantoms in an experimental setting. From a technical point of view the feasibility of fibre-Bragg navigation has been proven in our experimental setting with patient-based vascular models. Three-dimensional preoperative planning including registration and simulation of virtual angioscopy in real time are realised. Conclusion: The aim of the Nav-CARS-EVAR concept is reduction of contrast medium and radiation dose by a three-dimensional navigation during the EVAR procedure. To implement fibre-Bragg navigation further experimental studies are necessary to verify accuracy before clinical application.}, year = {2015}, issn = {0044-409X}, DOI = {10.1055/s-0035-1546261}, journal = {Zentralblatt f{\{\dq}u}r Chirurgie}, volume = {140}, pages = {493-499}, number = {05}, file_url = {https://doi.org/10.1055/s-0035-1546261} } @Article { Bahlmann2015, author = {Bahlmann, J. and Beckmann, I. and Kuhlemann, Ivo and Schweikard, Achim and M{\{\dq}u}nte, T. F.}, title = {Transcranial magnetic stimulation reveals complex cognitive control representations in the rostral frontal cortex}, abstract = {Convergent evidence suggests that the lateral frontal cortex is at the heart of a brain network subserving cognitive control. Recent theories assume a functional segregation along the rostro-caudal axis of the lateral frontal cortex based on differences in the degree of complexity of cognitive control. However, the functional contribution of specific rostral and caudal sub-regions remains elusive. Here we investigate the impact of disrupting rostral and caudal target regions on cognitive control processes, using Transcranial Magnetic Stimulation (TMS). Participants performed three different task-switching conditions that assessed differences in the degree of complexity of cognitive control processes, after temporally disrupting rostral, or caudal target regions, or a control region. Disrupting the rostral lateral frontal region specifically impaired behavioral performance of the most complex task-switching condition, in comparison to the caudal target region and the control region. These novel findings shed light on the neuroanatomical architecture supporting control over goal-directed behavior.}, year = {2015}, issn = {0306-4522}, DOI = {10.1016/j.neuroscience.2015.05.058}, journal = {Neuroscience}, volume = {300}, pages = {425-431}, keywords = {lateral frontal cortex}, file_url = {https://doi.org/10.1016/j.neuroscience.2015.05.058} } @Inproceedings { Blanck2015, author = {Blanck, Oliver and Sothmann, Thilo and Poels, Kenneth and Bruder, Ralf and Siebert, Frank-Andre and Grohmann, C. and Verellen, Dirk and Gauer, T.}, title = {Tracking-Precision-Comparison of two High-End-Linear Accelerator means 4D-Motion Platform and high resolution Flat Panel Detector}, year = {2015}, volume = {91}, series = {21st Annual Meeting of the German-Society-for-Radiation-Oncology}, tags = {UGRT} } @Inproceedings { wswb_15, author = {Wissel, Tobias and St{\{\dq}u}ber, Patrick and Wagner, Benjamin and Bruder, Ralf and Schweikard, Achim and Ernst, Floris}, title = {Enhanced Tissue Thickness Computation by Exploiting Local Neighborhoods}, year = {2015}, address = {Barcelona, Spain}, series = {International Journal of Computer Assisted Radiology and Surgery}, tags = {HPHT} } @Inproceedings { wsws_15b, author = {Wissel, Tobias and St{\{\dq}u}ber, Patrick and Wagner, Benjamin and Schweikard, Achim and Ernst, Floris}, title = {Efficient Estimation of Tissue Thicknesses using Sparse Approximation for Gaussian Processes}, abstract = {Highly accurate localization of the human skull is vital in cranial radiotherapy. Marker-less optical head tracking provides a fast and accurate way to monitor this motion. Recent research has given evidence that marker-less tracking of the forehead benefits from tissue thickness information in addition to the 3D surface geometry. Using Gaussian Processes (GPs) tissue thickness is determined from optical backscatter of a sweeping laser. However, the computational complexity of the GPs scales cubically with the number of training samples.}, year = {2015}, DOI = {10.1109/EMBC.2015.7320007}, publisher = {IEEE}, address = {Milano, Italy}, series = {EMBS}, pages = {7015-7018}, tags = {HPHT}, file_url = {https://doi.org/10.1109/EMBC.2015.7320007}, note = {High-Accuracy Head Tracking} } @Inproceedings { essb_15, author = {Ernst, Floris and Schweikard, Achim and St{\{\dq}u}ber, Patrick and Bruder, Ralf and Wagner, Benjamin and Wissel, Tobias}, title = {Analysis of feature stability for laser-based determination of tissue thickness}, abstract = {Localisation of the cranium is necessary for accurate stereotactic radiotherapy of malign lesions in the brain. This is achieved by immobilizing the patient's head (typically by using thermoplastic masks, bite blocks or combinations thereof) and X-ray imaging to determine the actual position of the patient with respect to the treatment device. In previous work we have developed a novel method for marker-less and non-invasive tracking of the skull using a combination of laser-based surface triangulation and the analysis of backscattered feature patterns of a tightly collimated NIR laser beam scanned over the patient's forehead. An HDR camera is coupled into the beam path of the laser scanning system to acquire one image per projected laser point. We have demonstrated that this setup is capable of accurately determining the tissue thickness for each triangulation point and consequently allows detecting the surface of the cranial bone with sub-millimetre accuracy. Typical clinical settings (treatment times of 15-90min) require feature stability over time, since the determination of tissue thickness is achieved by machine learning methods trained on initial feature scans. We have collected initial scans of the forehead as well as long-term backscatter data (20 images per seconds over 30min) from five subjects and extracted the relevant tissue features from the image streams. Based on the knowledge of the relationship between the tissue feature values and the tissue thickness, the analysis of the long-term data showed that the noise level is low enough to allow robust discrimination of tissue thicknesses of 0.5mm.}, year = {2015}, DOI = {10.1117/12.2078722}, volume = {9313}, address = {San Francisco, CA}, series = {Proceedings of SPIE}, pages = {93130Q}, tags = {HPHT}, file_url = {https://doi.org/10.1117/12.2078722}, note = {High-Accuracy Head Tracking} } @Inproceedings { mawmp_15, author = {Marshall, Lisa and Aumann, Dominic and Wilde, Christian and M{\{\dq}o}lle, Matthias and Parra, Lucas C.}, title = {Effects of Oscillatory Electric Fields on EEG Coupling: Slow oscillation and Spindle Activity}, year = {2015}, address = {G{\{\dq}o}ttingen}, series = {Neurowissenschaftliche Gesellschaft (NWG)}, tags = {TES} } @Article { pdvb_15, author = {Poels, Kenneth and Dhont, Jennifer and Verellen, Dirk and Blanck, Oliver and Ernst, Floris and Vandemeulebroucke, Jef and Depuydt, Tom and Storme, Guy and Ridder, Mark De}, title = {A comparison of two clinical correlation models used for real-time tumor tracking of semi-periodic motion: A focus on geometrical accuracy in lung and liver cancer patients}, year = {2015}, issn = {0167-8140}, DOI = {10.1016/j.radonc.2015.05.004}, journal = {Radiotherapy and Oncology}, volume = {115}, pages = {419-424}, number = {3}, keywords = {Cyberknife}, tags = {MCRT}, file_url = {https://doi.org/10.1016/j.radonc.2015.05.004}, note = {Motion Compensation in Radiosurgery} } @Article { Hagenah2015, author = {Hagenah, Jannis and Scharfschwerdt, Michael and Schlaefer, Alexander and Metzner, Christoph}, title = {A machine learning approach for planning valve-sparing aortic root reconstruction}, year = {2015}, issn = {ISSN (Online) 2364-5504}, journal = {Current Directions on Biomedical Engineering}, volume = {1}, pages = {361-365} } @Inproceedings { mwss_15, author = {Manit, Jirapong and Wissel, Tobias and St{\{\dq}u}ber, Patrick and Schweikard, Achim and Ernst, Floris}, title = {A Study of Gaussian Noise Effects on Skin Thickness Measurement}, year = {2015}, DOI = {10.1515/bmt-2015-5008}, volume = {60}, address = {L{\{\dq}u}beck, Germany}, series = {Biomedical Engineering}, pages = {S190}, number = {S1}, tags = {HPHT}, file_url = {https://doi.org/10.1515/bmt-2015-5008}, note = {High-Accuracy Head Tracking} } @Article { swwb_15, author = {St{\{\dq}u}ber, Patrick and Wagner, Benjamin and Wissel, Tobias and Bruder, Ralf and Schweikard, Achim and Ernst, Floris}, title = {An Approach to Improve Accuracy of Optical Tracking Systems in Cranial Radiation Therapy}, year = {2015}, journal = {Cureus}, volume = {7}, pages = {e239}, number = {1}, tags = {HPHT}, note = {doi: doi:10.7759/cureus.239} } @Inproceedings { Bruder2015a, author = {Bruder, Ralf and Wilde, Christian and Trillenberg, Peter and Binder, Sonja and Marshall, Lisa and Schweikard, Achim}, title = {An Electronically Configurable Multi-Channel tACS Device}, year = {2015}, address = {Duesseldorf, Germany}, series = {Deutsche Gesellschaft f{\{\dq}u}r Neurologie (DGN)}, tags = {TES} } @Inproceedings { Bruder2015b, author = {Bruder, Ralf and Ernst, Floris and Blanck, Oliver and Dunst, J{\{\dq}u}rgen and Schweikard, Achim}, title = {4D Ultrasound Image Guidance for Cardiac Radiosurgery}, year = {2015}, address = {Cookham, UK}, tags = {MCRT UGRT} } @Inproceedings { Hristov2015, author = {Hristov, Dimitre and Gong, Renhui and Schlosser, Jeffrey and Bruder, Ralf and Schweikard, Achim}, title = {Augmented reality system for robotic ultrasound guidance of external beam radiation therapy}, year = {2015}, address = {Barcelona, Spain}, series = {International Journal of Computer Assisted Radiology and Surgery}, tags = {MCRT UGRT} } @Article { wbbm_15, author = {Wilde, Christian and Bruder, Ralf and Binder, Sonja and Marshall, Lisa and Schweikard, Achim}, title = {Closed-loop transcranial alternating current stimulation of slow oscillations}, abstract = {Transcranial alternating current stimulation (tACS) is an emerging non-invasive tool for modulating brain oscillations. There is evidence that weak oscillatory electrical stimulation during sleep can entrain cortical slow oscillations to improve the memory consolidation in rodents and humans. Using a novel method and a custom built stimulation device, automatic stimulation of slow oscillations in-phase with the endogenous activity in a real-time closed-loop setup is possible. Preliminary data from neuroplasticity experiments show a high detection performance of the proposed method, electrical measurements demonstrate the outstanding quality of the presented stimulation device.}, year = {2015}, issn = {2364-5504}, DOI = {10.1515/cdbme-2015-0022}, journal = {Current Directions in Biomedical Engineering}, volume = {1}, pages = {85-88}, number = {1}, file_url = {https://doi.org/10.1515/cdbme-2015-0022} } @Article { wwss_15, author = {Wissel, Tobias and Wagner, Benjamin and St{\{\dq}u}ber, Patrick and Schweikard, Achim and Ernst, Floris}, title = {Data-driven Learning for Calibrating Galvanometric Laser Scanners}, year = {2015}, DOI = {10.1109/jsen.2015.2447835}, journal = {IEEE Sensors Journal}, volume = {15}, pages = {5709-5717}, number = {10}, tags = {HPHT}, file_url = {https://doi.org/10.1109/jsen.2015.2447835}, note = {timestamp=2015.06.26} } @Inproceedings { BMT15, title = {DGBMT Annual Conference}, year = {2015}, volume = {49}, address = {L{\{\dq}u}beck, Germany}, series = {DGBMT}, file_url = {http://www.bmt2015.de} } @Inproceedings { bgwh_15, author = {Blanck, Oliver and Grehn, Melanie and Wurster, S. and Hildebrandt, Guido and Dunst, J{\{\dq}u}rgen and Siebert, F. A. and Schweikard, Achim and Ernst, Floris}, title = {Dosimetrischer Einfluss von residualen Trackingfehlern in der robotergest{\{\dq}u}tzten Radiochirurgie von Lebertumoren}, abstract = {Fragestellung: Die robotergest{\{\dq}u}tzte Radiochirurgie f{\{\dq}u}r Lebertumore ist etabliert. W{\{\dq}a}hrend die technische Genauigkeit in der Dosisapplikation weitgehend bekannt ist, gab es bislang keine Analysen zum dosimetrischen Einfluss von residualen Trackingfehlern. Methodik: Untersucht wurden 29 Patienten, die aufgrund von Lebertumoren mit dem CyberKnife Synchrony Tracking System in 2-5 Fraktionen mit einer Dosis von 16-45 Gy behandelt wurden. Aus den insgesamt 100 Fraktionen wurden die einzelnen residualen Korrelations-, Pr{\{\dq}a}diktions- und Rotationsfehler bestimmt und in 10 Atemphasen unterteilt. Das jeweilige CTV bzw. PTV (CTV 3mm) wurde dann in einer Pseudo-4D-Dosisberechnung anhand der einzelnen Atemphasenfehler verschoben bzw. um den Schwerpunkt der implantierten Goldmarker, die w{\{\dq}a}hrend der Behandlung verfolgt wurden, rotiert. Ergebnis: Die {\{\dq}u}ber die Atemphasen gemittelten Korrelations-, Pr{\{\dq}a}diktions- und Rotationsfehler lagen bei (-0.14±2.17mm superior/inferior, -0.09±0.80mm links/rechts, -0.10±1.18mm anterior/posterior), (-0.01±0.24mm superior/inferior, 0.01±0.24mm links/rechts, 0.01±0.15mm anterior/posterior) und (-0.26±0.51° roll, 0.14±0.71° pitch, 0.61±0.61 yaw), wobei nur der Korrelationsfehler Atemphasen-unabh{\{\dq}a}ngig war. Die Dosissimulation ergab nicht unerhebliche Punktdosisfehler von -8.45Gy bis 15.01Gy und eine Reduktion der PTV-Coverage um durchschnittlich -1.52% (max -7.81%, min 0.82%), wobei dies fast ausschlie{\{\dq}s}lich auf die im CyberKnife bislang nicht korrigierbare atemabh{\{\dq}a}ngige Tumorrotation zur{\{\dq}u}ckzuf{\{\dq}u}hren ist. Dieser Effekt wurde verst{\{\dq}a}rkt, wenn die Goldmarker weiter vom Tumor entfernt lagen, wurde jedoch nicht von der Anordnung der Goldmarker oder der Dosisverteilung beeinflusst. Bei 11 Patienten (39.3%) reduzierte sich auch die CTV-Coverage um durchschnittlich -0,40% (max -1,03 %, min -0,07 %), so dass der 3mm gro{\{\dq}s}e Sicherheitssaum f{\{\dq}u}r diese Patienten nicht vollst{\{\dq}a}ndig ausreichte. Eine Korrelation der CTV-Dosisreduktion mit klinischen Rezidiven konnte jedoch bislang nicht belegt werden. Schlussfolgerung: Das CyberKnife ist in der Lage, translatorische Tumorbewegungen pr{\{\dq}a}zise auszugleichen, kann jedoch hinsichtlich rotierender Tumorbewegungen noch verbessert werden. Bei der robotergest{\{\dq}u}tzten Radiochirurgie von Lebertumoren ist ein Sicherheitssaum von 3mm nicht immer ausreichend und sollte bei starken atembasierten Deformationen oder Rotationsbewegungen auf 4-5mm erh{\{\dq}o}ht werden.}, year = {2015}, address = {Hamburg, Germany}, series = {Deutsche Gesellschaft f{\{\dq}u}r Radioonkologie (DEGRO)}, tags = {MCRT}, note = {Motion Compensation in Radiosurgery} } @Inproceedings { iobl_15, author = {Ipsen, Svenja and Oborn, Brad and Bode, F. and Liney, Gary and Hunold, P. and Rades, Dirk and Schweikard, Achim and Dunst, J{\{\dq}u}rgen and Keall, Paul J. and Blanck, Oliver}, title = {Echtzeit-Zielverfolgung f{\{\dq}u}r nicht invasive MRT-gest{\{\dq}u}tzte Herzradiochirurgie}, year = {2015}, address = {Hamburg, Germany}, series = {Deutsche Gesellschaft f{\{\dq}u}r Radioonkologie e.V. (DEGRO)}, tags = {MCRT} } @Inproceedings { Ludtke2015, author = {L{\{\dq}u}dtke, S. and Wagner, Benjamin and Bruder, Ralf and St{\{\dq}u}ber, Patrick and Ernst, Floris and Schweikard, Achim and Wissel, Tobias}, title = {Calibration of galvanometric laser scanners using statistical learning methods}, year = {2015}, DOI = {10.1007/978-3-662-46224-9_80}, publisher = {Springer}, address = {Berlin, Heidelberg, New York; L{\{\dq}u}beck, Germany}, pages = {467-472}, tags = {HPHT}, file_url = {https://doi.org/10.1007/978-3-662-46224-9_80} } @Inproceedings { mwsd_14, author = {Merkel, Katharina and Wissel, Tobias and Schweikard, Achim and D{\{\dq}u}richen, Robert}, title = {Respiratory motion prediction with surface EMG features}, year = {2014}, volume = {9}, address = {Fukuoka, Japan}, series = {International Journal of Computer Assisted Radiology and Surgery}, pages = {290-291}, number = {S1}, tags = {MCRT}, file_url = {http://www.cars-int.org}, note = {Motion Compensation in Radiosurgery} } @Article { ebws_13a, author = {Ernst, Floris and Bruder, Ralf and Wissel, Tobias and St{\{\dq}u}ber, Patrick and Wagner, Benjamin and Schweikard, Achim}, title = {Measuring cranial soft tissue thickness with MRI or pressure-compensated tracked ultrasound}, year = {2014}, journal = {British Journal of Medicine and Medical Research}, volume = {4}, pages = {937-948}, number = {4}, tags = {HPHT}, note = {High-Accuracy Head Tracking} } @Inproceedings { dpc_14, author = {D{\{\dq}u}richen, Robert and Pimentel, Marco A. F. and Clifton, Lei and Schweikard, Achim and Clifton, David A.}, title = {Multi-task Gaussian process models for biomedical applications}, abstract = {Gaussian process (GP) models are a flexible means of performing non-parametric Bayesian regression. However, the majority of existing work using GP models in healthcare data is defined for univariate output time-series, denoted as single-task GPs (STGP). Here, we investigate how GPs could be used to model multiple correlated univariate physiological time-series simultaneously. The resulting multi-task GP (MTGP) framework can learn the correlation within multiple signals even though they might be sampled at different frequencies and have training sets available for different intervals. We illustrate the basic properties of MTGPs using a synthetic casestudy with respiratory motion data. Finally, two real-world biomedical problems are investigated from the field of patient monitoring and motion compensation in radiotherapy. The results are compared to STGPs and other standard methods in the respective fields. In both cases, MTGPs learned the correlation between physiological time-series efficiently, which leads to improved modelling accuracy.}, year = {2014}, DOI = {10.1109/BHI.2014.6864410}, address = {Valencia, Spain}, pages = {492-495}, tags = {MCRT}, file_url = {https://doi.org/10.1109/BHI.2014.6864410}, note = {Motion Compensation in Radiosurgery} } @Article { dpcs_14, author = {D{\{\dq}u}richen, Robert and Pimentel, Marco A. F. and Clifton, Lei and Schweikard, Achim and Clifton, David A.}, title = {Multi-task Gaussian Processes for Multivariate Physiological Time-Series Analysis}, abstract = {Gaussian process (GP) models are a flexible means of performing non-parametric Bayesian regression. However, GP models in healthcare are often only used to model a single univariate output time-series, denoted as single-task GPs (STGP). Due to an increasing prevalence of sensors in healthcare settings, there is an urgent need for robust multivariate time-series tools. Here, we propose a new method using multi-task GPs (MTGPs) which can model multiple correlated multivariate physiological time-series simultaneously. The flexible MTGP framework can learn the correlation within multiple signals even though they might be sampled at different frequencies and have training sets available for different intervals. Furthermore, prior knowledge of any relationship between the time-series such as delays and temporal behaviour can be easily integrated. A novel normalisation is proposed to allow interpretation of the various hyperparameters used in the MTGP. We investigate MTGPs for physiological monitoring with synthetic datasets and two real-world problems from the field of patient monitoring and radiotherapy. The results are compared to standard Gaussian processes and other existing methods in the respective biomedical application areas. In both cases, we show that our proposed framework learned the correlation between physiological timeseries efficiently, outperforming the existing state-of-the-art.}, year = {2014}, DOI = {10.1109/TBME.2014.2351376}, journal = {IEEE Transactions on Biomedical Engineering}, volume = {62}, pages = {314-322}, number = {1}, tags = {MCRT}, file_url = {https://doi.org/10.1109/TBME.2014.2351376}, note = {Motion Compensation in Radiosurgery} } @Article { dwe2_14, author = {D{\{\dq}u}richen, Robert and Wissel, Tobias and Ernst, Floris and Schlaefer, Alexander and Schweikard, Achim}, title = {Multivariate respiratory motion prediction}, abstract = {In extracranial robotic radiotherapy, tumour motion is compensated by tracking external and internal surrogates. To compensate system specific time delays, time series prediction of the external optical surrogates is used. We investigate whether the prediction accuracy can be increased by expanding the current clinical setup by an accelerometer, a strain belt and a flow sensor. Four previously published prediction algorithms are adapted to multivariate inputs normalized least mean squares (nLMS), wavelet-based least mean squares (wLMS), support vector regression (SVR) and relevance vector machines (RVM) and evaluated for three different prediction horizons. The measurement involves 18 subjects and consists of two phases, focusing on long term trends (M1) and breathing artefacts (M2). To select the most relevant and least redundant sensors, a sequential forward selection (SFS) method is proposed. Using a multivariate setting, the results show that the clinically used nLMS algorithm is susceptible to large outliers. In the case of irregular breathing (M2), the mean root mean square error (RMSE) of a univariate nLMS algorithm is 0.66{\^A} mm and can be decreased to 0.46{\^A} mm by a multivariate RVM model (best algorithm on average). To investigate the full potential of this approach, the optimal sensor combination was also estimated on the complete test set. The results indicate that a further decrease in RMSE is possible for RVM (to 0.42{\^A} mm). This motivates further research about sensor selection methods. Besides the optical surrogates, the sensors most frequently selected by the algorithms are the accelerometer and the strain belt. These sensors could be easily integrated in the current clinical setup and would allow a more precise motion compensation.}, year = {2014}, issn = {0031-9155}, journal = {Physics in Medicine and Biology}, volume = {59}, pages = {6043}, number = {20}, tags = {MCRT}, note = {Motion Compensation in Radiosurgery} } @Article { ibob_14, author = {Ipsen, Svenja and Blanck, Oliver and Oborn, Brad and Bode, F. and Liney, Gary and Hunold, P. and Rades, Dirk and Schweikard, Achim and Keall, Paul J.}, title = {Radiotherapy beyond cancer: Target localization in real-time MRI and treatment planning for cardiac radiosurgery}, abstract = {PURPOSE: Atrial fibrillation (AFib) is the most common cardiac arrhythmia that affects millions of patients world-wide. AFib is usually treated with minimally invasive, time consuming catheter ablation techniques. While recently noninvasive radiosurgery to the pulmonary vein antrum (PVA) in the left atrium has been proposed for AFib treatment, precise target location during treatment is challenging due to complex respiratory and cardiac motion. A MRI linear accelerator (MRI-Linac) could solve the problems of motion tracking and compensation using real-time image guidance. In this study, the authors quantified target motion ranges on cardiac magnetic resonance imaging (MRI) and analyzed the dosimetric benefits of margin reduction assuming real-time motion compensation was applied. METHODS: For the imaging study, six human subjects underwent real-time cardiac MRI under free breathing. The target motion was analyzed retrospectively using a template matching algorithm. The planning study was conducted on a CT of an AFib patient with a centrally located esophagus undergoing catheter ablation, representing an ideal case for cardiac radiosurgery. The target definition was similar to the ablation lesions at the PVA created during catheter treatment. Safety margins of 0 mm (perfect tracking) to 8 mm (untracked respiratory motion) were added to the target, defining the planning target volume (PTV). For each margin, a 30 Gy single fraction IMRT plan was generated. Additionally, the influence of 1 and 3 T magnetic fields on the treatment beam delivery was simulated using Monte Carlo calculations to determine the dosimetric impact of MRI guidance for two different Linac positions. RESULTS: Real-time cardiac MRI showed mean respiratory target motion of 10.2 mm (superior-inferior), 2.4 mm (anterior-posterior), and 2 mm (left-right). The planning study showed that increasing safety margins to encompass untracked respiratory motion leads to overlapping structures even in the ideal scenario, compromising either normal tissue dose constraints or PTV coverage. The magnetic field caused a slight increase in the PTV dose with the in-line MRI-Linac configuration. CONCLUSIONS: The authors' results indicate that real-time tracking and motion compensation are mandatory for cardiac radiosurgery and MRI-guidance is feasible, opening the possibility of treating cardiac arrhythmia patients completely noninvasively.}, year = {2014}, issn = {0094-2405}, DOI = {10.1118/1.4901414}, journal = {Medical Physics}, volume = {41}, pages = {120702-1-8}, number = {12}, keywords = {Atrial fibrillation; cardiac radiosurgery; Image guidance; MRI-Linac; real-time tracking}, tags = {MCRT}, file_url = {https://doi.org/10.1118/1.4901414} } @Inproceedings { biob_14, author = {Blanck, Oliver and Ipsen, Svenja and Oborn, Brad and Bruder, Ralf and Werner, Ren{\'e} and Bode, F. and Hunold, P. and Liney, Gary and Rades, Dirk and Dunst, J{\{\dq}u}rgen and Schweikard, Achim and Keall, Paul J.}, title = {Treatment planning for cardiac radiosurgery -- initial human simulations}, year = {2014}, address = {Z{\{\dq}u}rich, Switzerland}, series = {Swiss, German and Austrian Society of Medical Physics (SSRMP, DGMP, {\{\dq}O}GMP)}, tags = {MCRT MCM} } @Inproceedings { vbs_14, author = {Viulet, Tiberiu and Blanck, Oliver and Schlaefer, Alexander}, title = {SU-ET-258: Parallel Optimization of Beam Configurations for CyberKnife Treatments}, year = {2014}, DOI = {10.1118/1.4888589}, volume = {41}, series = {Medical Physics}, pages = {283}, number = {6}, file_url = {https://doi.org/10.1118/1.4888589}, note = {SU-E-T-258} } @Inproceedings { wswd_14, author = {Wissel, Tobias and St{\{\dq}u}ber, Patrick and Wagner, Benjamin and D{\{\dq}u}richen, Robert and Bruder, Ralf and Schweikard, Achim and Ernst, Floris}, title = {Tissue Thickness Estimation for High Precision Head-Tracking using a Galvanometric Laser Scanner - A Case Study}, abstract = {Marker-less optical head-tracking constitutes a comfortable alternative with no exposure to radiation for realtime monitoring in radiation therapy. Supporting information such as tissue thickness has the potential to improve spatial tracking accuracy. Here we study how accurate tissue thickness can be estimated from the near-infrared (NIR) backscatter obtained from laser scans. In a case study, optical data was recorded with a galvanometric laser scanner from three subjects. A tissue ground truth from MRI was robustly matched via customized bite blocks. We show that Gaussian Processes accurately model the relationship between NIR features and tissue thickness. They were able to predict the tissue thickness with less than 0.5 mm root mean square error. Individual scaling factors for all features and an additional incident angle feature had positive effects on this performance.}, year = {2014}, publisher = {IEEE}, address = {Chicago, IL}, series = {EMBS}, pages = {3106-3109}, tags = {HPHT}, note = {High-Accuracy Head Tracking} } @Inproceedings { wbbms_14, author = {Wilde, Christian and Bruder, Ralf and Binder, Sonja and Marshall, Lisa and Schweikard, Achim}, title = {Towards Closed-Loop Transcranial Alternating Current Stimulation}, abstract = {Introduction: Transcranial alternating current stimulation (tACS) is a noninvasive tool for modulating brain oscillations. Simultaneous recording of endogenous cortical oscillations such as electroencephalography (EEG) enables frequency and phase selective stimulation, presumably optimizing the modulation of brain activity. Nevertheless, measuring EEG while stimulating the brain is a challenging problem. Often, different devices are used for signal acquisition, signal processing, and signal generation, each with specific latencies and distortions leading to bad overall signal quality. Furthermore, stimulation artifacts commonly exceed the endogenous EEG signals. Here, a unified approach for an EEG-driven tACS system with guaranteed undistorted input-to-output coupling is proposed as a first step towards closed-loop tACS. Methods: A device based on custom input/output peripherals and a FPGA (field-programmable gate array) is presented. In contrast to conventional computers, FPGAs are able to rapidly execute complex concurrent processes. So, signal acquisition, signal processing (e.g. fast Fourier transform), and signal generation can take place at the same time on the same device. Synchronous timestamps for measuring and stimulating guarantee direct coupling of input and output. The signal-to-noise ratio (SNR) and the total harmonic distortion (THD) are determined to confirm the quality of the device. Its functionality and efficiency are shown in first animal experiments. Results: A first prototype of the proposed system was built for stimulating small animals, primarily mice. The SNR and THD of the whole implementation were determined in a closed-loop setup, i.e. the generated output was fed back to the input. The measured SNR and THD are both -80 dB. In preliminary neuroplasticity animal experiments, the prototype was able to detect desired brain oscillations and stimulate in-phase with endogenous parameters. Conclusion: The current prototype will be used in more animal experiments, and thus provide relevant information for the further development of the whole system. In the future, a new device will be implemented for human stimulation. The next important step to achieve full closed-loop capabilities is the development of an appropriate artifact removal. This is current work in progress. In the long run, neuroplasticity experiments will benefit from the improved stimulation procedure. With increased quality, new fields of application of tACS may also arise.}, year = {2014}, address = {Munich, Germany}, series = {Deutsche Gesellschaft f{\{\dq}u}r Neurologie (DGN)}, tags = {TES} } @Article { amae_14, author = {Ansari, Rehman and Myrtus, Christian and Aherrahrou, Redouane and Erdmann, Jeanette and Schweikard, Achim and H{\{\dq}u}ttmann, Gereon}, title = {Ultrahigh-resolution, high-speed spectral domain optical coherence phase microscopy}, year = {2014}, DOI = {10.1364/ol.39.000045}, journal = {Optics Letters}, volume = {39}, publisher = {OSA}, pages = {45-47}, number = {1}, keywords = {Coherence imaging; Microscopy; Three-dimensional microscopy}, file_url = {https://doi.org/10.1364/ol.39.000045} } @Inproceedings { kbes_14, author = {Kuhlemann, Ivo and Bruder, Ralf and Ernst, Floris and Schweikard, Achim}, title = {WE-G-BRF-09: Force- and Image-Adaptive Strategies for Robotised Placement of 4D Ultrasound Probes}, abstract = {Purpose: To allow continuous acquisition of high quality 4D ultrasound images for non-invasive live tracking of tumours for IGRT, image- and force-adaptive strategies for robotised placement of 4D ultrasound probes are developed and evaluated. Methods: The developed robotised ultrasound system is based on a 6-axes industrial robot (adept Viper s850) carrying a 4D ultrasound transducer with a mounted force-torque sensor. The force-adaptive placement strategies include probe position control using artificial potential fields and contact pressure regulation by a PD controller strategy. The basis for live target tracking is a continuous minimum contact pressure to ensure good image quality and high patient comfort. This contact pressure can be significantly disturbed by respiratory movements and has to be compensated. All measurements were performed on human subjects under realistic conditions. When performing cardiac ultrasound, rib- and lung shadows are a common source of interference and can disrupt the tracking. To ensure continuous tracking, these artefacts had to be detected to automatically realign the probe. The detection is realised by multiple algorithms based on entropy calculations as well as a determination of the image quality. Results: Through active contact pressure regulation it was possible to reduce the variance of the contact pressure by 89.79% despite respiratory motion of the chest. The results regarding the image processing clearly demonstrate the feasibility to detect image artefacts like rib shadows in real-time. Conclusion: In all cases, it was possible to stabilise the image quality by active contact pressure control and automatically detected image artefacts. This fact enables the possibility to compensate for such interferences by realigning the probe and thus continuously optimising the ultrasound images. This is a huge step towards fully automated transducer positioning and opens the possibility for stable target tracking in ultrasoundguided radiation therapy requiring contact pressure of 5--10 N.}, year = {2014}, DOI = {10.1118/1.4889502}, volume = {41}, series = {Medical Physics}, pages = {523}, number = {6}, tags = {MCRT UGRT}, file_url = {https://doi.org/10.1118/1.4889502}, note = {RobLab, Motion Compensation in Radiosurgery} } @Article { Werner2014, author = {Werner, Ren{\'e} and Bode, F. and Bruder, Ralf and Gebhard, M. and Dunst, J{\{\dq}u}rgen and Rades, Dirk and Blanck, Oliver}, title = {Impact of cardiac and respiratory motion during cardiac radiosurgery: a dose accumulation study in a porcine model}, year = {2014}, DOI = {10.1016/S0167-8140(15)30608-3}, journal = {Radiotherapy and Oncology}, volume = {111}, pages = {S197-S198}, tags = {UGRT}, file_url = {https://doi.org/10.1016/S0167-8140(15)30608-3} } @Inproceedings { gbse_14, author = {Gra{\{\dq}s}hoff, Jan and Bruder, Ralf and Schweikard, Achim and Ernst, Floris}, title = {Kalman Filter based Head Tracking for Cranial Radiation Therapy with low-cost Range-Imaging Cameras}, year = {2014}, DOI = {10.1007/978-3-642-54111-7_60}, publisher = {Springer}, address = {Aachen, Germany; Berlin, Heidelberg}, series = {Informatik aktuell}, editor = {Deserno, Thomas M. and Handels, Heinz and Tolxdorff, Thomas and Meinzer, Hans-Peter and Ehrhardt, Jan}, pages = {324-329}, tags = {HPHT}, file_url = {https://doi.org/10.1007/978-3-642-54111-7_60}, note = {High-Accuracy Head Tracking} } @Inproceedings { swwb_14a, author = {St{\{\dq}u}ber, Patrick and Wissel, Tobias and Wagner, Benjamin and Bruder, Ralf and Schweikard, Achim and Ernst, Floris}, title = {A comparison of different hardware design approaches for feature-supported optical tracking with respect to angular dependencies}, abstract = {Purpose: Recent research has shown that optical features significantly improve marker-less optical head-tracking for cranial radiotherapy. Simulations, however, showed that these optical features, which are used to derive tissue thickness, depend on the incident angle of the IR scanning laser beam and the perspective of the camera analyzing the reflective patterns. We present an experimental analysis determining which is the most robust optical setup concerning angular influences. Methods: In three consecutive experiments, the incident angle of the laser (1), the perspective of the camera (2) or both simultaneously (3, `inBeam'-perspective) were changed with respect to the target. We analyzed how this affects feature intensity. These intensities were determined from seven concentric regions of interest (ROIs) around the laser spot. Two targets were used: a tissue-like silicone phantom and a human's forehead. Results: For each experiment, the feature intensity generally decreases with increasing angle. We found that the optical properties of the silicone phantom do not fit the properties of human skin. Furthermore, the angular influence of the laser on the features is significantly higher than the perspective of the camera. With the `inBeam'- perspective, the smoothest decays of feature intensity were found. We suppose that this is because of a fixed relationship between both devices. This smoothness, suggesting a predictable functional relationship, may simplify angle compensation for machine learning algorithms. This is particularly prominent for the medial ROIs. The inner ROIs highly depend on the angle and power of the laser. The outer ROIs show less angular dependency but the signal strength is critically low and prone to artifacts. Therefore and because of the smooth decays, medial ROIs are a suitable tradeoff between susceptibility, signal-noise-ratio and distance to the center of the laser spot. Conclusion: For tissue thickness correlated feature acquisition, the medial ROIs with the `inBeam'-setup provide most valuable features.}, year = {2014}, DOI = {10.1118/1.4888259}, volume = {41}, series = {Medical Physics}, pages = {204}, number = {6}, tags = {HPHT}, file_url = {https://doi.org/10.1118/1.4888259}, note = {High-Accuracy Head Tracking} } @Inproceedings { dfws_14, author = {D{\{\dq}u}richen, Robert and Fang, Xiao and Wissel, Tobias and Schweikard, Achim}, title = {Gaussian Process models for respiratory motion compensation}, year = {2014}, volume = {9}, address = {Fukuoka, Japan}, series = {International Journal of Computer Assisted Radiology and Surgery}, pages = {286-287}, number = {S1}, tags = {MCRT}, file_url = {http://www.cars-int.org}, note = {Motion Compensation in Radiosurgery} } @Misc { Bruder2014, author = {Bruder, Ralf and Schweikard, Achim}, title = {Apparatus and method for real-time tracking of tissue structures}, year = {2014} } @Phdthesis { Dürichen2014, author = {D{\{\dq}u}richen, Robert}, title = {From Univariate to Multivariate Respiratory Motion Compensation - A Bayesian Way to Increase Treatment Accuracy in Robotic Radiotherapy}, abstract = {Cancer is one of the most prevalent causes of death worldwide. Even though intense research effort has been dedicated to advance diagnostic and treatment techniques, statistics indicate that the five year survival rates especially for lung, liver and pancreas tumours are still very low. Radiotherapy is a relevant treatment option beside surgical and chemotherapeutic approaches. One treatment option for tumours located in the breast and abdominal regions is robotic radiotherapy. The advantage is that tumour motion caused by respiratory or cardiac motion of patients can be compensated which increases the treatment accuracy. Clinically used systems are the CyberKnife or multileaf collimators (MLCs). To perform an adaptive motion compensation (MC), two problems have to be addressed. First, time latencies of the specific treatment system (due to data processing and kinematic limitations) have to be compensated. Second, real-time acquisition of the internal tumour position is not possible without exposing the patient to an additional radiation dose. To overcome these problems, prediction and correlation models are used, which both depend on data of univariate external optical surrogates. The problem of respiratory motion compensation is relevant for various medical applications. In general, a diverse number of techniques has been developed to measure respiratory activity including different sensor modalities and measurement positions. However, data of a single sensor covers only information of a specific aspect of the more complex underlying process of respiration. Motivated by this observation, the first and main focus of this work is to develop multivariate extensions of current prediction and correlation models. The aim is to efficiently combine information of multiple sensors to further increase treatment accuracy. In particular, probabilistic algorithms will be applied for this purpose. Due to the increased power of modern computers, these computationally more demanding models have become applicable for real-time applications. In contrast to non-probabilistic models, the output of these algorithms is a probability distribution with predicted mean and variance. The variance contains relevant information about the {\dq}certainty{\dq} of the algorithm in the current output. Such information might be useful to control the prediction error during the treatment, which is the second main focus of this work. An extensive literature review confirms the initial assumptions that primarily optical surrogates were investigated in the literature. Furthermore, only one probabilistic algorithm was evaluated for the purpose of respiratory motion compensation - with controversial results. As a consequence, two new MC algorithms were developed, namely Gaussian process (GP) models and relevance vector machines (RVMs). Before applying these in a multivariate setting, the performance of these algorithms was examined for the purpose of standard univariate prediction models. The influence of model specific parameters such as the number of training pairs (in case of RVM) and covariance function (in case of GP) was studied on selected motion traces. Furthermore, a comprehensive evaluation was performed on a dataset consisting of 304 motion traces. They were compared to six previously published algorithms including support vector regression (SVR), Kalman Filter, and wavelet-based least mean square (wLMS) methods for four different prediction latencies. On average, the RVM model with a linear basis function had a superior accuracy and outperformed all previous algorithms independently of the prediction latencies. The result of the best GP model indicates a superior accuracy for shorter prediction horizons (h = {}77, 115, 154}, year = {2014}, address = {Institute for Robotics and Cognitive Systems}, series = {Universit{\{\dq}a}t zu L{\{\dq}u}beck}, tags = {MCRT} } @Inproceedings { dwe_14, author = {D{\{\dq}u}richen, Robert and Wissel, Tobias and Ernst, Floris and Pimentel, Marco A. F. and Clifton, David A. and Schweikard, Achim}, title = {A Unified Approach For Respiratory Motion Prediction and Correlation with Multi-Task Gaussian Processes}, abstract = {In extracranial robotic radiotherapy, tumour motion due to respiration is compensated based external markers. Two models are typically used to enable a real-time adaptation. A prediction model, which compensates time latencies of the treatment systems due to e.g. kinematic limitations, and a correlation model, which estimates the internal tumour position based on external markers. We present a novel approach based on multi-task Gaussian Processes (MTGP) which enables an efficient combination of both models by simultaneously learning the correlation and temporal delays between markers. The approach is evaluated using datasets acquired from porcine and human studies. We conclude that the prediction accuracy of MTGP is superior to that of existing methods and can be further increased by using multivariate input data. We investigate the dependency of the number of internal training points and the potential for using the marginal likelihood for model selection.}, year = {2014}, DOI = {10.1109/MLSP.2014.6958895}, address = {Reims, France}, pages = {1-6}, tags = {MCRT}, file_url = {https://doi.org/10.1109/MLSP.2014.6958895}, note = {Motion Compensation in Radiosurgery} } @Article { wswb_14c, author = {Wagner, Benjamin and St{\{\dq}u}ber, Patrick and Wissel, Tobias and Bruder, Ralf and Schweikard, Achim and Ernst, Floris}, title = {Accuracy analysis for triangulation and tracking based on time-multiplexed structured light}, abstract = {Purpose: Our research group is currently developing a new optical head tracking system for in10 tracranial radiosurgery. This tracking system utilises infrared laser light to measure features of the soft tissue on the patient's forehead. These features are intended to offer highly accurate registration with respect to the rigid skull structure by means of compensating for the soft tissue. In this context, the system also has to be able to quickly generate accurate reconstructions of the skin surface. For this purpose, we have developed a laser scanning device which uses time-multiplexed 15 structured light to triangulate surface points. Methods: The accuracy of our laser scanning device is analysed and compared for different triangulation methods. These methods are given by the Linear-Eigen method and a non-linear least squares method. Since Microsoft's Kinect camera represents an alternative for fast surface reconstruction, our results are also compared to the triangulation accuracy of the Kinect device. Moreover, our laser 20 scanning device was used for tracking of a rigid object to determine how this process is influenced by the remaining triangulation errors. For this experiment, the scanning device was mounted to the end-effector of a robot to be able to calculate a ground truth for the tracking. Results: The analysis of the triangulation accuracy of our laser scanning device revealed an RMS error of 0.16 mm. In comparison, the analysis of the triangulation accuracy of the Kinect device 25 revealed an RMS error of 0.89 mm. It turned out that the remaining triangulation errors only cause small inaccuracies for the tracking of a rigid object. Here, the tracking accuracy was given by a RMS translational error of 0.33 mm and a RMS rotational error of 0.12 degrees. Conclusion: This paper shows that time-multiplexed structured light can be used to generate highly accurate reconstructions of surfaces. Furthermore, the reconstructed point sets can be used 30 for high-accuracy tracking of objects, meeting the strict requirements of intracranial radiosurgery.}, year = {2014}, DOI = {10.1118/1.4890093}, journal = {Medical Physics}, volume = {41}, pages = {082701}, number = {8}, tags = {HPHT}, file_url = {https://doi.org/10.1118/1.4890093}, note = {High-Accuracy Head Tracking} } @Inproceedings { Hagenah2014b, author = {Hagenah, Jannis and Scharfschwerdt, Michael and Metzner, Christoph and Schlaefer, Alexander and Sievers, H. H. and Schweikard, Achim}, title = {An approach for patient specific modeling of the aortic valve leaflets}, year = {2014}, volume = {3}, publisher = {GRIN Verlag}, series = {Student Conference Medical Engineering Science 2014: Proceedings}, tags = {MCM} } @Inproceedings { AAPM14, title = {Annual Meeting of the AAPM}, year = {2014}, volume = {56}, publisher = {American Association of Physicists in Medicine}, address = {Austin, TX, USA}, series = {American Association of Physicists in Medicine}, file_url = {http://www.aapm.org/meetings/2014AM/} } @Inproceedings { wswb_14a, author = {Wissel, Tobias and St{\{\dq}u}ber, Patrick and Wagner, Benjamin and Bruder, Ralf and Schweikard, Achim and Ernst, Floris}, title = {Angle influence and compensation for marker-less head tracking based on laser scanners}, year = {2014}, volume = {9}, address = {Fukuoka, Japan}, series = {International Journal of Computer Assisted Radiology and Surgery}, pages = {62-63}, number = {S1}, tags = {HPHT}, file_url = {http://www.cars-int.org}, note = {High-Accuracy Head Tracking} } @Phdthesis { Metzner2014c, author = {Metzner, Christoph}, title = {Centre-Surround Suppression: Computational Modelling and Neural and Perceptual Correlates in Humans}, year = {2014}, series = {Universitaet zu Luebeck}, note = {Dissertation} } @Inproceedings { Metzner2014a, author = {Metzner, Christoph}, title = {Coding in the olfactory system: linking realistic and abstract models}, year = {2014}, volume = {3}, pages = {P10}, number = {Suppl. 1}, tags = {NM}, note = {Neurological Modelling} } @Inproceedings { Metzner2014b, author = {Metzner, Christoph and Schweikard, Achim and Zurowski, B.}, title = {Computational Multifactoriality in a Detailed Neural Network Model Resembling Centre-Surround Suppression Deficits in Schizophrenia}, year = {2014}, volume = {15}, series = {Proceedings CNS}, number = {Suppl. 1}, tags = {NM}, note = {Neurological Modelling} } @Article { dws2_14, author = {D{\{\dq}u}richen, Robert and Wissel, Tobias and Schweikard, Achim}, title = {Controlling motion prediction errors in radiotherapy with relevance vector machine}, abstract = {Purpose: Robotic radiotherapy can precisely ablate moving tumors when time latencies have been compensated. Recently, relevance vector machines (RVM), a probabilistic regression technique, outperformed six other prediction algorithms for respiratory compensation. The method has the distinct advantage that each predicted point is assumed to be drawn from a normal distribution. Second order statistics, the predicted variance, were used to control RVM prediction error during a treatment and to construct hybrid prediction algorithms. Methods: First, the duty cycle and the precision were correlated to the variance by interrupting the treatment if the variance exceeds a threshold. Second, two hybrid algorithms based on the variance were developed, one consisting of multiple RVMs (HYB R V M) and the other of a combination between a wavelet based least mean square algorithm (wLMS) and a RVM (HYB w LM S − R V M). The variance for different motion traces was analyzed to reveal a characteristic variance pattern which gives insight in what kind of prediction errors can be controlled by the variance. Results: Limiting the variance by a threshold resulted in an increased precision with a decreased duty cycle. All hybrid algorithms showed an increased prediction accuracy compared to using only their individual algorithms. The best hybrid algorithm, HYB R V M, can decrease the mean RMSE over all 304 motion traces from 0 .18 mm for a linear RVM to 0 .17 mm. Conclusions: The predicted variance was shown to be an efficient metric to control prediction errors, resulting in a more robust radiotherapy treatment. The hybrid algorithm HYB R V M could be translated to clinical practice. It do es not require further parameters, can b e completely parallelised and easily further extended.}, year = {2014}, DOI = {10.1007/s11548-014-1008-x}, journal = {International Journal of Computer Assisted Radiology and Surgery}, pages = {in-press}, keywords = {Computer-assisted radiation therapy; Relevance vector machines; Respiratory motion compensation; Uncertainty measures}, tags = {MCRT}, file_url = {https://doi.org/10.1007/s11548-014-1008-x}, note = {Motion Compensation in Radiosurgery} } @Article { Blanck2014, author = {Blanck, Oliver and Bode, F. and Gebhard, Maximilian P. E. and Hunold, P. and Brandt, Sebastian and Bruder, Ralf and Grossherr, M. and Vonthein, R. and Rades, Dirk and Dunst, J{\{\dq}u}rgen}, title = {Dose-Escalation Study for Cardiac Radiosurgery in a Porcine Model}, year = {2014}, DOI = {10.1016/j.ijrobp.2014.02.036}, journal = {International journal of radiation oncology, biology, physics}, pages = {89}, tags = {UGRT}, file_url = {https://doi.org/10.1016/j.ijrobp.2014.02.036} } @Inproceedings { Zellerhoff2014BMT, author = {Zellerhoff, Maria and Romeike, Ralf and Weber, Wolfgang}, title = {Educational Goals, Competencies, Performance --- How to Describe the Learning Outcomes of StudyProgrammes in Biomedical Engineering? 48th Annual Conference}, year = {2014}, address = {Hannover} } @Inproceedings { dws_14, author = {D{\{\dq}u}richen, Robert and Wissel, Tobias and Schweikard, Achim}, title = {Exploiting probabilistic uncertainty measures for respiratory motion prediction}, year = {2014}, volume = {9}, address = {Fukuoka, Japan}, series = {International Journal of Computer Assisted Radiology and Surgery}, pages = {59}, number = {S1}, tags = {MCRT}, file_url = {http://www.cars-int.org}, note = {Motion Compensation in Radiosurgery} } @Inproceedings { bbgh_13, author = {Blanck, Oliver and Bode, F. and Gebhard, M. and Hunold, P. and Brandt, Stephan A. and Bruder, Ralf and Schweikard, Achim and Grossherr, M. and Rades, Dirk and Dunst, J{\{\dq}u}rgen}, title = {Radiosurgery to Create Lesions in the Pulmonary Vein Antrum: Preliminary Results in a Porcine Model and Possible Implications for the Treatment of Atrial Fibrillation}, year = {2013}, publisher = {The Radiosurgery Society}, address = {Calsbad, CA, USA}, tags = {UGRT} } @Inproceedings { sewz_13, author = {Stender, Birgit and Ernst, Floris and Wang, Bo and Zhang, Z. X. and Schlaefer, Alexander}, title = {Motion compensation of optical mapping signals from isolated beating rat hearts}, abstract = {Optical mapping is a well established technique for recording monophasic action potential traces on the epicardial surface of isolated hearts. This measuring technique offers a high spatial resolution but it is sensitive towards myocardial motion. Motion artifacts occur because the mapping between a certain tissue portion sending out fluorescent light and a pixel of the photo detector changes over time. So far this problem has been addressed by suppressing the motion or ratiometric imaging. We developed a different approach to compensate the motion artifacts based on image registration. We could demonstrate how an image deformation field temporally changing with the heart motion could be determined. Using these deformation field time series for image transformation motion signals could be generated for each image pixel which were then successfully applied to remove baseline shift and compensate motion artifacts potentially leading to errors within maps of the first arrival time. The investigation was based on five different rat hearts stained with Di-4-ANEPPS.}, year = {2013}, DOI = {10.1117/12.2024847}, volume = {8856}, publisher = {SPIE}, address = {San Diego, CA}, series = {Proceedings of SPIE}, pages = {88561C-1 - 88561C-6}, tags = {MCM}, file_url = {https://doi.org/10.1117/12.2024847}, note = {Planning of Cardiac Interventions} } @Inproceedings { dwes_13b, author = {D{\{\dq}u}richen, Robert and Wissel, Tobias and Ernst, Floris and Schweikard, Achim}, title = {Multi-modal respiratory motion prediction using sequential forward selection method}, abstract = {In robotic radiotherapy, systematic latencies have to be compensated by prediction of external optical surrogates. We investigate possibilities to increase the prediction accuracy using multi-modal sensors. The measurement setup includes position, acceleration, strain and flow sensors. To select the most relevant and least redundant information from the sensors and to limit the size of the feature set, a sequential forward selection (SFS) method is proposed. The method is evaluated with three prediction algorithms -- the least means square (LMS) algorithm, a wavelet-based LMS algorithm (wLMS) and an algorithm using relevance vector machines (RVM). We show that multi-modal inputs can easily be integrated into general algorithms. The relative root mean square error (RMSrel) of the best predictor, RVM, could be decreased from 60.5 % to 48.4 %. Furthermore, the results indicate that more complex algorithms can efficiently use different modalities like acceleration which are less correlated with the optical sensor to be predicted.}, year = {2013}, volume = {12}, address = {Innsbruck, Austria}, series = {CURAC}, pages = {183-187}, tags = {MCRT}, note = {Motion Compensation in Radiosurgery} } @Article { rnos12, author = {Richter, Lars and Neumann, Gunnar and Oung, Stephen and Schweikard, Achim and Trillenberg, Peter}, title = {Optimal Coil Orientation for Transcranial Magnetic Stimulation}, year = {2013}, DOI = {10.1371/journal.pone.0060358}, journal = {PLoS ONE}, volume = {8}, pages = {e60358}, number = {4}, tags = {TMS}, file_url = {https://doi.org/10.1371/journal.pone.0060358}, note = {Transcranial Magnetic Stimulation} } @Inproceedings { dws_13, author = {D{\{\dq}u}richen, Robert and Wissel, Tobias and Schweikard, Achim}, title = {Optimized order estimation for autoregressive models to predict respiratory motion}, abstract = {Purpose: To successfully ablate moving tumors in robotic radio-surgery, it is necessary to compensate for motion of inner organs caused by respiration. This can be achieved by tracking the body surface and correlat-ing the external movement with the tumor position as it is implemented in CyberKnife Synchrony. Tracking errors, originating from system immanent time delays, are typically reduced by time series prediction. Many prediction algorithms exploit autoregressive (AR) properties of the signal. Estimating the optimal model order p for these algorithms constitutes a challenge often solved via grid search or prior knowledge about the signal. Methods: Aiming for a more e cient approach instead, this study evaluates the Akaike information criterion (AIC), the corrected AIC (AICc) and the Bayesian information criterion (BIC) on the first minute of the respiratory signal. Exemplarily, we evaluated the approach for an least mean square (LMS) and a wavelet-based LMS (wLMS) predictor. Results: Analyzing 12 motion traces, orders estimated by AIC had the highest prediction accuracy for both prediction algorithm. Extending the investiga-tions to 304 real motion traces, the prediction accuracy of wLMS using AIC was found to decrease for 85.1 % of the data compared to the original implementation. Conclusions: The overall results suggest that using AIC to estimate the model order p for prediction algorithms based on AR properties is a valid method which avoids intensive grid search and leads to high prediction accuracy.}, year = {2013}, issn = {1861-6410}, DOI = {10.1007/s11548-013-0900-0}, journal = {International Journal of Computer Assisted Radiology and Surgery}, volume = {8}, address = {Heidelberg, Germany}, series = {International Journal of Computer Assisted Radiology and Surgery}, pages = {accepted-for publication}, number = {S1}, tags = {MCRT}, file_url = {http://www.cars-int.org}, note = {Motion Compensation in Radiosurgery} } @Misc { s_13, author = {Ipsen, Svenja}, title = {Ortung eines Ultraschallkopfes in stereoskopischen R{\{\dq}o}ntgenbildern f{\{\dq}u}r den hybriden Bewegungsausgleich in der bildgest{\{\dq}u}tzten Strahlentherapie}, abstract = {Image guided radiation therapy is a common approach to cancer treatment in modern medicine. Ionizing radiation is accumulated in a target region to achieve irreversible damage of the tumor cells and at the same time best possible protection of the surrounding healthy tissue. Especially target regions inside the body with respiration- or pulsation-induced motion are difficult to treat since the movements cannot be observed directly in real-time. 4D ultrasound offers the possibility to observe target motion directly and with a high temporal resolution. The development of a hybrid tracking technique shall integrate this imaging modality into the motion compensation process during radiation therapy. In a first step the target volume inside the body is localized via ultrasound imaging. In combination with the exact tracking of the ultrasound probe the target position is computed in robot coordinates and the tumor can be irradiated with high precision. In this bachelor thesis the stereoscopic X-ray camera system of a robotic radiosurgery system is expanded to support the absolute ranging of an ultrasound probe. The characteristics of the radiosurgery system require an adaption of the software for camera calibration. The stability and convergence of the calibration results from this modified software are analyzed. Furthermore, algorithms for six-dimensional tracking of marker geometries are developed and validated using special phantoms. Test results indicate that markers can be localized with translational errors under 0.5 millimeters and a rotational error around 0.075 degrees. By consequently using the complete size and resolution of the X-ray detectors the effective image resolution can be enhanced by up to 79 percent compared to the integrated software of the CyberKnife. The rotatory precision increases by 75 percent while the available tracking volume can be doubled.}, year = {2013}, tags = {MCRT}, note = {Motion Compensation in Radiosurgery} } @Inproceedings { bjeb_13, author = {Blanck, Oliver and Jauer, Philipp and Ernst, Floris and Bruder, Ralf and Schweikard, Achim}, title = {Pilot-Phantomtest zur ultraschall-gef{\{\dq}u}hrten robotergest{\{\dq}u}tzten Radiochirurgie}, year = {2013}, volume = {44}, address = {Cologne, Germany}, series = {DGMP}, editor = {Treuer, Harald}, pages = {122-123}, tags = {MCRT UGRT}, note = {Motion Compensation in Radiosurgery} } @Inproceedings { wswb_13b, author = {Wissel, Tobias and St{\{\dq}u}ber, Patrick and Wagner, Benjamin and Bruder, Ralf and Schweikard, Achim and Ernst, Floris}, title = {Preliminary Study on Optical Feature Detection for Head Tracking in Radiation Therapy}, abstract = {Marker-less tracking provides a non-invasive as well as comfortable approach to compensate for head motion in high precision radiotherapy. However, it suffers from a lack of point-to-point correspondences, typically requiring charac- teristic spatial landmarks to match point clouds. In this study, we show that cutaneous and subcutaneous structures can be uncovered using an 850 nm laser setup. For three subjects, we compare features extracted from camera images with MR scans serving as an anatomical ground truth. The results confirm the validity of the optically detected structures. The negative correlation between skin thickness and reflected light energy is likewise predicted by Monte-Carlo simulations and can be used to improve spatial point cloud matching. Tissue thickness and its facial structure can be predicted with sub- millimeter accuracy using a Support Vector regression machine. In addition, the optical measurements reveal the location of vessels that are not immediately visible in the MR scan. These promising findings highly encourage its application for a marker-less tracking system.}, year = {2013}, DOI = {10.1109/BIBE.2013.6701632}, address = {Chania, Greece}, series = {IEEE}, pages = {1-5}, tags = {HPHT}, file_url = {https://doi.org/10.1109/BIBE.2013.6701632}, note = {High-Accuracy Head Tracking} } @Inproceedings { STU13, author = {St{\{\dq}u}ber, Patrick and Wissel, Tobias and Jauer, Philipp and Wagner, Benjamin and Bruder, Ralf and Schweikard, Achim}, title = {Towards high-accuracy head-tracking for radiation therapy}, abstract = {Current systems for cranial radiation therapy rely on stereotactic frames or rigid fixation of the patient's head. Drawbacks of these approaches include high mentoring effort during anesthesia and an invasive fixation of the head. Therefore, newer systems use real-time tracking combined with optical markers. In contrast, our system is aiming at non-invasive, marker-less tracking providing high accuracy of less than 1 mm. Using non-ionizing radiation within the optical and near-infrared spectral range, motion tracking is based on the skull bone rather than the skin surface to minimize the tracking error. As a reference we use a CT/MRI image, from which skull bone and skin are extracted using ray-tracing. The latter provides a higher accuracy than voxel-based methods and presents a more realistic point cloud of a given structure. For tracking, a second point cloud is sampled by the optical setup. For that, the forehead of the patient is illuminated with laser light, the reflected and scattered light is imaged and the skin thickness estimated using specific image features. Reliable features have been identified using Monte Carlo simulations for light tissue interactions. The feasibility for this application has been evaluated with an experimental setup. Using point-cloud-matching algorithms the spatial orientation and position of the head and tumor are obtained. This fully automatic system will provide improvements in precision and flexibility by avoiding direct and time-consuming human interactions during the positioning process.}, year = {2013}, publisher = {Varian Research Partnership Symposium}, address = {Atlanta, GA, USA}, series = {Varian Medical}, pages = {accepted} } @Inproceedings { ebws_13, author = {Ernst, Floris and Bruder, Ralf and Wissel, Tobias and St{\{\dq}u}ber, Patrick and Wagner, Benjamin and Schweikard, Achim}, title = {Real time contact-free and non-invasive tracking of the human skull first light and initial validation}, abstract = {In an increasing number of fields in medicine, precise and fast localisation of targets inside the body is essential. We present a new technology to directly track the position of the human skull through tissue in real time using infrared lasers. To achieve this, an experimental optical setup has been developed to target a position on a subject's skin and compute the soft tissue thickness using analysis of the scattering pattern. Using this setup and validation data from high-resolution MRI and optically tracked force-controlled ultrasound, we succeeded in computing the soft tissue thickness on the subjects' foreheads with sub-millimetre accuracy.}, year = {2013}, DOI = {10.1117/12.2024851}, volume = {8856}, address = {San Diego, CA}, series = {Proceedings of SPIE}, pages = {88561G-1 - 88561G-8}, tags = {HPHT}, file_url = {https://doi.org/10.1117/12.2024851}, note = {High-Accuracy Head Tracking} } @Inproceedings { dwes_13a, author = {D{\{\dq}u}richen, Robert and Wissel, Tobias and Ernst, Floris and Schweikard, Achim}, title = {Respiratory Motion Compensation with Relevance Vector Machines}, abstract = {In modern robotic radiation therapy, tumor movements due to respiration can be compensated. The accuracy of these methods can be increased by time series prediction of external optical surrogates. An algorithm based on relevance vector machines (RVM) is introduced. We evaluate RVM with linear and nonlinear basis functions on a real patient data set containing 304 motion traces and compare it with a wavelet based least mean square algorithm (wLMS), the best algorithm for this data set so far. Linear RVM outperforms wLMS significantly and increases the prediction accuracy for 80.3 % of the data. We show that real time prediction is possible in case of linear RVM and discuss how the predicted variance can be used to construct promising hybrid algorithms, which further reduce the prediction error.}, year = {2013}, DOI = {10.1007/978-3-642-40763-5_14}, volume = {8150}, publisher = {Springer}, address = {Nagoya, Japan}, series = {Lecture Notes in Computer Science}, editor = {Mori, Kensaku and Sakuma, Ichiro and Sato, Yoshinobu and Barillot, Christian and Navab, Nassir}, pages = {108-115}, tags = {MCRT}, file_url = {https://doi.org/10.1007/978-3-642-40763-5_14}, note = {Motion Compensation in Radiosurgery} } @Book { r_13, author = {Richter, Lars}, title = {Robotized Transcranial Magnetic Stimulation}, year = {2013}, isbn = {978-1-4614-7359-6}, publisher = {Springer}, address = {New York}, tags = {TMS}, file_url = {http://www.springer.com/computer/ai/book/978-1-4614-7359-6}, note = {ISBN Ebook: 978-1-4614-7360-2} } @Misc { d_13, author = {Dineley, Jude}, title = {Skin measurements improve motion tracking}, abstract = {Measurements of subcutaneous tissue thickness have the potential to improve the accuracy of real-time optical markerless tracking of patient motion during intracranial radiotherapy. In new work, researchers in Germany have provided proof of concept for a laser-based system, with simulated measurements of tissue thickness reaching accuracies of up to 18m (Biomed. Opt. Express 4 1176).}, year = {2013}, tags = {HPHT}, file_url = {http://medicalphysicsweb.org/cws/article/research/54249}, note = {High-Accuracy Head Tracking} } @Inproceedings { wbs_13, author = {Wissel, Tobias and Bruder, Ralf and Schweikard, Achim}, title = {Skin thickness estimation for high precision optical head tracking during cranial radiation therapy a simulation study}, year = {2013}, DOI = {10.1016/j.ijrobp.2013.06.1775}, volume = {87}, address = {Atlanta, GA, USA}, series = {International Journal of Radiation Oncology, Biology, Physics}, pages = {S669}, number = {2}, tags = {HPHT}, file_url = {https://doi.org/10.1016/j.ijrobp.2013.06.1775}, note = {High-Accuracy Head Tracking} } @Article { rtss_12, author = {Richter, Lars and Trillenberg, Peter and Schweikard, Achim and Schlaefer, Alexander}, title = {Stimulus intensity for hand held and robotic transcranial magnetic stimulation}, year = {2013}, issn = {1935-861X}, DOI = {10.1016/j.brs.2012.06.002}, journal = {Brain Stimulation}, volume = {6}, pages = {315-321}, number = {3}, tags = {TMS}, file_url = {https://doi.org/10.1016/j.brs.2012.06.002} } @Inproceedings { wswb_13c, author = {Wagner, Benjamin and St{\{\dq}u}ber, Patrick and Wissel, Tobias and Bruder, Ralf and Schweikard, Achim and Ernst, Floris}, title = {Time-multiplexed structured light for head tracking}, year = {2013}, volume = {44}, address = {Cologne, Germany}, series = {DGMP}, editor = {Treuer, Harald}, pages = {199-202}, tags = {HPHT}, note = {High-Accuracy Head Tracking} } @Article { Amengual2013, author = {Amengual, Juli{\'a} L. and Marco-Pallar{\'e}s, Josep and Richter, Lars and Oung, Stephen and Schweikard, Achim and Mohammadi, Bahram and Rodriguez-Fornells, Antoni and M{\{\dq}u}nte, Thomas F.}, title = {Tracking post-error adaptation in the motor system by transcranial magnetic stimulation}, year = {2013}, issn = {0306-4522}, DOI = {10.1016/j.neuroscience.2013.07.024}, journal = {Neuroscience}, volume = {250}, pages = {342-351}, tags = {TMS}, file_url = {https://doi.org/10.1016/j.neuroscience.2013.07.024}, note = {Transcranial Magnetic Stimulation} } @Misc { bbs_13, author = {Bruder, Ralf and Bruder, Gerd and Schweikard, Achim}, title = {Verfahren zum Auffinden der Position eines Schallkopfes}, year = {2013}, tags = {MCRT UGRT}, note = {Motion Compensation in Radiosurgery} } @Inproceedings { bije_13, author = {Bruder, Ralf and Ipsen, Svenja and Jauer, Philipp and Ernst, Floris and Blanck, Oliver and Schweikard, Achim}, title = {MO-D-144-02: Ultrasound Transducer Localization Using the CyberKnife's X-Ray System}, abstract = {Purpose: 4D ultrasound has become an alternative for image guidance and motion compensation in radiosurgery. Nevertheless, a two‐step localization has to be performed when using ultrasound. In addition to target localization inside the ultrasound volume, the transducer itself has to be localized and the target position has to be transformed into treatment coordinates. Methods: The CyberKnife (Accuray Inc.) features a stereo X‐ray system which is used for patient and fiducial marker localization. Accessing only the raw X‐ray images, we designed a software package for additional marker detection. To measure the physical camera parameters, X‐ray phantoms were designed and a non‐orthogonal stereo camera calibration was performed on 50 calibration X‐ray pairs. Algorithms were developed for three‐dimensional single marker localization and six‐dimensional localization of marker geometries. Different X‐ray marker geometries were designed and attached to the ultrasound transducer. The final system was evaluated and compared to the on‐board localization system using a 6‐axis industrial robot to position different marker geometries at 150 randomly distributed positions over the acquisition volume. Results: Two marker geometries with 20 and 50mm base lengths were localized using the on‐board and newly developed software. The mean translational error for the on‐board localization is 0.202mm, for the new system 0.218mm. The rotational error of the on‐board system could be reduced from 0.212 to 0.053 degrees for the 50mm marker and from 0.272 to 0.076 degrees for the 20mm marker geometry. Conclusion: We have shown that ultrasound transducers can be localized using the CyberKnife x‐ray system. The rotational accuracy of the localization could be increased by a factor of four, which is important for high marker‐to‐ultrasound‐target distances. Furthermore, using the full area of the flat‐panel detectors without pre‐processing steps the tracking volume was increased by 70 percent, which helps detecting patient/fiducials and transducer at the same time.}, year = {2013}, DOI = {10.1118/1.4815272}, volume = {40}, publisher = {American Association of Physicists in Medicine}, address = {Indianapolis, IN, USA}, series = {Medical Physics}, pages = {405}, number = {6}, tags = {UGRT}, file_url = {https://doi.org/10.1118/1.4815272}, note = {MO-D-144-02} } @Article { Wissel2013, author = {Wissel, Tobias and Pfeiffer, Tim and Frysch, Robert and Knight, Robert T. and Chang, Edward F. and Hinrichs, Hermann and Rieger, Jochem W. and Rose, Georg}, title = {Hidden Markov model and support vector machine based decoding of finger movements using electrocorticography}, abstract = {Objective . Support vector machines (SVM) have developed into a gold standard for accurate classification in brain computer interfaces (BCI). The choice of the most appropriate classifier for a particular application depends on several characteristics in addition to decoding accuracy. Here we investigate the implementation of hidden Markov models (HMM) for online BCIs and discuss strategies to improve their performance. Approach . We compare the SVM, serving as a reference, and HMMs for classifying discrete finger movements obtained from electrocorticograms of four subjects performing a finger tapping experiment. The classifier decisions are based on a subset of low-frequency time domain and high gamma oscillation features. Main results . We show that decoding optimization between the two approaches is due to the way features are extracted and selected and less dependent on the classifier. An additional gain in HMM performance of up to 6% was obtained by introducing model constraints. Comparable accuracies of up to 90% were achieved with both SVM and HMM with the high gamma cortical response providing the most important decoding information for both techniques. Significance . We discuss technical HMM characteristics and adaptations in the context of the presented data as well as for general BCI applications. Our findings suggest that HMMs and their characteristics are promising for efficient online BCIs.}, year = {2013}, journal = {Journal of Neural Engineering}, volume = {10}, pages = {056020}, number = {5}, file_url = {http://stacks.iop.org/1741-2552/10/i=5/a=056020}, note = {doi: doi:10.1088/1741-2560/10/5/056020} } @Article { h_13a, author = {Hollinde, Michael}, title = {F{\{\dq}u}r mehr Pr{\{\dq}a}zision in der Tumorbestrahlung}, year = {2013}, journal = {L{\{\dq}u}becker Nachrichten}, tags = {HPHT}, file_url = {http://www.ln-online.de/Uni/Studieren-in-Luebeck/Fuer-mehr-Praezision-in-der-Tumorbestrahlung}, note = {High-Accuracy Head Tracking} } @Inproceedings { wvfh_13, author = {Wilde, Christian and Volz, Silvanie and Feuerstein, Thomas J. and Hofmann, Ulrich G.}, title = {Automatic Seizure Detection in Rats using ECoG: A Comparison of Methods}, abstract = {Introduction: Precise automated seizure detection is a challenging problem. Nevertheless, the accurate detection of seizures plays an important role, especially in promoting the development of {\dq}closed-loop{\dq} therapies. Several detection methods have been developed and published so far. Mostly, the performance of these systems cannot be analysed or compared properly due to the use of heterogeneous data, varying seizure definitions or just because concrete information about the implementations are not available. Methods: Several new approaches for automatic seizure detection were implemented next to the most common methods available from the literature. Visually analysed ECoG obtained from rats with focal neocortical epilepsy upon local tetanus toxin plus cobalt chloride application have been used to compare the methods' performance. Results: None of the investigated methods was able to detect all existent seizures with reasonable degree of accuracy. Some methods showed a high performance for certain specific seizure types, but there is no {\dq}one size fits all{\dq} detection method. The implemented tool is suitable for performance tests and comparison of detection methods on arbitrary EEG/ECoG data. Conclusion: In the future, the present implementation can be used to evaluate and compare new seizure detection methods, and thus the performance of these can be verified fast and independently.}, year = {2013}, address = {Dresden, Germany}, series = {Deutsche Gesellschaft f{\{\dq}u}r Neurologie (DGN)} } @Inproceedings { ASTRO2013, title = {2013 Annual Meeting of the ASTRO}, year = {2013}, volume = {55}, address = {Atlanta, GA, USA}, series = {American Society for Therapeutic Radiology and Oncology}, file_url = {https://www.astro.org/Meetings-and-Events/2013-Annual-Meeting/Index.aspx} } @Inproceedings { wsm_12, author = {Weiss, Patrick and Heldmann, M. and M{\{\dq}u}nte, Thomas F. and Schweikard, Achim and Maehle, Erik}, title = {A Rehabilitation System for Training based on Visual Feedback Distortion: Proceedings of the International Conference on Neurorehabilitation (ICNR) 2012}, year = {2013}, DOI = {10.1007/978-3-642-34546-3\_47}, volume = {1}, publisher = {Springer}, address = {Toledo, Spain}, series = {Biosystems Biorobotics}, editor = {Pons, Jos{\'e} L. and Torricelli, Diego and Pajaro, Marta}, pages = {299-303}, file_url = {https://doi.org/10.1007/978-3-642-34546-3\_47} } @Techreport { k_13, author = {Kuhlemann, Ivo}, title = {Force and Image Adaptive Strategies for Robotised Placement of 4D Ultrasound Probes}, year = {2013}, series = {University of Luebeck}, editor = {Bruder, Ralf}, tags = {MCRT UGRT}, note = {RobLab, Motion Compensation in Radiosurgery} } @Inproceedings { wswb_13d, author = {Wagner, Benjamin and St{\{\dq}u}ber, Patrick and Wissel, Tobias and Bruder, Ralf and Schweikard, Achim and Ernst, Floris}, title = {Accuracy of object tracking based on time-multiplexed structured light}, abstract = {Our research group is currently developing a new optical head tracking system which utilises infrared laser light to measure features of the soft tissue on the patient's forehead. These features are intended to offer highly accurate registration with respect to the rigid skull structure by means of compensating for the soft tissue. In this context, the system also has to be able to quickly generate accurate reconstructions of the skin surface. For this purpose, we have developed a laser scanning device which uses time-multiplexed structured light to triangulate surface points. This paper shows, that time-multiplexed structured light can be used to generate highly accurate reconstructions of surfaces (RMS error 0.17 mm, Kinect: RMS error 0.89 mm). Moreover, we used our laser scanner for tracking of a rigid object to determine how this process is influenced by the remaining triangulation errors. It turned out that our scanning device can be used for high-accuracy tracking of objects (RMS errors of 0.33 mm and 0.12 degrees).}, year = {2013}, volume = {12}, address = {Innsbruck, Austria}, series = {CURAC}, pages = {139-142}, tags = {HPHT}, note = {High-Accuracy Head Tracking} } @Inproceedings { Wang2013, author = {Wang, Bo and Stender, Birgit and Long, T. and Zhang, Z. and Schlaefer, Alexander}, title = {An approach to validate ultrasound surface segmentation of the heart}, year = {2013}, volume = {58}, series = {Biomed Tech 2013}, number = {Suppl. 1}, tags = {MCM} } @Inproceedings { swwb_13b, author = {St{\{\dq}u}ber, Patrick and Wissel, Tobias and Wagner, Benjamin and Bruder, Ralf and Schweikard, Achim and Ernst, Floris}, title = {An improvement for the scanning process in high accuracy head tracking}, abstract = {Optical tracking systems have become state-of-the-art in radiation therapy. Nevertheless, they still cannot cope with the properties of soft tissue. We are developing a non-invasive method to automatically detect the cranial bone's sur-face using only infrared laser light. Here, we present simulations to describe the influence of increased incident an-gles of the laser ray on the forehead's surface caused by replacing the original robotic setup by galvanometric scan-ning mirrors. We show that the usable area on the forehead (angles below 45°) will decrease, but that successful scanning is still possible when the scanning distance is increased from 300 to 500 mm. These results are confirmed when comparing optical scans acquired with the robotic setup and the scanning mirror assembly. Additionally, we could determine the needed depth of field for three subjects (based on high-resolution MRI scans). At a distance of 500 mm, it ranges from 37 to 86 mm.}, year = {2013}, volume = {12}, address = {Innsbruck, Austria}, series = {CURAC}, pages = {179-182}, tags = {HPHT}, note = {High-Accuracy Head Tracking} } @Misc { Adler2013, author = {Adler, John R. and Bruder, Ralf and Ernst, Floris and Schweikard, Achim}, title = {Apparatus and method for real-time tracking of bony structures}, year = {2013} } @Inproceedings { dbdh_13, author = {D{\{\dq}u}richen, Robert and Blanck, Oliver and Dunst, J{\{\dq}u}rgen and Hildebrandt, Guido and Schlaefer, Alexander and Schweikard, Achim}, title = {Atemphasenabh{\{\dq}a}ngige Pr{\{\dq}a}diktionsfehler in der extrakraniellen stereotaktischen Strahlentherapie}, abstract = {Fragestellung: Die Kompensation von atembedingten Tumorbewegungen w{\{\dq}a}hrend der extrakraniellen stereotaktischen Strahlentherapie ist nicht trivial. Beim robotergest{\{\dq}u}tzten CyberKnife, einem immer h{\{\dq}a}ufiger eingesetzten aktive Bewegungskompensationssystem, werden dabei interne Tumorbewegungen mit optischen Marker auf der Brust korreliert und w{\{\dq}a}hrend der Behandlung mittels Pr{\{\dq}a}diktionsalgorithmen vorhergesagt, um den Roboter synchron mit dem Tumor bewegen zu k{\{\dq}o}nnen. Genauigkeitsanalysen des Systems wurden mehrfach publiziert. Wir untersuchten nun, in wie weit die Pr{\{\dq}a}diktionsgenauigkeit von der Atemphase abh{\{\dq}a}ngig ist, um Fehler besser bewerten und Patienten besser auf die Behandlung vorbereiten zu k{\{\dq}o}nnen. Methodik: F{\{\dq}u}r die Analyse verwendeten wir Patientendaten von 37 Abdominellen- und 34 Lungenbehandlungen (143 bzw. 124 Fraktionen), die in unserem Zentrum behandelt wurden. Zur Untersuchung des Pr{\{\dq}a}diktionsfehlers unterteilten wir die gemessene und pr{\{\dq}a}dizierte Atembewegung jedes Patienten, die in den CyberKnife Log-Dateien gespeichert werden, in je 10 Atemphasen. Anschlie{\{\dq}s}end berechneten wir die mittleren und maximalen Pr{\{\dq}a}diktionsfehlers pro Phase in x, y und z Richtung und in 3D und verglichen die jeweiligen Atemphasen miteinander. Ergebnis: Der Median f{\{\dq}u}r den mittleren 3D Pr{\{\dq}a}diktionsfehler f{\{\dq}u}r alle Leberpatienten betrug exemplarisch 0.14 mm (Phase 1), 0.09 mm (Phase 3), 0.07 mm (Phase 5) und 0.08 mm (Phase 8). F{\{\dq}u}r Lungenpatienten betr{\{\dq}a}gt der Median exemplarisch 0.05 mm (Phase 1), 0.03 mm (Phase 3), 0.03 mm (Phase 5) und 0.03 mm (Phase 8). Im Mittel sind die Pr{\{\dq}a}diktionsfehler f{\{\dq}u}r Leberpatienten gr{\{\dq}o}{\{\dq}s}er als f{\{\dq}u}r Lungenpatienten, was auf die gr{\{\dq}o}{\{\dq}s}eren Bewegungen in der Leber zur{\{\dq}u}ckzuf{\{\dq}u}hren sein mag. Der maximale mittlere Pr{\{\dq}a}diktionsfehler f{\{\dq}u}r einen Leberpatienten betr{\{\dq}a}gt 0.7 mm (Phase 1) und f{\{\dq}u}r einen Lungenpatienten 0.81 mm (Phase 3). Die Ergebnisse zeigen, dass eine gro{\{\dq}s}e Abh{\{\dq}a}ngigkeit zwischen Atemphasen und Pr{\{\dq}a}diktionsfehler besteht. Der Pr{\{\dq}a}diktionsfehler ist besonders an den {\{\dq}U}berg{\{\dq}a}ngen von Ex- zu Inspiration (Phase 1/10) gr{\{\dq}o}{\{\dq}s}er als in den Phasen von reiner Inspiration (Phase 3), Exspirationen (Phase 8) und {\{\dq}U}bergang von In- zu Exspiration (Phase 5/6). Diese Fehlerverteilung ist f{\{\dq}u}r Lungen und Leber Patienten gleich. Schlussfolgerung: Diese Analyse zeigt, dass der mittlere atemphasenabh{\{\dq}a}ngige Pr{\{\dq}a}diktionsfehler f{\{\dq}u}r Lungen- und Leberpatienten zwar sehr klein ist, jedoch f{\{\dq}u}r einzelne Patienten dennoch teilweise hohe mittlere Pr{\{\dq}a}diktionsfehler auftreten k{\{\dq}o}nnen. Dies ist vor allem dadurch bedingt, dass die Pr{\{\dq}a}diktion der Atmungsbewegung nach l{\{\dq}a}ngerer Ruhephase (Ausatmung) schwierig ist. Besseres Training der Patienten hinsichtlich einer regelm{\{\dq}a}{\{\dq}s}igen Atmung ohne Pause k{\{\dq}o}nnten hier Verbesserungen schaffen. Als n{\{\dq}a}chsten Schritt planen wir den dosimetrischen Effekt f{\{\dq}u}r Patienten mit einem hohen Pr{\{\dq}a}diktionsfehler genauer zu untersuchen. Zus{\{\dq}a}tzlich soll das Potential von neueren Pr{\{\dq}a}diktionsalgorithmen untersucht werden.}, year = {2013}, address = {Berlin, Germany}, series = {19. Jahrestagung der Deutschen Gesellschaft f{\{\dq}u}r Radioonkologie (DEGRO)}, tags = {MCRT}, note = {Motion Compensation in Radiosurgery} } @Inproceedings { Hagenah2013a, author = {Hagenah, Jannis and Scharfschwerdt, Michael and Stender, Birgit and Ott, Sven and Friedl, R. and Sievers, H. H. and Schlaefer, Alexander}, title = {A setup for ultrasound based assessment of the aortic root geometry}, year = {2013}, volume = {58}, series = {Biomed Tech 2013}, number = {Suppl. 1}, tags = {MCM} } @Inproceedings { Metzner2013, author = {Metzner, Christoph and Schweikard, Achim and Zurowski, B.}, title = {Center-Surround Interactions in a Network Model of Layer 4C$\alpha$ of Primary Visual Cortex}, year = {2013}, volume = {14}, number = {Suppl. 1}, tags = {NM}, note = {Neurological Modelling} } @Inproceedings { Zurowski2013, author = {Zurowski, B. and Hamm, F. and Metzner, Christoph and Scholand-Engler, H. and Wells, A. and Hohagen, F.}, title = {Cortical levels of GABA in patients with panic disorder are associated with the strength of metacognitive beliefs}, year = {2013}, tags = {NM}, note = {Neurological Modelling} } @Inproceedings { swwb_13, author = {St{\{\dq}u}ber, Patrick and Wissel, Tobias and Wagner, Benjamin and Bruder, Ralf and Schweikard, Achim and Ernst, Floris}, title = {Design and evaluation of a highly accurate optical setup for backscatter analysis}, year = {2013}, volume = {44}, address = {Cologne, Germany}, series = {DGMP}, editor = {Treuer, Harald}, pages = {181-186}, tags = {HPHT}, note = {High-Accuracy Head Tracking} } @Article { rb12, author = {Richter, Lars and Bruder, Ralf}, title = {Design, implementation and evaluation of an independent real-time safety layer for medical robotic systems using a force-torque-acceleration (FTA) sensor}, abstract = {Purpose Most medical robotic systems require direct interaction or contact with the robot. Force--Torque (FT) sensors can easily be mounted to the robot to control the contact pressure. However, evaluation is often done in software, which leads to latencies. Methods To overcome that, we developed an independent safety system, named FTA sensor, which is based on an FT sensor and an accelerometer. An embedded system (ES) runs a real-time monitoring system for continuously checking of the readings. In case of a collision or error, it instantaneously stops the robot via the robot's external emergency stop. Results We found that the ES implementing the FTA sensor has a maximum latency of 1±0.03 ms to trigger the robot's emergency stop. For the standard settings in the application of robotized transcranial magnetic stimulation, the robot will stop after at most 4 mm. Conclusion Therefore, it works as an independent safety layer preventing patient and/or operator from serious harm.}, year = {2013}, DOI = {10.1007/s11548-012-0791-5}, journal = {International Journal of Computer Assisted Radiology and Surgery}, volume = {8}, pages = {429-436}, number = {3}, tags = {TMS}, file_url = {https://doi.org/10.1007/s11548-012-0791-5}, note = {Transcranial Magnetic Stimulation} } @Techreport { Hagenah2013b, author = {Hagenah, Jannis}, title = {Erstellung eines patientenindividuellen Modells der Aortenklappe}, year = {2013}, series = {Universit{\{\dq}a}t zu L{\{\dq}u}beck}, tags = {MCM} } @Article { wbse_13, author = {Wissel, Tobias and Bruder, Ralf and Schweikard, Achim and Ernst, Floris}, title = {Estimating soft tissue thickness from light-tissue interactions a simulation study}, abstract = {Immobilization and marker-based motion tracking in radiation therapy often cause decreased patient comfort. However, the more comfortable alternative of optical surface tracking is highly inaccurate due to missing point-to-point correspondences between subsequent point clouds as well as elastic deformation of soft tissue. In this study, we present a proof of concept for measuring subcutaneous features with a laser scanner setup focusing on the skin thickness as additional input for high accuracy optical surface tracking. Using Monte-Carlo simulations for multi-layered tissue, we show that informative features can be extracted from the simulated tissue reflection by integrating intensities within concentric ROIs around the laser spot center. Training a regression model with a simulated data set identifies patterns that allow for predicting skin thickness with a root mean square error of down to 18 m. Different approaches to compensate for varying observation angles were shown to yield errors still below 90 m. Finally, this initial study provides a very promising proof of concept and encourages research towards a practical prototype.}, year = {2013}, DOI = {10.1364/BOE.4.001176}, journal = {Biomedical Optics Express}, volume = {4}, pages = {1176-1187}, number = {7}, tags = {HPHT}, file_url = {https://doi.org/10.1364/BOE.4.001176}, note = {High-Accuracy Head Tracking} } @Article { edss_13, author = {Ernst, Floris and D{\{\dq}u}richen, Robert and Schlaefer, Alexander and Schweikard, Achim}, title = {Evaluating and comparing algorithms for respiratory motion prediction}, abstract = {In robotic radiosurgery, it is necessary to compensate for systematic latencies arising from target tracking and mechanical constraints. This compensation is usually achieved by means of an algorithm which computes the future target position. In most scientific works on respiratory motion prediction, only one or two algorithms are evaluated on a limited amount of very short motion traces. The purpose of this work is to gain more insight into the real world capabilites of respiratory motion prediction methods by evaluating many algorithms on an unprecedented amount of data. We have evaluated six algorithms, the normalized Least Mean Squares (nLMS), Recursive Least Squares (RLS), Multi-step Linear Methods (MULIN), Wavelet-based Multiscale Autoregression (wLMS), Extended Kalman Filtering (EKF), and $\epsilon$-Support Vector Regression (SVRpred) methods, on an extensive database of 304 respiratory motion traces. The traces were collected during treatment with the CyberKnife (Accuray, Inc., Sunnyvale, CA/USA) and feature an average length of 71 minutes. Evaluation was done using a graphical prediction toolkit, which is available to the general public, as is the data we used. The experiments show that the nLMS algorithm---which is one of the algorithms currently used in the CyberKnife---is outperformed by all other methods. This is especially true in the case of the wLMS, the SVRpred, and the MULIN algorithms, which perform much better. The nLMS algorithm produces a relative Root Mean Squared (RMS) error of 75% or less (i.e., a reduction in error of 25% or more when compared to not doing prediction) in only 38% of the test cases, whereas the MULIN and SVRpred methods reach this level in more than 77 %, the wLMS algorithm in more than 84% of the test cases. Our work shows that the wLMS algorithm is the most accurate algorithm and does not require parameter tuning, making it an ideal candidate for clinical implementation. Additionally, we have seen that the structure of a patient's respiratory motion trace has strong influence on the outcome of prediction. Further work is needed to determine a priori the suitability of an individual's respiratory behaviour to motion prediction.}, year = {2013}, DOI = {10.1088/0031-9155/58/11/3911}, journal = {Physics in Medicine and Biology}, volume = {58}, pages = {3911-3929}, number = {11}, tags = {MCRT}, file_url = {https://doi.org/10.1088/0031-9155/58/11/3911}, note = {Motion Compensation in Radiosurgery} } @Inproceedings { ddbw_13, author = {D{\{\dq}u}richen, Robert and Davenport, Lucas and Bruder, Ralf and Wissel, Tobias and Ernst, Floris and Schweikard, Achim}, title = {Evaluation of the potential of multi-modal sensors for respiratory motion prediction and correlation}, abstract = {In modern robotic radiotherapy, precise radiation of moving tumors is possible by tracking external optical surrogates. The surrogates are used to compensate for time delays and to predict internal landmarks using a correlation model. The correlation depends significantly on the surrogate position and breathing characteristics of the patient. In this context, we aim to increase the accuracy and robustness of prediction and correlation models by using a multi-modal sensor setup. Here, we evaluate the correlation coefficient of a strain belt, an acceleration and temperature sensor (air flow) with respect to external optical sensors and one internal landmark in the liver, measured by 3D ultrasound. The focus of this study is the influence of breathing artefacts, like coughing and harrumphing. Evaluating seven subjects, we found a strong decrease of the correlation for all modalities in case of artefacts. The results indicate that no precise motion compensation during these times is possible. Overall, we found that apart from the optical markers, the strain belt and temperature sensor data show the best correlation to external and internal motion.}, year = {2013}, DOI = {10.1109/EMBC.2013.6610839}, address = {Osaka, Japan}, pages = {5678-5681}, tags = {MCRT UGRT}, file_url = {https://doi.org/10.1109/EMBC.2013.6610839}, note = {Motion Compensation in Radiosurgery} } @Inproceedings { dbdw_13, author = {D{\{\dq}u}richen, Robert and Bruder, Ralf and Davenport, Lucas and Wissel, Tobias and Ernst, Floris and Schweikard, Achim}, title = {Correlation and variation of a multi-modal sensor setup for respiratory motion prediction and correlation}, abstract = {Purpose: In robotic radiosurgery, tumor movements are compensated by tracking external optical surrogates. These surrogates are used to compensate for time delays (prediction) and to calculate the internal fiducial position (correlation). We aim to increase the accuracy and robustness by using a multi-modal sensor approach including different physiological sensors. We evaluate the correlation coefficient of a strain belt, acceleration and air flow sensor with respect to external standard optical sensors and an internal landmark in the liver tracked using 3D ultrasound and evaluate the variance for a measurement over 20 minutes. Methods: We recorded sensor data from 6 subjects (5 male/1 female). All sensors have been synchronized and downsampled to the optical sampling rate (fs = 47 Hz) or in case of internal correlation to the ultrasound sampling rate (fs = 17 Hz). Pearson's correlation coefficient r was calculated for each minute, discarding the first and last minute. Results: The mean (standard deviation) external correlation coefficients over all subjects and time periods were obtained as: 0.88 (0.036) for strain, 0.75 (0.024) for flow and 0.73 (0.052) for acceleration with respect to an optical marker on the chest. The mean (standard deviation) internal correlation coefficients are: 0.81 (0.045) for strain, 0.76 (0.041) for flow, 0.58 (0.088) for acceleration and 0.80 (0.057) for the optical marker on the chest with respect to the internal landmark. Conclusion: This study indicates that apart from the optical markers, strain and flow data show the best correlation to external and internal motion and seem to be promising for increasing the prediction and correlation accuracy as well as robustness. Among the investigated sensors, the strain data have the lowest standard deviation for internal and external correlation, being even lower than the standard deviation of the optical chest marker.}, year = {2013}, DOI = {10.1118/1.4814365}, volume = {40}, publisher = {American Association of Physicists in Medicine}, address = {Indianapolis, USA; Indianapolis, IN, USA}, series = {Medical Physics}, pages = {186}, number = {6}, tags = {MCRT UGRT}, file_url = {https://doi.org/10.1118/1.4814365}, note = {Motion Compensation in Radiosurgery} } @Techreport { Ammann2012, author = {Ammann, Nikolaus}, title = {Robotized 4D Ultrasound for cardiac Image- Guided Radiation Therapy}, year = {2012}, series = {University of Luebeck}, editor = {Bruder, Ralf}, tags = {MCRT UGRT}, note = {Motion Compensation in Radiosurgery} } @Article { Shahin2012, author = {Shahin, Osama and Martens, Volker and Be{\v{s}}irevi{\c}, Armin and Kleemann, Markus and Schlaefer, Alexander}, title = {Localization of liver tumors in freehand 3D laparoscopic ultrasound}, year = {2012}, journal = {SPIE Medical Imaging}, pages = {83162C-83162C-7} } @Inproceedings { Wissel2012, author = {Wissel, Tobias and Anders, Silke and Schweikard, Achim}, title = {On state-like behavior of temporal nonstationarities in patterns of resting-state brain activity.}, year = {2012}, publisher = {3rd Biennnial Conference on Resting State Brain Connectivity, Magdeburg, Germany} } @Inproceedings { ohks_12, author = {Otte, Christoph and H{\{\dq}u}ttmann, Gereon and Kov{\'a}cs, Gy{\{\dq}o}rgy and Schlaefer, Alexander}, title = {Phantom validation of optical soft tissue navigation for brachytherapy}, abstract = {In high dose rate brachytherapy, needles are inserted into soft tissue and subsequently radioactive sources are used to deliver a high dose inside the target region. While this approach can achieve a steep dose gradient and o ers a focused, organ sparing treatment, it also requires a careful positioning of the needles with respect to the tissue. We have previously proposed to use an optical ber embedded in the needle to detect soft tissue deformation. To validate the approach, we have developed an experimental setup to compare the actual needle motion with the motion estimated via the ber. Our results show a good agreement between actual and estimated motion, indicating that optical deformation detection through the needle is possible.}, year = {2012}, address = {Nice, France}, series = {MICCAI}, editor = {Birkfellner, Wolfgang and McClelland, Jamie R. and Rit, Simon and Schlaefer, Alexander}, pages = {96-100} } @Inproceedings { dws_12a, author = {D{\{\dq}u}richen, Robert and Wissel, Tobias and Schweikard, Achim}, title = {Prediction of respiratory Motion using Wavelet-based Support Vector Regression}, abstract = {In order to successfully ablate moving tumors in robotic radiosurgery, it is necessary to compensate the motion of inner organs caused by respiration. This can be achieved by tracking the body surface and correlating the external movement with the tumor position as it is implemented in CyberKnife R Synchrony. Due to time delays, errors occur which can be reduced by time series prediction. A new prediction algorithm is presented, which combines a trous wavelet decomposition and support vector regression (wSVR). The algorithm was tested and optimized by grid search on simulated as well as on real patient data set. For these real data, wSVR outperformed a wavelet based least mean square (wLMS) algorithm by > 13% and standard Support Vector regression (SVR) by > 7:5%. Using approximate estimates for the optimal parameters wSVR was evaluated on a data set of 20 patients. The overall results suggest that the new approach combines beneficial characteristics in a promising way for accurate motion prediction.}, year = {2012}, DOI = {10.1109/MLSP.2012.6349742}, address = {Santander, Spain}, series = {IEEE Signal Processing Society}, pages = {1-6}, tags = {MCRT}, file_url = {https://doi.org/10.1109/MLSP.2012.6349742}, note = {Motion Compensation in Radiosurgery} } @Article { brost12, author = {Bremer, Susan and Richter, Lars and Oung, Stephen and Schweikard, Achim and Trillenberg, Peter}, title = {Roboternavigierte Untersuchung der Tiefenabh{\{\dq}a}ngigkeit der Reizst{\{\dq}a}rke bei der transkraniellen Magnetstimulation}, abstract = {Abstract Ansicht: Eingereicht von: Susan Bremer, [Erstautor], Klinik f{\{\dq}u}r Neurologie, UKSH, Campus L{\{\dq}u}beck; L{\{\dq}u}beck Titel des Abstracts: Roboternavigierte Untersuchung der Tiefenabh{\{\dq}a}ngigkeit der Reizst{\{\dq}a}rke bei der transkraniellen Magnetstimulation Untertitel des Abstracts: Autoren: Susan Bremer, [Erstautor], Klinik f{\{\dq}u}r Neurologie, UKSH, Campus L{\{\dq}u}beck; L{\{\dq}u}beck Lars Richter, Institute for Robotics and Cognitive Systems, University of L{\{\dq}u}beck, L{\{\dq}u}beck, Germany Steven Oung, Graduate School for Computing in Medicine and Life Sciences, L{\{\dq}u}beck, Germany Achim Schweikard, Institute for Robotics and Cognitive Systems, University of L{\{\dq}u}beck, L{\{\dq}u}beck, Germany Peter Trillenberg, Klinik f{\{\dq}u}r Neurologie, UKSH, Campus L{\{\dq}u}beck; L{\{\dq}u}beck Schl{\{\dq}u}sselw{\{\dq}o}rter: Magnetstimulation, Mapping, Reizspule Abstract-Text: Ziele/Fragestellung: Die Tiefenabh{\{\dq}a}ngigkeit der Reizst{\{\dq}a}rke (R.) ist relevant f{\{\dq}u}r die Korrektur der R. bei bekanntem Reizort und f{\{\dq}u}r dessen Suche bei bekannter Schwelle f{\{\dq}u}r verschiedene Reizspulen. Wir untersuchen diese Abh{\{\dq}a}ngigkeit f{\{\dq}u}r das Beinfeld des Motorkortex. Methoden: Wir verwendeten die Doppelspulen MCB-70 und MCF-B65 und den MagPro X100 Stimulator mit MagOption. Die Abh{\{\dq}a}ngigkeit der R. vom Spulenabstand wurde in-vitro bestimmt und mit einem analytischen Ausdruck verglichen. Ein stereo-optisches Tracking- System und ein Roboter sorgten f{\{\dq}u}r die Positionierung der Spulen.Wir ermittelten mit beiden Spulen bei 8 gesunden Probanden den Hotspot und bestimmten dann anhand von 30 Reizen mit der Maximum-Likelihood-Methode die Schwelle f{\{\dq}u}r ein MEP {\{\dq}u}ber dem linken M. abductor hallucis > 50V, f{\{\dq}u}r in 2mm Schritten anwachsendem Abstand der Spule zur Kopfoberfl{\{\dq}a}che [1]. Ergebnisse: Unsere in-vitro-Messung l{\{\dq}a}sst sich gut mit der Theorie, die einen etwa exponentiellen Abfall des elektrischen Feldes mit der Tiefe besagt, vereinbaren: S = S0*exp(-d/d0) mit d0 = 22,6 mm f{\{\dq}u}r MCB-70 und 23,6 mm f{\{\dq}u}r MCF-B65. Die in-vivo Messungen ergaben d0 = 23,6 /-1,2 f{\{\dq}u}r MCB-70 und 24,3 /-2,1 f{\{\dq}u}r MCF-B65; beide Abweichungen nach oben ohne Signifikanz. Das Verh{\{\dq}a}ltnis der Schwellen bei d = 0 ist deutlich gr{\{\dq}o}{\{\dq}s}er als vorhergesagt: 0,88 /-1,14 (p < 0,005) (in-vitro = 0,647). Schlussfolgerung: Die publizierte Annahme einer linearen Abh{\{\dq}a}ngigkeit der R. von der Tiefe kann widerlegt werden [2]. Die von Epstein et al. [3] zur Tiefenbestimmung vorgeschlagene Methode kann nicht angewendet werden, da wir bei gleichem Abfall des elektrischen Feldes mit der Tiefe unterschiedliche Schwellenverh{\{\dq}a}ltnisse gefunden haben. Dies muss Folge der Feldausbreitung in den unterschiedlich leitenden Medien im Sch{\{\dq}a}del sein.}, year = {2012}, journal = {Klin Neurophysiol}, volume = {43}, pages = {49-49}, number = {1}, tags = {TMS}, note = {Transcranial Magnetic Stimulation} } @Article { rgrl12, author = {L{\{\dq}o}ffler, Susanne and Gasca, Fernando and Richter, Lars and Leipscher, Ulrike and Trillenberg, Peter and Moser, Andreas}, title = {The Effect of Repetitive Transcranial Magnetic Stimulation on Monoamine Outflow in the Accumbens Nucleus Shell in Freely Moving Rats}, year = {2012}, journal = {Neuropharmacology}, volume = {63}, pages = {898-904}, number = {5}, tags = {TMS}, note = {Transcranial Magnetic Stimulation} } @Phdthesis { r_12, author = {Richter, Lars}, title = {Safe and clinically applicable robotized Transcranial Magnetic Stimulation}, abstract = {Transcranial Magnetic Stimulation (TMS) allows for non-invasive and painless stimulation of the (human) brain, in particular of its cortical structures. A strong, rapidly increasing current is driven through a magnetic coil placed on the head of a subject. The generated magnetic field passes through the human skull and induces an electric current inside the cortex which can lead to local stimulation. Currently, neuro-navigated TMS is the state-of-the-art procedure to assist the operator in placing the coil on the head. However, the coil is positioned and held at the target by hand. An optical tracking system visually assists the operator for target localization and coil positioning. Recently, robotized TMS has been introduced, combining neuro-navigation with automation. It is based on a serial robot arm for coil placement and an optical tracking system for head tracking and navigation. In this way, robotized TMS allows for precise and repeatable coil placement. Furthermore, the robotized TMS system employs active motion compensation (MC) to maintain the correct coil position throughout stimulation -- even when the head moves naturally. Even though the system provides increased accuracy, repeatability and comparability, it is not yet mature. In its current state, only experienced and trained users can employ the system without difficulty. This fact is the mainspring of this work, which describes the systematic further development of the current system to a safe and clinically applicable robotized TMS system. To date, a systematic analysis and practical evaluation of the current system is still missing. Therefore, we foremost perform this investigation. We recorded head motion in realistic TMS scenarios and analyzed the impact of head motion on the accuracy of TMS. This analysis fundamentally showed the importance of active motion compensation for accurate TMS. After 30min of stimulation, on average 32% of the induced electric field strength is lost due to head motion in a conventional TMS setup. In contrast, with robotized TMS on average less than 5% of the induced electric field strength is lost. Furthermore, we practically evaluate the robotized TMS system (in its present state) during TMS studies. On the one side, the studies and their outcomes support the special features of robotized TMS for precise and accurate coil positioning. On the other side, however, this practical evaluation shows the deficits of the present implementation. Therefore, there is a need for an user-friendly, safe and clinically applicable system. As primarily researchers, neuroscientists, physicians and medical staff are the operators of TMS, we improve the robotized TMS system for an easy and unproblematic clinical application. The robotized system requires a calibration between tracking system and robot. As the system design is partially mobile, the calibration step might have to be performed frequently, which takes additional time. When the robot and/or the tracking system shift, calibration must be re-performed. It is even worse when such a shift occurs unrecognized during treatment. We develop an online calibration method that is able to update and check the current calibration during application in real-time. For that purpose, a marker is attached to the robot's third link in such a way that it is visible for the tracking system throughout the application. By using a rigid transformation from the marker to the coordinate system in the robot's fourth joint, the calibration can be calculated directly. The marker is tracked by the tracking system and the robot's forward calculation is applied to the fourth joint. A practical evaluation shows that the positioning accuracy of the robotized TMS system is in the same range as with the current calibration method. As an industrial robot is a complex and potentially dangerous system, the allowed robot trajectories are strongly restricted in the current implementation. Any potentially dangerous trajectory for the patient is forbidden by the software control. Therefore, a manual pre-positioning of the robot is required frequently to allow a safe and automatic coil placement afterwards. This is a quite difficult task for unexperienced users. For this reason, we implement a positioning method that allows to position the robot in a hand-guided fashion. To this end, we install a force-torque sensor onto the system. The sensor detects the occurrent forces and torques on the coil and transfers these values into robot movements instantaneously. In this way, the user is able to position the coil easily and fast, without need of the complex, manual pre-positioning with the robot controller. Additionally, the force-torque sensor allows to measure the contact pressure of the coil to the head. In this way, the coil is optimally placed on the patient's head. In combination with motion compensation, the force-torque control maintains the optimal contact pressure during application. This guarantees an optimal stimulation. Due to the direct interaction of robot and patient/operator, safety is a very critical aspect in the development of medical robotic systems. Many systems, such as the robotized TMS system, are based on industrial robots that are adapted to the specific requirements of the application. Safety measures are then purely implemented in the software. Typically, the workspace is restricted and the robot velocity is limited. Even though this implementation is sufficient for most situations, overall system safety cannot be achieved. Programming errors or communication faults can bypass the safety mechanisms. To overcome this, we develop an independent safety layer, named FTA sensor, for the robotized TMS system. It combines a force-torque sensor with an accelerometer for independence from robot input. An embedded system performs the required computations in real-time (roughly 1 ms) and is directly connected to the robot's emergency circuit. In case of an error or collision, the robot is stopped immediately to protect the patient and/or the user from harm. Beside this safety feature, the sensor provides the same functionality as a standard force-torque sensor. As the computations on the embedded systems are much faster as in a pure software implementation, the above presented methods for hand-assisted positioning and contact pressure control were further optimized. Currently, indirect head tracking is the standard technique for neuro-navigated and robotized TMS. This method requires a marker on the patient's head, which is registered to the patient's head. Therefore, the marker must not shift after the registration, as this would lead to inaccuracies and errors in coil positioning. Direct tracking systems, on the contrary, straightly measure the surface of the head or specific facial feature points. This data can then be automatically matched to three-dimensional (3D) head scans of the patient. We test different systems for direct head tracking. First results show that 3D laser scanning systems can be utilized on principle. With advanced technologies, the 3D laser scanning systems will further improve for their application in direct head tracking for TMS. In summary, we implement a safe and clinically applicable robotized TMS system. A key feature is the developed FTA sensor with the optimized hand-assisted positioning method and the contact pressure control. The FTA sensor is now available as an extension to SmartMove (Advanced Neuro Technology B.V., Enschede, The Netherlands), called TouchSense, for the clinical market.}, year = {2012}, series = {Universit{\{\dq}a}t zu L{\{\dq}u}beck}, tags = {TMS}, note = {Transcranial Magnetic Stimulation} } @Inproceedings { Gasca2012, author = {Gasca, Fernando and Wissel, Tobias and Hadjar, Hamid and Schlaefer, Alexander and Schweikard, Achim}, title = {Sparsely optimized multi-electrode transcranial direct current stimulation}, year = {2012}, DOI = {10.3389/conf.fncom.2012.55.00136}, address = {Munich}, series = {Front. Comput. Neurosci.}, keywords = {Constrained optimization; finite element modelling (FEM); transcranial direct current stimulation}, tags = {TES}, file_url = {https://doi.org/10.3389/conf.fncom.2012.55.00136} } @Inproceedings { Metzner2012, author = {Metzner, Christoph and Guth, Fabian and Schweikard, Achim and Zurowski, B.}, title = {Spike-timing Dependent Plasticity Facilitates Excitatory/Inhibitory Disbalances in Early Phases of Tinnitus Manifestation}, year = {2012}, volume = {13}, number = {Suppl. 1}, tags = {NM}, note = {Neurological Modelling} } @Inproceedings { Rahman2012, author = {Rahman, Asif and Reato, Davide and Arlotti, Mattia and Gasca, Fernando and Datta, Abhishek and Parra, Lucas C. and Bikson, Marom}, title = {Tangential electric fields during tDCS modulates synaptic efficacy by synaptic terminal polarization}, year = {2012}, address = {New Orleans, USA}, keywords = {finite element modelling (FEM); transcranial direct current stimulation} } @Article { Reato2012b, author = {Reato, Davide and Gasca, Fernando and Datta, Abhishek and Bikson, Marom and Marshall, Lisa and Parra, Lucas C.}, title = {Transcranial electrical stimulation accelerates human sleep homeostasis}, year = {2012}, journal = {PLoS Computational Biology}, pages = {accepted}, keywords = {transcranial stimulation} } @Inproceedings { Reato2012a, author = {Reato, Davide and Gasca, Fernando and Datta, Abhishek and Bikson, Marom and Marshall, Lisa and Parra, Lucas C.}, title = {Transcranial electrical stimulation accelerates sleep homeostasis in humans}, year = {2012}, address = {New Orleans, USA}, tags = {TES} } @Article { tboe12, author = {Trillenberg, Peter and Bremer, Susan and Oung, Stephen and Erdmann, Christian and Schweikard, Achim and Richter, Lars}, title = {Variation of Stimulation Intensity in Transcranial Magnetic Stimulation with Depth}, abstract = {The quantification of stimulation intensity in transcranial magnetic stimulation (TMS) as a function of depth is of interest in order to adjust stimulator output when non-motor regions are stimulated. Currently, a linear increase of stimulator output to correct for depth has been suggested. This is contrary to the physical properties of the electric field that is induced by the stimulation coil as measured in vitro. For two stimulation coils, we determined the characteristics of their field in air. We then measured motor thresholds for the abductor hallucis muscle of 10 healthy subjects. Coil position, distance from the scalp, and orientation were controlled with a head tracking robotic system that corrected for head movements. In both coils an approximately exponential increase, rather than a linear increase, of the threshold with the scalp-coil distance was measured. The slope of the increase was slightly smaller than expected from the field characteristic, but overall in good agreement. With respect to the depth of the TMS target, different results were obtained from the threshold ratios of the coils and from the slopes of the threshold increase with distance. For the adjustment of stimulator output to scalp-to-cortex distances exponential functions with parameters motivated by physical properties of the coils should be used. Estimation of the target depth from the thresholds, with different coils, is not reliable. Our results resolve a conflict between physiological data and physical properties of TMS coils. They provide a more reliable base for depth dependent corrections for TMS stimulator output.}, year = {2012}, DOI = {10.1016/j.jneumeth.2012.09.007}, journal = {Journal of Neuroscience Methods}, volume = {211}, pages = {185-190}, number = {2}, tags = {TMS}, file_url = {https://doi.org/10.1016/j.jneumeth.2012.09.007}, note = {Transcranial Magnetic Stimulation} } @Article { ermm_12, author = {Ernst, Floris and Richter, Lars and Matth{\{\dq}a}us, Lars and Martens, Volker and Bruder, Ralf and Schlaefer, Alexander and Schweikard, Achim}, title = {Non-orthogonal Tool/Flange and Robot/World Calibration for Realistic Tracking Scenarios}, abstract = {This work presents a novel method for simultaneous tool/flange and robot/world calibration by estimating a solution to the common matrix equation AX=YB. This solution is computed using a least-squares approach. Since real robots and localisation are all afflicted by certain errors, our approach allows for non-orthogonal matrices, partially compensating for imperfect calibration of the robot or localisation device. Additionally, we also introduce a new method where full robot/world and partial tool/flange calibration is possible using localisation devices providing less than six degrees of freedom. The methods are evaluated on simulation data and on real-world measurements collected using optical and magnetical tracking devices (NDI's Polaris Spectra and Aurora systems), volumetric ultrasound (a modified GE Vivid7 Dimension station, providing 3-DOF data), and a surface laser scanning device (LAP GALAXY). We compare our methods to two classical approaches: the method by Tsai/Lenz and the Dual Quaternion method by Daniilidis. In all experiments, the new algorithms strongly outperform the classical methods in terms of translational accuracy (by as much as 80%) and perform similarly in terms of rotational accuracy. Additionally, the methods are shown to be stable: the number of calibration stations used has far less influence on calibration quality than for the classical methods.}, year = {2012}, DOI = {10.1002/rcs.1427}, journal = {International Journal of Medical Robotics and Computer Assisted Surgery}, volume = {8}, pages = {407-420}, number = {4}, tags = {MCRT TMS}, file_url = {https://doi.org/10.1002/rcs.1427}, note = {Transcranial Magnetic Stimulation, Motion Compensation in Radiosurgery} } @Inproceedings { dbes_12, author = {D{\{\dq}u}richen, Robert and Blanck, Oliver and Ernst, Floris and Schweikard, Achim}, title = {Evaluation of a wavelet-based least mean square algorithm for prediction of respiratory movements}, abstract = {Objectives: To successfully ablate a tumor in robotic radiotherapy, it is necessary to compensate the motion of inner organs caused by respiration. This can be achieved by tracking the body surface and correlation of the external movement to the tumor position, as it is implemented in Cyberknife Synchrony. A systematic error is produced from the delays, which arise from the data acquisition, signal processing and kinematical limitations of the system. The error can be decreased by predicting the time series of human respiration. A wavelet-based least mean square algorithm (wLMS) is evaluated on 17 patients and compared to the results of the Cyberknife Synchrony prediction algorithm and a multi-step linear method (MULIN). Methods: The algorithms were evaluated on 17 patients of the Cyberknife Center North Germany. The patients were treated with up to 5 fractions, in total 62 fractions. The fractions have a mean duration of 51 minutes. During the treatment, 3 markers were recorded at a frequency of 26 Hz. Besides respiratory movements, the data also contains movements due to the alignment of the patient. These periods have been cut out of the data. The prediction horizon was set to 4 samples (approx. 150 ms), which is in line with the latency of the Cyberknife. The wLMS prediction algorithm is based on the {\'a} trous wavelet decomposition. The signal is decomposed into J wavelet scales and a residual. With this decomposition it is possible to perform prediction on each individual scale. At each time step, a new weight vector is calculated depending on the past observations and is used to calculate the next prediction. The wavelet scale J was set to 3 according to previous experiments. The basic idea behind the MULIN algorithm is to compute the predicted signal from an expansion of the error signal. This linear prediction algorithm can be extended to the MULIN algorithm by taking higher derivatives into account. The algorithms are evaluated with respect to the relative root mean square error (RMS) and the relative Jitter of the predicted signal. The rel. RMS error is a measure of the accuracy of the prediction and is defined as the RMS error between the predicted signal and the real signal divided by the RMS error between the real signal and the real signal delayed by 4 samples. The Jitter is a measure of the stability and smoothness of the predicted signal. It is defined as the sum of the differences between the data points divided by the time steps. Results: Evaluating the data, the Cyberknife algorithm has the highest averaged rel. RMS error over all fractions. The mean averaged rel. RMS error for all fractions and the directions is 64.6%. The averaged rel. RMS error for the wLMS prediction algorithm is in average 13 % better (51.3%). Compared with the MULIN algorithm, the wLMS algorithm is in average 6 % better (57.2%). The standard deviation of the relative RMS error is also the highest for the Cyberknife algorithm. The standard deviation averaged over all 3 directions and all fractions is 25.5% for the Cyberknife, 17.7% for wLMS and 21.1% for the MULIN algorithm. In terms of the rel. Jitter, the results are very similar. The wLMS algorithm outperforms the Cyberknife algorithm. The mean average rel. Jitter over all fractions and direction is 141.6% for the Cyberknife, 114.5% wLMS and 125.1% for MULIN. In general all rel. Jitter values are above 100% for the 3 predictors above 100 %. This means that the delayed signal without prediction is smoother as the predicted signals. Conclusion: The evaluation clearly shows that the wLMS algorithm is superior compared to the MULIN algorithm and the Cyberknife. The wLMS algorithm has lowest rel. RMS error, standard deviation of the rel. RMS error and rel. Jitter. This means that the accuracy of the treatments and the smoothness of the robot control are increased.}, year = {2012}, address = {Carlsbad, CA, USA}, series = {The SRS/SBRT Scientific Meeting}, pages = {accepted-for publication}, tags = {MCRT}, note = {Motion Compensation in Radiosurgery} } @Inproceedings { rbs_12a, author = {Richter, Lars and Bruder, Ralf and Schweikard, Achim}, title = {Hand-assisted positioning and contact pressure control for motion compensated robotized transcranial magnetic stimulation}, abstract = {Purpose In Transcranial Magnetic Stimulation (TMS), the principle of magnetic induction is used to stimulate the brain non-invasively. Currently, robotic TMS systems are developed to guarantee precise coil placement on the head and in this way achieve the repeatability of stimulation results. However, usability concerns such as the complicated coil positioning are still unsolved for motion compensated robotized TMS. In this paper, we demonstrate the integration of a force-torque control into a robotic TMS system to improve usability, safety, and precision. Methods We integrated a force-torque sensor between robot effector and TMS coil. Coil calibration and gravity compensation have been developed. Based on them, we have implemented hand-assisted positioning for easy and fast coil placement. Furthermore, we have enhanced the existing motion compensation algorithms with a contact pressure control. Results The positioning time for an experienced user decreased up to 40% with the help of hand-assisted positioning in comparison with not hand-assisted robotized positioning. It also enabled an inexperienced user to use the system safely. Conclusion Integration of a force-torque control into the motion compensated robotized TMS system greatly enhances systems usability, which is a prerequisite for integration in the clinical workflow and clinical acceptance.}, year = {2012}, issn = {1861-6410}, DOI = {10.1007/s11548-012-0708-3}, journal = {International Journal of Computer Assisted Radiology and Surgery}, volume = {7}, publisher = {Springer Berlin / Heidelberg}, address = {Pisa, Italy}, series = {International Journal of Computer Assisted Radiology and Surgery}, pages = {123-124}, number = {Supplement 1}, tags = {UGRT TMS}, file_url = {https://doi.org/10.1007/s11548-012-0708-3}, note = {Transcranial Magnetic Stimulation} } @Article { rtss12, author = {Richter, Lars and Trillenberg, Peter and Schweikard, Achim and Schlaefer, Alexander}, title = {Comparison of stimulus intensity in hand held and robotized motion compensatedtranscranial magnetic stimulation}, abstract = {Transcranial Magnetic Stimulation (TMS) is based on a changing magnetic field passing through the skull and inducing an electric field in the cortex [1,2]. The latter results in cortical stimulation and needs to be aligned with the target region. Conventionally, the TMS coil is mounted to a static holder and the subject is asked to avoid head motion. Additionally, head resting frames have been used [3]. In contrast, our robotized TMS system employs active motion compensation (MC) to maintain the correct coil position [4]. To assess the potential impact of patient motion, we study the induced electric field for the different setups. We recorded 30 min of head motion for six subjects in three scenarios: (a) using a coil holder and avoiding head motion, (b) using a coil holder and a head rest, and (c) using the robotized system with motion compensation. The motion traces were fed into a second robot to mimic head motion for a field sensor integrated in a head phantom. We found that after 30 minutes the induced electric field was reduced by 32.0% and 19.7% for scenarios (a) and (b), respectively. For scenario (c) it was reduced by only 4.9%. Furthermore, the orientation of the induced field changed by 5.5°, 7.6°, and 0.4° for scenarios (a), (b), and (c), respectively. None of the scenarios required rigid head fixation [5], which is often considered impractical and uncomfortable. We conclude that active motion compensation is a viable approach to maintain a stable stimulation during TMS treatments.}, year = {2012}, issn = {0987-7053}, DOI = {10.1016/j.neucli.2011.11.028}, journal = {Neurophysiologie Clinique/Clinical Neurophysiology}, volume = {42}, pages = {61-62}, number = {1-2}, tags = {TMS}, file_url = {https://doi.org/10.1016/j.neucli.2011.11.028}, note = {Transcranial Magnetic Stimulation} } @Inproceedings { ESTRO2012, title = {2012 Annual Meeting of the ESTRO}, year = {2012}, volume = {31}, address = {Barcelona, Spain}, series = {European Society for Therapeutic Radiology and Oncology}, file_url = {http://www.estro-events.org/Pages/ESTRO31.aspx} } @Article { Finke2012a, author = {Finke, Markus and Kantelhardt, Sven and Schlaefer, Alexander and Bruder, Ralf and Lankenau, E. and Giese, Alf and Schweikard, Achim}, title = {Automatic scanning of large tissue areas in neurosurgery using optical coherence tomography}, abstract = {Background With its high spatial and temporal resolution, optical coherence tomography (OCT) is an idealmodality for intra-operative imaging. One possible application is to detect tumour invaded tissue in neurosurgery, e.g. during complete resection of glioblastoma. Ideally, the whole resection cavity is scanned. However, OCT is limited to a small field of view (FOV) and scanning perpendicular to the tissue surface. Methods We present a new method to use OCT for scanning of the resection cavity during neurosurgical resection of brain tumours. The main challenges are creating a map of the cavity, scanning perpendicular to the surface and merging the three-dimensional (3D) data for intra-operative visualization and detection of residual tumour cells. Results Our results indicate that the proposed method enables creating high-resolution maps of the resection cavity. An overlay of these maps with the microscope images provides the surgeon with important information on the location of residual tumour tissue underneath the surface. Conclusion We demonstrated that it is possible to automatically acquire an OCT image of the complete resection cavity. Overlaying microscopy images with depth information from OCT could lead to improved detection of residual tumour cells.}, year = {2012}, DOI = {10.1002/rcs.1425}, journal = {International Journal of Medical Robotics and Computer Assisted Surgery}, volume = {8}, pages = {327-336}, number = {3}, keywords = {brain tumor; neurosurgery; optical coherence tomography; registration; Robotics; surgical microscope}, file_url = {https://doi.org/10.1002/rcs.1425} } @Book { Abdel-Haq2012DGBMT, author = {Abdel-Haq, Anja and Baumann, Martin and Fincke, Sabine and Kraft, Marc and Morgenstern, Ute and Schmitt, Thomas and Seidl, Karsten and Zellerhoff, Maria}, title = {Biomedizinische Technik: Aus- und Weiterbildung in deutschsprachigen L{\{\dq}a}ndern Empfehlungen zur Verbesserung der Rahmenbedingungen f{\{\dq}u}r die Aus- und Weiterbildung von Fachkr{\{\dq}a}ften sowie f{\{\dq}u}r die Nachwuchsf{\{\dq}o}rderung}, year = {2012}, publisher = {DGBMT --- Deutsche Gesellschaft f{\{\dq}u}r Biomedizinische Technik im VDE}, note = {VDE-Positionspapier} } @Article { rbs_12, author = {Richter, Lars and Bruder, Ralf and Schweikard, Achim}, title = {Calibration of Force/Torque and Acceleration for an Independent Safety Layer in Medical Robotic Systems}, abstract = {Background: Most medical robotic systems require direct interaction with the robot. Force-Torque (FT) sensors can easily be mounted to the robot. However, an accurate FT control requires the current robot position to compute the spatial orientation of the sensor for gravity compensation. Methods: We developed an independent safety system, named FTA sensor, which is based on an FT sensor and an accelerometer. With a calibration of accelerations to the FT coordinate frame, the current spatial orientation of the sensor is computed. Results: We found that the calibration of accelerations into the FT coordinate frame can be performed with a median rotational error of 3.5°. The median error for gravity compensation based on accelerations was 0.3N and 0.04Nm for forces and torques, respectively. Conclusion: By combining accelerations with force-torque readings, the FTA sensor works independently from robot input. Furthermore, the accuracy of the FTA sensor is sufficient for the purpose of medical robotic systems.}, year = {2012}, DOI = {10.7759/cureus.59}, journal = {Cureus}, volume = {4}, pages = {e59}, number = {9}, tags = {UGRT TMS}, file_url = {https://doi.org/10.7759/cureus.59}, note = {Transcranial Magnetic Stimulation} } @Article { heinig2012, author = {Heinig, Max and Hofmann, Ulrich G. and Schlaefer, Alexander}, title = {Calibration of the Motor Assisted Robotic Stereotaxy System: MARS}, year = {2012}, journal = {International Journal of Computer Assisted Radiology and Surgery}, volume = {accepted for publication}, keywords = {application accuracy; stereotactic neurosurgery; stereotaxy}, tags = {SM}, note = {doi: 0.1007/s11548-012-0676-7} } @Inproceedings { bded_12, author = {Blanck, Oliver and D{\{\dq}u}richen, Robert and Ernst, Floris and Dunst, J{\{\dq}u}rgen and Rades, Dirk and Hildebrandt, Guido and Schweikard, Achim}, title = {Evaluation of a wavelet-based least mean square motion prediction algorithm for lung and liver patients}, abstract = {Objectives: Accurate radiation therapy and radiosurgery treatment of lung and liver tumors are challenging problems due to continuous target motion due to the patients breathing. Motion compensation systems are often needed such as CyberKnife® tracking (Accuray Inc, USA), where internal tumor motion is estimated on stereo x-ray images and correlated with external optical markers attached to the patients' chest. During treatment the system compensates the target motion based on time series prediction of the optical marker movements. Errors for this method mainly come from delays, which arise from data acquisition, signal processing, kinematical limitations of the system and the quality of the predication. We analyzed a new wavelet-based least mean square algorithm (wLMS) and compared the results to the CyberKnife prediction algorithm and a multi-step linear method (MULIN). [2] Materials / Methods: The algorithms were evaluated on 7 lung and 17 liver patients treated with the CyberKnife in 3-5 fractions, a total of 103 fractions. The prediction horizon was set to 115 ms, which is in line with the latency of the CyberKnife. The wLMS prediction algorithm is based on the {\'a} trous wavelet decomposition. The signal is decomposed into J wavelet scales and a residual. With this decomposition it is possible to perform prediction on each individual scale [1]. The algorithms are evaluated with respect to the relative root mean square error (RMS) and the relative jitter of the predicted signal. The rel. RMS error is defined as the RMS error between the predicted signal and the real signal divided by the RMS error between the real signal and the real signal delayed by 4 samples. The jitter is defined as the sum of the differences between the data points divided by the time steps. Results: Figure 1 and table 1 show the averaged rel. RMS error and rel. jitter with standard deviation. In general the rel. RMS errors are higher for lung as for liver patients. The current CyberKnife algorithm was found to have the highest error for both patient categories whereas the wLMS algorithm was found to have the lowest rel. RMS error (fig. 1a,b). Also the averaged rel. jitter of the wLMS algorithm and MULIN algorithm is lower compared to the Cyberknife algorithm (fig 1c,d). Conclusion: In summary all algorithms predict the respiratory movement with high accuracy and lead to a significant improvement compared to no prediction. However the evaluation clearly shows that the wLMS algorithm is superior for both patient categories compared to the MULIN and the currently implemented CyberKnife algorithm. With the new wLMS algorithm the treatment accuracy and the smoothness of the robot motion control can be increased.}, year = {2012}, volume = {103}, address = {Barcelona, Spain}, series = {Radiotherapy and Oncology}, pages = {S12-S13}, number = {S1}, tags = {MCRT}, file_url = {http://www.estro-events.org/Pages/ESTRO31.aspx}, note = {Motion Compensation in Radiosurgery} } @Inproceedings { Stender2012, author = {Stender, Birgit and Wang, Bo and Schlaefer, Alexander}, title = {Computing Synthetic Echocardiography Volumes for Automatic Validation of 3D Segmentation Results}, year = {2012}, volume = {57}, series = {Biomed Tech 2012}, number = {Suppl. 1}, tags = {MCM} } @Phdthesis { h_12, author = {Heinig, Max}, title = {Design and Evaluation of the Motor Assisted Robotic Stereotaxy System MARS}, abstract = {The scope of this thesis is the development and clinical evaluation of a robotic system for stereotactic neurosurgery. Furthermore, a new intracranial localization method for neurosurgical instruments is presented. Potential clinical applications for the robot are brain biopsies, e.g. for tumors or deep brain stimulation, e.g. in the treatment of Parkinson's disease. The requirements for a new hybrid robotic system are derived from a detailed analysis of existing manual and robotic stereotactic systems. The aim of the development is to combine the advantages of the two approaches and to enable both, manual and automatic positioning. The core of this work is the development and implementation of the Motor Assisted Robotic Stereotaxy system, short MARS. The kinematic chain of the MARS consists of ve axes. Their alignment is similar to that of the clinically established ZD stereotaxy system from the industrial partner inomed Medizintechnik GmbH. The actuators, sensors and other components as well as the mechanical and electrical design of the MARS are described in detail. The MARS is evaluated in numerous experiments regarding its suitability for surgical interventions. Therefore, its absolute accuracy and repeatability are measured. Then, the electromagnetic compatibility of the system with other devices in the operating theater is validated and its application accuracy is determined in a simulated surgery. After successful testing, the MARS is clinically evaluated in a brain tumor biopsy. The second part of the thesis addresses the localization of instruments in the brain. Various error sources such as probe-tissue interaction during surgery can cause a deviation of the instrument from the planned trajectory with potentially fatal consequences. Continuous monitoring of the position of the instrument is hence of great relevance in neurosurgical interventions. A method for localization of probes based on static magnetic elds is developed and evaluated. The localization method is characterized by its high spatial resolution and the fact that it does not require additional components in the brain of the patient. In summary, the MARS presents a highly accurate, safe and mobile tool for stereotactic neurosurgery. The successful clinical evaluation of the robot and its combination with the magnetic localization method emphasize the quality of the system.}, year = {2012}, series = {Institute for Robotics and Cognitive Systems, University of L{\{\dq}u}beck}, keywords = {calibration; DBS; functional neurosurgery; MER; Motor Assisted Robotic Stereotaxy system; neurosurgery; stereotaxy}, tags = {SM}, note = {Stereotactic Micronavigation} } @Inproceedings { dws_12, author = {D{\{\dq}u}richen, Robert and Wissel, Tobias and Schweikard, Achim}, title = {Efficient SVR model update approaches for respiratory motion prediction}, abstract = {In order to successfully ablate moving tumours in robotic radiosurgery, respiratory motion prediction is needed to compensate time delays. In this context, recent studies revealed a high potential of support vector regression (SVR). However, high computational cost is one major drawback, particularly caused by batch mode training. We evaluate two approaches to reduce the update rate as well as computation time, while keeping a low prediction error. The update rules are either based on information about the respiratory phase or based on the current prediction error. An evaluation on patient data sets revealed that the second approach on average decreases computation time by 88.53% compared to a batch mode implementation. The prediction error increased by 0.3%, hence indicating enhanced efficiency.}, year = {2012}, volume = {11}, address = {D{\{\dq}u}sseldorf, Germany}, series = {CURAC}, tags = {MCRT}, note = {Motion Compensation in Radiosurgery} } @Phdthesis { Finke2012b, author = {Finke, Markus}, title = {Entwicklung eines chirurgischen Assistenzsystems auf Basis eines motorisierten OP-Mikroskops}, year = {2012}, series = {Universit{\{\dq}a}t zu L{\{\dq}u}beck} } @Inproceedings { Viulet2012, author = {Viulet, Tiberiu and Schlaefer, Alexander}, title = {Error compensated sparse optimization for fast radiosurgery treatment planning}, abstract = {Purpose: Radiosurgical treatment planning requires a good approximation of the dose distribution which is typically computed on a high resolution grid. However, the resulting optimization problem is large, and leads to substantial runtime. We study a sparse grid approach, for which we estimate and compensate for the expected deviations from the bounds. Methods: We buildup an estimate of the hotspot error distribution by measuring the maximum dose deviation within a voxel for a large number of randomly generated beam configurations. This results in a conservative estimation of overdosage as a function of upper bound reduction for different grid sizes. We adjust the bounds for voxels inside the target volume (PTV) according to our estimation thus maintaining the likelihood of dose deviations within acceptable limits. The approach was applied to a prostate case, where the volumes of interest are large and close to each other. Our planning objective is a prescribed dose of 36.25 Gy to the 87% isodose. We employed constrained optimization to optimize the lower PTV bound on 2, 4, and 8mm isotropic grids. Results were computed on 1mm grid. Results: The initial coverage was 93.7%, 92%, and 91%, and the volume exceeding the upper bound was 0.74%, 1.71%, and 9% for grid sizes of 2, 4, and 8mm, respectively. Changing the upper bound by 0.5% and 2.5% for the 4 and 8 mm grids resulted in only 0.75% and 2.2% of the volume exceeding the bound. The coverage did not change. Mean optimization times were 141.1, 22.6 and 3.4 minutes using the 2, 4 or 8mm grid, respectively. Conclusions: Experiments show that planning on a sparse grid can achieve comparable results with those of a high resolution grid, as long as the bounds are carefully balanced. This leads to substantially lower optimization times which facilitates interactive planning.}, year = {2012}, DOI = {10.1118/1.4735708}, volume = {39}, publisher = {Medical Physics}, file_url = {https://doi.org/10.1118/1.4735708} } @Inproceedings { gsrb_12, author = {Gr{\{\dq}u}ning, Philipp and St{\{\dq}u}ber, Patrick and Richter, Lars and Blanck, Oliver and Bruder, Ralf and Schweikard, Achim}, title = {Estimation of error sources for optical head tracking in cranial radiation therapy}, year = {2012}, volume = {11}, address = {D{\{\dq}u}usseldorf, Germany}, series = {CURAC}, tags = {HPHT}, note = {High-Accuracy Head Tracking} } @Article { ebss_12b, author = {Ernst, Floris and Bruder, Ralf and Schlaefer, Alexander and Schweikard, Achim}, title = {Correlation between external and internal respiratory motion: a validation study}, year = {2012}, DOI = {10.1007/s11548-011-0653-6}, journal = {International Journal of Computer Assisted Radiology and Surgery}, volume = {7}, publisher = {Springer}, pages = {483-492}, number = {3}, tags = {MCRT UGRT}, file_url = {https://doi.org/10.1007/s11548-011-0653-6}, note = {Motion Compensation in Radiosurgery} } @Article { ress_11, author = {Richter, Lars and Ernst, Floris and Schlaefer, Alexander and Schweikard, Achim}, title = {Robust robot-camera calibration for robotized Transcranial Magnetic Stimulation}, abstract = {Transcranial Magentic Stimulation (TMS) is a method to painlessly and noninvasively stimulate parts of the brain. For robotized TMS, the magnetic coil is placed on the patient's head by a robot. As the robotized TMS system requires tracking of head movements, robot and tracking camera need to be calibrated. Conventionally, such calibration is done by tracking the robot's end effector, i.e., moving the robot into different poses and measuring the position and orientation of a marker attached to the end effector. Hence, robot motions can be related to the respective motion in camera coordinates. Generally, solving this problem is called hand-eye-calibration, and several methods for precise estimation of the related transformations exist. However, for robotized TMS in a clinical setting such calibration is required frequently, especially since robot and tracking system are partially mobile. Mounting / unmounting a marker to the end effector and moving the robot into different poses is rather impractical. Moreover, if either system is moved during treatment, recalibration is required. To overcome this limitation, we propose to directly track link three of the articulated arm. Using forward kinematics and a constant marker transform, the calibration can be performed instantly. This robust online calibration greatly enhances the system's user-friendliness as the paramount aim for all medical robotized systems is easy and safe usability in clinical routine and research. Furthermore, we can recompute the transformation throughout the treatment, i.e., we can constantly check for changes and potentially interrupt the treatment. Our experimental results indicate an accuracy similar to standard hand-eye calibration approaches. For the robotized TMS system, the overall accuracy was 2.2mm using the proposed approach, which is more than twice the accuracy of other navigated TMS systems.}, year = {2011}, DOI = {10.1002/rcs.411}, journal = {International Journal of Medical Robotics and Computer Assisted Surgery}, volume = {7}, pages = {414-422}, number = {4}, tags = {TMS}, file_url = {https://doi.org/10.1002/rcs.411}, note = {Transcranial Magnetic Stimulation} } @Inproceedings { bseb_11, author = {Stender, Birgit and Scharfschwerdt, Michael and Ernst, Floris and Bruder, Ralf and Hadjar, Hamid and Schlaefer, Alexander}, title = {Optical Imaging of Cardiac Function: System setup and calibration}, year = {2011}, volume = {6}, address = {Berlin, Germany}, series = {International Journal of Computer Assisted Radiology and Surgery}, pages = {S42-S43}, number = {S1}, tags = {MCM}, file_url = {http://www.cars-int.org}, note = {Planning of Cardiac Interventions} } @Inproceedings { ebss_11a, author = {Ernst, Floris and Bruder, Ralf and Schlaefer, Alexander and Schweikard, Achim}, title = {Performance Measures and Pre-Processing for Respiratory Motion Prediction}, abstract = {Purpose: Much research has been done on prediction of respiratory motion traces for motion compensation in radiotherapy. Unfortunately, the results of different groups cannot be compared easily due to different standards in preprocessing and analysis of the results. Furthermore, it has been speculated that the typically used measure for prediction quality, the RMS error, is not sufficient alone. Methods: We propose a set of guidelines for signal preprocessing (i.e., for scaling, detrending, resampling, and denoising) as well as measures for the analysis of the prediction results. The latter complement the RMS error with confidence intervals, the signal's smoothness (called jitter) and a measure for the periodicity of the error (called frequency content). Additionally, we have developed an extendable cross‐platform prediction toolkit for easy analysis of prediction algorithms. Results: We found that very different signals (corrupted by noise, scaled by a constant factor, delayed in time, and scaled by random factors for each respiratory period) feature the exact same RMS error when compared to the original signal. The fundamental difference in the error signals can only be determined when using spectral measures, like the frequency content. Conclusion: Using the guidelines developed, the proposed evaluation measures, as well as the publicly available prediction toolkit, should help the community in establishing a better understanding for the capabilities and shortcomings of individual prediction methods. Additionally, it should allow others to more readily compare newly developed methods to already published algorithms. In the future, it would be desirable to also create a database of motion traces from various sources. If these signals would represent the characteristics of motion traces observed in the clinic, it could serve as a general benchmark for the quality of algorithms for motion prediction.}, year = {2011}, DOI = {10.1118/1.3613523}, volume = {38}, address = {Vancouver, BC, Canada}, series = {Medical Physics}, pages = {3857}, number = {6}, tags = {MCRT}, file_url = {https://doi.org/10.1118/1.3613523}, note = {Motion Compensation in Radiosurgery} } @Article { ess_11, author = {Ernst, Floris and Schlaefer, Alexander and Schweikard, Achim}, title = {Predicting the Outcome of Respiratory Motion Prediction}, abstract = {Purpose: Prediction of respiratory motion traces has become an important research topic. Especially for motion compensated radiotherapy, compensation of the latencies arising from mechanical constraints and signal processing is necessary. In recent years, many algorithms have been developed and evaluated. It is, however, still unclear how well a specific patient will be suited to motion prediction before the treatment actually starts. Methods: In this work, we have analyzed 304 respiratory motion traces with an average duration of 71 min. A total of 21 features characterizing these signals (12 from the frequency domain and 9 from the time domain) have been determined for each motion trace. The correlation between these features and the overall prediction quality for three different algorithms (based on wavelet-based multiscale autoregression, support vector regression, and linear expansion of the prediction error) has been analyzed and six dominant features have been identified (three each from the time and frequency domains). Additionally, the optimized results of the multistep-linear method (MULIN) prediction algorithm on the first 300 s of motion data have been used as a seventh, independent feature. Assessing the prediction algorithms' quality was done by calculating the relative root mean squared (RMSrel) error, i.e., the ratio between the RMS error of the prediction output and the RMS error of the delayed signal (the RMS error obtained when doing no prediction). Then, for each algorithm, the signals themselves were grouped into four classes according to the quality of prediction: relative RMS less than 0.8 (C1), between 0.8 and 0.9 (C2), between 0.9 and 1.0 (C3), and over 1.0 (C4). The goal of this work is to identify, prior to treatment, those patients whose respiratory behavior indicates probable (RMS≥0.9) or certain (RMS≥1.0) failure of respiratory motion prediction. Consequently, all signals from C4 must be identified and rejected and no signals from C1 may be falsely rejected. The restriction on C2 and C3 is slightly weaker: C2 are those signals that should be kept and C3 are those signals that should be rejected. Results: Rejecting all signals from C4 and C3, keeping as many signals from C1 and as few from C2 as possible, has been achieved for the wLMS algorithm when using six feature pairs and the result of prediction on the short signal. Here, the false rejectance rate for C1 was less than 13% and the false acceptance rate for C2 was 15%. For the SVRpred and MULIN algorithms, the results are somewhat worse: in both cases, signals from C3 were falsely accepted (25.0% and 14.3%, respectively) but all signals from C4 were rejected. The false rejectance rate for C1 was 11.4% (MULIN) and 26.3% (SVRpred). Conclusions: In general, it has been shown that pretreatment classification of the quality of respiratory motion prediction is possible and that signals with high relative RMS error can be identified with great reliability. This is especially true for the wLMS algorithm, which has also been identified as the most precise and robust of the presented methods.}, year = {2011}, DOI = {10.1118/1.3633907}, journal = {Medical Physics}, volume = {38}, pages = {5569-5582}, number = {10}, tags = {MCRT}, file_url = {https://doi.org/10.1118/1.3633907}, note = {Motion Compensation in Radiosurgery} } @Inproceedings { bjer_11, author = {Bruder, Ralf and Jauer, Philipp and Ernst, Floris and Richter, Lars and Schweikard, Achim}, title = {Real-time 4D ultrasound visualization with the Voreen framework}, abstract = {Voreen is an open source volume rendering engine which allows interactive visualization of volumetric data sets with high flexibility when integrating new visualization techniques. It is designed with minimal overhead, so that, even for difficult processing networks, high rendering speeds can be achieved. While Voreen is well-equipped to display Cartesian volumes, volumes in polar coordinates, such as raw ultrasound beam data, have to be interpolated and converted to Cartesian coordinates to be displayed. This is highly time-consuming on a CPU while interpolation and volume rendering can be done on a graphics card in real-time. We have added the functionality to display volumetric data in polar coordinates, where the volume is sampled along rays with a common center point and two angles of direction. Raycasters for 3d ultrasound volumes have been implemented as Voreen processors. In this way they can be used inside the Voreen framework and combined with other processors of the framework. We have also implemented a TCP/IP volume source which can receive volumetric streaming data via Ethernet and provide it to Voreen. In this way the visualization of live ultrasound data becomes possible. Screening for Parkinson's disease has been identified as a possible application for our work. Physicians look for hyperechogeneic regions in the mesencephalon. This task is greatly simplified when the ultrasound volume is supplemented by an MRI scan which features much higher spatial resolution and clarity. To show the functionality of the extension we have created an application which displays a static MRI head volume and the output of a GE Vivid 7 Dimension 4D ultrasound station with interactive (>20fps) frame rates.}, year = {2011}, isbn = {978-1-4503-0971-4}, DOI = {10.1145/2037715.2037798}, publisher = {ACM}, address = {Vancouver, BC, Canada; New York, NY, USA}, series = {SIGGRAPH '11}, pages = {74:1}, tags = {MCRT UGRT}, file_url = {https://doi.org/10.1145/2037715.2037798}, note = {Motion Compensation in Radiosurgery} } @Inproceedings { rbss11, author = {Richter, Lars and Bruder, Ralf and Schlaefer, Alexander and Schweikard, Achim}, title = {Realisierung einer schnellen und wiederholbaren Hot-Spot-Bestimmung f{\{\dq}u}r die robotergest{\{\dq}u}tzte Transkranielle Magnet-stimulation mittels Kraft-Momenten-Steuerung}, abstract = {Das Robotersystem f{\{\dq}u}r die Transkranielle Magnetstimulation (TMS) erm{\{\dq}o}glicht eine pr{\{\dq}a}zise und wiederholbare Posi-tionierung der TMS-Spule auf dem Kopf des Patienten. Um einen sicheren Einsatz des Roboters zu gew{\{\dq}a}hrleisten, ist oftmals eine manuelle Vorpositionierung des Roboters n{\{\dq}o}tig, um einen gew{\{\dq}u}nschten Stimulationspunkt zu erreichen. Mittels der Kraft-Momenten-Steuerung (KMS) ist es m{\{\dq}o}glich die Spule intuitiv per Hand zu bewegen. Wir haben die KMS verwendet und erweitert, um sie f{\{\dq}u}r eine schnelle Hot-Spot-Bestimmung einsetzen zu k{\{\dq}o}nnen. Bei unseren Tests haben wir gezeigt, dass es einem unerfahrenen Benutzer nur schwer m{\{\dq}o}glich ist, eine Hot-Spot-Bestimmung mit dem Robotersystem ohne Kraft-Momenten-Steuerung durchzuf{\{\dq}u}hren. Die KMS verk{\{\dq}u}rzt die Dauer der Hot-Spot-Bestimmung wesentlich und ist daher entscheidend f{\{\dq}u}r den breiten Einsatz des Robotersystems in Klinik und Forschung.}, year = {2011}, publisher = {CURAC}, pages = {31-34}, tags = {TMS}, note = {Transcranial Magnetic Stimulation} } @Inproceedings { Viulet2011a, author = {Viulet, Tiberiu and Rzezovski, Norman and Schlaefer, Alexander}, title = {Towards interactive planning for radiotherapy by three-dimensional iso-dose manipulation}, year = {2011}, tags = {TP} } @Inproceedings { bes_11, author = {Bruder, Ralf and Ernst, Floris and Schweikard, Achim}, title = {SU‐D‐220‐02: Optimal transducer positions for 4D ultrasound guidance in cardiac IGRT}, abstract = {Purpose: Currently effort is taken to use radiation therapy to cure arrhythmia. In this circumstance the left atrium and the pulmonary veins have to be irradiated. While the precise robot system placing the beam onto a moving target already exists, sensory information for target movement acquisition and heart‐beat motion compensation still have to be analyzed. One possibility for real‐time, direct target localization during treatment is three‐dimensional, transthoracic ultrasound requiring a transducer to be positioned on the patient's chest. The imaging and ‐as a result ‐tracking quality highly depends on this positioning choice. Especially when a patient lies in treatment position on his back, it is difficult to find a transducer position, which allows suitable imaging quality. Methods: We present an automatic algorithm which calculates the patient‐specific ultrasound imaging quality from a given CT scan. A quality function is executed in real‐time on the graphics card calculating the target reflectivity in beam direction as well as the distance and the absorption in the line of sight from transducer to the chosen target. The optimal transducer position is found as the area on the skin with the best results of the quality function and at least the area of the size of the ultrasound transducer. Results: We have tested the algorithm with 10 CTs. For general cardiac imaging the calculated transducer positions mostly fit with the typical ultrasound views found in literature. Nevertheless, the acquisition of special targets, such as the atria and pulmonary veins, often requires or at least profits from an off‐standard transducer placement. Conclusions: We have found a reliable method to calculate an optimal transducer position for a specific target inside the heart without the need to iteratively search and optimize it. In this way electronic (e.g. robotic) transducer placement during treatment becomes possible.}, year = {2011}, DOI = {10.1118/1.3611550}, volume = {38}, address = {Vancouver, BC, Canada}, series = {Medical Physics}, pages = {3390}, number = {6}, tags = {UGRT}, file_url = {https://doi.org/10.1118/1.3611550}, note = {SU‐D‐220‐02} } @Inproceedings { Viulet2011b, author = {Viulet, Tiberiu and Rzezovski, Norman and Schlaefer, Alexander}, title = {Three-Dimensional Isodose Surface Manipulation for Multi-Criteria Inverse Planning in Radiosurgery}, year = {2011}, tags = {TP} } @Article { tnosr11, author = {Trillenberg, Peter and Neumann, Gunnar and Oung, Stephen and Schweikard, Achim and Richter, Lars}, title = {Threshold for Transcranial Magnetic Stimulation of the foot: precise control of coil orientation with a robotized system}, year = {2011}, issn = {1434-0275}, DOI = {10.1055/s-0031-1272727}, journal = {Klin Neurophysiol}, volume = {42}, pages = {P280}, number = {01}, tags = {TMS}, file_url = {https://doi.org/10.1055/s-0031-1272727}, note = {EN} } @Inproceedings { Zellerhoff2011BMT, author = {Zellerhoff, Maria}, title = {{\{\dq}U}bersicht Weiterbildung Biomedizinische Technik: 45th Annual Conference}, year = {2011}, address = {Freiburg} } @Inproceedings { ebss_11, author = {Ernst, Floris and Bruder, Ralf and Schlaefer, Alexander and Schweikard, Achim}, title = {Validating an SVR-based Correlation Algorithm on Human Volumetric Ultrasound Data}, year = {2011}, volume = {6}, address = {Berlin, Germany}, series = {International Journal of Computer Assisted Radiology and Surgery}, pages = {S59-S60}, number = {S1}, file_url = {http://www.cars-int.org} } @Techreport { Wilde2011, author = {Wilde, Christian}, title = {YaSST -- A Signal Processing Toolbox for Extracellular Multi-Unit Recordings}, year = {2011}, series = {University of Luebeck} } @Inproceedings { rbts_11, author = {Richter, Lars and Bruder, Ralf and Trillenberg, Peter and Schweikard, Achim}, title = {Navigated and Robotized Transcranial Magnetic Stimulation based on 3D Laser Scans}, year = {2011}, publisher = {Gesellschaft f{\{\dq}u}r Informatik (GI)}, address = {L{\{\dq}u}beck, Germany}, series = {Informatik akuell}, pages = {164-168}, tags = {TMS}, note = {Transcranial Magnetic Stimulation} } @Inproceedings { MSZ11_1, author = {Metzner, Christoph and Schweikard, Achim and Zurowski, B.}, title = {Neurochemical Mechanisms of Perceptual Deficits in Schizophrenic Patients -- A Spiking Neural Network Approach: BC11 : Computational Neuroscience Neurotechnology Bernstein Conference {\\&} Neurex Annual Meeting}, year = {2011}, tags = {NM}, note = {Neurological Modelling} } @Inproceedings { MSZ11_2, author = {Metzner, Christoph and Schweikard, Achim and Zurowski, B.}, title = {Towards Realistic Receptive Field Properties in a Biologically Inspired Spiking Network Model of the Mammalian Primary Visual Cortex: BC11 : Computational Neuroscience Neurotechnology Bernstein Conference {\\&} Neurex Annual Meeting}, year = {2011}, tags = {NM}, note = {Neurological Modelling} } @Inproceedings { heinig2011, author = {Govela, Maria Fernanda and Mart{\'i}nez, Jorge and Heinig, Max}, title = {MARS robot}, year = {2011} } @Inproceedings { heinig2011b, author = {Heinig, Max and Christ, Olaf and Tronnier, Volker and Hofmann, Ulrich G. and Schlaefer, Alexander and Schweikard, Achim}, title = {Electromagnetic noise measurement of the Motor Assisted Robotic Stereotaxy System (MARS)}, year = {2011}, editor = {Yang, Guang-Zhong and Darzi, Ara}, pages = {63-64}, number = {4}, keywords = {Deep brain stimulation; electromagnetic noise; neurosurgery; Robotics; stereotaxy}, tags = {SM}, note = {Stereotactic Micronavigation} } @Inbook { schlaefer2011, author = {Schlaefer, Alexander and Beckmann, Daniel and Heinig, Max and Bruder, Ralf}, title = {A New Class for Robotic Sailing: The Robotic Racing Micro Magic}, year = {2011}, isbn = {978-3-642-22835-3}, DOI = {10.1007/978-3-642-22836-0_5}, publisher = {Springer Berlin Heidelberg}, editor = {Schlaefer, Alexander and Blaurock, Ole}, pages = {71-84}, file_url = {https://doi.org/10.1007/978-3-642-22836-0_5} } @Phdthesis { e_11a, author = {Ernst, Floris}, title = {Algorithms for Compensation of Quasi-periodic Motion in Robotic Radiosurgery}, year = {2011}, series = {University of L{\{\dq}u}beck}, tags = {MCRT}, file_url = {http://vg06.met.vgwort.de/na/4b54bacdd0374f409563bcdc35fc1a3b?l=http://www.medphys.org/PhDAbstracts/ernstphd.pdf}, note = {Motion Compensation in Radiosurgery} } @Inproceedings { bess_11, author = {Bruder, Ralf and Ernst, Floris and Schlaefer, Alexander and Schweikard, Achim}, title = {A Framework for Real-Time Target Tracking in Radiosurgery using Three-dimensional Ultrasound}, year = {2011}, volume = {6}, address = {Berlin, Germany}, series = {International Journal of Computer Assisted Radiology and Surgery}, pages = {S306-S307}, number = {S1}, tags = {MCRT}, file_url = {http://www.cars-int.org}, note = {Motion Compensation in Radiosurgery} } @Book { e_11, author = {Ernst, Floris}, title = {Compensating for Quasi-periodic Motion in Robotic Radiosurgery}, abstract = {Compensating for Quasi-periodic Motion in Robotic Radiosurgery outlines the techniques needed to accurately track and compensate for respiratory and pulsatory motion during robotic radiosurgery. The algorithms presented within the book aid in the treatment of tumors that move during respiration. In Chapters 1 and 2, the book introduces the concept of stereotactic body radiation therapy, motion compensation strategies and the clinical state-of-the-art. In Chapters 3 through 5, the author describes and evaluates new methods for motion prediction, for correlating external motion to internal organ motion, and for the evaluation of these algorithms' output based on an unprecedented amount of real clinical data. Finally, Chapter 6 provides a brief introduction into currently investigated, open questions and further fields of research. Compensating for Quasi-periodic Motion in Robotic Radiosurgery targets researchers working in the related fields of surgical oncology, artificial intelligence, robotics and more. Advanced-level students will also find this book valuable.}, year = {2011}, isbn = {978-1-4614-1911-2}, DOI = {10.1007/978-1-4614-1912-9}, publisher = {Springer}, address = {New York}, tags = {MCRT}, file_url = {https://doi.org/10.1007/978-1-4614-1912-9}, note = {Motion Compensation in Radiosurgery} } @Inproceedings { MMSZ11, author = {Metzner, Christoph and Menzinger, M. and Schweikard, Achim and Zurowski, B.}, title = {Early Signs of Tinnitus in a Simulation of the Mammalian Primary Auditory Cortex}, year = {2011}, volume = {12 (Suppl. 1)}, pages = {P383}, tags = {NM}, note = {Neurological Modelling} } @Book { m_11, author = {Ernst, Floris and Schweikard, Achim}, title = {Adaptive Motion Compensation in Radiotherapy}, year = {2011}, publisher = {Taylor Francis}, series = {Imaging in Medical Diagnosis and Therapy}, editor = {Murphy, Martin J.}, pages = {47-63}, tags = {MCRT}, note = {Motion Compensation in Radiosurgery} } @Article { bkcl_11, author = {Bismuth, Jean and Kashef, Elika and Cheshire, Nicolas and Lumsden, Alan B.}, title = {Feasibility and safety of remote endovascular catheter navigation in a porcine model.}, abstract = {Purpose: To evaluate the feasibility and safety of a redesigned remotely operated vascular catheter versus manual catheter manipulation in a porcine model. Methods: Following femoral artery puncture and wire insertion, 4 pigs had either a robotically steered catheter (3 animals) or standard manual catheter manipulation to cannulate the contralateral iliac artery, bilateral renal arteries, and the superior mesenteric artery. After harvesting, the vessels were evaluated histologically by an independent laboratory using hematoxylin and eosin staining. Each cannulated artery was assessed for disruption of the intimal surface, intimal thrombus, damage to the tunica muscularis (dissection), mural hemorrhage, and inflammation by a pathologist who was blinded to the technique utilized for cannulation. Results: No histological evidence of intimal thrombus, disruption, inflammation, or hemorrhage was demonstrated in any vessel section from the robotic cases. In the SMA, 1 of 61 sections from the robotic cases demonstrated mild focal dissection, while 1 of 9 slices from the manual control showed intimal thrombus. Of 129 slices from the renal arteries catheterized by the robotic system, 4 sections demonstrated mild focal dissection, while 2 of 23 sections from the manual control showed grade 1 intimal thrombus. In the iliofemoral arteries, 3 of 91 sections showed mild focal dissection in the robotic cases; in the manual control, 1 of 9 slices demonstrated extensive dissection and another showed mild intimal thrombus. Conclusion: The robotically operated catheter was at least as safe as manual manipulation. More extensive injury was actually observed with the manual technique. This newly designed robotic catheter has the potential to offer many advantages in terms of flexibility and range of motion.}, year = {2011}, issn = {1074-6218}, DOI = {10.1583/10-3324R.1}, journal = {Journal of Endovascular Therapy}, volume = {18}, pages = {243-249}, number = {2}, keywords = {Animals; Catheter; Equipment Design; Feasibility Studies; Female; Risk Assessment; Robotics; Swine}, file_url = {https://doi.org/10.1583/10-3324R.1} } @Inproceedings { Shahin2011, author = {Shahin, Osama and Martens, Volker and Be{\v{s}}irevi{\c}, Armin and Kleemann, Markus and Schlaefer, Alexander}, title = {Intraoperative tumor localization in laparoscopic liver surgery}, year = {2011} } @Article { sd_11, author = {Schlaefer, Alexander and Dieterich, Sonja}, title = {Feasibility of case-based beam generation for robotic radiosurgery}, abstract = {Objective Robotic radiosurgery uses the kinematic flexibility of a robotic arm to target tumors and lesions from many different directions. This approach allows to focus the dose to the target region while sparing healthy surrounding tissue. However, the flexibility in the placement of treatment beams is also a challenge during treatment planning. We study an approach to make the search for treatment beams more efficient by considering previous treatment plans. Methods and material Conventionally, a beam generation heuristic based on randomly selected candidate beams has been proven to be most robust in clinical practice. However, for prevalent types of cancer similarities in patient anatomy and dose prescription exist. We present a case-based approach that introduces a problem specific measure of similarity and allows to generate candidate beams from a database of previous treatment plans. Similarity between treatments is established based on projections of the organs and structures considered during planning, and the desired dose distribution. Solving the inverse planning problem a subset of treatment beams is determined and adapted to the new clinical case. Results Preliminary experimental results indicate that the new approach leads to comparable plan quality for substantially fewer candidate beams. For two prostate cases, the dose homogeneity in the target region and the sparing of critical structures is similar for plans based on 400 and 600 candidate beams generated with the novel and the conventional method, respectively. However, the runtime for solving the inverse planning problem for could be reduced by up to 47%, i.e., from approximately 19min to less than 11min. Conclusion We have shown the feasibility of case-based beam generation for robotic radiosurgery. For prevalent clinical cases with similar anatomy the cased-based approach could substantially reduce planning time while maintaining high plan quality.}, year = {2011}, issn = {0933-3657}, DOI = {10.1016/j.artmed.2011.04.008}, journal = {Artificial Intelligence in Medicine}, volume = {52}, pages = {67-75}, number = {2}, keywords = {case based reasoning}, file_url = {https://doi.org/10.1016/j.artmed.2011.04.008} } @Inproceedings { amrm11, author = {Amengual, Juli{\'a} L. and Marco-Pallar{\'e}s, Josep and Richter, Lars and Mohammadi, Bahram and Grau, Carles and Rodriguez-Fornells, Antoni and M{\{\dq}u}nte, Thomas F.}, title = {IS POST ERROR SLOWING A POST ERROR INHIBITION? A TRANSCRANIAL MAGNETIC STIMULATION APPROACH}, abstract = {The commission of an error triggers cognitive control processes which help to avoid similar errors in the future. An example of such processes is post-error slowing, a delay in correct responses in trials following an error. Two hypotheses have been proposed to explain this phenomenon. The inhibitory account (Ridderinkhof, 2002) holds that, after an erroneous response, an increase of selective inhibition of motor planning occurs. Alternatively, the conflict monitoring account (Botvinick et al, 2001) suggests that the detection of an error triggers the activation of a system monitoring network reducing the excitatory input at the motor plan. In the present study, single pulse transcranial magnetic stimulation (TMS) was applied to the motor cortex ipsilateral to the responding hand, while participants were performing a modified Eriksen Flanker Task. A robotic arm with a movement compensation system (Mathaus et al., 2008) was used to maintain the TMS coil in the correct position during the experiment. A magnetic pulse was delivered at different times (150, 300, 450 ms) after correct and erroneous responses, and the motor evoked potentials (MEP) of the contralateral first dorsal interosseous muscle (FDI) were recorded. Results show an increase of the peak-to-peak post-error MEP amplitude, produced by the magnetic pulse delivered 450 ms post-response which might correspond to a decrease in the excitability of the contralateral motor cortex occurring by transcallosal inhibition. Present data are in agreement with the inhibition account and thus contribute to our understanding of compensatory mechanisms after error commission.}, year = {2011}, DOI = {10.3389/conf.fnhum.2011.207.00385}, address = {Palma, Mallorca, Spain}, tags = {TMS}, file_url = {https://doi.org/10.3389/conf.fnhum.2011.207.00385}, note = {Transcranial Magnetic Stimulation} } @Inproceedings { heinig2011a, author = {Heinig, Max and Govela, Maria Fernanda and Gasca, Fernando and Dold, Christian and Hofmann, Ulrich G. and Tronnier, Volker and Schlaefer, Alexander and Schweikard, Achim}, title = {MARS - Motor Assisted Robotic Stereotaxy System}, abstract = {We report on the design, setup and first results of a robotized system for stereotactic neurosurgery. It features three translational and two rotational axes, as well as a motorized MicroDrive, thereby resembling the Zamorano-Duchovny (ZD) design of stereotactic frames (inomed Medizintechnik GmbH). Both rotational axes intersect in one point, the Center of the Arc, facilitating trajectory planning. We used carbon fiber-reinforced plastic to reduce the weight of the system. The robot can be mounted to standard operating table's side rails and can be transported on an operation theatre (OT) instrument table. We discuss the design paradigms, the resulting design and the actual robot. Kinematic calculations for the robot based on the Denavit- Hartenberg (DH) rules are presented. Positioning accuracy of our system is determined using two perpendicular cameras mounted on an industrial robot. The results are compared to a manual ZD system. We found that the robot's mean position deviation is 0.231 mm with a standard deviation of 0.076 mm.}, year = {2011}, isbn = {978-1-4244-4140-2}, address = {Cancun, Mexico}, pages = {334-337}, keywords = {accuracy; Deep brain stimulation; medical robotics; neurosurgery; stereotaxy}, tags = {SM}, note = {Stereotactic Micronavigation} } @Inproceedings { bges_11, author = {Bruder, Ralf and Griese, Florian and Ernst, Floris and Schweikard, Achim}, title = {High-accuracy ultrasound target localization for hand-eye calibration between optical tracking systems and three-dimensional ultrasound}, abstract = {Real-time target localization in ultrasound is useful in many clinical and scientific areas. For example in radiation therapy tumors can be localized in real-time and irradiated with a high accuracy. To measure the position of an ultrasound target in a global coordinate system or to extend the tracking volume by moving the ultrasound transducer an optical marker is attached to it and observed by an optical tracking system. The necessary calibration matrices from marker to ultrasound volume are obtained using hand-eye calibration algorithms which take sets of corresponding observations of the optical marker and an ultrasound target as input. The quality of these calibration matrices is highly dependent on the measured observations. While the accuracy of optical tracking systems is very high, accurate tracking in ultrasound is difficult because of the low resolution of the ultrasound volume, artifacts and noise. Therefore accurate hand-eye calibration is difficult between ultrasound and optical tracking systems. We have tested different phantoms, matching- and sub-pixel strategies to provide highly accurate tracking results in 3D ultrasound volumes as basis for hand-eye calibration. Tests have shown that -- using the described methods - calibration results with RMS errors of less than 1mm between observed and calibrated targets can be reached.}, year = {2011}, isbn = {978-3-642-19335-4}, DOI = {10.1007/978-3-642-19335-4_38}, publisher = {Springer}, address = {Berlin, Heidelberg}, series = {Informatik aktuell}, editor = {Handels, Heinz and Ehrhardt, Jan and Deserno, Thomas M. and Meinzer, Hans-Peter and Tolxdorff, Thomas}, pages = {179-183}, tags = {MCRT UGRT}, file_url = {https://doi.org/10.1007/978-3-642-19335-4_38}, note = {Motion Compensation in Radiosurgery} } @Article { ebss_10, author = {Ernst, Floris and Bruder, Ralf and Schlaefer, Alexander and Schweikard, Achim}, title = {Forecasting Pulsatory Motion for Non-invasive Cardiac Radiosurgery}, abstract = {Objective: Recently, radiosurgical treatment of cardiac arrhythmia, especially atrial fibrillation, has been proposed. Using the CyberKnife, focussed radiationwill be used to create ablation lines on the beating heart to block unwanted electrical activity. Since this procedure requires high accuracy, the inevitable latency of the system (i.e., the robotic manipulator following the motion of the heart) has to be compensated for. Materials and methods: We examine the applicability of prediction algorithms developed for respiratory motion prediction to the prediction of pulsatory motion. We evaluated the MULIN, nLMS, wLMS, SVRpred and EKF algorithms. The test data used has been recorded using external infrared position sensors, 3D ultrasound and the NavX catheter systems. Results: With this data, we have shown that the error from latency can be reduced by at least 10 and as much as 75% (44% average), depending on the type of signal. It has also been shown that, although the SVRpred algorithm was successful in most cases, it was outperformed by the simple nLMS algorithm, the EKF or the wLMS algorithm in a number of cases. Conclusion: We have shownthat prediction of cardiac motion is possible and that the algorithms known from respiratory motion prediction are applicable. Since pulsation is more regular than respiration, more research will have to be done to improve frequency-tracking algorithms, like the EKF method, which performed better than expected from their behaviour on respiratory motion traces.}, year = {2011}, DOI = {10.1007/s11548-010-0424-9}, journal = {International Journal of Computer Assisted Radiology and Surgery}, volume = {6}, pages = {93-101}, number = {1}, tags = {MCRT UGRT}, file_url = {https://doi.org/10.1007/s11548-010-0424-9}, note = {Motion Compensation in Radiosurgery} } @Inproceedings { Gasca2011, author = {Gasca, Fernando and Marshall, Lisa and Binder, Sonja and Schlaefer, Alexander and Hofmann, Ulrich G. and Schweikard, Achim}, title = {Finite Element Simulation of Transcranial Current Stimulation in Realistic Rat Head Model}, year = {2011}, volume = {5}, address = {Cancun, Mexico}, pages = {36-39} } @Article { fs_10, author = {Finke, Markus and Schweikard, Achim}, title = {Motorization of a Surgical Microscope for intra-operative navigation and intuitive control}, abstract = {Background: During surgical procedures, various medical systems (e.g. microscope or C-arm) are used. Their precise and repeatable manual positioning can be very cumbersome and interrupts the surgeon's work flow. Robotized systems can assist the surgeon but they require suitable kinematics and control. However, positioning must be fast, flexible and intuitive. Methods: We describe a fully motorized surgical microscope. Hardware components as well as implemented applications are specified. The kinematic equations are described and a novel control concept is proposed. Results: Our microscope combines fast manual handling with accurate, automatic positioning. Intuitive control is provided by a small remote control mounted to one of the surgical instruments. Positioning accuracy and repeatability are less than 1mm and vibrations caused by automatic movements fade away in about one second. Conclusion: The robotic system assists the surgeon, so that he can position the microscope precisely and repeatedly without interrupting the clinical workflow. The combination of manual und automatic control guarantees fast and flexible positioning during surgical procedures.}, year = {2010}, DOI = {10.1002/rcs.314}, journal = {International Journal of Medical Robotics and Computer Assisted Surgery}, volume = {6}, pages = {269-280}, number = {3}, tags = {SMi}, file_url = {https://doi.org/10.1002/rcs.314}, note = {online=Published Online: 28 Apr 2010} } @Article { Lefaucheur2010, author = {Lefaucheur, Jean-Pascal}, title = {Why image-guided navigation becomes essential in the practice of transcranial magnetic stimulation}, year = {2010}, issn = {0987-7053}, DOI = {10.1016/j.neucli.2009.10.004}, journal = {Neurophysiologie Clinique/Clinical Neurophysiology}, volume = {40}, pages = {1-5}, number = {1}, file_url = {https://doi.org/10.1016/j.neucli.2009.10.004} } @Inproceedings { esss_10, author = {Ernst, Floris and Stender, Birgit and Schlaefer, Alexander and Schweikard, Achim}, title = {Using ECG in Motion Prediction for Radiosurgery of the Beating Heart}, year = {2010}, isbn = {978-0-9563776-1-6}, volume = {3}, address = {The Royal Society, London}, editor = {Yang, Guang-Zhong and Darzi, Ara}, pages = {37-38}, tags = {MCRT}, note = {Motion Compensation in Radiosurgery} } @Inproceedings { soa+2010, author = {Schlaefer, Alexander and Otte, Christoph and Ansari, Rehman and H{\{\dq}u}ttmann, Gereon and Richter, Lars and Bruder, Ralf and Heinig, Max and Sommerauer, Markus and Kov{\'a}cs, Gy{\{\dq}o}rgy}, title = {Towards high resolution image guided navigation for prostate brachytherapy}, year = {2010}, volume = {5}, address = {Geneva, Switzerland}, series = {International Journal of Computer Assisted Radiology and Surgery}, pages = {S24-S25}, number = {Suppl. 1}, file_url = {http://www.cars-int.org/} } @Inproceedings { rbss_10, author = {Richter, Lars and Bruder, Ralf and Schlaefer, Alexander and Schweikard, Achim}, title = {Towards Direct Head Navigation for robot-guided Transcranial Magnetic Stimulation using 3D Laserscans: Idea, Setup and Feasibility}, abstract = {Direct tracking is more robust than tracking that is based on additional markers. 3D laser scans can be used for direct tracking because they result in a 3D data set of surface points of the scanned object. For head-navigated robotized systems, it is crucial to know where the patient's head is positioned relatively to the robot. We present a novel method to use a 3D laserscanner for direct head navigation in the robotized TMS system that places a coil on the patient's head using an industrial robot. First experimental results showed a translational error < 2mm in the robot hand-eye-calibration with the laserscanner. The rotational error was 0.75° and the scaling error < 0.001. Furthermore, we found that the error of a scanned head to a reference head image was < 0.2mm using ICP. These results have shown that a direct head navigation is feasible for the robotized TMS system. Additional effort has to be made in future systems to speed up the compution time for real time capability.}, year = {2010}, isbn = {978-1-4244-4124-2}, issn = {1557-170X}, DOI = {10.1109/IEMBS.2010.5627660}, volume = {32}, address = {Buenos Aires, Argentina}, series = {IEEE}, editor = {Armentano, Ricardo and Hudson, Donna and Monzon, Jorge and Patton, Jim}, pages = {2283-2286}, keywords = {Head Navigation; Laser scanner; robotic motion compensation; Transcranial Magnetic Stimulation}, tags = {TMS}, file_url = {https://doi.org/10.1109/IEMBS.2010.5627660}, note = {Transcranial Magnetic Stimulation} } @Inproceedings { Ammann2010, author = {Ammann, Nikolaus and Biemann, Ronny and Hartmann, Florian and Hauft, Carina and Heinecke, Ivo and Jauer, Philipp and Kr{\{\dq}u}ger, Julia and Meyer, Tobias and Bruder, Ralf and Schlaefer, Alexander}, title = {Towards autonomous one-design sailboat racing: navigation, communication and collision avoidance}, year = {2010}, address = {Kingston, ON}, series = {International Robotics Sailing Conference} } @Inproceedings { grs10, author = {Gasca, Fernando and Richter, Lars and Schweikard, Achim}, title = {Simulation of a Conductive Shield Plate for the Focalization of Transcranial Magnetic Stimulation in the Rat}, year = {2010}, isbn = {978-1-4244-4124-2}, issn = {1557-170X}, volume = {32}, address = {Buenos Aires, Argentina}, series = {IEEE}, editor = {Armentano, Ricardo and Hudson, Donna and Monzon, Jorge and Patton, Jim}, pages = {1593-1596}, keywords = {Brain stimulation; Finite element simulation; Transcranial Magnetic Stimulation}, tags = {TMS}, note = {Transcranial Magnetic Stimulation} } @Article { Kantelhardt2010, author = {Kantelhardt, Sven and Fadini, Tommaso and Finke, Markus and Kallenberg, K. and Siemerkus, J. and Bockermann, V. and Matth{\{\dq}a}us, Lars and Paulus, Walter and Schweikard, Achim and Rohde, V. and Giese, Alf}, title = {Robot-assisted image-guided transcranial magnetic stimulation for somatotopic mapping of the motor cortex: a clinical pilot study}, abstract = {Purpose Shape and exact location of motor cortical areas varies among individuals. The exact knowledge of these locations is crucial for planning of neurosurgical procedures. In this study, we have used robot-assisted image-guided transcranial magnetic stimulation (Ri-TMS) to elicit MEP response recorded for individual muscles and reconstruct functional motor maps of the primary motor cortex. Methods One healthy volunteer and five patients with intracranial tumors neighboring the precentral gyrus were selected for this pilot study. Conventional MRI and fMRI were obtained. Transcranial magnetic stimulation was performed using a MagPro X100 stimulator and a standard figure-of-eight coil positioned by an Adept Viper s850 robot. The fMRI activation/Ri-TMS response pattern were compared. In two cases, Ri-TMS was additionally compared to intraoperative direct electrical cortical stimulation. Results Maximal MEP response of the m. abductor digiti minimi was located in an area corresponding to the {\dq}hand knob{\dq} of the precentral gyrus for both hemispheres. Repeated Ri-TMS measurements showed a high reproducibility. Simultaneous registration of the MEP response for m. brachioradialis, m. abductor pollicis brevis, and m. abductor digiti minimi demonstrated individual peak areas of maximal MEP response for the individual muscle groups. Ri-TMS mapping was compared to the corresponding fMRI studies. The areas of maximal MEP response localized within the {\dq}finger tapping{\dq} activated areas by fMRI in all six individuals. Conclusions Ri-TMS is suitable for high resolution non-invasive preoperative somatotopic mapping of the motor cortex. Ri-TMS may help in the planning of neurosurgical procedures and may be directly used in navigation systems.}, year = {2010}, DOI = {10.1007/s00701-009-0565-1}, journal = {Acta Neurochirurgica}, volume = {152}, pages = {333-343}, number = {2}, tags = {TMS}, file_url = {https://doi.org/10.1007/s00701-009-0565-1} } @Inproceedings { rbs_10, author = {Richter, Lars and Bruder, Ralf and Schlaefer, Alexander}, title = {Proper Force-Torque Sensor System for robotized TMS: Automatic Coil Calibration}, year = {2010}, volume = {5}, address = {Geneva, Switzerland}, series = {International Journal of Computer Assisted Radiology and Surgery}, pages = {S422-S423}, number = {supp. 1}, tags = {TMS}, file_url = {http://www.cars-int.org/}, note = {Transcranial Magnetic Stimulation} } @Article { ess_10, author = {Ernst, Floris and Schlaefer, Alexander and Schweikard, Achim}, title = {Processing of Respiratory Motion Traces for Motion-Compensated Radiotherapy}, abstract = {Purpose: The CyberKnife system has been used successfully for several years to radiosurgically treat tumors without the need for stereotactic fixation or sedation of the patient. It has been shown that tumor motion in the lung, liver, and pancreas can be tracked with acceptable accuracy and repeatability. However, highly precise targeting for tumors in the lower abdomen, especially for tumors which exhibit strong motion, remains problematic. Reasons for this are manifold, like the slow tracking system operating at 26.5 Hz, and using the signal from the tracking camera {\dq}as is.{\dq} Since the motion recorded with the camera is used to compensate for system latency by prediction and the predicted signal is subsequently used to infer the tumor position from a correlation model based on x-ray imaging of gold fiducials around the tumor, camera noise directly influences the targeting accuracy. The goal of this work is to establish the suitability of a new smoothing method for respiratory motion traces used in motion-compensated radiotherapy. The authors endeavor to show that better prediction---With a lower rms error of the predicted signal---and/or smoother prediction is possible using this method. Methods: The authors evaluated six commercially available tracking systems (NDI Aurora, PolarisClassic, Polaris Vicra, MicronTracker2 H40, FP5000, and accuTrack compact). The authors first tracked markers both stationary and while in motion to establish the systems' noise characteristics. Then the authors applied a smoothing method based on the trous wavelet decomposition to reduce the devices' noise level. Additionally, the smoothed signal of the moving target and a motion trace from actual human respiratory motion were subjected to prediction using the MULIN and the nLMS2 algorithms. Results: The authors established that the noise distribution for a static target is Gaussian and that when the probe is moved such as to mimic human respiration, it remains Gaussian with the exception of the FP5000 and the Aurora systems. The authors also showed that the proposed smoothing method can indeed be used to filter noise. The signal's jitter dropped by as much as 95% depending on the tracking system employed. Subsequently, the 3D prediction error (rms) for a prediction horizon of 150 ms on a synthetic signal dropped by up to 37% when using a normalized LMS prediction algorithm (nLMS2) and hardly changed when using a MULIN algorithm. When smoothing a real signal obtained in our laboratory, the improvement of prediction was similar: Up to 30% for both the nLMS2 and the best MULIN algorithm. The authors also found a noticeable increase in smoothness of the predicted signal, the relative jitter dropped by up to 95% on the real signal, and on the simulated signal. Conclusions: In conclusion, the authors can say that preprocessing of marker data is very useful in motion-compensated radiotherapy since the quality of prediction increases. This will result in better performance of the correlation model. As a side effect, since the prediction of a preprocessed signal is also less noisy, the authors expect less robot vibration resulting in better targeting accuracy and less strain on the robot gears.}, year = {2010}, DOI = {10.1118/1.3271684}, journal = {Medical Physics}, volume = {37}, pages = {282-294}, number = {1}, keywords = {motion compensation; noise reduction; Respiration; Signal Processing; smoothing; wavelets}, tags = {MCRT}, file_url = {https://doi.org/10.1118/1.3271684}, note = {Motion Compensation in Radiosurgery} } @Inproceedings { ebps_10, author = {Ernst, Floris and Bruder, Ralf and Pohl, Melanie and Schlaefer, Alexander and Schweikard, Achim}, title = {Prediction of Cardiac Motion}, year = {2010}, volume = {5}, address = {Geneva, Switzerland}, series = {International Journal of CARS}, pages = {273-274}, number = {supp. 1}, tags = {MCRT}, file_url = {http://www.cars-int.org/}, note = {Motion Compensation in Radiosurgery} } @Inproceedings { Finke2010b, author = {Finke, Markus and Schweikard, Achim}, title = {Usability of a Robotic Surgical Microscope}, abstract = {During surgical procedures, various medical systems (e.g. microscope or C-arm) are used. Their precise and repeatable manual positioning can be very cumbersome and interrupts the surgeon's workflow. Robotized systems can assist the surgeon but they require suitable kinematics and control. However, positioning must be fast, flexible and intuitive. We describe a fully motorized surgical microscope. Hardware components like motors, encoders and controllers as well as implemented applications are specified. Our microscope combines fast manual handling with accurate, automatic positioning. Intuitive control is provided by a small remote control mounted to one of the surgical instruments. Positioning accuracy and repeatability are less than 1mm and vibrations caused by automatic movements fade away in about one second.}, year = {2010}, address = {The University of Tokyo, Tokyo, Japan}, pages = {235-240} } @Inproceedings { Martens2010BMT, author = {Martens, Volker and Be{\v{s}}irevi{\c}, Armin and Shahin, Osama and Kleemann, Markus}, title = {LapAssistent -- computer assisted laparoscopic liver surgery}, year = {2010}, address = {Rostock}, tags = {NLS}, note = {Navigation in liver surgery} } @Inproceedings { Bruder2010, author = {Bruder, Ralf and Stender, Birgit and Schlaefer, Alexander}, title = {Model Sailboats as a Testbed for Artificial Intelligence Methods}, year = {2010}, address = {Kingston, ON}, series = {International Robotics Sailing Conference} } @Inproceedings { Finke2010c, author = {Finke, Markus and Schweikard, Achim}, title = {Automatische Untersuchung gro{\{\dq}s}er Gewebefl{\{\dq}a}chen mittels Optischer Koh{\{\dq}a}renztomographie}, abstract = {Die Optische Koh{\{\dq}a}renztomographie stellt ein nicht-invasives Verfahren zur in-vivo Untersuchung von Gewebe dar, das bereits in zahlreichen Gebieten der Medizin zum Einsatz kommt, z.B. Neurochirurgie, Ophthalmologie, Laryngologie. Dabei erm{\{\dq}o}glicht die Integration der OCT-Sonde in ein motorisiertes Operationsmikroskop den navigierten Einsatz der Sonde. Dies schafft f{\{\dq}u}r den Chirurgen die Voraussetzung, gro{\{\dq}s}e Gewebefl{\{\dq}a}chen automatisch zu untersuchen, ohne dass zus{\{\dq}a}tzliche Instrumente w{\{\dq}a}hrend der Operation zum Einsatz kommen m{\{\dq}u}ssen. Dabei gew{\{\dq}a}hrleistet das Mikroskop stets eine optimale Ausrichtung der Sonde senkrecht zur Gewebeoberfl{\{\dq}a}che. Aus den OCT-Aufnahmen kann ein 3D Modell des Resektionsvolumens sowie zus{\{\dq}a}tzliche Informationen zu Gewebestel-len gewonnen werden, die mit blo{\{\dq}s}em Auge nicht zu erkennen sind. Dies erleichtert die intraoperative Orientierung f{\{\dq}u}r den Chirurgen.}, year = {2010}, address = {D{\{\dq}u}sseldorf, Deutschland}, pages = {221-224}, keywords = {Mikroskop; Optische Koh{\{\dq}a}renztomographie; Robotik} } @Misc { rsts_10, author = {Richter, Lars and Schlaefer, Alexander and Trillenberg, Peter and Schweikard, Achim}, title = {Kraft-Momenten-Steuerung f{\{\dq}u}r die robotergest{\{\dq}u}tzte Transkranielle Magnetstimulation (TMS)}, year = {2010}, tags = {TMS}, note = {Transcranial Magnetic Stimulation} } @Inproceedings { 5515423, author = {Heinig, Max and Bruder, Ralf and Schlaefer, Alexander and Schweikard, Achim}, title = {3D Localization of a Thin Steel Rod Using Magnetic Field Sensors: Feasibility and Preliminary Results}, year = {2010}, issn = {2151-7614}, DOI = {10.1109/icbbe.2010.5515423}, pages = {1-4}, keywords = {biomagnetism; brain; Degrees of freedom; industrial robot; magnetic field measurement; magnetic field sensors; Magnetic sensors; magnetized steel rod; navigation system; neurophysiology; neurosurgery; Rats; rods (structures); size 0.5 mm; size 30 mm; static magnetic field; steel; thin steel rod 3D localization}, file_url = {https://doi.org/10.1109/icbbe.2010.5515423} } @Inproceedings { 5627435, author = {Heinig, Max and Schlaefer, Alexander and Schweikard, Achim}, title = {3D localization of ferromagnetic probes for small animal neurosurgery}, year = {2010}, isbn = {978-1-4244-4123-5}, issn = {1557-170X}, DOI = {10.1109/iembs.2010.5627435}, pages = {2321-2324}, keywords = {3D localization; bioelectric phenomena; biomagnetism; Computer Vision; electrophysiological recordings; ferromagnetism; ground truth position; lookup table; magnetic devices; magnetic navigation system; magnetized ferromagnetic probes; medical image processing; medical robotics; Navigation; neurophysiology; probes; small animal stereotactic neurosurgery; spherical assistant for stereotactic surgery robot; stereo image processing; Surgery; table lookup; trilinear interpolation}, tags = {SM}, file_url = {https://doi.org/10.1109/iembs.2010.5627435}, note = {Stereotactic Micronavigation} } @Inproceedings { Finke2010a, author = {Finke, Markus and Stender, Birgit and Bruder, Ralf and Schlaefer, Alexander and Schweikard, Achim}, title = {An experimental comparison of control devices for automatic movements of a surgical microscope}, year = {2010}, address = {Geneva, Switzerland}, pages = {311-312}, tags = {SMI} } @Inproceedings { eks_10, author = {Ernst, Floris and Koch, Christoph and Schweikard, Achim}, title = {A Novel Recording Tool for Education and Quality Assurance in Digital Angiography}, abstract = {Background: A draw-back of current digital angiography systems is that diagnostic and interventional procedures cannot be completely recorded by the angiography device. In most clinical settings, however, it is desirable to be able to review the angiographic procedure in order to see what can be done better or what went wrong. Additionally, it would be convenient to be able to annotate parts of the procedure, to retrospectively select important scenes and to be able to show them to colleagues or use them in teaching medical students and residents. Evaluation: We have attached a state-of-the-art, high-speed frame grabbing device (Matrox Helios) to the high line video output of a biplane neuroangiography system (Philips Allura Xper FD20/10). Using our software, it now is possible to record complete angiographic procedures biplane either as video streams or as a sequence of images. Additional information about the patient is stored in additional XML files. By compressing the data on the fly, recording can be continuous up to 12 hours. The system also allows for retrospective annotation of the video streams, for editing and cutting out parts of the sequences as well as playing the sequences at different speeds. Discussion: With our new system, we can more easily educate students and get a better grasp at problems which might occur during an angiographic procedure. Additionally, since we plan to use the system for all interventions, it is also a valuable tool for quality assurance and legal purposes. Since editing and annotating the image or video streams does not actually modify the stream data (crop marks and annotations are saved in an XML file), it is possible to assure that the stream data has not been modified after the end of the angiographic procedure. Conclusion: Our new recording and playback system is the first step towards better teaching and quality assurance. In the future, we plan to also attach a video camera to document the neuroradiologist's manual actions and to include links to existing PACS data.}, year = {2010}, address = {Chicago, IL/USA}, tags = {MCRT}, note = {Motion Compensation in Radiosurgery} } @Inproceedings { remm_10, author = {Richter, Lars and Ernst, Floris and Martens, Volker and Matth{\{\dq}a}us, Lars and Schweikard, Achim}, title = {Client/Server Framework for robot control in medical assistance systems}, year = {2010}, volume = {5}, address = {Geneva, Switzerland}, series = {International Journal of Computer Assisted Radiology and Surgery}, pages = {306-307}, number = {S1}, keywords = {Hand-eye calibration; Medical Applications; Robotics; TCP/IP; Tracking}, tags = {MCRT TMS}, file_url = {http://www.cars-int.org/}, note = {Transcranial Magnetic Stimulation, Motion Compensation in Radiosurgery} } @Inproceedings { Stille2010, author = {Stille, Maik and Finke, Markus}, title = {Combination of a Robotic Surgical Microscope and an Augmented Reality for Intraoperative Navigation}, abstract = {We describe the combination of a robotic surgical microscope and an Augmented Reality (AR) for intraoperative navigation. The virtual elements of the AR are segmented from preoperative images. Both virtual and real environments can be overlaid intraoperatively. This simplifies the localization of critical structures even if they are located beneath the surface of the tissue. The robotic microscope can automatically focus crucial structures taking the spatial relations of the AR into considera-tion. Such targets can easily be defined using the virtual environment. The variation of about 1mm, which results from overlaying virtual and real environment, is tolerable for most surgical interventions.}, year = {2010}, DOI = {10.1515/BMT.2010.414}, address = {Rostock-Warnem{\{\dq}u}nde, Germany}, file_url = {https://doi.org/10.1515/BMT.2010.414} } @Inproceedings { MSZ10, author = {Metzner, Christoph and Schweikard, Achim and Zurowski, B.}, title = {Context Integration in Visual Processing: A Computational Model of Center-Surround Suppression in the Visual System}, year = {2010}, volume = {11 (Suppl. 1)}, pages = {P100}, tags = {NM}, note = {Neurological Modelling} } @Inproceedings { rmss_10, author = {Richter, Lars and Matth{\{\dq}a}us, Lars and Schlaefer, Alexander and Schweikard, Achim}, title = {Fast robotic compensation of spontaneous head motion during Transcranial Magnetic Stimulation (TMS)}, year = {2010}, isbn = {978-184600-0386}, volume = {8}, address = {Coventry, United Kingdom; Coventry, UK}, series = {United Kingdom Automatic Control Council}, pages = {872-877}, keywords = {Head motion; medical robotics; motion compensation; Online adaptation; Robotized TMS; Tracking; Transcranial Magnetic Stimulation}, tags = {TMS}, note = {Transcranial Magnetic Stimulation} } @Inproceedings { ebss_10b, author = {Ernst, Floris and Bruder, Ralf and Schlaefer, Alexander and Schweikard, Achim}, title = {Improving the Quality of Biomedical Signal Tracking using Prediction Algorithms}, abstract = {The use of optical and magnetical tracking systems is widely spread throughout modern operating theatres. One thing that is not taken into account so far is the fact that all systems which need to make two or more sequential measurements to determine an object's pose will exhibit systematic measurement errors. These errors can be attributed on the nonsimultaneous acquisition process. We have analysed this problem for the atracsys accuTrack system which is an optical tracking system using three line cameras. Using robotised and manual experiments we found that, using a marker with four LEDs at a single LED acquisition rate of 331.04 Hz, these errors can be as much as 1.4 mm and 2.1° (RMS). With lower acquisiton rates---which are commonplace in other tracking systems---these errors are expected to be even higher. Using the proposed compensation methods, they may be reduced to as little as 0.2 mm and 0.6° (RMS), respectively.}, year = {2010}, isbn = {978-184600-0386}, DOI = {10.1049/ic.2010.0298}, volume = {8}, address = {Coventry, United Kingdom; Coventry, UK}, series = {United Kingdom Automatic Control Council}, pages = {301-305}, tags = {MCRT}, file_url = {https://doi.org/10.1049/ic.2010.0298}, note = {Motion Compensation in Radiosurgery} } @Article { kffk_09, author = {Kantelhardt, Sven and Fadini, Tommaso and Finke, Markus and Kallenberg, K. and Bockermann, V. and Matth{\{\dq}a}us, Lars and Siemerkus, J. and Paulus, Walter and Schweikard, Achim and Rohde, V. and Giese, Alf}, title = {Robotized image-guided transcranial magnetic stimulation, a novel technique for functional brain-mapping}, abstract = {Introduction: One of the major difficulties for neurosurgical interventions in or close of the central region of the brain is the individual distribution of functional areas. This is particularly important when dealing with tumours that cause displacement or migration of such areas. The functional MRI (fMRI) is the most common procedure for non-invasive functional brain-mapping. However, this technique does not completely meet the needs of neurosurgeons, because it does not allow the localization of single functional areas, like motor cortical areas of specific muscles. We here present a novel non-invasive and painless technique for motor cortex mapping: The robotized image-guided transcranial magnetic stimulation (Ri-TMS). Methods: Three patients with brain tumours of the central region and one healthy volunteer were examined by Ri-TMS. A figure-of-eight coil was placed over the central region of the examined persons according to a grid of up to 90 points with a fixed distance of 1cm between the grid points. The coil was positioned by an image-guided robot. Image-guidance was based on an anatomical MRI and a neuronavigaional device, tracking all movements of the patient. All grid points were stimulated by 10 single pulses (interstimulus interval = 5 seconds) successively. Motor evoked potentials (MEPs) of three representative muscles (m. abductor digiti minimi, m. abductor pollicis brevis and m. brachioradialis) were simultaneously recorded by Ag/AgCl surface electrodes connected to an Endeavor CR electromyographic device. The peak-to-peak amplitudes of the averaged MEP curves were measured online. The results obtained for each stimulated spot were used for calculating brain surface maps showing the regions of maximal MEP responses. To proof the reproducibility of Ri-TMS the examinations were repeated after 3-5 days. The results were compared to fMRI images acquired under finger-tapping protocol. Additionally direct brain stimulation was performed intraoperativ}, year = {2009}, DOI = {10.1016/j.clinph.2008.07.203}, journal = {Clinical Neurophysiology}, volume = {120}, pages = {e84}, number = {1}, tags = {TMS}, file_url = {https://doi.org/10.1016/j.clinph.2008.07.203}, note = {a novel technique for functional brain-mapping .pdf:PDF} } @Inproceedings { e_09b, author = {Ernst, Floris}, title = {Motion Compensation in Radiosurgery}, year = {2009}, publisher = {Institute for Robotics, University of L{\{\dq}u}beck}, address = {L{\{\dq}u}beck, Germany}, series = {Institute for Robotics, University of L{\{\dq}u}beck}, tags = {MCRT}, note = {Motion Compensation in Radiosurgery} } @Book { Henke2009PhD, author = {Henke, Maria}, title = {Multidimensionale adaptive Filterung zur Rauschreduktion in der Computertomographie: Vergleich und Kombination faltungs- und splinebasierter Verfahren}, year = {2009}, volume = {19}, publisher = {Shaker Verlag Aachen}, series = {Berichte aus dem Institut f{\{\dq}u}r Medizinische Physik}, editor = {Kalender, W. A.}, note = {Dissertation} } @Misc { p_09, author = {Pohl, Melanie}, title = {Pr{\{\dq}a}diktion von Herzbewegungen}, abstract = {Herzrhythmusst{\{\dq}o}rungen sind die wohl am weitesten verbreiteten Herzleiden. Dabei werden alle Rhythmen, die vom normalen Sinusrhythmus abweichen, als St{\{\dq}o}rung beschrieben. In der vorliegenden Arbeit soll ein Teilaspekt der Behandlung von Vorhofflimmern durch Bestrahlung betrachtet werden -- die Pr{\{\dq}a}diktion von Herzbewegungen. Die Bestrahlung soll durch einen Roboter erfolgen, dessen Bewegungen sich an die unvermeidlichen Bewegungen des Patienten wie Herzschlag und Atmung anpassen sollen. Da der Roboter nur mit einer Latenzzeit auf die Bewegungen des Patienten reagieren kann, ist es notwendig diese vorherzusagen. Um zun{\{\dq}a}chst einen {\{\dq}U}berblick {\{\dq}u}ber den Bau und die Funktionsweise des Herzens zu erhalten, wird in Kapitel 1 dieser Hintergrund erl{\{\dq}a}utert. Kapitel 2 besch{\{\dq}a}ftigt sich mit der Einf{\{\dq}u}hrung der vier verschiedenen Pr{\{\dq}a}diktionsalgorithmen, die zur Bestimmung einer synchronen Bewegung von Mensch und Roboter untersucht werden sollen: der MULIN-Algorithmus, der waveletbasierte Least-Mean-Squares-Algorithmus, die Support Vector-Regression und das erweiterte Kalmanfilter. Getestet werden diese vier Algorithmen an Datens{\{\dq}a}tzen, die auf drei verschiedene Weisen erhoben werden: Zun{\{\dq}a}chst werden die Algorithmen an einem computergenerierten Datensatz zur Volumen{\{\dq}a}nderung getestet, anschlie{\{\dq}s}end an einem an zwei Probanden extern aufgezeichneten und im dritten Versuch an zwei inneren Signalen. Die Pr{\{\dq}a}diktion erfolgt jeweils {\{\dq}u}ber ein Vorhersageprogramm, das derzeit im Institut f{\{\dq}u}r Robotik und kognitive Systeme entwickelt wird. Die Ergebnisse dieser Untersuchungen sind in Kapitel 3 dargestellt. Im letzten Kapitel erfolgt die Bewertung der Ergebnisse.}, year = {2009}, tags = {MCRT}, note = {Motion Compensation in Radiosurgery} } @Inproceedings { es_09a, author = {Ernst, Floris and Schweikard, Achim}, title = {Predicting Respiratory Motion Signals using Accurate Online Support Vector Regression (SVRpred)}, abstract = {Object: To accurately deliver radiation in image-guided robotic radiosurgery, highly precise prediction algorithms are required. A new prediction method is presented and evaluated. Materials and Methods: SVRpred, a new prediction method based on Support Vector Regression (SVR), has been developed and tested. Computer-generated data mimicking human respiratory motion with a prediction horizon of 150 ms was used for lab tests. The algorithm was subsequently evaluated on a respiratory motion signal recorded during actual radiosurgical treatment using the CyberKnife. The algorithm's performance was compared to the MULIN prediction methods and Wavelet-based multi scale autoregression (wLMS). Results: The SVRpred algorithm clearly outperformed both the MULIN and the wLMS algorithms on both real (by 15 and 16 percentage points, respectively) and noise-corrupted simulated data (by 13 and 48 percentage points, respectively). Only on noise-free artificial data, the SVRpred algorithm did perform as well as the MULIN algorithms but not as well as the wLMS algorithm. Conclusion: This new algorithm is a feasible tool for the prediction of human respiratory motion signals significantly outperforming previous algorithms. The only drawback is the high computational complexity and the resulting slow prediction speed. High performance computers will be needed to use the algorithm in live prediction of signals sampled at a high resolution.}, year = {2009}, DOI = {10.1007/s11548-009-0340-z}, volume = {4}, address = {Berlin, Germany}, series = {International Journal of CARS}, pages = {255-256}, number = {supp. 1}, tags = {MCRT}, file_url = {https://doi.org/10.1007/s11548-009-0340-z}, note = {Motion Compensation in Radiosurgery} } @Article { lrhsm_09, author = {L{\{\dq}o}ffler, Susanne and Ramrath, Lukas and Hofmann, Ulrich G. and Schweikard, Achim and Moser, Andreas}, title = {Robot Assisted Stereotaxic Targeting for STN-DBS in the Rat Brain}, abstract = {Introduction: Severe motoric symptoms in parkinson's disease arise from the loss of dopaminergic input into the striatum. The striatal efferent nuclei are thus affected by a lack of GABAergic input. Deep brain stimulation (DBS) in the subthalamic nucleus (STN) seems to counterbalance this effect by a hitherto unknown molecular mechanism. Based on the hypothesis that high frequency electrical stimulation may have an effect on neurotransmitter release in the local environment of the stimulation electrode we established an in vivo rat model allowing for simultaneous and collocated high frequency stimulation and microdialysis in freely moving rats. Methods: Using standard stereotaxic techniques we implanted a double tube guiding cannula right above the corresponding target nucleus and fixed it on the skull for permanent disposition. After a 7-day period of recovery we inserted a microdialysis probe and a stimulation electrode into the guiding cannula such that the tips of the probes were placed in the center of the target nucleus. The electrode surface was pointing to the microdialysis membrane with a distance smaller than 1 mm. Thus we were able to sample neurotransmitter outflow during the periods of electrical high frequency stimulation in different target nuclei. After the experiment we removed the brain and examined the accuracy of the probe placement using histological slices of the rat brain. Problem: Though leading to promising results in the rat caudate nucleus with a targeting accuracy of 100% we had to face problems with the placement of stimulation electrode and microdialysis membrane into the small sized rat STN using standard stereotaxic techniques. Solution: We employed a new robot-assisted neuronavigation framework for small animal stereotaxy. The robotized spherical assistant for stereotaxic surgery (SASSU) allows automated, precise and repeatible implantation of probes into the brain. It is controlled by a navigation software based on coronal slices of the rat brain. Therefore, software assisted preoperative planning could be easily performed using the software. Bregma and Lambda were used as landmarks for the registration of the rat skull like it is done with the standard stereotaxic methods. Software parameter definition took place according to the surgical workflow. The SASSU step size and velocity were adjusted on demand. By definition of five different parameters we were able to guide a microdialysis probe and a stimulation electrode near together into the rat STN with any specified angle of entry and a positioning accuracy smaller than 45 $\mu$m. The SASSU therefore provides a new stereotaxic tool for target optimization in DBS of the rat STN.}, year = {2009}, journal = {Clinical Neurophysiology}, volume = {120}, address = {Magdeburg}, pages = {e49}, number = {1} } @Article { bds_09a, author = {Bodensteiner, Christoph and Darolti, Christina and Schweikard, Achim}, title = {Vascular Tree Reconstruction with Discrete Tomography - Intensity Based Camera Correction for 3D-Reconstruction}, abstract = {Purpose This paper is concerned with the reconstruction of vascular trees from few projections using discrete tomography. However, its computational cost is high and it lacks robustness when the data are inconsistent. We improve robustness by incorporating an intensity-based camera-correction method. The proposed approach is also capable of handling small motion artifacts by modeling them as repositionings of a virtual X-ray camera. We also present a parallel implementation which substantially reduces reconstruction time. Methods We propose a data-driven reduction of positional inconsistencies by minimizing the reconstruction residual to increase the robustness. Inspired by motion compen-sation algorithms in SPECT imaging, we combine an intensity-based 2D/3D-registration method with itera-tive reconstruction methods. Our objective is the robust vascular-tree reconstruction from positionally inconsistent data. The speed of the reconstruction is substantially increased by a volume-splitting scheme that allows parallel processing. Results Vascular trees in the liver can be accurately reconstructed from few positionally inconsistent projections using digitally reconstructed radiographs. We have tested the proposed method on synthetic projection data and on objects imaged with a new robotized C-arm. We measured a decrease in the average reconstruction residual of about 13% for real data compared to projection data without preprocessing. Over 4,600 reconstruction experiments were conducted to evaluate the speed-up obtained when employing the volume-splitting scheme. Reconstruction time decreased linearly with increased number of processor-cores, both for real and synthetic data. Conclusions The proposed method reduces inconsistencies caused by positioning errors and small motion artifacts. No prior segmentation or detection of correspondences between projections is necessary, because all algorithms are intensity-based. As a result, the proposed method allows for robust, high-quality reconstructions, while reducing radiation dose substantially.}, year = {2009}, issn = {1861-6410}, DOI = {10.1007/s11548-009-0283-4}, journal = {International Journal of Computer Assisted Radiology and Surgery}, volume = {4}, pages = {189-202}, number = {2}, keywords = {2D-3D-registration; 3D Reconstruction; Algebraic reconstruction; Camera calibration; digital subtraction angiography}, tags = {ICA}, file_url = {https://doi.org/10.1007/s11548-009-0283-4}, note = {Interactive C-Arm} } @Phdthesis { b_09, author = {Bodensteiner, Christoph}, title = {R{\{\dq}o}ntgenbasierte Bildgebung mittels eines roboterisierten C-Bogen-Systems}, year = {2009}, address = {Ratzeburger Allee 160}, series = {University of L{\{\dq}u}beck}, tags = {ICA}, file_url = {http://d-nb.info/100185876X/34}, note = {Interactive C-Arm} } @Inproceedings { bds_09b, author = {Bodensteiner, Christoph and Darolti, Christina and Schweikard, Achim}, title = {Super-Resolution f{\{\dq}u}r mobile C-Bogen-Systeme}, year = {2009}, publisher = {Springer-Verlag}, address = {Heidelberg}, tags = {ICA}, note = {Interactive C-Arm} } @Article { Heinig2009, author = {Heinig, Max and Schlaefer, Alexander and Schweikard, Achim}, title = {Super-resolution in Optical Coherence Tomography(OCT)}, abstract = {Introduction: Optical Coherence Tomography (OCT) is a commonly used imaging technology in medicine, for example in ophthalmology, dermatology and urology. Some applications would benefit from higher spatial resolution and speckle noise reduction. We present a robust and effective method to enhance spatial resolution in OCT. The proposed method also reduces the inherent speckle noise. Materials and Methods: The probe of a Thorlabs FD-OCT spectral radar (frequency 1.2kHz, resolution 6.2um) was mounted on a piezo XY stage, pointing in direction of the X-axis. To acquire images, the probe was moved stepwise in longitudinal direction. Every step moved the probe a forth of the spatial resolution of the OCT system. After each step data was gathered from the OCT and stored at the appropriate position of the so called virtual detector array (VDA). The VDA's data was processed by a super-resolution algorithm. Data for the same depth in the tissue was averaged to account for speckle noise. The resulting 1D image was low-pass filtered, yielding a low noise image at twice the resolution of the OCT system. To acquire 2D images, the probe was moved along the lateral direction using the piezo stage. Results: Canvas tape was used as phantom to test the system. Spatial resolution of the Thorlabs FD-OCT spectral radar was doubled from 6.2um to 3.1um. Images were acquired with and without using the super-resolution algorithm. The results show that speckle noise is substantially reduced and spatial resolution of the image is effectively doubled. Conclusion: Applying super-resolution algorithms to OCT yields promising results in enhancing resolution. A second benefit is clearly visible reduction of speckle noise. We plan to test the presented approach with real tissue and in-vivo to study its potential use for micro-navigation, e.g., in neurosurgery.}, year = {2009}, journal = {Medical Physics and Biomedical Engineering World Congress, Munich, Germany} } @Inproceedings { bess_09, author = {Bruder, Ralf and Ernst, Floris and Schlaefer, Alexander and Schweikard, Achim}, title = {TH-C-304A-07: Real-Time Tracking of the Pulmonary Veins in 3D Ultrasound of the Beating Heart}, abstract = {Purpose: Currently effort is taken to use radiation therapy to cure heart diseases like arrhythmia. This approach requires high accuracy localisation and tracking of the pulmonary veins. Because of the high speed of motion of the heart, fluoroscopic tracking of fiducials or anatomical structures as in IGRT would on the one hand require high frame rates and, on the other hand, it would be dangerous to place fiducials near the target. We propose to use live 3D ultrasound to perform the landmark localization and tracking. Methods and materials: We have modified a GE Vivid7 dimension 3D cardiovascular ultrasound station for real-time volume processing and target localisation. It is capable of providing ultrasound volume scans of the target region with more than 20 fps. A framework was established to upload and run image-processing algorithms directly on the ultrasound machine which is necessary to handle the high amount of data. This prevents the bottleneck of Ethernet data streaming and external processing. We propose to localise the pulmonary veins using a template matching algorithm with multiple templates. Approximately 20 templates are manually generated during one heart beat cycle. To increase the speed and accuracy of the matching process, electrical pulse signals were recorded by the ultrasound station. This allows selecting two or three pulse-dependent templates in the live matching stage. Results: The accuracy of the localization process is highly dependent on the templates chosen. The best results were achieved providing a full heart cycle as template data. As a compromise between speed and accuracy, we used 9x9x9 points as template, corresponding to 4.5x4.5x4.5mm3. Conclusion: The presented approach is a new and robust approach to semi-automatically track small substructures in the beating heart. Furthermore, the generated signal is suitable as input to numerous prediction algorithms currently used to compensate for breathing motion in radiosurgery.}, year = {2009}, DOI = {10.1118/1.3182643}, volume = {36}, address = {Anaheim, CA, USA}, series = {Medical Physics}, pages = {2804}, number = {6}, tags = {MCRT UGRT}, file_url = {https://doi.org/10.1118/1.3182643}, note = {Motion Compensation in Radiosurgery} } @Inproceedings { Bruder2009, author = {Bruder, Ralf}, title = {Ultrasound tracking for motion compensation in radiation therapy}, year = {2009}, publisher = {Institute for Robotics, University of L{\{\dq}u}beck}, address = {L{\{\dq}u}beck, Germany}, tags = {UGRT} } @Inproceedings { CARS09, title = {International Congress and Exhibition on Computer Assisted Radiology and Surgery}, year = {2009}, volume = {23}, address = {Berlin, Germany}, series = {CARS}, file_url = {http://www.cars-int.org/} } @Misc { s_09, author = {Senger, Lisa}, title = {Liver Motion Tracking and Correlation to Surrogate Signals using 3D Ultrasound}, abstract = {In this work two different types of correlation models are described and tested with modeled and real breathing data with regard to their use in the stereotactic radiosurgery. The CyberKnife system is one device in the stereotactic radiosurgery to treat a tumor without the fixation of the patient. Correlation models are needed in this system to compute the position of the tumor in real time, so that the radiation beam can be focused on the tumor during the whole treatment. Depending on the accuracy of the correlation model the tumor can be irradiated more exactly and the healthy tissue around it can be saved. The correlation model used in the CyberKnife system is the polynomial model. A new model based on {\dq}-SVR is compared to this model in this work. Therefore the two models are described first. Afterwards the models are compared with modeled and real breathing data. The focus is on the observation of liver movement, because the liver moves with breathing. Therefore the treatment of a tumor in the liver is more difficult. The liver movement were determined with 3D ultrasound. The movement of LEDs on the chest of the test person were used as external markers for the correlation models. The comparison of the two correlation models shows that the new model based on e-SVR represents the correlation between internal target and external marker better than the polynomial actually model used in the CyberKnife. With all test data the error between the real and the calculated correlation of the polynomial model is at least twice as high as the error of the SVR model. The same result is observed with the maximum error ofthe models. As conclusion of this work can be stated in the examples analysed in this work an irradiation of a tumor using the SVR model would be more exactly than using the polynomial model.}, year = {2009}, tags = {MCRT}, note = {Motion Compensation in Radiosurgery} } @Inproceedings { es_09d, author = {Ernst, Floris and Schweikard, Achim}, title = {A Survey of Algorithms for Respiratory Motion Prediction in Robotic Radiosurgery}, abstract = {In robotic radiosurgery, a standard six-jointed industrial robot carries a linear accelerator. The accelerator can be moved such as to compensate for respiratory motion. Unfortunately, this motion cannot be compensated perfectly since the motion of the robot lags behind the motion of the target organ by -- in systems currently employed clinically -- approximately 150 ms. This delay is compensated by prediction algorithms, i.e., the time series stemming from human respiration is forecast. We have compared the performance of seven algorithms implemented in a common prediction tool kit. They are: multi-frequency tracking with Extended Kalman Filtering (EKF), normalised and regular Least Mean Squares filters (LMS and nLMS), wavelet-based multiscale autoregression (wLMS), a recursive least squares filter (RLS), multi-step linear methods (MULIN) and prediction based on support vector regression (SVRpred). All algorithms were tested on two signals: a simulated signal, corrupted by Gaussian noise, and a real breathing motion signal from a treatment session with the CyberKnife at Georgetown University Hospital. The results are clear: the SVRpred algorithm outperforms the best other algorithm (wLMS for the real signal and MULIN for the simulated signal) by 15 and 9 percentage points, respectively.}, year = {2009}, volume = {154}, publisher = {Bonner K{\{\dq}o}llen}, address = {L{\{\dq}u}beck, Germany}, series = {Lecture Notes in Informatics}, editor = {Fischer, Stefan and Maehle, Erik}, pages = {1035-1043}, tags = {MCRT}, file_url = {http://www.informatik2009.de}, note = {Motion Compensation in Radiosurgery} } @Article { fmrstspn_09, author = {Fadini, Tommaso and Matth{\{\dq}a}us, Lars and Rothkegel, Holger and Sommer, Martin and Tergau, Frithjof and Schweikard, Achim and Paulus, Walter and Nitsche, Michael A.}, title = {H-coil: Induced electric field properties and input/output curves on healthy volunteers, comparison with a standard figure-of-eight coil}, abstract = {Objective: To acquire information about the physical properties and physiological effects of the H-coil. Methods: We used a robotized system to measure the electric field (E-field) generated by a H-coil prototype and compared it with a standard figure-of-eight coil. To explore the physiological properties of the coils, input/output curves were recorded for the right abductor digiti minimi muscle (ADM) as target muscle. To explore focality of stimulation, simultaneous recordings were performed for the left ADM, right abductor pollicis brevis (APB), extensor digitorum communis (EDC) and biceps brachii (BB) muscles. Results: Physical measurements of the H-coil showed four potentially stimulating foci, generating different electric field intensities along two different spatial orientations. RMT was significantly lower for Hcoil- as compared to figure-of-eight coil stimulation. When stimulation intensity for the input--output curve was determined by percent of maximum stimulator output, the H-coil produced larger MEPs in the right ADM, as compared to the figure-of-eight coil, due to the larger relative enhancement of stimulation intensity of the H-coil. When stimulation intensity was adjusted to RMT, MEPs elicited at the right ADM were larger for figure-of-eight coil than for H-coil stimulation, while this relation was reversed for distant non-target muscles, with low stimulation intensities. With high stimulation intensities, the H-coil elicited larger MEPs for all tested muscles. Onset latency of the MEPs was never shorter for H-coil than for figure-of-eight coil stimulation of the target muscles. Conclusions: These results are in favor for a non-focal, but not deeper effect of the H-coil, as compared to a figure-of-eight coil. Significance: This is the first neurophysiological study exploring the focality and depth of stimulation delivered by the H-coil systematically in humans. We found no advantage of this coil with regard to depth of stimulation in comparison to the figure-of-eight coil. Future studies have to show if the nonfocality of this coil differs relevantly from that of other non-focal coils, e.g. the round coil.}, year = {2009}, DOI = {10.1016/j.clinph.2009.02.176}, journal = {Clinical Neurophysiology}, volume = {120}, pages = {1174-1182}, number = {6}, keywords = {Brain stimulation; Electric field; H-coil; Latency; Motor threshold; Transcranial Magnetic Stimulation}, file_url = {https://doi.org/10.1016/j.clinph.2009.02.176} } @Inproceedings { kim2009, title = {Advances in Robotics}, abstract = {This volume is an edition of the papers selected from the 12th FIRA RoboWorld Congress, held in Incheon, Korea, August 16--18, 2009. The Federation of International Robosoccer Association (FIRA -- www.fira.net) is a non-profit organization, which organizes robotic competitions and meetings around the globe annually. The RoboSoccer competitions started in 1996 and FIRA was established on June 5, 1997. The Robot Soccer competitions are aimed at promoting the spirit of science and technology to the younger generation. The congress is a forum in which to share ideas and future directions of technologies, and to enlarge the human networks in robotics area. The objectives of the FIRA Cup and Congress are to explore the technical development and achievement in the field of robotics, and provide participants with a robot festival including technical presentations, robot soccer competitions and exhibits under the theme {\dq}Where Theory and Practice Meet.{\dq} Under the umbrella of the 12th FIRA RoboWorld Congress Incheon 2009, six international conferences were held for greater impact and scientific exchange: - 6th International Conference on Computational Intelligence, Robotics and Autonomous Systems (CIRAS) - 5th International Symposium on Autonomous Minirobots for Research and Edutainment (AMiRE) - International Conference on Social Robotics (ICSR) - International Conference on Advanced Humanoid Robotics Research (ICAHRR) • International Conference on Entertainment Robotics (ICER) • International Robotics Education Forum (IREF) This volume consists of selected quality papers from the six conferences. The volume is intended to provide readers with the recent technical progresses in robotics, human--robot interactions, cooperative robotics and the related fields. The volume has 31 papers from the 115 contributed papers at the FIRA RoboWorld Congress Incheon 2009. This volume is organized into seven sections: • Emotion and Behavior, Human--Robot Interaction, Biped / Humanoid Robotics, Localization, Path Planning, Obstacle Avoidance, Control, Communication, Terrain mapping, and, Classification. The editors hope that this volume is informative to the readers. We thank Springer for undertaking the publication of this volume.}, year = {2009}, volume = {5744}, publisher = {Springer}, address = {Berlin}, series = {Lecture Notes in Computer Science}, editor = {Kim, Jong-Hwan and Ge, Shuzhi Sam and Vadakkepat, Prahlad and Jesse, Norbert and Manum, Abdullah Al and Puthusserypady K, Sadasivan and R{\{\dq}u}ckert, Ulrich and Sitte, Joaquin and Witkowski, Ulf and Nakatsu, Ryohei and Braunl, Thomas and Baltes, Jacky and Anderson, John and Wong, Ching-Chang and Verner, Igor and Ahlgren, David}, note = {FIRA RoboWorld Congress 2009} } @Article { es_09b, author = {Ernst, Floris and Schweikard, Achim}, title = {Forecasting Respiratory Motion with Accurate Online Support Vector Regression (SVRpred)}, abstract = {Object: To accurately deliver radiation in image-guided robotic radiosurgery, highly precise prediction algorithms are required. A new prediction method is presented and evaluated. Materials and Methods: SVRpred, a new prediction method based on Support Vector Regression (SVR), has been developed and tested. Computer-generated data mimicking human respiratory motion with a prediction horizon of 150 ms was used for lab tests. The algorithm was subsequently evaluated on a respiratory motion signal recorded during actual radiosurgical treatment using the CyberKnife. The algorithm's performance was compared to the MULIN prediction methods and Wavelet-based multi scale autoregression (wLMS). Results: The SVRpred algorithm clearly outperformed both the MULIN and the wLMS algorithms on both real (by 15 and 16 percentage points, respectively) and noise-corrupted simulated data (by 13 and 48 percentage points, respectively). Only on noise-free artificial data, the SVRpred algorithm did perform as well as the MULIN algorithms but not as well as the wLMS algorithm. Conclusion: This new algorithm is a feasible tool for the prediction of human respiratory motion signals significantly outperforming previous algorithms. The only drawback is the high computational complexity and the resulting slow prediction speed. High performance computers will be needed to use the algorithm in live prediction of signals sampled at a high resolution.}, year = {2009}, DOI = {10.1007/s11548-009-0355-5}, journal = {International Journal of Computer Assisted Radiology and Surgery}, volume = {4}, pages = {439-447}, number = {5}, keywords = {Algorithms; Forecasting; prediction; Radiosurgery; Respiration; Support vector regression}, tags = {MCRT}, file_url = {https://doi.org/10.1007/s11548-009-0355-5}, note = {Motion Compensation in Radiosurgery} } @Inproceedings { bds_09c, author = {Bodensteiner, Christoph and Darolti, Christina and Schweikard, Achim}, title = {A Fast Intensity Based Non-rigid 2D-3D-Registration Using Statistical Regularization with Application in Radiosurgery}, year = {2009}, address = {San Jose}, tags = {ICA}, note = {Interactive C-Arm} } @Inproceedings { bces_09, author = {Bruder, Ralf and Cai, T. and Ernst, Floris and Schweikard, Achim}, title = {3D ultrasound-guided motion compensation for intravascular radiation therapy}, year = {2009}, DOI = {10.1007/s11548-009-0309-y}, volume = {4}, address = {Berlin, Germany}, series = {International Journal of CARS}, pages = {25-26}, number = {supp. 1}, tags = {MCRT UGRT}, file_url = {https://doi.org/10.1007/s11548-009-0309-y}, note = {Motion Compensation in Radiosurgery} } @Inproceedings { ebuh_09, author = {Ens, Svitlana and Bruder, Ralf and Ulrici, J. and Hell, E. and Buzug, T. M.}, title = {A Validation Framework for Head-Motion Artifacts in Dental Cone-Beam CT}, abstract = {Patient motion during CT data acquisition degrades image quality. Therefore, the development of motion detection and motion correction methods are in the focus of many research groups. In general the strength of motion artefacts depends on the motion parameters and on the structures of the anatomical area of interest. Unfortunately, a realistic ground truth data and the corresponding artefact prone reconstructions with known motion parameters during data acquisition are often not available or tedious to obtain. In this work, a framework is presented to generate a database for motion quantification in dental cone-beam CT. Practical aspects and challenges will be described. Furthermore, the generated database will be utilized to investigate the influence of head motion on the reconstruction image quality. Different assessment criteria will be proposed for the motion distorted data. This work provides a basis for data-driven motion detection and correction methods and serves as a first step to understand the effects of motion.}, year = {2009}, DOI = {10.1007/978-3-642-03879-2}, volume = {25/II}, publisher = {Springer}, address = {Munich, Germany}, series = {IFMBE Proceedings}, editor = {D{\{\dq}o}ssel, O. and Schlegel, Wolfgang C.}, pages = {658-661}, tags = {UGRT}, file_url = {https://doi.org/10.1007/978-3-642-03879-2} } @Inproceedings { dbbh_09, author = {Darolti, Christina and Bodensteiner, Christoph and Barth, Erhardt and Hofmann, Ulrich G.}, title = {Active Contours that Grow and Compete Driven by Local Region Descriptors}, year = {2009}, address = {San Jose} } @Article { bds_09, author = {Bodensteiner, Christoph and Darolti, Christina and Schweikard, Achim}, title = {Achieving super-resolution X-ray imaging with mobile C-arm devices}, abstract = {The term super-resolution refers to the process of combining a set of low-resolution images into a high-resolution image using image processing methods. This work is concerned with the reconstruction of high-resolution X-ray images. Specifically, we address the problem of acquiring X-ray images from multiple, very close view points.We propose to use a novel experimental robotic C-arm device to create high-resolution X-ray images. For this purpose, we suggest different strategies for acquiring multiple low-resolution images, and we provide the steps to achieve acquisition-error compensation. Compared to visible light images, X-ray images have the particularity that parallax effects render super-resolution very difficult. Using the acquired multi-frame data, we evaluate recent well-known super-resolution reconstruction algorithms. The same algorithms are evaluated based on synthetic 3D phantom data and real X-ray images.In experiments with both synthetic and real projection data, we successfully reconstruct up to four times higher-resolution images. These images reveal structures and details which are not perceivable in the low-resolution images.The advantage of super-resolution techniques for X-ray is the potential reduction of radiation dose for patients and medical personnel. Potential medical applications include the diagnosis of early-stage osteoporosis and the detection of very small calcifications. Copyright 2009 John Wiley Sons, Ltd.}, year = {2009}, issn = {1478-596X}, DOI = {10.1002/rcs.255}, journal = {International Journal of Medical Robotics and Computer Assisted Surgery}, volume = {5}, pages = {243-256}, number = {3}, tags = {ICA}, file_url = {https://doi.org/10.1002/rcs.255}, note = {Interactive C-Arm} } @Misc { ehl_09, author = {Ehlers, Kristian}, title = {Anwendung der FaceAPI zur Bewegungskompensation f{\{\dq}u}r die robotergest{\{\dq}u}tzte Transkranielle Magnetstimulation}, abstract = {This bachelor thesis is for analyzing possibilities of integrating the face tracking software FaceAPI (Seeing Machines, Braddon, Canberra, Australia) in medical treatments like the robot based transcranial magnetic stimulation (TMS). A common use of the TMS is the therapy of tinnitus. The FaceAPI offers to track a human face and to get the head position regarding the basis coordinate frame of the used webcam. An integration of the FaceAPI would increase safety and comfort for patients during the robot based TMS. For this purpose we evaluate the accuracy of the FaceAPI by comparing with the accuracy of the Polaris Spectra tracking system (Northern Digital Inc., Waterloo, Ontario, Canada). The Polaris Spectra system is actually used for navigation in the robot-based TMS and could be supported or even replaced by the FaceAPI. For realizing the comparison we track a model of a human head which is moved by an Adept Viper s850 industrial robot (Adept Technology Inc., Livermore, California, USA) and evaluate the recorded data. For a better understanding theoretical backgrounds of controlling a robot using data recorded by head tracking systems are presented. To facilitate the exchange of other tracking systems and to offer an easy and comfortable use via TCP/IP interface the FaceAPI will be integrated in the tracking system developed by the Institute for Robotics and Cognitive Systems.}, year = {2009}, tags = {TMS}, note = {Transcranial Magnetic Stimulation} } @Article { Gasca2009, author = {Gasca, Fernando and Ramrath, Lukas and H{\{\dq}u}ttmann, Gereon and Schweikard, Achim}, title = {Automated segmentation of tissue structures in optical coherence tomography data}, abstract = {Segmentation of optical coherence tomography (OCT) images provides useful information, especially in medical imaging applications. Because OCT images are subject to speckle noise, the identification of structures is complicated. Addressing this issue, two methods for the automated segmentation of arbitrary structures in OCT images are proposed. The methods perform a seeded region growing, applying a model-based analysis of OCT A-scans for the seed's acquisition. The segmentation therefore avoids any user intervention dependency. The first region-growing algorithm uses an adaptive neighborhood homogeneity criterion based on a model of an OCT intensity course in tissue and a model of speckle noise corruption. It can be applied to an unfiltered OCT image. The second performs region growing on a filtered OCT image applying the local median as a measure for homogeneity in the region. Performance is compared through the quantitative evaluation of artificial data, showing the capabilities of both in terms of structures detected and leakage. The proposed methods were tested on real OCT data in different scenarios and showed promising results for their application in OCT imaging.}, year = {2009}, journal = {Journal of Biomedical Optics}, volume = {14}, pages = {034046-1-21}, number = {3}, keywords = {optical coherence tomograpy segmentation} } @Inproceedings { fmss_09, author = {Finke, Markus and Meyer, Tobias and Stille, Maik and Schweikard, Achim}, title = {Automatic Positioning of a Surgical Microscope}, abstract = {A procedure for interactive navigation of a fully motorized surgical microscope is presented. This procedure uses preoperative MRT- or CT-images to generate a 3D-model of the patient which then acts as the basis for navigation during surgery. The relation between tracking system, microscope and 3D-model is established using a simple calibration method based on the Horn algorithm. It enables positioning the microscope by defining target points either directly on the patient using an optical marker or on his 3D-model. After reaching the target position the microscope focuses automatically by calculating the focus score of the current field of view as function of the working distance. Thus, not only the surgeon will be discharged from positioning the microscope but he can also continue his work almost immediately. Manual interaction becomes unnecessary.}, year = {2009}, volume = {154}, publisher = {Bonner K{\{\dq}o}llen}, address = {L{\{\dq}u}beck, Germany}, series = {Lecture Notes in Informatics}, editor = {Fischer, Stefan and Maehle, Erik}, pages = {998-1009}, file_url = {http://www.informatik2009.de} } @Inproceedings { RMT+09, author = {Richter, Lars and Matth{\{\dq}a}us, Lars and Trillenberg, Peter and Diekmann, Claudia and Rasche, Dirk and Schweikard, Achim}, title = {Behandlung von chronischem Tinnitus mit roboterunterst{\{\dq}u}tzter TMS}, year = {2009}, volume = {154}, publisher = {GI}, address = {L{\{\dq}u}beck}, series = {Lecture Notes in Informatics (LNI)}, pages = {86;1018-1027}, keywords = {medizinische Robotik; motion compensation; Robotik; Transkranielle Magnetstimulation (TMS)}, tags = {TMS}, note = {Transcranial Magnetic Stimulation} } @Article { rvjhs_09, author = {Ramrath, Lukas and Vogt, Simon and Jensen, Winnie and Hofmann, Ulrich G. and Schweikard, Achim}, title = {Computer and robot-assisted stereotaxy for high-precision small animal brain exploration}, abstract = {This contribution introduces a computer- and robot-assisted framework for stereotactic neurosurgery on small animals. Two major elements of this framework are presented in detail: a robotic stereotactic assistant and the software framework for placement of probes into the brain. The latter integrates modules for registration, insertion control, and preoperative path planning. Two options for path planning are addressed: (a) atlas-based planning and (b) image-based planning based on computed tomography data. The framework is tested performing robot-assisted insertion of microelectrodes and acquisition of electrophysiological recordings in vivo. Concepts for data analysis pointing towards a mapping of position and neural structure to functional data are introduced. Results show that the presented framework allows precise small animal stereotaxy and therefore offers new options for brain research.}, year = {2009}, issn = {1862-278X}, DOI = {10.1515/BMT.2009.002}, journal = {Biological Psychiatry}, volume = {54}, pages = {8-13}, number = {1}, keywords = {Brain Mapping; Electrophysiology; Elektrophysiologie; Gehirnkartographierung; medical robotics; medizinische Robotik; microelectrode recordings; Mikroelektrodenableitungen; neural engineering; Neuroengineering; stereotaxy}, tags = {SM}, file_url = {https://doi.org/10.1515/BMT.2009.002}, note = {Stereotactic Micronavigation} } @Inproceedings { emsb_09, author = {Ernst, Floris and Martens, Volker and Schlichting, Stefan and Be{\v{s}}irevi{\c}, Armin and Kleemann, Markus and Koch, Christoph and Petersen, Dirk and Schweikard, Achim}, title = {Correlating Chest Surface Motion to Motion of the Liver using ε-SVR -- a Porcine Study}, abstract = {In robotic radiosurgery, the compensation of motion of internal organs is vital. This is currently done in two phases: an external surrogate signal (usually active optical markers placed on the patient's chest) is recorded and subsequently correlated to an internal motion signal obtained using stereoscopic X-ray imaging. This internal signal is sampled very infrequently to minimise the patient's exposure to radiation. We have investigated the correlation of the external signal to the motion of the liver in a porcine study using $\epsilon$-support vector regression. IR LEDs were placed on the swines' chest. Gold fiducials were placed in the swines' livers and were recorded using a two-plane X-ray system. The results show that a very good correlation model can be built using $\epsilon$-SVR, in this test clearly outperforming traditional polynomial models by at least 45 and as much as 74 %. Using multiple markers simultaneously can increase the new model's accuracy.}, year = {2009}, DOI = {10.1007/978-3-642-04271-3_44}, volume = {5762}, publisher = {Springer}, address = {London, United Kingdom; London}, series = {Lecture Notes in Computer Science}, editor = {Yang, Guang-Zhong and Hawkes, David J. and Rueckert, Daniel and Noble, Alison and Taylor, C.}, pages = {356-364}, tags = {MCRT}, file_url = {https://doi.org/10.1007/978-3-642-04271-3_44}, note = {Motion Compensation in Radiosurgery} } @Article { es_08b, author = {Ernst, Floris and Schweikard, Achim}, title = {Predicting Respiratory Motion Signals for Image-Guided Radiotherapy using Multi-step Linear Methods (MULIN)}, abstract = {Objective Forecasting of respirationmotion in image-guided radiotherapy requires algorithms that can accurately and efficiently predict target location. Improved methods for respiratory motion forecasting were developed and tested. Materials and methods MULIN, a new family of prediction algorithms based on linear expansions of the prediction error, was developed and tested. Computer-generated data with a prediction horizon of 150ms was used for testing in simulation experiments. MULIN was compared to Least Mean Squares-based predictors (LMS; normalized LMS, nLMS; wavelet-based multiscale autoregression, wLMS) and a multi-frequency Extended Kalman Filter (EKF) approach. The in vivo performance of the algorithms was tested on data sets of patients who underwent radiotherapy. Results The new MULIN methods are highly competitive, outperforming the LMS and the EKF prediction algorithms in real-world settings and performing similarly to optimized nLMS and wLMS prediction algorithms. On simulated, periodic data the MULIN algorithms are outperformed only by the EKF approach due to its inherent advantage in predicting periodic signals. In the presence of noise, the MULIN methods significantly outperform all other algorithms. Conclusion The MULIN family of algorithms is a feasible tool for the prediction of respiratory motion, performing as well as or better than conventional algorithms while requiring significantly lower computational complexity. The MULIN algorithms are of special importance wherever high-speed prediction is required.}, year = {2008}, DOI = {10.1007/s11548-008-0211-z}, journal = {International Journal of Computer Assisted Radiology and Surgery}, volume = {3}, pages = {85-90}, number = {1--2}, keywords = {Algorithms; Forecasting; Radiosurgery; Respiration}, tags = {MCRT}, file_url = {https://doi.org/10.1007/s11548-008-0211-z}, note = {timestamp=2008.05.02} } @Inproceedings { fbs_08, author = {Finke, Markus and Bruder, Ralf and Schweikard, Achim}, title = {Kinematics of a Robotized Operation Microscope}, abstract = {We present the methods for calculating the forward and inverse kinematics of a fully motorized operation microscope. With these procedures the handling of the microscope in the surgical theatre can be facilitated. Computer-controlled positioning simplifies the pivotation around a defined focus point, improves its accuracy and makes the handling intuitive. The kinematics calculations enable new functions, such as automatic alignment of the microscope at the desired position or following a trajectory of previously chosen points.}, year = {2008}, address = {Orlanda, Florida, USA}, pages = {1638-1643}, tags = {SMI}, note = {Interactive C-Arm} } @Inproceedings { msbk_08, author = {Martens, Volker and Schlichting, Stefan and Be{\v{s}}irevi{\c}, Armin and Kleemann, Markus}, title = {LapAssistent - a laparoscopic liver surgery assistence system}, abstract = {In this work we present a navigation system for laparoscopic interventions on the liver. Our system provides a convenient global interface for guiding the surgeon through the surgical workflow. Instruments are tracked magnetically and registration with preoperative data can be performed in several ways. Currently, we evaluate the system in an animal study.}, year = {2008}, DOI = {10.1007/978-3-540-89208-3_31}, volume = {22}, publisher = {Springer}, address = {Antwerpen, Belgium}, series = {IFMBE Proceedings}, editor = {Magjarevic, Ratko and Sloten, Jos and Verdonck, Pascal and Nyssen, Marc and Haueisen, Jens}, pages = {121-125}, tags = {NLS}, file_url = {https://doi.org/10.1007/978-3-540-89208-3_31}, note = {Navigation in liver surgery} } @Article { dmbh_08, author = {Darolti, Christina and Mertins, A. and Bodensteiner, Christoph and Hofmann, Ulrich G.}, title = {Local Region Descriptors for Active Contours Evolution}, abstract = {Edge-based and region-based active contours are frequently used in image segmentation. While edges characterize small neighborhoods of pixels, region descriptors characterize entire image regions that may have overlapping probability densities. In this paper, we propose to characterize image regions locally by defining local region descriptors (LRDs). These are essentially feature statistics from pixels located within windows centered on the evolving contour, and they may reduce the overlap between distributions. LRDs are used to define general-form energies based on level sets. In general, a particular energy is associated with an active contour by means of the logarithm of the probability density of features conditioned on the region. In order to reduce the number of local minima of such energies, we introduce two novel functions for constructing the energy functional which are both based on the assumption that local densities are approximately Gaussian. The first uses a similarity measure between features of pixels that involves confidence intervals. The second employs a local Markov Random Field (MRF) model. By minimizing the associated energies, we obtain active contours that can segment objects that have largely overlapping global probability densities. Our experiments show that the proposed method can accurately segment natural large images in very short time when using a fast level-set implementation.}, year = {2008}, issn = {1057-7149}, DOI = {10.1109/TIP.2008.2006443}, journal = {IEEE Transactions on Image Processing}, volume = {17}, pages = {2275-2288}, number = {12}, file_url = {https://doi.org/10.1109/TIP.2008.2006443} } @Article { rlct_08, author = {Ramrath, Lukas and Levering, J. and Conrad, Matthias and Thuemen, A. and Fuellgraf, H. and Moser, Andreas}, title = {Mathematical Identification of a Neuronal Network Consisting of GABA and DA in Striatal Slices of the Rat Brain}, abstract = {High frequency stimulation (HFS) has been used to treat various neurological and psychiatric diseases. Although further disorders are under investigation to extend the clinical application of HFS, the complex effect of HFS within a neuronal network is still unknown. Thus, it would be desirable to find a theoretical model that allows an estimation of the expected effect of applied HFS. Based on neurochemical analysis of effects of the GABAA receptor antagonist bicuculline, the D2-like receptor antagonist sulpiride and the D1-like receptor antagonist SCH-23390 on high-frequency stimulation (HFS) evoked -aminobutyric acid (GABA) and dopamine (DA) release from striatal slices of the rat brain, a mathematical network model is proposed including the neurotransmitters GABA, DA and glutamate (GLU). The model reflects inhibitory and excitatory interactions of the neurotransmitters outflow in the presence of HFS. Under the assumption of linear interactions and static measurements, the model is expressed analytically. Numerical identification of inhibition and excitation are performed on a basis of real outflow levels of GABA and DA in the rat striatum. Results validate the nature of the proposed model. This therefore leads to an analytical model of the interactions within distinct neural network components of the rat striatum.}, year = {2008}, journal = {Computational and Mathematical Methods in Medicine}, tags = {SM}, note = {Stereotactic Micronavigation} } @Article { mpc_08, author = {Matth{\{\dq}a}us, Lars and Pham, Trieu and Croft, Rodney J.}, title = {One-channel EOG artifact correction: An analytic approach}, abstract = {This article approaches the problem of EOG artifact correction using one EOG channel from a biophysical point of view. It shows that recordings from one EOG channel are sufficient to correct artifacts from one-dimensional eye movements not exceeding 30°. We prove that the subtraction method {\dq}corrected EEG=measured EEG---backward propagation * measured EOG{\dq} yields the uncorrupted EEG trace up to scaling despite possible influences of forward propagation. Further, a special calibration paradigm (aligned artifact average, AAA) is investigated, and algorithms are presented to calculate the exact backward propagation. Experimental results from 13 subjects are shown, supporting the theoretical prediction of optimal correction.}, year = {2008}, DOI = {10.1111/j.1469-8986.2008.00642.x}, journal = {Psychophysiology}, volume = {45}, pages = {569-578}, number = {4}, file_url = {https://doi.org/10.1111/j.1469-8986.2008.00642.x} } @Inproceedings { bbhhs_08, author = {Bruder, Ralf and Bonsanto, Matteo C. M. and Hackbarth, T. and Hansen, F. and Schweikard, Achim}, title = {Zeitsparende Navigationsl{\{\dq}o}sung zum Platzieren von Pedikelschrauben}, year = {2008}, address = {Ulm} } @Inproceedings { es_08c, author = {Ernst, Floris and Schweikard, Achim}, title = {Prediction of respiratory motion using a modified Recursive Least Squares algorithm}, abstract = {In robotic radiosurgery, a robot-mounted LINAC follows the motion of the target region. Due to delays in signal acquisition and robot motion, there is the need for prediction of the measured motion. In this work, we present a slight modification of the Recursive Least Squares (RLS) algorithm for the prediction of human respiration. We have modified the RLS algorithm as to include an exponential memory term to cope with signal irregularities and system noise. The new algorithm is evaluated on synthetic and real breathing motion signals. The prediction results compare favourably to other methods like Least Mean Squares prediction, Wavelet-based Multiscale Autoregression and Multi-step Linear Methods.}, year = {2008}, volume = {7}, address = {Leipzig, Germany}, series = {CURAC}, editor = {Bartz, Dirk and Bohn, S. and Hoffmann, J.}, pages = {157-160}, keywords = {Cyberknife; prediction; Respiration}, tags = {MCRT}, note = {timestamp=2008.08.12} } @Inproceedings { Loeffler2008, author = {Loeffler, S. and Ramrath, Lukas and Hofmann, Ulrich G. and Schweikard, Achim and Moser, Andreas}, title = {Robot Assisted Stereotaxic Targeting for STN-DBS in the Rat Brain.}, abstract = {Severe motoric symptoms in parkinson's disease arise from the loss of dopaminergic input into the striatum. The striatal efferent nuclei are thus affected by a lack of GABAergic input. Deep brain stimulation (DBS) in the subthalamic nucleus (STN) seems to counterbalance this effect by a hitherto unknown molecular mechanism. Based on the hypothesis that high frequency electrical stimulation may have an effect on neutrotransmitter release in the local environment of the stimulation electrode we established an in vivo rat model allowing for simultaneous and collocated high frequency stimulation and microdialysis in freely moving rats.}, year = {2008}, DOI = {10.1055/s-2008-1072910}, volume = {39}, address = {Magdeburg}, series = {Klin Neurophysiol 2008}, tags = {SM}, file_url = {https://doi.org/10.1055/s-2008-1072910}, note = {Stereotactic Micronavigation} } @Inproceedings { rhbt_08, author = {Ramrath, Lukas and Hofmann, Ulrich G. and Bonsanto, Matteo C. M. and Tronnier, Volker and Loeffler, S. and Moser, Andreas and Schweikard, Achim}, title = {Robotic Framework for Small Animal Stereotaxy}, abstract = {This contribution presents the design of a robot-assisted neuronavigation framework for small animal stereotaxy. The aim is to improve brain research by providing a tool for accurate and repeatable insertion of microprobes. The frame consists of two major modules: a robotic, stereotactic assistant part and a software package allowing interactive planning and control (navigation). Small animal stereotaxy is a common procedure in brain research, e. g. research on the effect of deep brain stimulation for the treatment of Parkinson's disease. Herein, microelectrodes and/or microdialysis probes are placed in predefined brain target areas. The major difficulty of current probe implantation is the manual handling of the stereotactic frame which causes positioning inaccuracies. Especially as the target areas in the rodent model are of small size, the allocation of the measured signal to the spatial position is unreliable. Following the known center-of-arc principle used in human stereotactic applications, a robotized spherical assistant for stereotactic surgery (SASSU) is designed. It provides 5 degrees of freedom (DOF) for the tool placement, three translational DOF and two rotational DOF. Thus, a tool can be placed at a desired position and with a preferred insertion angle with a positioning accuracy less than 0.045 mm. The SASSU is controlled by a navigation software and integrated into the surgical workflow. Preoperative planning is based on labeled coronal slices of the rat brain. It allows the specification of the target point (A/P, DV, and Lateral position) and of a preferred entry path. Registration to the rat skull is done using anatomical landmarks on the rat skull (Lambda and Bregma points). For the final insertion of the probe, parameters such as step size and velocity can be specified. To summarize, the presented framework provides improved accuracy and repeatability of tool placement in small animal brain research.}, year = {2008}, volume = {4}, address = {Geneva}, tags = {SM}, note = {Stereotactic Micronavigation} } @Inproceedings { rplm_08, author = {Ramrath, Lukas and Pohl, Matthias and Loeffler, S. and Mankodiya, K. and Xie, Y. and Hofmann, Ulrich G. and Schweikard, Achim}, title = {Single fibre Optical Coherence Tomography for Brain Imaging - A preliminary in vitro study}, year = {2008}, volume = {7}, address = {Leipzig, Deutschland; Leipzig, Germany}, series = {CURAC}, editor = {Bartz, Dirk and Bohn, S. and Hoffmann, J.}, pages = {179-180} } @Article { bbhh_08, author = {Bonsanto, Matteo C. M. and Bruder, Ralf and Hackbarth, T. and Hansen, F.}, title = {Timesaving navigation for pedicle screw placement}, year = {2008}, journal = {European Spine Journal}, pages = {1571-1572} } @Inproceedings { rmmb_08, author = {Ramrath, Lukas and Moreno, G. and Mueller, Heike and Bonin, Tim and H{\{\dq}u}ttmann, Gereon and Schweikard, Achim}, title = {Towards Multi-Directional OCT for Speckle Noise Reduction}, abstract = {Multi-directional optical coherence tomography (MD-OCT) applies and extends the concept of angular compounding for speckle noise reduction to the area of OCT imaging. OCT images are acquired from a wide range of angles of view. Averaging of the rotated images therefore requires compensation of the parallax which is achieved by simple image registration for image reconstruction. Test measurements of a sample structure in a low and highly scattering environment show that the method improves the signal-to-noise ratio by a factor of 4 and hence reduces speckle noise significantly. Experimental results also show that the proposed averaging increases the performance of common edgedetection algorithms.}, year = {2008}, DOI = {10.1007/978-3-540-85988-8}, volume = {5241}, address = {New York, NY, USA}, editor = {Metaxas, Dimitris and Axel, Leon and Fichtinger, Gabor and Sz{\'e}kely, G{\'a}bor}, pages = {815-823}, tags = {OCT}, file_url = {https://doi.org/10.1007/978-3-540-85988-8}, note = {OCT-based Neuro-Imaging} } @Misc { Bodensteiner2008, author = {Bodensteiner, Christoph and Schweikard, Achim}, title = {Vascular Tree Reconstruction with Discrete Tomography - Parallel 3D-reconstruction Algorithms for Inconsistent Projection Data based on Linear Optimization}, year = {2008}, tags = {ICA}, note = {Interactive C-Arm} } @Inproceedings { CURAC08, title = {Jahrestagung der Deutschen Gesellschaft f{\{\dq}u}r Computer- und Roboterassistierte Chirurgie}, year = {2008}, volume = {7}, address = {Leipzig, Germany}, series = {CURAC}, editor = {Bartz, Dirk and Bohn, S. and Hoffmann, J.} } @Inproceedings { fbs_08a, author = {Finke, Markus and Bruder, Ralf and Schweikard, Achim}, title = {Intraoperative Fernsteuerung eines Operationsmikroskopes}, abstract = {Nach der Motorisierung eines Operationsmikroskops stellt die Entwicklung einer Funkfernsteuerung einen wichtigen Schritt dar, die stark erweiterte Funktionalit{\{\dq}a}t des Operationsmikroskops dem Chirurgen auf eine intuitiv zu bedienende, seinen Arbeitsablauf nur minimal beeinflussende Weise zur Verf{\{\dq}u}gung zu stellen. Durch die Fernbedienung kann die Positionierung des Mikroskops erheblich vereinfacht und der Zeitaufwand f{\{\dq}u}r diesen Arbeitsschritt deutlich reduziert werden. H{\{\dq}a}ufig auftretende, relativ kleine Positions{\{\dq}a}nderungen k{\{\dq}o}nnen ohne Unterbre-chung des derzeitigen Arbeitsschrittes mit Hilfe der Fernsteuerung durchgef{\{\dq}u}hrt werden. Der Vorteil der Motorisierung liegt hier zudem in der hohen Genauigkeit, mit der anzufahrende Positionen eingenommen werden k{\{\dq}o}nnen. Die zeitauf-w{\{\dq}a}ndige und ungenaue Positionierung von Hand wird hier intelligent abgel{\{\dq}o}st. Durch eine weitere Funktion der Fernbedienung k{\{\dq}o}nnen Positionen auf Knopfdruck gespeichert und zu einem sp{\{\dq}a}teren Zeitpunkt vom Mikroskop erneut angefahren werden. So kann ber{\{\dq}u}hrungslos zwischen Mikroskop-unterst{\{\dq}u}tzter und nicht unterst{\{\dq}u}tzter Betrachtung des Operationsgebiets gewechselt oder das Mikroskop bei Nichtbenutzung in eine Park-position gefahren werden. Die manuelle Bedienung des Mikroskops ist weiterhin jederzeit m{\{\dq}o}glich, so dass gro{\{\dq}s}e Ver-{\{\dq}a}nderungen der Position schnell ausgef{\{\dq}u}hrt werden k{\{\dq}o}nnen.}, year = {2008}, volume = {7}, address = {Leipzig, Deutschland; Leipzig, Germany}, series = {CURAC}, editor = {Bartz, Dirk and Bohn, S. and Hoffmann, J.}, pages = {31-34}, tags = {SMI}, note = {Interactive C-Arm} } @Inproceedings { re_08, author = {Rzezovski, Norman and Ernst, Floris}, title = {Graphical Tool for the Prediction of Respiratory Motion Signals}, abstract = {In robotic radiosurgery, there currently is no tool available which can be used for testing and comparing different prediction algorithms. In this work, we present a new graphical tool which has the capability of automatically creating a graphical front end for parameter manipulation from XML-based prediction algorithm definition files, computing prediction errors and determining optimal prediction parameters. The tool is based on the wxWidgets toolkit and can be used on both Windows and Linux operating systems.}, year = {2008}, volume = {7}, address = {Leipzig, Germany}, series = {CURAC}, editor = {Bartz, Dirk and Bohn, S. and Hoffmann, J.}, pages = {179-180}, keywords = {Algorithms; prediction; Respiration; tools}, tags = {MCRT}, note = {timestamp=2008.08.12} } @Article { mtffs_08, author = {Matth{\{\dq}a}us, Lars and Trillenberg, Peter and Fadini, Tommaso and Finke, Markus and Schweikard, Achim}, title = {Brain mapping with Transcranial Magnetic Stimulation using a refined Correlation Ratio and Kendall's tau}, abstract = {Transcranial magnetic stimulation provides a mean to stimulate the brain non-invasively and painlessly. The effect of the stimulation hereby depends on the stimulation coil used and on its placement. This paper presents a mapping algorithm based on the assumption of a monotonous functional relationship between the applied electric field strength at the representation point of a muscle and the evoked motor potential. We combine data from coil characteristics, coil placement, and stimulation outcome to calculate a likelihood map for the representation of stimulated muscles in the brain. Hereby, correlation ratio (CR) and Kendall's rank coefficient are used to find areas in the brain where there is most likely a functional or monotonous relationship between electric field strength applied to this area and the muscle response. First results show a good accordance of our method with mapping from functional magnetic resonance imaging. In our case, classical evaluation of CR with binning is impossible, because sample data sets are too small and data are continuous. We therefore introduce a refined CR formula based on a Parzen windowing of the X-data to solve the problem. In contrast to usual windowing approaches, which require numeric integration, it can be evaluated directly in O(n^2) time. Hence, its advantage lies in fast evaluation while maintaining robust applicability to small sample sets. We suggest that the presented formula can generally be used in CR-related problems where sample size is small and data range is continuous.}, year = {2008}, DOI = {10.1002/sim.3353}, journal = {Statistics in Medicine}, volume = {27}, pages = {5252-5270}, number = {25}, tags = {TMS}, file_url = {https://doi.org/10.1002/sim.3353}, note = {Transcranial Magnetic Stimulation} } @Inproceedings { ke_08, author = {Kn{\{\dq}o}pke, Matthias and Ernst, Floris}, title = {Flexible Markergeometrien zur Erfassung von Atmungs- und Herzbewegungen an der K{\{\dq}o}rperoberfl{\{\dq}a}che}, abstract = {In der robotergest{\{\dq}u}tzten Strahlenchirurgie wird zur Zeit die Bewegung von bis zu drei Infrarot-LEDs, die auf der K{\{\dq}o}rperoberfl{\{\dq}a}che des Patienten befestigt sind, als Surrogatsignal benutzt, um die Bewegung eines nicht in Echtzeit lokalisierbaren Tumors vorherzusagen. In dieser Arbeit stellen wir eine neuartige, flexible Markergeometrie vor, die mit Hilfe eines Hochgeschwindigkeits-Trackingsystems (atracsys accuTrack Compact) die pr{\{\dq}a}zise und schnelle Erfassung von Bewegungsmustern an der K{\{\dq}o}rperoberfl{\{\dq}a}che erm{\{\dq}o}glicht. Hierbei wurde festgestellt, dass sowohl der Herzschlag als auch Bewegung in anderen Achsen als der Hauptachse der Atmung gemessen werden k{\{\dq}o}nnen. Diese Erkenntnisse stellen die momentan benutzten Korrelations- und Pr{\{\dq}a}diktionsmethoden zumindest teilweise in Frage.}, year = {2008}, volume = {7}, address = {Leipzig, Germany}, series = {CURAC}, editor = {Bartz, Dirk and Bohn, S. and Hoffmann, J.}, pages = {15-16}, keywords = {Atmunsbewegung; Herzbewegung; Strahlenchirurgie}, tags = {MCRT}, note = {timestamp=2008.08.12} } @Inproceedings { es_08a, author = {Ernst, Floris and Schweikard, Achim}, title = {A family of linear algorithms for the prediction of respiratory motion in image-guided radiotherapy}, year = {2008}, DOI = {10.1007/s11548-008-0169-x}, volume = {3}, address = {Barcelona, Spain}, series = {International Journal of CARS}, pages = {31-32}, number = {supp. 1}, tags = {MCRT}, file_url = {https://doi.org/10.1007/s11548-008-0169-x}, note = {timestamp=2008.01.24} } @Article { esds_08, author = {Ernst, Floris and Schlaefer, Alexander and Dieterich, Sonja and Schweikard, Achim}, title = {A Fast Lane Approach to LMS Prediction of Respiratory Motion Signals}, abstract = {As a tool for predicting stationary signals, the Least Mean Squares (LMS) algorithm is widely used. Its improvement, the family of normalised LMS algorithms, is known to outperform this algorithm. However, they still remain sensitive to selecting wrong parameters, being the learning coefficient mu and the signal history length M. We propose an improved version of both algorithms using a Fast Lane Approach, based on parallel evaluation of several competing predictors. These were applied to respiratory motion data from motion-compensated radiosurgery. Prediction was performed using arbitrarily selected values for the learning coefficient mu in ]0,0:3] and the signal history lengthM in [1, 15]. The results were compared to prediction using the globally optimal values of mu and M found using a grid search. When the learning algorithm is seeded using locally optimal values (found using a grid search on the first 96 s of data), more than 44% of the test cases outperform the globally optimal result. In about 38% of the cases, the result comes to within 5% and, in about 9% of the cases, to within 5--10% of the global optimum. This indicates that the Fast Lane Approach is a robust method for selecting the parameters mu and M.}, year = {2008}, DOI = {10.1016/j.bspc.2008.06.001}, journal = {Biomedical Signal Processing and Control}, volume = {3}, pages = {291-299}, number = {4}, keywords = {LMS; Parameter selection; Radiosurgery; Respiratory motion prediction}, tags = {MCRT}, file_url = {https://doi.org/10.1016/j.bspc.2008.06.001}, note = {timestamp=2008.01.24} } @Phdthesis { m_08, author = {Matth{\{\dq}a}us, Lars}, title = {A robotic assistance system for transcranial magnetic stimulation and its application to motor cortex mapping}, abstract = {To overcome the problems of conventional image guided transcranial magnetic stimulation (TMS), we developed a robotic system to place the coil at a target position and to keep it in place even if the head of the patient moves. The system is able to position the coil tangentially at any point on the head with any predefined rotation about the coil's vertical axis. Motions of the head are detected using a tracking system and compensated by steering the robot to the updated target position. The introduction of a robot for TMS coil positioning does not only solve the problems of exact targeting and motion compensation, it also enables a number of novel features: Firstly, it allows for precise continuation of the stimulation in consecutive sessions. Secondly, it makes it simple to stimulate in a predefined grid pattern. Thirdly, it separates treatment planning from treatment execution as it is known from radiotherapy and radiosurgery. Finally, it might offer new possibilities of treatment, e.g. by controlled coil movement over the scalp during repetitive stimulation. The system's main components are a serial robot arm with six joints and a marker-based optical tracking system. Both devices are linked by a control computer, which converts the target coordinates from the medical image data into real world coordinates and commands robot joint settings to place the TMS coil there. Hereby, real-time tracking data from the camera system is used to determine the current position of the head. Two major challenges had to be overcome for robot aided TMS. Firstly, we developed a new way to deal with robot redundancy, i.e. an algorithm how to chose a configuration from the set of possible joint settings encoding the same pose of the TMS coil. When we command the robot to a new position, we first calculate all possible target joint settings and choose the one closest to the actual joint setting according to the Euclidean metric in joint space. The second challenge was to define a safe, robust, and fast heuristic for the trajectory fromthe actual position to the target position for the coil. Our solution is to combine a foolproof trajectory for the centre of the coil -- namely a circular motion with some distance from the head from the start to the target spot -- with an optimised orientation change along the way. The resulting heuristic is safe, because of the simple trajectory of the coil's centre. It is also robust, because the freedom in orientation allows to find a realisable coil path for most of the start and target points around the head. The heuristic can be implemented in a fast way; it usually needs about 100 ms to compute a trajectory. Evaluation of the system yielded a mean accuracy of the system of about 1 mm. The motion compensation module was evaluated to work with a latency of about 100 ms, i.e. it takes about 0.1 seconds before the robot starts to compensate for a head movement. Our experiments with 20 subjects show that these data allow for successful stimulation in the areas of tinnitus treatment, treatment of chronic pain, and motor cortex mapping. One major application of our robot aided TMS system has been the precise localisation of cortical representations of muscles. The use of the robot for the procedure has two advantages compared to manual (image guided) TMS: it makes it easy to define and approach target points, e.g. along a grid-like pattern, and it keeps the TMS coil at the target position, even if the head moves, so that several MEPs can be averaged. The second point is of special importance as TMS evoked MEPs have been shown to possess great variability. Thus, averaging strongly improves the mapping results. We approach the problem of motor cortex mapping from a biophysical point of view. Our model assumes a monotonic functional relationship between the electric field strength at a cortical representation of a muscle and its MEP. Thus, we find the cortical representation by identifying the point on the cortex where such a relationship is most likely given the experimental data. In detail, for a point p on the cortex we approximate the electric field strength Ep for each stimulation point (coil position) i. We then estimate the likelihood of a monotonic functional relationship by looking at the list of pairs (Ep(i);MEP(i)). We show in this thesis that if we use Kendall's tau as an estimator for the monotonic relationship, we get a clear maximum site for the cortical representation. Furthermore, applied to a mapping with a figure-of-eight coil the predicted representation agrees with data from fMRI within the resolution of the fMRI data (4 mm). For the first time, our method allows mapping with non-focal coils like circular coils. ...}, year = {2008}, series = {Universit{\{\dq}a}t zu L{\{\dq}u}beck}, tags = {TMS}, note = {timestamp=2009.01.05} } @Article { rhs_08, author = {Ramrath, Lukas and Hofmann, Ulrich G. and Schweikard, Achim}, title = {A Robotic Assistant for Stereotactic Neurosurgery on Small Animals}, abstract = {BACKGROUND: This work presents the development and performance analysis of a robotic system for stereotactic neurosurgery on small animals. The system is dedicated to the precise placement of probes in the small animal brain, thus providing an improved framework for brain research. METHODS: Based on an analysis of small animal stereotaxy, the mechanical design of the robotic system is presented. Details of the structure and mechanical components and a kinematic description are outlined. The calibration process of the system for arbitrary probes is described. To analyse the mechanical positioning accuracy of the system, a testbed is presented. RESULTS: Positioning performance results show that the system features a mean mechanical positioning accuracy of 32 microm and a mean positioning repeatability of 11 microm. CONCLUSION: The system meets the requirements of targeting small functional areas within the brain of small animals and thus offers a new tool for small animal brain research.}, year = {2008}, DOI = {10.1002/rcs.218}, journal = {International Journal of Medical Robotics and Computer Assisted Surgery}, volume = {4}, pages = {295-303}, number = {4}, keywords = {medical robotics; Neuronavigation; neurosurgery; stereotaxy}, tags = {SM}, file_url = {https://doi.org/10.1002/rcs.218}, note = {Stereotactic Micronavigation} } @Article { sgs_08, author = {Schlaefer, Alexander and Gill, Jakub and Schweikard, Achim}, title = {A simulation and training environment for robotic radiosurgery}, year = {2008}, issn = {1861-6410}, DOI = {10.1007/s11548-008-0159-z}, journal = {International Journal of Computer Assisted Radiology and Surgery}, volume = {3}, publisher = {Springer-Verlag}, pages = {267-274}, number = {3-4}, keywords = {Beam selection; Robotic radiosurgery; simulation; Training; Treatment planning; Virtual Reality; Visualization}, file_url = {https://doi.org/10.1007/s11548-008-0159-z}, note = {language=English} } @Inproceedings { fs_08, author = {Finke, Markus and Schweikard, Achim}, title = {3D Simulation of a motorized operation microscope}, abstract = {We present a 3D-simulation which is used to develop automatic applications for a motorized operation microscope. It is implemented using java and java3d and enables a hardware independent evaluation of the system by the manufacturer as well as the user. An easy switch-over from simulation to the real system is possible because of software interfaces which are used to separate input and output methods. The simulation is also used to specify the parameters of the motorisation so that the microscope can be positioned accurately.}, year = {2008}, publisher = {Springer-Verlag Berlin Heidelberg}, address = {Venice, Italy}, pages = {258-369}, tags = {SMi}, note = {Interactive C-Arm} } @Inproceedings { ffkg_08, author = {Finke, Markus and Fadini, Tommaso and Kantelhardt, Sven and Giese, Alf and Matth{\{\dq}a}us, Lars and Schweikard, Achim}, title = {Brain-Mapping using robotized TMS}, abstract = {We present first results of brain-mapping using robotic Transcranial Magnetic Stimulation. This non-invasive procedure enables the reliable detection of the representation of indiviual muscles or muscle groups in the motor-cortex. The accuracy is only exceeded by direct electrical stimulation of the brain during surgery. Brain-mapping using robotic TMS can also be used to detect displacements of brain regions caused by tumors. The advantage of TMS is that it is non-invasive. In this study, we compare results from statistical mapping with robotic TMS to results achived from direct stimulation done during tumor surgery. To our knowledge this is the first study of this type. We mapped the representation of three muscle groups (forearm, pinky and thumb) in tumor patients with the robot-aided TMS protocoll and with direct stimulation. The resulting maps agree within 5mm.}, year = {2008}, address = {Vancouver, British Columbia, Canada}, pages = {3929-3932}, tags = {TMS}, note = {Transcranial Magnetic Stimulation} } @Phdthesis { r_08b, author = {Ramrath, Lukas}, title = {Design of a Surgical Robot and Brain Exploration Framework for Small Animal Stereotaxy}, abstract = {This thesis presents the development of a computer- and robot-assisted framework for small animal stereotaxy. From a detailed analysis of stereotactic procedures on small animals, a conceptional layout of the framework is described. Two major parts are addressed. The first part presents the design of a robotic assistant for small animal stereotaxy. It provides information on the kinematic design, the construction, and the utilized components. An analytic description of the system is provided by the forward and inverse kinematics. Important issues concerning the operation such as system calibration are outlined. The second part describes the brain exploration software framework integrating the robotic assistant. Two subareas of brain exploration are elaborated on. First, a basic stereotactic control framework which provides planning, registration, and insertion control modalities is presented. Second, the technique of Optical Coherence Tomography (OCT) imaging is set into the context of brain imaging and optical brain exploration. The resulting computer- and robot-assisted stereotactic framework is then tested with respect to its performance in a testbed setup and in the real surgical scenario. First, the mechanical positioning accuracy is analyzed. Second, the framework is applied to two future applications in the context of brain exploration: robot-assisted microelectrode recordings and robot-assisted intracranial imaging using OCT. Concepts for data analysis pointing towards electrophysiological and optical brain mapping are introduced and evaluated based on the acquired data. Arising in the context of OCT imaging, two methods of image segmentation and filtering adapted to OCT images are presented. Analyzing the mechanical positioning accuracy shows that the presented framework allows for precise small animal stereotaxy. Results of the electrophysiological and optical data analysis support the idea of robot-assisted brain mapping via characteristic features of certain areas. This, in turn, gives rise to the idea of near field navigation in the vicinity of the probe tip, a novel navigation modality. In summary, the resulting system offers new alternatives for brain research on the small animal model.}, year = {2008}, series = {University of L{\{\dq}u}beck}, tags = {SM}, note = {Stereotactic Micronavigation} } @Inproceedings { mefm_08, author = {Martens, Volker and Ernst, Floris and Fr{\{\dq}a}nkler, Thomas and Matth{\{\dq}a}us, Lars and Schlichting, Stefan and Schweikard, Achim}, title = {Ein Client-Server Framework f{\{\dq}u}r Trackingsysteme in medizinischen Assistenzsystemen}, abstract = {Wir pr{\{\dq}a}sentieren ein Framework f{\{\dq}u}r die einfache und universelle Verwendung von verschiedenen Trackingsystemen f{\{\dq}u}r medizinische Assistenzsysteme. Im Fokus steht hierbei die Trennung der Anwendung von der direkten Kommunikation mit den unterschiedlichen Trackingger{\{\dq}a}ten. Dank einer TCP/IP Schnittstelle ist eine Sprachen-, Plattform- und Computer-unabh{\{\dq}a}ngige Entwicklung und Benutzung m{\{\dq}o}glich. Beispielsweise k{\{\dq}o}nnen dadurch verschiedene Anwendungen gleichzeitig auf denselben Tracker zugreifen, um so die Dokumentation oder Fehlersuche zu vereinfachen. F{\{\dq}u}r Anwendungsentwicklungen in Java bietet eine zugeh{\{\dq}o}rige Java-Bibliothek h{\{\dq}a}ufig gebrauchte Verarbeitungsmethoden wie Kalibrierungen und St{\{\dq}o}rungskorrekturen. Eine Java-Bedienoberfl{\{\dq}a}che gew{\{\dq}a}hrt einfachen Zugriff auf diese Funktionen sowie die Anzeige und Speicherung von Trackingwerten und Kalibrationsergebnissen. Mittels XML werden die Ergebnisse strukturiert abgelegt und k{\{\dq}o}nnen auch von nicht in Java geschriebenen Anwendungen sicher verwendet werden.}, year = {2008}, volume = {7}, address = {Leipzig, Germany}, series = {CURAC}, editor = {Bartz, Dirk and Bohn, S. and Hoffmann, J.}, pages = {7-10}, keywords = {Anwendungsentwicklung; Hand-Auge-Kalibrierung; St{\{\dq}o}rungskorrektur; TCP/IP; Tracking}, tags = {NLS}, note = {timestamp=2008.08.12} } @Techreport { r_08, author = {Richter, Lars}, title = {Evaluation von Korrelationsmodellen zwischen Surrogatsignalen und internen Featurepoints auf Basis von 4D-CTs}, abstract = {The aim of radiotherapy is to insert a dose into a selceted target region and to destroy tumor tissue, for example. In this process, healthy tissue should be affected as less as possible. Particularly by moving pieces of the body, this task is difficult. Especially by tumors in the lung, the respiration is responsible for large movements of the tumor. Conventionally, the dose has to be inserted into the whole movement track of the target region. The CyberKnife is a tool that can compensate the tumor movements. Because, if the position of the tumor is known at every single timepoint, the irradiation source can follow the tumor movement. Thus, the additional irradiation region will be reduced considerably. Because the tumor isn't visible, direct tracking of the tumor is hardly possible. X-rays have to be used for estimating the tumor position. This has to be done with a high frequency to compensate the tumor movements. This would mean an additional damage to the patient, because of the required X-rays. Instead, the surface of the abdomen and of the chest is visible. Positions on these surfaces can be estimated accurately. The chest and the abdomen are moving during respiration as the tumor does. A solution of this problem gives the measurement of so called surrogate signals. This are signals that can be estimated easier and can be linked to the real position of the tumor via a mathematical modell. These mathematical modells are called correlation modells. External markers, i.e. LEDs, can be tracked precisely. As well, this applies to recognizable structures in the 4D-CT at or in the heart, at the backbone or at other points, but not necessarily for fiducials implanted in the target region. But, it isn't always easy to find a proper surrogatesignal for a selected target region. This work concentrates on the purpose to provide a simple user enviroment for finding surrogate signals. Additionally, internal featurepoints are to be found. CT datasets that reflect the progress of a respiration cycle serve as basis of the analysis of the movements. During this work, the handling of medical data in the DICOM-format and the realtime visualisation of 4D volume data was developed. Furthermore, algorithms for the realtime localisation and tracing of distinctive points were implemented and the results were evaluated.}, year = {2008}, series = {Universit{\{\dq}a}t zu L{\{\dq}u}beck}, keywords = {correlation; feature points; Respiration surrogates} } @Misc { b_08, author = {Barnes, Eric}, title = {Faster respiratory motion prediction aids radiotherapy}, year = {2008}, tags = {MCRT}, file_url = {http://www.auntminnie.com/redirect/redirect.asp?itemid=82752}, note = {Motion Compensation in Radiosurgery} } @Inproceedings { scck_08, author = {Strulik, Konrad L. and Cho, Min H. and Collins, Brian T. and Khan, Noureen and Banovac, Filip and Slack, Rebecca and Cleary, Kevin}, title = {Fiducial migration following small peripheral lung tumor image-guided CyberKnife stereotactic radiosurgery: Visualization, Image-guided Procedures, and Modeling. Proceedings of SPIE}, abstract = {To track respiratory motion during CyberKnife stereotactic radiosurgery in the lung, several (three to five) cylindrical gold fiducials are implanted near the planned target volume (PTV). Since these fiducials remain in the human body after treatment, we hypothesize that tracking fiducial movement over time may correlate with the tumor response to treatment and pulmonary fibrosis, thereby serving as an indicator of treatment success. In this paper, we investigate fiducial migration in 24 patients through examination of computed tomography (CT) volume images at four time points: pre-treatment, three, six, and twelve month post-treatment. We developed a MATLAB based GUI environment to display the images, identify the fiducials, and compute our performance measure. After we semi-automatically segmented and detected fiducial locations in CT images of the same patient over time, we identified them according to their configuration and introduced a relative performance measure (ACD: average center distance) to detect their migration. We found that the migration tended to result in a movement towards the fiducial center of the radiated tissue area (indicating tumor regression) and may potentially be linked to the patient prognosis.}, year = {2008}, DOI = {10.1117/12.769042}, volume = {6918}, address = {San Diego, CA}, series = {SPIE}, pages = {69181A-69181A-9}, tags = {MCRT}, file_url = {https://doi.org/10.1117/12.769042}, note = {Motion Compensation in Radiosurgery} } @Inproceedings { kfkf_08, author = {Kantelhardt, Sven and Fadini, Tommaso and Kallenberg, K. and Finke, Markus and Matth{\{\dq}a}us, Lars and Schweikard, Achim and Rohde, V. and Giese, Alf}, title = {Comparison of functional brain mapping by computer controled roboterized transcranial-magnet-stimulation and functional MRI}, abstract = {The knowledge of the exact localization of motor cortical areas can be crucial for neurosurgical therapy planning in patients suffering from processes near the central region. For the time beeing functional magnet resonance imaging (f-MRI, so called BOLD-sequences) can be regarded as the gold-standard for non-invasive localization of the functional areas of the brain. Yet in some cases this technique might be insufficient. We here present a novel technique designed for this task: The image-guided computer controled roboterized transcranial-magnet-stimulation (R-TMS). For R-TMS a roboter-arm moves a transcranial magnet-stimulation coil over the patients head. The movements follow a grid placed on a virtuall (MRI-)image of the central region. At each point of the grid a number of stimulating impulses is given and the resulting motor-response is recorded by electromyography of the concerned muscles (in our study M. Brachioradialis, thenar and hypothenar). The resulting data is projected on a surface map of the brain. A healthy probande and 6 consecutive patients suffering form tumors in or near the central region were examined by R-TMS and f-MRI (finger-tapping). The resulting Data of both techniques were compared. R-TMS examinations were feasible and provided high resolution functional maps of the central region. The data corresponded to the classical anatomical landmarks (hand notch and central gyrus). It also matched the results from the f-MRIs closely. In contrast to the f-MRI the motor-areas of single muscles or muscle groups could be clearly located and delineated from one another by R-TMS. R-TMS is a feasible method for functional imaging of the motor cortex. The resolution allows the identification of motor areas of individual muscle groups and is in so far superior to the conventional f-MRI. It might help neurosurgical and interventional therapy planning in patients suffering from processes in or near the central region of the cortex.}, year = {2008}, address = {W{\{\dq}u}rzburg}, tags = {TMS}, note = {Transcranial Magnetic Stimulation} } @Inproceedings { ebs_07, author = {Ernst, Floris and Bruder, Ralf and Schlaefer, Alexander}, title = {Processing of Respiratory Signals from Tracking Systems for Motion Compensated IGRT}, abstract = {Purpose: Improving the quality of signals obtained with optical and magnetic tracking systems. Special focus is placed on the measurement of respiratory motion signals for motion compensated IGRT and the possibility of filtering this data to obtain low-noise breathing signals. Method and Materials: The accuracy of five different tracking systems (NDI Polaris®, active and passive, Clarion MicronTracker®, BIG FP5000, NDI Aurora®) was examined by (a) tracking stationary markers over several hours, and (b) by attaching the markers to a Kuka KR16 robot to simulate human respiration. The {\`a} trous wavelet decomposition was used to decompose the measured signal into scales, and to remove scales related to high frequencies, i.e., noise. The method was applied to a sinusoidal signal with artificial noise modeled according to (a), to real measurements for a sinusoidal motion of the robot, and to a set of breathing motion data from an actual patient treated with the CyberKnife®. Motion prediction was applied to the data. Results: The error on the measurements of the stationary marker approaches a Gaussian distribution. For a tracking rate of 60 Hz, information related to breathing motion is represented by higher scales of the {\`a} trous wavelet decomposition. Removing the first three scales and resconstructing the signal from the remaining scales and trend it is possible to obtain close and smooth approximations of the original signal. The normalized RMS error for motion prediction is 0.3368 mm and 0.1378 mm for a simulated and the smoothed signal using normalized LMS prediction. Conclusion: Data from tracking devices is subject to device specific measurement noise. The {\`a} trous wavelet decomposition can be used to remove frequencies related to noise from measured breathing signals. The resulting signal is suitable for further processing, e.g., correlation with or prediction of tumor motion in the context of motion compensated IGRT.}, year = {2007}, DOI = {10.1118/1.2761413}, volume = {34}, address = {Minneapolis-St. Paul, MN, USA}, series = {Medical Physics}, pages = {2565}, number = {6}, tags = {MCRT}, file_url = {https://doi.org/10.1118/1.2761413}, note = {timestamp=2007.03.30} } @Inproceedings { bdsm_07, author = {Bodensteiner, Christoph and Darolti, Christina and Schumacher, H. and Matth{\{\dq}a}us, Lars and Schweikard, Achim}, title = {Motion and Positional Error Correction for Cone Beam 3D-Reconstruction with Mobile C-Arms}, year = {2007}, address = {Brisbane, Australia}, tags = {ICA}, note = {Interactive C-Arm} } @Article { khmm_07, author = {Kleemann, Markus and Hildebrand, Philipp and Mirow, Lutz and Martens, Volker and Schlichting, Stefan and Be{\v{s}}irevi{\c}, Armin and B{\{\dq}u}rk, Conny and Roblick, Uwe and Schweikard, Achim and Bruch, Hans-Peter}, title = {Navigationsunterst{\{\dq}u}tzte Leberchirurgie: Stand der klinischen und experimentellen Forschung}, year = {2007}, journal = {Schleswig-Holsteinisches {\{\dq}A}rzteblatt}, volume = {10}, pages = {51-56}, tags = {NLS}, note = {Navigation in liver surgery} } @Inproceedings { sjks_07, author = {Schlaefer, Alexander and Jungmann, O. and Kilby, Warren and Schweikard, Achim}, title = {Objective specific beam generation for image guide robotic radiosurgery}, year = {2007}, address = {Berlin}, tags = {TP} } @Inproceedings { rsed_07, author = {Ramrath, Lukas and Schlaefer, Alexander and Ernst, Floris and Dieterich, Sonja and Schweikard, Achim}, title = {Prediction of respiratory motion with a multi-frequency based Extended Kalman Filter}, abstract = {In this work, an Extended Kalman Filter formulation for respiration motion tracking is introduced. Based on the assumption of multiple sinusoidal components contributing to respiratory motion, a state-space model is developed. Performance of the filter is tested on data sets of patients subject to radiotherapy. Comparison to an nLMS predictor shows that the Kalman filter is less sensitive to systematic errors during target prediction.}, year = {2007}, DOI = {10.1007/s11548-007-0083-7}, volume = {2}, address = {Berlin, Germany}, series = {International Journal of CARS}, pages = {56-58}, number = {supp. 1}, tags = {MCRT}, file_url = {https://doi.org/10.1007/s11548-007-0083-7}, note = {timestamp=2007.03.30} } @Inproceedings { shmb_07, author = {Schlichting, Stefan and Hildebrand, Philipp and Martens, Volker and Be{\v{s}}irevi{\c}, Armin and Kleemann, Markus and Roblick, Uwe and Mirow, Lutz and B{\{\dq}u}rk, Conny and Schweikard, Achim and Bruch, Hans-Peter}, title = {Intraoperative documentation of laparoscopic radiofrequency ablation of liver tumors -- First Experiences}, year = {2007}, volume = {21}, address = {Berlin, Germany}, series = {CARS}, tags = {NLS}, file_url = {http://www.cars-int.org/}, note = {timestamp=2007.03.30} } @Inproceedings { rsh_07, author = {Ramrath, Lukas and Schweikard, Achim and Hofmann, Ulrich G.}, title = {Spherical Assistant for Stereotactic Surgery}, year = {2007}, address = {San Diego, CA, USA}, tags = {SM}, note = {Stereotactic Micronavigation} } @Article { hsmb_07, author = {Hildebrand, Philipp and Schlichting, Stefan and Martens, Volker and Be{\v{s}}irevi{\c}, Armin and Kleemann, Markus and Roblick, Uwe and Mirow, M. and B{\{\dq}u}rk, Conny and Schweikard, Achim and Bruch, Hans-Peter}, title = {Prototype of an intraoperative navigation and documentation system for laparoscopic radiofrequency ablation: First experiences}, abstract = {Aims: Laparoscopic radiofrequency ablation (RFA) is an accepted approach to treat unresectable liver tumours, distinguishing itself from other techniques by combining minimal invasiveness and the advantages of a surgical approach. The major task of laparoscopic RFA is the accurate needle placement according to preoperative planning to achieve complete tumour ablation. This study investigates the value of an image-guided surgery system to accomplish this task. Methods: An image-guided surgery system for laparoscopic liver treatments (LapAssistent) based on a 3D-navigation scene was developed. A laparoscopic ultrasound probe and a RFA needle could be navigated using an electromagnetic tracking system. The system was studied using a perfused tumour-mimic-model of a porcine liver. Navigating the RFA needle, the tumours were ablated. Results: The system enables the surgeon to intraoperatively update the three-dimensional planning data in case of new findings. The RFA needle could be placed accurately in a targeted tumour, even out of the ultrasound plane. In case of multiple tumours lying in close spatial relationship, the documentation module helps to keep track of the already ablated tumours and those that still need to be treated. Conclusion: The system adds benefit to laparoscopic RFA enabling the surgeon to place the needle accurately inside the targeted tumours using the navigation scene. A manual alignment of the preoperative data to the physical space produces a feasible result for a restricted region. A precise measurement of the accuracy of this process has to be done. The possibility to update the three-dimensional model with new intraoperative findings enables the surgeon to adapt to a new intraoperative situation. Furthermore the possibility to mark ablated tumours helps to keep track of the operation plan.}, year = {2007}, issn = {0748-7983}, journal = {European Journal of Surgical Oncology}, volume = {34}, pages = {418-421}, number = {4}, keywords = {Image-guided surgery; Laparoscopic; liver; Navigation; Radiofrequency ablation}, tags = {NLS}, note = {Navigation in liver surgery} } @Phdthesis { b_07, author = {Binder, Norbert}, title = {Realisierung eines robotischen R{\{\dq}o}ntgen-C-Bogens. Technische Umsetzung und Applikationen}, year = {2007}, series = {Universit{\{\dq}a}t zu L{\{\dq}u}beck}, tags = {ICA}, note = {Interactive C-Arm} } @Inproceedings { Kyriakou2007CAOS, author = {Kyriakou, Yiannis and Lapp, Robert and Niebler, Christine and Prell, Daniel and Henke, Maria and Kalender, Willi}, title = {Rekonstruktionsplattform f{\{\dq}u}r die intraoperative Bildgebung: 7th Annual Meeting of CAOS-International}, year = {2007}, booktitle = {Computer Assisted Orthopaedic Surgery : 7th Annual Meeting of CAOS-International}, address = {Heidelberg} } @Inproceedings { fbms_07, author = {Finke, Markus and Bruder, Ralf and Matth{\{\dq}a}us, Lars and Schweikard, Achim}, title = {Spulenpositionierung bei TMS-Behandlungen mit Hilfe von Kraftsensorik}, abstract = {Die roboterassistierte Positionierung der Magnetspule bei transkranieller Magnetstimulation erm{\{\dq}o}glicht es, Behandlungspositionen gezielt und wiederholt anzufahren, sowie Patientenbewegungen auszugleichen. Um die Spule direkt auf dem Kopf aufzusetzen, wird die Feinpositionierung derzeit in mehreren Schritten manuell kommandiert, wobei der Operateur auf die Mithilfe des Patienten und dessen subjektives Andruckempfinden angewiesen ist. Gerade in F{\{\dq}a}llen, in denen die Sensitivit{\{\dq}a}t im Untersuchungsbereich eingeschr{\{\dq}a}nkt ist, f{\{\dq}a}llt diese Mithilfe oft weg. Zur Erh{\{\dq}o}hung der Sicherheit verwenden wir nun Kraftmesszellen, die auftretende Kr{\{\dq}a}fte an der Spule messen und Ber{\{\dq}u}hrungen melden. Dieses Feedback erm{\{\dq}o}glicht eine automatisierte Initialpositionierung der Spule und stellt eine Bescheunigung des aufw{\{\dq}a}ndigen Feinpositionierungsprozesses in Aussicht.}, year = {2007}, keywords = {Kraftsensorik; Positionierung; Robotik; Sicherheit; Transkranielle Magnetstimulation (TMS)}, tags = {TMS}, note = {Transcranial Magnetic Stimulation} } @Article { mdws_07, author = {Muacevic, Alexander and Drexler, Christian and Wowra, A. and Schweikard, Achim and Schlaefer, Alexander and Hoffmann, R. T. and Wilkowski, R. and Winter, H.}, title = {Technical Description, Phantom Accuracy, and Clinical Feasibility for Single-session Lung Radiosurgery Using Robotic Image-guided Real-time Respiratory Tumor Tracking}, abstract = {To describe the technological background, the accuracy, and clinical feasibility for single session lung radiosurgery using a real-time robotic system with respiratory tracking. The latest version of image-guided real-time respiratory tracking software (Synchrony®, Accuray Incorporated, Sunnyvale, CA) was applied and is described. Accuracy measurements were performed using a newly designed moving phantom model. We treated 15 patients with 19 lung tumors with robotic radiosurgery (CyberKnife®, Accuray) using the same treatment parameters for all patients. Ten patients had primary tumors and five had metastatic tumors. All patients underwent computed tomography-guided percutaneous placement of one fiducial directly into the tumor, and were all treated with single session radiosurgery to a dose of 24 Gy. Follow up CT scanning was performed every two months. All patients could be treated with the automated robotic technique. The respiratory tracking error was less than 1 mm and the overali shape of the dose profile was not affected by target motion and/or phase shift between fiducial and optical marker motion. Two patients required a chest tube insertion after fiducial implantation because of pneumothorax. One patient experienced nausea after treatment. No other short-term adverse reactions were found. One patient showed imaging signs of pneumonitis without a clinical correlation. Single-session radiosurgery for lung tumor tracking using the described technology is a stable, safe, and feasible concept for respiratory tracking of tumors during robotic lung radiosurgery in selected patients. Longer follow-up is needed for definitive clinical results.}, year = {2007}, issn = {1533-0346}, journal = {Technology in Cancer Research and Treatment}, volume = {6}, pages = {321-328}, number = {4}, keywords = {Cyberknife; Image guided robotics; Lung radiosurgery; Radiosurgery}, tags = {MCRT}, note = {Motion Compensation in Radiosurgery} } @Inproceedings { rhhms_07, author = {Ramrath, Lukas and Hofmann, Ulrich G. and H{\{\dq}u}ttmann, Gereon and Moser, Andreas and Schweikard, Achim}, title = {Towards Automated OCT-based Identification of White Brain Matter}, abstract = {A novel model-based identification of white brain matter in OCT A-scans is proposed. Based on nonlinear energy operators used in the classification of neural activity, candidates for white matter structures are extracted from a baseline-corrected signal. Validation of candidates is done by evaluating the correspondence to a simplified intensity model which is parametrized beforehand. Results for identification of white matter in rat brain in vitro show the capability of the proposed algorithm.}, year = {2007}, DOI = {10.1007/978-3-540-71091-2}, keywords = {gray matter; OCT; white matter}, tags = {OCT}, file_url = {https://doi.org/10.1007/978-3-540-71091-2}, note = {OCT-based Neuro-Imaging} } @Inproceedings { hms_07, author = {Hennings, Arne and Martens, Volker and Schweikard, Achim}, title = {Videooptische 3D-Lagebestimmung zylinderf{\{\dq}o}rmiger Instrumente f{\{\dq}u}r die Laparoskopie}, year = {2007}, address = {Karlsruhe}, tags = {NLS}, note = {Navigation in liver surgery} } @Inproceedings { gr_07, author = {Gasca, Fernando and Ramrath, Lukas}, title = {Model-Based Detection of White Matter in Optical Coherence Tomography Data}, abstract = {A method for white matter detection in Optical Coherence Tomography A-Scans is presented. The Kalman filter is used to obtain a slope change estimate of the intensity signal. The estimate is subsequently analyzed by an spike detection algorithm and then evaluated by a neural network binary classifier (Perceptron). The capability of the proposed method is shown through the quantitative evaluation of simulated A-Scans, as well as applying the method on data obtained from a rat's brain in vitro. Results show that the developed algorithm identifies less false positives than other two spike detection methods, thus, enhancing the robustness and quality of detection.}, year = {2007}, address = {Lyon, France}, tags = {OCT}, note = {OCT-based Neuro-Imaging} } @Inproceedings { ess_07, author = {Ernst, Floris and Schlaefer, Alexander and Schweikard, Achim}, title = {Prediction of Respiratory Motion with Wavelet-based Multiscale Autoregression}, abstract = {In robotic radiosurgery, a photon beam source, moved by a robot arm, is used to ablate tumors. The accuracy of the treatment can be improved by predicting respiratory motion to compensate for system delay. We extend the wavelet-based multiscale autoregressive prediction algorithm by introducing a new exponential averaging parameter and the use of the Moore-Penrose pseudo inverse to cope with long-term signal dependencies and system matrix irregularity, respectively. In test cases, this new algorithm outperforms normalized LMS predictors by as much as 50%. In settings with real data, we achieve an improvement around 5-10%.}, year = {2007}, DOI = {10.1007/978-3-540-75759-7\_81}, volume = {4792}, publisher = {Springer}, address = {Brisbane, Australia}, series = {Lecture Notes in Computer Science}, editor = {Ayache, Nicholas and Ourselin, S. and Maeder, A.}, pages = {668-675}, tags = {MCRT}, file_url = {https://doi.org/10.1007/978-3-540-75759-7\_81}, note = {timestamp=2007.03.30} } @Inproceedings { MICCAI07, title = {International Conference on Medical Image Computing and Computer Assisted Intervention (MICCAI)}, year = {2007}, volume = {10}, address = {Brisbane, Australia}, editor = {Ayache, Nicholas and Ourselin, S. and Maeder, A.}, file_url = {www.miccai2009.org}, note = {timestamp=2007.03.30} } @Inproceedings { Martens2007b, author = {Martens, Volker and Schlichting, Stefan and Be{\v{s}}irevi{\c}, Armin and Hildebrand, Philipp and Kleemann, Markus and Bruch, Hans-Peter and Schweikard, Achim}, title = {Der LapAssistent - Ein System zur Navigation bei laparoskopischen Leberoperationen}, year = {2007}, address = {Berlin}, tags = {NLS}, note = {Navigation in liver surgery} } @Inproceedings { bds_07, author = {Bodensteiner, Christoph and Darolti, Christina and Schweikard, Achim}, title = {3D-reconstruction of bone surfaces from sparse projection data with a robotized c-arm by deformable 2D/3D registration}, year = {2007}, volume = {21}, address = {Berlin, Germany}, series = {CARS}, tags = {ICA}, file_url = {http://www.cars-int.org/}, note = {timestamp=2007.03.30} } @Inproceedings { bmsb_07, author = {Bodensteiner, Christoph and Martens, Volker and Schlichting, Stefan and Binder, Norbert and Burgkart, Rainer and Schweikard, Achim}, title = {3D-Rekonstruktion aus DSA-Projektionsdaten mittels diskreter Tomographie - Ein Kombinationsansatz mit einem iterativen Rekonstruktionsverfahren}, year = {2007}, address = {Munich, Germany}, tags = {ICA}, note = {Interactive C-Arm} } @Inproceedings { Singla2007, author = {Singla, P. and Singh, T. and Schweikard, Achim}, title = {A Multiresolution Adaptive Approach for Respiratory Motion Modeling}, year = {2007}, address = {Bethesda, Maryland} } @Inproceedings { Bodensteiner2007, author = {Bodensteiner, Christoph and Darolti, Christina and Schweikard, Achim}, title = {Approximative Rekonstruktion von Knochenoberfl{\{\dq}a}chen mittels elastischer 2D-3D Registrierung eines generischen Modells mit Flouroskopieaufnahmen}, year = {2007}, address = {Karlsruhe}, tags = {ICA}, note = {Interactive C-Arm} } @Article { mbbs_07, author = {Matth{\{\dq}a}us, Lars and Binder, Norbert and Bodensteiner, Christoph and Schweikard, Achim}, title = {Closed-form inverse kinematic solution for fluoroscopic C-arms}, abstract = {This paper presents a closed-form solution to the inverse kinematic problem for general fluoroscopic C-arms. The resulting algorithm determines the necessary joint parameters for imaging a given point of interest p from a given direction z. The existence and uniqueness of the solution is proven for all p and z. The inverse kinematics lays the basis for a completely robotized C-arm. The paper describes some applications for such an automatized device and presents the first results.}, year = {2007}, DOI = {10.1163/156855307780851957}, journal = {Advanced Robotics}, volume = {21}, pages = {869-886}, number = {8}, keywords = {computed tomography; digital subtraction angiography; Inverse kinematics; robotized fluoroscopic C-arm}, tags = {ICA}, file_url = {https://doi.org/10.1163/156855307780851957}, note = {Interactive C-Arm} } @Phdthesis { Schlaefer2007b, author = {Schlaefer, Alexander}, title = {Computer Assisted Planning for Robotic Radiosurgery}, year = {2007}, address = {L{\{\dq}u}beck}, series = {Technisch-Naturwissenschaftliche Fakult{\{\dq}a}t der Universit{\{\dq}a}t zu L{\{\dq}u}beck}, note = {Dissertation} } @Inproceedings { Schlaefer2007a, author = {Schlaefer, Alexander and Blanck, Oliver and Schweikard, Achim}, title = {Interactive Multi-criteria Inverse Planning for Robotic Radiosurgery}, year = {2007}, address = {Toronto, Canada,}, tags = {TP} } @Article { hbks_07, author = {Hildebrand, Philipp and Be{\v{s}}irevi{\c}, Armin and Kleemann, Markus and Schlichting, Stefan and Martens, Volker and Schweikard, Achim and Bruch, Hans-Peter}, title = {Design and development of adapters for electromagnetic trackers to perform navigated laparoscopic radiofrequency ablation}, abstract = {Background: Laparoscopic radiofrequency ablation (RFA) is an accepted approach to treat unresectable liver tumours distinguishing itself from other techniques by combining minimal invasiveness and the advantages of a surgical approach. The major task of laparoscopic RFA is the accurate needle placement to achieve complete tumour ablation. The use of an ultrasound-based, laparoscopic online-navigation system could increase the safety and accuracy of punctures. To connect such a system with the laparoscopic ultrasound (LUS) transducer or the RFA needle especially designed adapters are needed. In this article we present our first experiences and prototypes for different sterilizable adapters for an electromagnetic navigation system for laparoscopic RFA. Methods: All adapters were constructed with the help of a standard 3D CAD software. The adapters were built from medical stainless steel alloys and polyetherketone (PEEK). Prototypes were built in aluminium and polyoxymethilen (POM). We have designed and developed several adapters for the connection of electromagnetical tracking systems with different RFA needles and a laparoscopic ultrasound transducers. Results: Based on earlier experiences of the initial version of the adapter, sterilisable adapters have been developed using biocompatible materials only. After short introduction, the adapters could be mounted to the laparoscopic ultrasound probe and the RFA needle under sterile conditions without any difficulties. Laboratory tests showed no disturbance of laparoscopic navigation system by the adapters. Anatomic landmarks in the liver could be safely reached. The adapters showed good feasibility, ergonomics, sterilizability and stability. Conclusion: The development of usable adapters is the prerequisite for accurate tracking of a RFA needle for laparoscopic navigation purposes as well as 3D navigated ultrasound data acquisition. We designed, tested and used different adapters for the use of a laparoscopic navigation system for the improvement of laparoscopic RFA.}, year = {2007}, DOI = {10.1186/1750-1164-1-7}, journal = {Annals of Surgical Innovation and Research}, volume = {1}, number = {7}, tags = {NLS}, file_url = {https://doi.org/10.1186/1750-1164-1-7}, note = {Navigation in liver surgery} } @Inproceedings { Beširević2007, author = {Be{\v{s}}irevi{\c}, Armin and Schlichting, Stefan and Martens, Volker and Hildebrand, Philipp and Roblick, Uwe and Mirow, Lutz and B{\{\dq}u}rk, Conny and Schweikard, Achim and Kleemann, Markus and Bruch, Hans-Peter}, title = {Design und Entwicklung von sterilisierbaren Adaptern f{\{\dq}u}r navigierte viszerale (Leber) Chirurgie und erste praktische Erfahrungen}, year = {2007}, address = {Berlin}, tags = {NLS}, note = {Navigation in liver surgery} } @Inproceedings { Kyriakou2007RSNA, author = {Kyriakou, Yiannis and Lapp, Robert and Niebler, Christine and Prell, Daniel and Henke, Maria and Kalender, Willi}, title = {Development and Integration of Correction Methods in a Vendor-independent Intraoperative Flat-Detector CT Image Reconstruction Platform}, year = {2007}, address = {Chicago}, note = {LL-PH6111-B01} } @Inproceedings { Martens2007a, author = {Martens, Volker and Be{\v{s}}irevi{\c}, Armin and Schlichting, Stefan and Kleemann, Markus and Hildebrand, Philipp and Bruch, Hans-Peter and Schweikard, Achim}, title = {Ein magnetisches Navigationssystem f{\{\dq}u}r die minimal-invasive Leberchirurgie}, year = {2007}, address = {Aachen 2007}, tags = {NLS}, note = {Navigation in liver surgery} } @Article { Ramrath2007, author = {Ramrath, Lukas and H{\{\dq}u}ttmann, Gereon and Hofmann, Ulrich G. and Bonsanto, Matteo C. M. and Tronnier, Volker and Moser, Andreas and Schweikard, Achim}, title = {Entwicklung eines robotergest{\{\dq}u}tzten Stereotaxieassistenten f{\{\dq}u}r die Kleintierhirnforschung}, year = {2007}, journal = {FOCUS MUL}, volume = {24}, pages = {229-231}, number = {4}, tags = {SM}, note = {Stereotactic Micronavigation} } @Article { hmss_07, author = {Hildebrand, Philipp and Martens, Volker and Schweikard, Achim and Schlichting, Stefan and Be{\v{s}}irevi{\c}, Armin and Kleemann, Markus and Roblick, Uwe and Mirow, Lutz and B{\{\dq}u}rk, Conny and Bruch, Hans-Peter}, title = {Evaluation of an online navigation system for laparoscopic interventions in a perfused ex vivo artificial tumor model of the liver}, abstract = {Background. Laparoscopic radiofrequency ablation (RFA) is a safe and effective method for tumor destruction in patients with unresectable liver tumors. However, accurate probe placement using laparoscopic ultrasound guidance is required to achieve complete tumor ablation. After evaluation of an ultrasound navigation system for transcutaneous and open RFA, we now intend to tranfer this technique to laparoscopic liver surgery. This study aimed to evaluate an electromagnetic navigation system for laparoscopic interventions using a perfusable ex vivo artificial tumor model. Materials and methods. First a special adapter was developed to attach the ultrasound and electromagnetic tracking-based navigation system to a laparoscopic ultrasound probe. The laparoscopic online navigation system was studied in a laparoscopic artificial tumor model using perfused porcine livers. Artificial tumors were created by injection of a mixture of 3% agarose, 3% cellulose, and 7% glycerol, creating hyperechoic lesions in ultrasound. Results. This study showed that laparoscopic ultrasound-guided navigation is technically feasible. Even in cases of angulation of the ultrasound probe no disturbances of the navigation system could be detected. Artificial tumors were clearly visible on laparoscopic ultrasound and not felt during placement of the RFA probe. Anatomic landmarks and simulated 'tumors' in the liver could be reached safely. Discussion. Laparoscopic RFA requires advanced laparoscopic ultrasound skills for accurate placement of the RFA probe. The use of an ultrasound-based, laparoscopic online navigation system offers the possibility of out-of-plane needle placement and could increase the safety and accuracy of punctures. The perfused artificial tumor model presented a realistic model for the evaluation of this new technique.}, year = {2007}, issn = {1477-2574}, DOI = {10.1080/13651820601089077}, journal = {The Official Journal of the International Hepato Pancreato Biliary Association}, volume = {9}, pages = {190-194}, number = {3}, keywords = {artificial tumor model; laparoscopic ultrasound; liver; Navigation; Radiofrequency ablation}, tags = {NLS}, file_url = {https://doi.org/10.1080/13651820601089077}, note = {Navigation in liver surgery} } @Inproceedings { mabe_07, author = {Martens, Volker and Be{\v{s}}irevi{\c}, Armin and Schlichting, Stefan and Schweikard, Achim}, title = {Evaluation und relative Positionskorrektur eines magnetischen Trackingsystems f{\{\dq}u}r die minimal-invasive Chirurgie}, year = {2007}, address = {Karlsruhe}, pages = {271-274}, tags = {NLS}, note = {Navigation in liver surgery} } @Inproceedings { bsmk_07, author = {Be{\v{s}}irevi{\c}, Armin and Schlichting, Stefan and Martens, Volker and Kleemann, Markus and Hildebrand, Philipp and Roblick, Uwe and B{\{\dq}u}rk, Conny and Schweikard, Achim and Bruch, Hans-Peter}, title = {Design and Development of sterilisable adapters for navigated visceral (liver) surgery and first practical experiences}, year = {2007}, address = {Berlin}, tags = {NLS}, note = {Navigation in liver surgery} } @Article { mgws_06, author = {Matth{\{\dq}a}us, Lars and Giese, Alf and Wertheimer, Daniel and Schweikard, Achim}, title = {Planning and analyzing robotized TMS using virtual reality.}, abstract = {Transcranial Magnetic Stimulation (TMS) is a powerful method to examine the brain and non-invasively treat disorders of the central nervous system. Magnetic stimulation of the motor cortex results in the activation of corresponding muscle groups. Hereby, accurate placement of the TMS coil to the patient's head is crucial to successful stimulation. We developed a way to position the TMS coil using a robot and navigate it in virtual reality based on an online registration of the cranium relative to 3D magnetic resonance imaging data. By tracking the head and robotic motion compensation, fixation of the patient's head becomes obsolete. Furthermore, a novel method for motor cortex mapping is presented. The robotized TMS system is used to obtain the characteristic field of a TMS coil. This field is registered to the field of motor evoked potential measurements at the patient's head to yield a prediction of the motoric center of a target muscle.}, year = {2006}, journal = {Studies in Health Technology and Informatics}, volume = {119}, pages = {373-378}, keywords = {Brain Mapping; Germany; Humans; Robotics; Transcranial Magnetic Stimulation; User-Computer Interface}, tags = {TMS}, note = {timestamp=2006.11.21} } @Inbook { bbmbs_06, author = {Binder, Norbert and Bodensteiner, Christoph and Matth{\{\dq}a}us, Lars and Burgkart, Rainer and Schweikard, Achim}, title = {Mobile Robots - Towards New Applications}, abstract = {Industry is using robots for years to achieve high working precision at reasonable costs. When performing monotonous work, attention of human operators weakens over time, resulting in mistakes. This increases production costs and reduces productivity. There is also a constant pressure to reduce costs for industrial processes while keeping or increasing their quality. The idea of integrating robots into the OR was born over a decade ago. Most of these robots are designed for invasive tasks, i.e. they are active tools for medical treatment. Some are telemanipulation systems, filtering tremor and scaling the movements of the user. Others move according to pre-operatively calculated plans positioning instruments of all kinds. Main goal was to achieve a higher precision in comparison to human surgeons, often ignoring the time- and financial aspect. As the economic situation at hospitals becomes more and more strained, economic factors such as costs, time and OR-utilization become more and more important in medical treatment. Now, only few systems can fulfil both requirements: increase precision and reduce the duration of an intervention. We want to introduce another type of robot which assists the surgeon by simplifying the handling of everyday OR equipment. Main goal is to integrate new features such as enhanced positioning modes or guided imaging while keeping the familiar means of operation and improving workflow. The robotic assistance system works in the background until the user wants to use the additional features. On base of a common non-isocentric fluoroscopic C-arm we will explain the way from a manually operated device into an interactive fluoroscope with enhanced positioning and imaging functionality. We first discuss problems of a common C-arm and present possible solutions. We then examine the mechanical structure and derive the direct and inverse kinematics solutions. In the next section, we describe how the device was equipped with motors, encoders and controllers. Finally, we discuss the results of the functionality study and show ways to improve the next generation of robotized C-arms.}, year = {2006}, isbn = {3-86611-198-3}, publisher = {Pro Literatur Verlag, Germany / Advanced Robotic Systems, Austria}, editor = {Lazinica, Aleksandar}, pages = {403-418} } @Inbook { bbmb_06, author = {Binder, Norbert and Bodensteiner, Christoph and Matth{\{\dq}a}us, Lars and Burgkart, Rainer and Schweikard, Achim}, title = {Mobile Robots: towards new applications}, year = {2006}, isbn = {3-86611-198-3}, DOI = {10.5772/4701}, publisher = {Pro Literatur Verlag}, address = {Germany,Austria}, editor = {Lazinica, Aleksandar}, pages = {403-418}, tags = {ICA}, file_url = {https://doi.org/10.5772/4701}, note = {Interactive C-Arm} } @Techreport { Kleemann2006a, author = {Kleemann, Markus and Hildebrand, Philipp and Schlichting, Stefan and Be{\v{s}}irevi{\c}, Armin and Martens, Volker and Mirow, Lutz and Roblick, Uwe and B{\{\dq}u}rk, Conny and Schweikard, Achim and Bruch, Hans-Peter}, title = {Navigationsunterst{\{\dq}u}tzte Leberchirurgie: Stand der klinische und experimentellen Forschung}, year = {2006}, series = {Universit{\{\dq}a}t zu L{\{\dq}u}beck}, tags = {NLS}, note = {Navigation in liver surgery} } @Inbook { sa_06, author = {Schweikard, Achim and Adler Jr., John R.}, title = {New Technologies in Radiation Oncology}, year = {2006}, DOI = {10.1007/3-540-29999-8_26}, publisher = {Springer}, editor = {Schlegel, Wolfgang C. and Bortfeld, Thomas and Grosu, A.-L.}, pages = {337-343}, tags = {MCRT}, file_url = {https://doi.org/10.1007/3-540-29999-8_26}, note = {timestamp=2008.05.16} } @Inproceedings { BodensteinerCURAC06, author = {Bodensteiner, Christoph and Matth{\{\dq}a}us, Lars and Binder, Norbert and Burgkart, Rainer and Schweikard, Achim}, title = {Vascular tree reconstruction with discrete tomography - a practical approach}, year = {2006}, address = {Hannover}, series = {5. Jahrestagung}, tags = {ICA}, note = {Interactive C-Arm} } @Article { sbss_06, author = {Schlaefer, Alexander and Blanck, Oliver and Shiomi, Hiroya and Schweikard, Achim}, title = {Radiosurgery: identification of efficient treatment beams guided by autostereoscopic visualization}, abstract = {In robotic radiosurgery, an arrangement of cylindrical beams forms a high dose area conformal to the target region. Beams start at various positions around the patient, and are oriented towards arbitrary points in the target. Due to the large number of potential beams, only a small subset of beams can be considered during treatment planning. An efficient heuristics to select promising candidate beams can substantially shorten and improve treatment planning. We have developed a tool to visualize the 3D dose distribution and the beams. Using a hypsometric color scheme, the visualization toolkit (VTK), and an autostereoscopic display, we established the spatial extent of cold and hot spots and the effect of beams. With this new visualization tool we assessed the dose distribution and the beam arrangement of two treatment plans for intra-cranial tumors. Based on the visual analysis of the dose distribution and the effect of the beams, we derived a heuristics to place beams. Treatment plans computed for the heuristically placed beams were compared to the original plans. The results suggest that a heuristic pre-selection of potential treatment beams is possible. The visualization proved useful for 3D analysis of treatment plans and as a tool for rapid development of beam placement heuristics.}, year = {2006}, journal = {GMS CURAC}, volume = {1}, keywords = {auto-stereoscopic visualization; inverse planning; Radiosurgery; Robotics}, file_url = {http://www.egms.de/en/journals/curac/2006-1/curac000014.shtml} } @Article { ssa_06, author = {Schweikard, Achim and Schlaefer, Alexander and Adler Jr., John R.}, title = {Resampling: An optimization method for inverse planning in robotic radiosurgery}, abstract = {By design, the range of beam directions in conventional radiosurgery are constrained to an isocentric array. However, the recent introduction of robotic radiosurgery dramatically increases the flexibility of targeting, and as a consequence, beams need be neither coplanar nor isocentric. Such a nonisocentric design permits a large number of distinct beam directions to be used in one single treatment. These major technical differences provide an opportunity to improve upon the wellestablished principles for treatment planning used with GammaKnife or LINAC radiosurgery. With this objective in mind, our group has developed over the past decade an inverse planning tool for robotic radiosurgery. This system first computes a set of beam directions, and then during an optimization step, weights each individual beam. Optimization begins with a feasibility query, the answer to which is derived through linear programming. This approach offers the advantage of completeness and avoids local optima. Final beam selection is based on heuristics. In this report we present and evaluate a new strategy for utilizing the advantages of linear programming to improve beam selection. Starting from an initial solution, a heuristically determined set of beams is added to the optimization problem, while beams with zero weight are removed. This process is repeated to sample a set of beams much larger compared with typical optimization. Experimental results indicate that the planning approach efficiently finds acceptable plans and that resampling can further improve its efficiency.}, year = {2006}, DOI = {10.1118/1.2357020}, journal = {Medical Physics}, volume = {33}, pages = {4005-4011}, number = {11}, keywords = {inverse planning; optimization; Radiosurgery}, file_url = {https://doi.org/10.1118/1.2357020} } @Inproceedings { Schweikard2006, author = {Schweikard, Achim}, title = {Robotic Radiosurgery: The Kindest Cut of All, 2006. The Institution of Engineering and Technology Seminar on (Ref. No. 2006/11372)}, year = {2006}, pages = {73-92}, tags = {MCRT}, note = {timestamp=2006.11.22} } @Article { mgws_06a, author = {Matth{\{\dq}a}us, Lars and Giese, Alf and Wertheimer, Daniel and Schweikard, Achim}, title = {Solving the positioning problem in TMS}, abstract = {Transcranial Magnetic Stimulation (TMS) is a powerful method to examine the brain and tread disorders of the head painlessly and non-invasively. With TMS it is possible to stimulate regions of the motoric cortex which results in the activation of the corresponding muscles. Furthermore, TMS is becoming an alternative treatment for depressions. In all cases correct placement of the TMS coil at the patients head is crucial to the success of the application. We developed a way to guide the TMS coil by a KUKA robot with six degrees of freedom and navigate it using an online registration of the subject's head to its 3D magnetic resonance imaging (MRI) data. Furthermore, we used the advantages of a robotized system to acquire detailed magnetic field data for the TMS coil in use. Combining them with navigated measures of motor evoked potential using techniques from multimodal image registration gave rise to an alternative way of brain mapping.}, year = {2006}, journal = {GMS CURAC}, volume = {1}, address = {Berlin}, series = {4. Jahrestagung}, tags = {TMS}, note = {Transcranial Magnetic Stimulation} } @Article { grsb_06, author = {Gottschling, Heiko and Roth, Michael and Schweikard, Achim and Burgkart, Rainer}, title = {Intraoperative, Fluoroscopy-Based Planning for Complex Osteotomies of the Proximal Femur}, abstract = {Intertrochanteric osteotomy of the proximal femur is a surgical technique that aims at changing the orientation of the proximal part of the femur in the hip joint by removing a bone wedge between the trochanters. Due to its six degrees of freedom, it presents a complex planning problem for the surgeon. In this paper, we propose an intraoperative planning system for proximal femur osteotomies. Based on two fluoroscopic images taken during the procedure, a primitive femur model is reconstructed, which then allows the user to interactively determine the osteotomy parameters and perform the intervention with the help of a navigation system. Besides the fluoroscopic images, no other imaging is needed. Compared to the traditional approach, this system allows the intervention to be performed with higher precision and less radiation exposure for both patient and surgeon, requiring only little time overhead. An in vitro study has demonstrated the high accuracy and ease of use of this system.}, year = {2006}, DOI = {10.1002/rcs.29}, journal = {International Journal of Medical Robotics and Computer Assisted Surgery}, volume = {1}, pages = {67-73}, number = {3}, keywords = {Femur; fluoroscopy-based planning; intraoperative navigation; Osteotomy}, file_url = {https://doi.org/10.1002/rcs.29} } @Misc { s_06b, author = {Schweikard, Achim}, title = {Verfahren zur Bestimmung der Abbildungseigenschaften einer R{\{\dq}o}ntgendiagnostikeinrichtung mit einem C-Bogen}, year = {2006}, note = {DE Nr. 101 39 329, Patenteinreichung 10.08.2001} } @Inproceedings { Ramrath2006b, author = {Ramrath, Lukas and Muenchhof, M. and Isermann, R.}, title = {Local Linear Neural Networks Based on Principal Component Analysis}, year = {2006}, address = {Minneapolis, MN,} } @Inproceedings { mtbgs_06, author = {Matth{\{\dq}a}us, Lars and Trillenberg, Peter and Bodensteiner, Christoph and Giese, Alf and Schweikard, Achim}, title = {Robotized TMS for motion compensated navigated brain stimulation}, abstract = {This paper describes the setup and first applications of a computer-aided robotized Transcranial Magnetic Stimulation (TMS) system for motion compensated brain stimulation. The system uses a registration of the cranium to its 3D magnetic resonance imaging (MRI) data and constant infrared stereo optical tracking to establish a real-time link between the digital anatomical data and the head. Based on this registration the robot implements the planned stimulation. Tracking of the head and subsequent refinement of the robot position ensures that the stimulation coil is always at the right position relative to the cranium. The second part of the paper describes a novel approach to brain mapping. Assuming a functional relationship between electric field strength at the representation site of a muscle in the brain and its MEP response to stimulation, an algorithm is derived to calculate the representation site. The algorithm uses a map of the produced electric field of the TMS coil which is measured in a separate experiment. The results of a first mapping experiment that shows good correspondence between fMRI and TMS prediction is presented at the end of the paper.}, year = {2006}, address = {Osaka, Japan}, keywords = {electric field measurement; human brain mapping; robotic motion compensation; robotized navigated transcranial magnetic stimulation}, tags = {TMS}, note = {Transcranial Magnetic Stimulation} } @Article { sds_06, author = {Schlaefer, Alexander and Dieterich, Sonja and Schweikard, Achim}, title = {Incorporating interfractional motion in the treatment planning for motion compensated radiosurgery}, abstract = {In robotic radiosurgery cyclic movements of the target, like respiratory motion, can be compensated by moving the beams accordingly. However, conventionally treatment planning is performed on 3D image data and does not account for organ motion. We propose to discretize the target motion into steps along its spatial dimensions. For each step we compute its fraction of the breathing cycle, calculate the dose coefficient and incorporate this information in the optimization phase of the planning problem. Simulating planning and dose delivery for a simplified test case we show that the new approach can mitigate potential problems when treating highly mobile targets with motion compensated radiosurgery.}, year = {2006}, journal = {GMS CURAC}, volume = {1}, keywords = {inverse planning; motion compensation; Radiosurgery; Robotics}, file_url = {http://www.egms.de/en/journals/curac/2006-1/curac000016.shtml} } @Techreport { Kleemann2006b, author = {Kleemann, Markus and Martens, Volker and Hildebrand, Philipp and Be{\v{s}}irevi{\c}, Armin and Schlichting, Stefan and Schweikard, Achim and Bruch, Hans-Peter}, title = {Die Erfassung des Raumes - Grundlagen der Trackingtechnologie}, year = {2006}, series = {Universit{\{\dq}a}t zu L{\{\dq}u}beck}, tags = {NLS}, note = {Navigation in liver surgery} } @Inproceedings { BinderCARS06, author = {Binder, Norbert and Bodensteiner, Christoph and Matth{\{\dq}a}us, Lars and Burgkart, Rainer and Schweikard, Achim}, title = {Image Guided Positioning For an Interactive C-arm Fluoroscope}, year = {2006}, address = {Osaka, Japan}, tags = {ICA}, note = {Interactive C-Arm} } @Inproceedings { Ramrath2006a, author = {Ramrath, Lukas and Fuellgraf, H. and Winter, C. and Hofmann, Ulrich G. and H{\{\dq}u}ttmann, Gereon and Moser, Andreas and Schweikard, Achim}, title = {3D Visualization and Identification of Rat Brain Structures using Optical Coherence Tomography}, abstract = {Optical coherence tomography (OCT) is a powerful, real-time technique for investigating depth structure of biomedical tissue. Since entering the field of medical imaging it has been well established for imaging purposes in certain medical disciplines e.g. ophthalmology and dermatology. Major advantages are the high resolution, the video-rate scanning capability, and the non-invasive nature of OCT-imaging. Recent research results show the applicability of OCT to image brain morphology ex vivo and in vitro. OCT therefore presents a novel imaging modality in neuronavigation applications e.g. intraoperative path validation for instrument guidance. This contribution examines 2D-OCT scans of coronal sectioned rat brain in order to identify different brain regions and provides a 3D reconstruction for better visualization of OCT images.}, year = {2006}, address = {Hannover}, tags = {OCT}, note = {OCT-based Neuro-Imaging} } @Inproceedings { bss_06b, author = {Blanck, Oliver and Schlaefer, Alexander and Schweikard, Achim}, title = {3D visualization of radiosurgical treatment plans - experience with Java3D and VTK}, year = {2006}, isbn = {978-0415-43349-5}, publisher = {Taylor {\\&} Francis Group}, pages = {101-106}, tags = {TP} } @Misc { Kluzik2006, author = {Kluzik, Dr. Jacek and Immerz, Martin and Bodensteiner, Christoph and Brack, Ch.}, title = {Apparatus and method for the position checking of markers}, year = {2006}, note = {Patent EP1647236} } @Techreport { e_06, author = {Ernst, Floris}, title = {Dedekind, Pr{\{\dq}u}fer and Skolem Rings}, abstract = {Working on proofs of Fermat's Last Theorem, several fascinating mathematical discoveries were made. One famous mistake, which arguably is the reason for the work shown in this thesis, was made by the French mathematician Gabriel Lam{\'e} in 1847: when trying to factor Xn Y n in Z[e2pii/n], Lam{\'e} assumed uniqueness of factorisation to prove Fermat's Last Theorem. This work was shown to be false, though, in a paper by Ernst Kummer which had appeared three years earlier: this factorisation is not unique for n > 23. While trying to save Lam{\'e}'s proof, Kummer invented {\dq}ideal primes{\dq} to restore uniqueness in the factorisation. With this he was able to prove the theorem for more n than Lame, in fact, for all prime exponents p such that the class number h(p) of the cyclotomic ring Z[e2pii/p] is not divided by p. In doing so, he -- together with Richard Dedekind, who introduced ideals as we know them today -- laid the foundation for a whole new part of Algebra: ideal theory. In this thesis, chapter 1 serves as a stepping stone: key concepts of Algebra are introduced and ideals defined. Then, in chapter 2, things become more interesting. Quotient rings and fields are introduced together with fractional ideals which, in turn, enable us to speak of factorisation of ideals. Furthermore, an important example for a ring without unique factorisation is given. In chapter 3 we then delve deeper into unique factorisation: Dedekind domains are introduced, rings in which all ideals can be uniquely factored into products of prime ideals and are multiplicatively invertible. This is then generalised to Pr{\{\dq}u}fer domains where this invertibility needs to be possible for finitely generated ideals only. In between, section 3.4 introduces concepts from Algebraic Number Theory used later in this thesis. Chapter 4 goes away from the general line by explaining the concept of absolute values, places and valuations...}, year = {2006}, address = {Erlangen, Germany}, series = {Friedrich-Alexander-Universit{\{\dq}a}t Erlangen-N{\{\dq}u}rnberg, Mathematisches Institut}, note = {Diploma Thesis} } @Article { rssa_06, author = {Romanelli, Pantaleo and Schweikard, Achim and Schlaefer, Alexander and Adler Jr., John R.}, title = {Computer aided robotic radiosurgery}, abstract = {Radiosurgery involves the precise delivery of sharply collimated high-energy beams of radiation to a distinct target volume along selected trajectories. Historically, accurate targeting required the application of a stereotactic frame, thus limiting the use of this procedure to single treatments of selected intracranial lesions. However, the scope of radiosurgery has undergone a remarkable broadening since the introduction of image-guided robotic radiosurgery. Recent developments in real-time image guidance provide an effective frameless alternative to conventional radiosurgery and allow both the treatment of lesions outside the skull and the possibility of performing hypofractionation. As a consequence, targets in the spine, chest and abdomen can now also be radiosurgically ablated with submillimetric precision. Meanwhile, the combination of image guidance, robotic beam delivery, and non-isocentric inverse planning can greatly enhance the conformality and homogeneity of radiosurgery. The aim of this article is to describe the technological basis of image-guided radiosurgery and provide a perspective on future developments. The current clinical usage of robotic radiosurgery will be reviewed with an emphasis on those applications that may represent a major shift in the therapeutic paradigm.}, year = {2006}, DOI = {10.1080/10929080600886393}, journal = {Computer Aided Surgery}, volume = {11}, pages = {161-174}, number = {4}, tags = {MCRT TP}, file_url = {https://doi.org/10.1080/10929080600886393}, note = {timestamp=2008.04.16} } @Techreport { Martens2006, author = {Martens, Volker and Hildebrand, Philipp and Schlichting, Stefan and Be{\v{s}}irevi{\c}, Armin and Schweikard, Achim and Bruch, Hans-Peter and Kleemann, Markus}, title = {Entwicklung einer Navigationsumgebung (LapAssistent) f{\{\dq}u}r die ultraschallnavigierte laparoskopische Leberchirurgie}, year = {2006}, series = {Universit{\{\dq}a}t zu L{\{\dq}u}beck}, tags = {NLS}, note = {Navigation in liver surgery} } @Inproceedings { khmb_06, author = {Kleemann, Markus and Hildebrand, Philipp and Martens, Volker and Be{\v{s}}irevi{\c}, Armin and Schlichting, Stefan and Schweikard, Achim and Bruch, Hans-Peter}, title = {Entwicklung eines sonografischen Navigationssystems f{\{\dq}u}r die Laparoskopie}, year = {2006}, tags = {NLS}, note = {Navigation in liver surgery} } @Inproceedings { MartensCARS06, author = {Martens, Volker and Kleemann, Markus and Matth{\{\dq}a}us, Lars and Bruch, Hans-Peter and Schweikard, Achim}, title = {Evaluation of EM tracking systems for laparoscopic liver surgery}, year = {2006}, address = {Osaka, Japan}, tags = {NLS}, note = {Navigation in liver surgery} } @Phdthesis { b_06, author = {Berlinger, Kajetan}, title = {Fiducial-Less Compensation of Breathing Motion in Extracranial Radiosurgery}, year = {2006}, series = {Technische Universit{\{\dq}a}t M{\{\dq}u}nchen}, note = {timestamp=2007.09.21} } @Inproceedings { smrs_06, author = {Schlichting, Stefan and Martens, Volker and Rzezovski, Norman and Schweikard, Achim and Bruch, Hans-Peter}, title = {First results of accuracy of virtual liver cut classification for automatic landmark extraction}, year = {2006}, tags = {NLS}, note = {Navigation in liver surgery} } @Article { brsv_06, author = {Berlinger, Kajetan and Roth, Michael and Sauer, Otto and Vences, Lucia and Schweikard, Achim}, title = {Fully automatic detection of corresponding anatomical landmarks in volume scans of different respiratory state.}, abstract = {A method is described which provides fully automatic detection of corresponding anatomical landmarks in volume scans taken at different respiratory states. The resulting control points are needed for creating a volumetric deformation model for motion compensation in radiotherapy. Prior to treatment two CT volumes are taken, one scan during inhalation, one during exhalation. These scans and the detected control point pairs are taken as input for creating the four-dimensional model by using thin-plate splines.}, year = {2006}, journal = {Medical Physics}, volume = {33}, pages = {1569-1572}, number = {6}, keywords = {Algorithms; Automation; computer-assisted; Humans; Lung; Magnetic Resonance Imaging; Radiographic Image Interpretation; Reproducibility of Results; Respiration; Respiratory Mechanics; Sensitivity and Specificity; Tomography; X-Ray Computed}, note = {timestamp=2006.11.22} } @Article { ssa_05, author = {Schweikard, Achim and Shiomi, Hiroya and Adler Jr., John R.}, title = {Respiration tracking in radiosurgery without fiducials}, abstract = {In robotic radiosurgery, a focused beam of radiation is moved by a robot arm. We investigated methods for soft-tissue navigation using robotic radiosurgery. In previous work we described a method for real-time tracking based on correlation between the motion of implanted fiducial markers and external skin markers. In this work we extend our method of correlation-based tracking to tracking without implanted fiducials. We propose to use deformation algorithms on CT data sets combined with registration of digitally reconstructed radiographs and intra-treatment X-ray images to obtain intermittent information on the target location. This information is then combined with our basic correlation method to achieve real-time tracking. Our study investigates the feasibility of this approach from the point of view of computing time and required level of user interaction. The term 7D registration coined to describe the underlying method for performing this task.}, year = {2005}, issn = {1478-596X}, DOI = {10.1002/rcs.38}, journal = {International Journal of Medical Robotics and Computer Assisted Surgery}, volume = {1}, pages = {19-27}, number = {2}, keywords = {medical robot; Navigation; Radiation therapy; Respiration; soft-tissue tracking}, tags = {MCRT}, file_url = {https://doi.org/10.1002/rcs.38}, note = {timestamp=2008.04.18} } @Article { bgrgs_05, author = {Burgkart, Rainer and Gottschling, Heiko and Roth, Michael and Gradinger, Reiner and Schweikard, Achim}, title = {Fluoroscopy-based 3D-navigation of complex correction osteotomies at the proximal femur}, abstract = {Background: Besides great advances in hip-alloarthroplasty there are still numerous indications for joint saving procedures as correction osteotomies. Often these procedures include complex 3D rearrangements of the proximal femur, which are for the surgeon technically very demanding. The project aim was to develop a precise intraoperative virtual 3D planning tool including a detailed biomechanical analysis and enable the surgeon to realize exactly this plan by using computer assisted techniques. Methods: Using only 2 different angled fluoro frames a simplified femoral model was inversely constructed. For navigation a passive optical system was used with a C-arm calibration kit and PC-based developed software. For in vitro evaluation complex osteotomies were performed on 10 femora under simulated OR conditions. Results: The mean difference between the planning and real surgical outcome for the wedge size was less then 2° and for the femur head center position less then 4 mm. No implant penetrated the femur neck isthmus. Conclusion: Without changing the standard operative procedure the method can be of high clinical importance to improve the accuracy of the planning and the consecutive operative realization for a precise fragment positioning and the plate location without penetrating the isthmus of the femoral neck. And - beside precision - it can potentially help to reduce intraoperative complications as implant penetration and minimize x-ray use.}, year = {2005}, issn = {1433-0431}, DOI = {10.1007/s00132-005-0859-9}, journal = {Der Orthop}, volume = {34}, pages = {1137-1143}, number = {11}, keywords = {biomechanical planning; computer assisted navigation; Femur; Fluoroscopy; Osteotomy}, file_url = {https://doi.org/10.1007/s00132-005-0859-9} } @Inproceedings { Schlaefer2005, author = {Schlaefer, Alexander and Blanck, Oliver and Shiomi, Hiroya and Schweikard, Achim}, title = {Radiochirurgie: Identifizierung effizienter Behandlungsstrahlen mittels autostereoskopischer Visualisierung}, year = {2005}, address = {Berlin} } @Inbook { Schweikard2005, author = {Schweikard, Achim and Adler Jr., John R.}, title = {Predictive Compensation of Breathing Motion in Lung Cancer Radiosurgery}, year = {2005}, isbn = {3-540-00321-5}, publisher = {Springer Verlag}, address = {Heidelberg}, tags = {MCRT}, note = {Motion Compensation in Radiosurgery} } @Inproceedings { Matthaus2005, author = {Matth{\{\dq}a}us, Lars and Giese, Alf and Wertheimer, Daniel and Schweikard, Achim}, title = {Planning and Analyzing Robotized TMS Using Virtual Reality: Accelerating Change in Healthcare: Next Medical Toolkit}, year = {2005}, volume = {119}, publisher = {IOS Press}, series = {Stud Health Technol Inform}, pages = {373-8}, note = {timestamp=2007.04.20} } @Inproceedings { KleemannCURAC05, author = {Kleemann, Markus and Hildebrand, Philipp and Matth{\{\dq}a}us, Lars and Schweikard, Achim and Birth, M. and Bruch, Hans-Peter}, title = {Navigation in der Viszeralchirurgie}, year = {2005}, address = {Berlin}, series = {4. Jahrestagung}, tags = {NLS}, note = {Navigation in liver surgery} } @Inproceedings { Berlinger2005, author = {Berlinger, Kajetan and Roth, Michael and Sauer, Otto and Vences, Lucia and Schweikard, Achim}, title = {Motion compensation in radiotherapy using advanced volumetric deformation models}, year = {2005}, address = {Berlin} } @Inproceedings { Henke2005ICMP, author = {Henke, Maria and Hiltawsky, Karsten and Ermert, Helmut and Reibiger, Albrecht}, title = {Models for the Ultrasound Intensity Distribution on Blood Vessels}, year = {2005}, booktitle = {14th International Conference of Medical Physics Supplement}, pages = {5-6} } @Techreport { h_05b, author = {Hennings, Arne}, title = {Greifer-Programmierung mit Beispiel-Anwendung Roboter-Schach}, year = {2005}, series = {Universit{\{\dq}a}t zu L{\{\dq}u}beck}, note = {Studienarbeit} } @Inproceedings { Finke2005, author = {Finke, Markus and Koay, Kheng Lee and Dautenhahn, Kerstin and Nehaniv, C. L. and Walters, M. L. and Saunders, J.}, title = {Hey, I'm over here - How can a robot attract people's attention?}, abstract = {This paper describes how sonar sensors can be used to recognize human movements. The robot distinguishes objects from humans by assuming that only people move by themselves. Two methods using either rules or hidden Markov models are described. The robot classifies different movements to provide a basis for judging if a person is interested in an interaction. A comparison of two experiment results is presented. The use of orienting cues by the robot in response to detected human movement for eliciting interaction is also studied.}, year = {2005}, DOI = {10.1109/ROMAN.2005.1513748}, address = {Nashville, USA}, pages = {7-12}, file_url = {https://doi.org/10.1109/ROMAN.2005.1513748} } @Article { sfdscs_05, author = {Schlaefer, Alexander and Fisseler, J. and Dieterich, Sonja and Shiomi, Hiroya and Cleary, K. and Schweikard, Achim}, title = {Feasibility of four-dimensional conformal planning for robotic radiosurgery.}, abstract = {Organ motion can have a severe impact on the dose delivered by radiation therapy, and different procedures have been developed to address its effects. Conventional techniques include breath hold methods and gating. A different approach is the compensation for target motion by moving the treatment beams synchronously. Practical results have been reported for robot based radiosurgery, where a linear accelerator mounted on a robotic arm delivers the dose. However, not all organs move in the same way, which results in a relative motion of the beams with respect to the body and the tissues in the proximity of the tumor. This relative motion can severely effect the dose delivered to critical structures. We propose a method to incorporate motion in the treatment planning for robotic radiosurgery to avoid potential overdosing of organs surrounding the target. The method takes into account the motion of all considered volumes, which is discretized for dose calculations. Similarly, the beam motion is taken into account and the aggregated dose coefficient over all discrete steps is used for planning. We simulated the treatment of a moving target with three different planning methods. First, we computed beam weights based on a 3D planning situation and simulated treatment with organ motion and the beams moving synchronously to the target. Second, beam weights were computed by the 4D planning method incorporating the organ and beam motion and treatment was simulated for beams moving synchronously to the target. Third, the beam weights were determined by the 4D planning method with the beams fixed during planning and simulation. For comparison we also give results for the 3D treatment plan if there was no organ motion and when the plan is delivered by fixed beams in the presence of organ motion. The results indicate that the new 4D method is preferable and can further improve the overall conformality of motion compensated robotic radiosurgery.}, year = {2005}, DOI = {10.1118/1.2122607}, journal = {Medical Physics}, volume = {32}, pages = {3786-3792}, number = {12}, keywords = {Biophysics; computer-assisted; Conformal; Humans; Movement; Neoplasms; Non-U.S. Gov't; Radiosurgery; Radiotherapy; Radiotherapy Planning; Research Support; Respiration; Robotics}, file_url = {https://doi.org/10.1118/1.2122607}, note = {timestamp=2006.11.22} } @Inproceedings { fhbr_05, author = {Fritsche, L. and Hoerstrup, J. and Budde, K. and P., Reinke and Neumayer, H.-H. and Frei, U. and Schlaefer, Alexander}, title = {Accurate prediction of kidney allograft outcome based on creatinine course in the first 6 months posttransplant}, year = {2005}, volume = {2}, series = {37}, number = {731-3} } @Inbook { ssua_05, author = {Schweikard, Achim and Shiomi, Hiroya and Uchida, M. and Adler Jr., John R.}, title = {Extracranial Stereotactic Radiotherapy and Radiosurgery}, year = {2005}, isbn = {0824726979}, publisher = {Taylor and Francis}, address = {New York}, editor = {Slotman, Solberg, Wurm}, pages = {71-87}, tags = {MCRT}, note = {Motion Compensation in Radiosurgery} } @Inproceedings { sbs_05a, author = {Schlaefer, Alexander and Blanck, Oliver and Schweikard, Achim}, title = {3D dose visualization for evaluation of radiosurgical treatment plans}, year = {2005} } @Article { bmbs_05, author = {Binder, Norbert and Matth{\{\dq}a}us, Lars and Burgkart, Rainer and Schweikard, Achim}, title = {A Robotic C-arm Fluoroscope}, abstract = {Fluoroscopic C-arms are common devices for acquiring images during surgery. Manual positioning is timeconsuming and requires considerable experience. Trained users must often take several images to find the best viewing direction. If a second image must be taken from the same position, e.g. for postoperative control, the C-arm must be moved to the exact same position. Without guidance, this is often difficult to accomplish. We developed the idea to completely robotize a standard C-arm, i.e. to equip all joints with motors and encoders. A software environment provides for intelligent control. To archive this goal a complete kinematic analysis of the fluoroscope was necessary. On the basis of this analysis a number of clinical applications have been developed: (1) simplified positioning via cartesian control; (2) automatic acquisition of panoramic images; (3) 3D CT with arbitrary viewing angles; (4) 4D intraoperative CT with/without respiration triggering; (5) automated anatomy-oriented positioning. The goal of this research is thus three-fold: minimise radiation exposure of the OR staff, reduce positioning time and offer enhanced imaging capability.}, year = {2005}, DOI = {10.1002/rcs.34}, journal = {International Journal of Medical Robotics and Computer Assisted Surgery}, volume = {1}, pages = {108-116}, number = {3}, keywords = {3D fluoroscope; C-arm kinematic; intra-surgical imaging; medical robotics; robot-assisted surgery; robotized C-arm}, tags = {ICA}, file_url = {https://doi.org/10.1002/rcs.34}, note = {Interactive C-Arm} } @Inproceedings { Ramrath2005, author = {Ramrath, Lukas and Singh, T.}, title = {A Minimax Approach To Robust Repetitive Learning Control}, abstract = {This paper investigates a robust repetitive control scheme based on a minimax problem formulation. As non-robust repetitive control loops often lead to decreased suppression or amplification of the disturbing signal if the frequency of the disturbance is not exactly known or slowly varying, robust design approaches have to be used in such cases. Results of the new approach are compared to existing approaches and the trade-off between cancellation performance and robustness is pointed out.}, year = {2005}, address = {Budapest, Hungary} } @Article { sbs_05, author = {Schlaefer, Alexander and Blanck, Oliver and Schweikard, Achim}, title = {Autostereoscopic Display of the 3D Dose Distribution to Assess Beam Placement for Robotic Radiosurgery}, abstract = {Purpose: To study whether a 3D view of the dose distribution and treatment beams on an autostereoscopic display facilitates a `smart' placement of additional beams for robotic radiosurgery. Method and Materials: Treatment plans for robotic radiosurgery with the CyberKnife system (Accuray Inc., Sunnyvale) consist of a large number of non-isocentrical, cylindrical beams directed towards arbitrary points within the target volume. We implemented a tool to visualize the resulting 3D dose distribution and the beam directions using the visualization toolkit (VTK). A hypsometric color scheme allows to identify cold and hot spots in the target volume, i.e. regions where the dose is close to the lower or upper bound specified for the target. Given this information we manually added a 20 beams to an existing treatment plan with 1200 beams for an intracranial tumor. The beams where placed such that a large number of cold voxels were hit but hot voxels were avoided. To assess the spatial extent of the cold and hot regions and the orientation of the beams an autostereoscopic display (SeeReal Technologies GmbH, Dresden) was used. An inverse planning algorithm similar to the one used by the CyberKnife system was implemented to re-optimize the plan, the result was compared to the original plan. Results: The original plan consisted of 119 weighted beams with an accumulated weight of 21763.3 MU. Adding 20 beams we obtained a plan with 123 beams with the total weight reduced to 21610.7 MU. All 20 new beams got the maximum weight of 250 MU per beam, i.e. other, less efficient beams were discarded by the optimizer. Conclusion: The visualization tool proved to be useful in the guidance of beam placement. A direction of additional beams towards cold spots in the target volume can improve the plan quality.}, year = {2005}, DOI = {10.1118/1.1998500}, journal = {Medical Physics}, volume = {32}, pages = {2122-2122}, number = {6}, file_url = {https://doi.org/10.1118/1.1998500} } @Inproceedings { MatthaeusCAS-H05, author = {Matth{\{\dq}a}us, Lars and Giese, Alf and Wertheimer, Daniel and Schweikard, Achim}, title = {Brainmapping With TMS Using A Robot Based Protocol And Image Registration Techniques}, year = {2005}, publisher = {VDI-Verlag}, address = {Berlin}, series = {Proceedings, Fortschritt-Berichte VDI, Reihe 17 Biomechanik/Medizintechnik}, pages = {23}, number = {258}, tags = {TMS}, note = {Transcranial Magnetic Stimulation} } @Inproceedings { bsvr_05, author = {Berlinger, Kajetan and Sauer, Otto and Vences, Lucia and Roth, Michael and D{\{\dq}o}tter, M. and Schweikard, Achim}, title = {Computed 4D patient models for motion compensation in radiotherapy}, abstract = {Purpose: We designed a system that can track tumors moving due to respiratory motion, allowing more specific and effective irradiation of the tumor. Method and Materials: First two CT scans are taken during maximal inhalation and exhalation. Then several synthetic intermediate scans are computed by using morphing methods, yielding a 3D motion picture. Before treatment x-ray images are taken periodically and compared to the 4D model. After registration of the x-ray with the model we know the best matching stack and therefore tumor position and respiratory state. Thus we acquire correlation from respiratory state to tumor position. Due to a registration time of 10 seconds for each stack, we only get intermittent information about the target location. The target may already have moved. Therefore we use an infrared tracking system, with emitters attached to significant positions of the patient's body, to report information on the current state of respiration in real-time. The information of the sensor is correlated to the target location computed by the comparison between the live shot and the model. Results: To create the model we use a thin-plate spline-based method. 47 corresponding control points were manually selected for deforming a lung. To evaluate the results transversal snap shots were compared with the model, yielding the corresponding respiratory state. We also tested the 2D/4D registration process by generating two mutually orthogonal DRRs, which we matched afterwards to the model. The best match was the stack containing the DRRs, furthermore the neighboring stacks led to the next best results. Conclusion: We have shown that it is possible to determine the respiratory state by matching a synthetic x-ray to a generated 4D model of an internal organ. Next steps will be to improve our method of generating the model and to test the registration with real x-rays.}, year = {2005}, DOI = {10.1118/1.1997558}, volume = {32}, address = {Seattle, WA, USA}, series = {Medical Physics}, pages = {1922}, number = {6}, file_url = {https://doi.org/10.1118/1.1997558}, note = {timestamp=2007.03.30} } @Article { mws_05, author = {Muacevic, Alexander and Wowra, Berndt and Schweikard, Achim}, title = {Cyberknife Radiochirurgie}, year = {2005}, journal = {Medizintechnik in Bayern}, pages = {32-36}, tags = {MCRT}, note = {Motion Compensation in Radiosurgery} } @Inproceedings { BinderCURAC04, author = {Binder, Norbert and Matth{\{\dq}a}us, Lars and Burgkart, Rainer and Schweikard, Achim}, title = {The Inverse Kinematics of Fluoroscopic C-Arms}, abstract = {Introduction Flouroscopic C-arms are common devices to acquire images during surgery. Manual positioning is time consuming and requires a lot of experience. Even trained personal must typically take a series of images to find an appropriate viewing angle. The approach for an interactive fluoroscope introduced here simplifies the positioning process and reduces the number of x-ray images to be taken. We derived an inverse robot kinematic solution for the c-arm. Our goal is a fully motorized c-arm capable of autonomous motion. Methods The mechanical construction was analyzed and the direct kinematic problem was solved according to Denavit-Hartenberg method. Due to the limitation of five axes, there is a dependency between the region of interest (ROI) and the orientation of the optical system. During usage, only the ROI and the direction of the beam-center are given. As the last degree of freedom, the rotation around the beam-center, is missing, there is no explicit definition of the transformation matrix between the optical system and the base of the fluoroscope. After setting up the partial homogeneous transformation matrix with the scarce information given, a closed form solution for the inverse problem for c-arms was found. Results The kinematic results were applied to our visualization software. The first application was the extraction of 3D information and calculation of the best position for the final image. A large number of potential clinical applications were tested in this context. Conclusion Tests were sucessfully applied on our simulation and confirmed by neurosurgical staff of the university clinical center. Future steps include the motorization of our fluoroscope and additional testing in laboratory and clinical environment.}, year = {2004}, volume = {3}, address = {M{\{\dq}u}nchen}, series = {CURAC}, pages = {1-5}, tags = {ICA}, note = {Interactive C-Arm} } @Inproceedings { rdbs_04, author = {Roth, Michael and D{\{\dq}o}tter, M. and Burgkart, Rainer and Schweikard, Achim}, title = {Schnelle und pr{\{\dq}a}zise intensit{\{\dq}a}tsbasierte 2D/3D Fusion fluoroskopischer R{\{\dq}o}ntgenaufnahmen mit CT und deren objektive Evaluierung durch Gold Standard-Datens{\{\dq}a}tze}, year = {2004}, publisher = {Deutsche Gesellschaft f{\{\dq}u}r Computer- und Roboterassistierte Chirurgie}, address = {M{\{\dq}u}nchen}, series = {138}, file_url = {medicstream.de} } @Misc { Groß2004, author = {Gro{\{\dq}s}, R. and Binder, Norbert and Schweikard, Achim}, title = {R{\{\dq}o}ntgen-C-Bogen Simulator}, year = {2004}, tags = {ICA}, file_url = {www.medicstream.de}, note = {Interactive C-Arm} } @Inproceedings { kgbs_04, author = {Knopp, U. and Giese, Alf and Binder, Norbert and Schweikard, Achim}, title = {Roboterunterst{\{\dq}u}tzung eines OP-Mikroskops}, year = {2004}, publisher = {Deutsche Gesellschaft f{\{\dq}u}r Computer- und Roboterassistierte Chirurgie}, address = {M{\{\dq}u}nchen}, series = {23}, file_url = {www.medicstream.de} } @Article { ssa_04, author = {Schweikard, Achim and Shiomi, Hiroya and Adler Jr., John R.}, title = {Respiration Tracking in Radiosurgery}, abstract = {Respiratory motion is difficult to compensate for with conventional radiotherapy systems. An accurate tracking method for following the motion of the tumor is of considerable clinical relevance. We investigate methods to compensate for respiratory motion using robotic radiosurgery. In this system the therapeutic beam is moved by a robotic arm, and follows the moving target through a combination of infrared tracking and synchronized x-ray imaging. Infrared emitters are used to record the motion of the patient's skin surface. The position of internal gold fiducials is computed repeatedly during treatment, via x-ray image processing. We correlate the motion between external and internal markers. From this correlation model we infer the placement of the internal target during time intervals where no x-ray images are taken. Fifteen patients with lung tumors have recently been treated with a fully integrated system implementing this new method. The clinical trials confirm our hypothesis that internal motion and external motion are indeed correlated. In a preliminar study we have extended our work to tracking without implanted fiducials, based on algorithms for computing deformation motions and digitally reconstructed radiographs.}, year = {2004}, DOI = {10.1118/1.1774132}, journal = {Medical Physics}, volume = {31}, publisher = {American Association of Physicists in Medicine}, pages = {2738-2741}, number = {10}, keywords = {respiration tracking; soft-tissue navigation; whole body radiosurgery}, tags = {MCRT}, file_url = {https://doi.org/10.1118/1.1774132}, note = {timestamp=2007.03.01} } @Inproceedings { Hanne2004, author = {Hanne, Robert and Golias, D. and Schweikard, Achim}, title = {Neuartige Eingabekonzepte f{\{\dq}u}r inverse, intensit{\{\dq}a}tsmodulierte Planungssysteme in der Strahlentherapie}, year = {2004}, publisher = {Deutsche Gesellschaft f{\{\dq}u}r Computer- und Roboterassistierte Chirurgie}, address = {M{\{\dq}u}nchen}, series = {64}, file_url = {www.medicstream.de} } @Techreport { e_04, author = {Ernst, Floris}, title = {Multiplicative Ideal Theory}, year = {2004}, address = {Dunedin, New Zealand}, series = {University of Otago, Department of Mathematics and Statistics}, note = {Honours Thesis} } @Inproceedings { brds_04, author = {Berlinger, Kajetan and Roth, Michael and D{\{\dq}o}tter, M. and Sauer, Otto and Vences, Lucia and Fisseler, J. and Schweikard, Achim}, title = {Lageerkennung des Tumors mithilfe eines intensit{\{\dq}a}tsbasierten 4D Registrierungsverfahrens}, year = {2004}, publisher = {Deutsche Gesellschaft f{\{\dq}u}r Computer- und Roboterassistierte Chirurgie}, address = {M{\{\dq}u}nchen}, series = {143}, file_url = {www.medicstream.de} } @Phdthesis { r_04, author = {Riesner, Stefan}, title = {Korrelations- und Pr{\{\dq}a}diktionsverfahren zur Lageverfolgung in der perkutanen Radioonkologie}, year = {2004}, series = {Technische Universit{\{\dq}a}t M{\{\dq}u}nchen}, note = {timestamp=2007.01.30} } @Inproceedings { ssf_04, author = {Schweikard, Achim and Shiomi, Hiroya and Fisseler, J. and D{\{\dq}o}tter, M. and Berlinger, Kajetan and Gehl, H.-B. and Adler Jr., John R.}, title = {Fiducial-Less Respiration Tracking in Radiosurgery}, abstract = {Respiratory motion is difficult to compensate for with conventional radiotherapy systems. An accurate tracking method for following the motion of the tumor is of considerable clinical relevance. We investigate methods to compensate for respiratory motion using robotic radiosurgery. Infrared emitters are used to record the motion of the patient's skin surface. The position of internal gold fiducials is computed repeatedly during treatment, via x-ray image processing. We correlate the motion between external and internal markers. From this correlation model we infer the placement of the internal target. 15 patients with lung tumors have recently been treated with a fully integrated system implementing this new method. In this work we extend our method to tracking without implanted fiducials. We propose to use deformation algorithms on CT data sets combined with registration of digitally reconstructed radiographs to obtain intermittent information on the target location. This information is then combined with our basic correlation method to achieve real-time tracking. The term 7D registration is coined to describe the underlying method for performing this task}, year = {2004}, volume = {3217}, publisher = {Springer}, series = {Lecture Notes in Computer Science}, pages = {992-9}, tags = {MCRT}, note = {timestamp=2006.11.22} } @Inproceedings { sbrv_04, author = {Sauer, Otto and Berlinger, Kajetan and Roth, Michael and Vences, Lucia and Schweikard, Achim}, title = {Erstellung von Testdaten f{\{\dq}u}r 4D Patienten Modelle}, year = {2004}, publisher = {Deutsche Gesellschaft f{\{\dq}u}r Computer- und Roboterassistierte Chirurgie}, address = {M{\{\dq}u}nchen}, series = {148,}, file_url = {www.medicstream.de} } @Inproceedings { hwls_04, author = {Hoerauf, H. and Wollnack, J. and Laqua, H. and Schweikard, Achim}, title = {Entwicklung einer mikrochirurgischen Technik zur intraoperativen Lyse bei retinalen Gef{\{\dq}a}{\{\dq}s}verschl{\{\dq}u}ssen}, year = {2004}, publisher = {Deutsche Gesellschaft f{\{\dq}u}r Computer- und Roboterassistierte Chirurgie}, address = {M{\{\dq}u}nchen}, series = {16}, file_url = {www.medicstream.de} } @Inproceedings { sks_04, author = {Schlaefer, Alexander and Kneschaurek, Peter and Schweikard, Achim}, title = {Beam placement for robotic radiosurgery}, year = {2004}, publisher = {Elsevier}, address = {Chicago, USA}, series = {International Congress Series 1268} } @Inproceedings { grbs_04, author = {Gottschling, Heiko and Roth, Michael and Burgkart, Rainer and Schweikard, Achim}, title = {Intraoperative, fluoroskopiebasierte Planung komplexer Osteotomien des proximalen Femurs}, year = {2004}, address = {M{\{\dq}u}nchen}, series = {135}, file_url = {www.medicstream.de} } @Article { bsb_03, author = {Burkhardt, S. and Schweikard, Achim and Burgkart, Rainer}, title = {Numerical determination of the susceptibility caused geometric distortions in magnetic resonance imaging}, abstract = {The goal of this work is the design of highly accurate surgical navigation methods purely based on magnetic resonance imaging. In this context we numerically examine the geometrical distortions which occur in magnetic resonance imaging. We extend an existing method for computing magnitude and direction of distortions for any internal point. In particular, a multi-grid approach for a fast and efficient calculation of the static magnetic field throughout the imaging volume is presented and compared to the analytical solution for simple geometries. We found that shifts in the range of up to 2.5 mm occur in MRI of femur bones with 1.5 Tesla. Our new method was implemented and has been found capable of accurately correcting for geometrical distortions within reasonable computing times. In particular, we show that the registration accuracy for mutual information (MI) based MR-CT fusion can be much improved. Thus the value of the optimization functional in MI registration for MR-CT substantially increases after our distortion correction.}, year = {2003}, DOI = {10.1016/S1361-8415(02)00109-3}, journal = {Medical Image Analysis}, volume = {7}, pages = {221-236}, number = {3}, keywords = {Abdomen; Abdomi; Algorithms; Artifacts; Biological; Cadaver; Comparative Study; computer-assisted; Electromagnetic Fields; Femur; Humans; Image Enhancement; Image Interpretation; Imaging; Lumbar Vertebrae; Magnetic Resonance Imaging; Models; nal; Non-U.S. Gov't; Prostheses and Implants; Quality Control; Radiography; Research Support; Subtraction Technique; Surgery; Three-Dimensional; Tomography; X-Ray Computed}, file_url = {https://doi.org/10.1016/S1361-8415(02)00109-3}, note = {timestamp=2006.11.22} } @Misc { Schweikard2003b, author = {Schweikard, Achim and Doetter, M.}, title = {Verfahren und Vorrichtung zur Bestimmung der Position des Fokuspunktes einer R{\{\dq}o}ntgenstrahlenquelle}, year = {2003}, note = {DE Nr. 101 39 500, Patenteinreichung 10.08.2001} } @Inproceedings { schw_03, author = {Schweikard, Achim}, title = {Robotic fiducial-less tracking of respiratory motion in radiosurgery}, year = {2003}, address = {Kyoto, Japan} } @Inbook { Burkhardt2003, author = {Burkhardt, S. and Roth, Michael and Schweikard, Achim and Burgkart, Rainer}, title = {Registrierung von pr{\{\dq}a}operativen 3D-MRT-Daten mit intraoperativen 2D-Fluoroskopieaufnahmen zur Patientenlageerkennung}, year = {2003}, publisher = {Springer Verlag}, address = {Berlin}, pages = {16-20}, note = {Edition: Bildverarbeitung f{\{\dq}u}r die Medizin 2003} } @Inproceedings { srs_03, author = {Singh, T. and Ramrath, Lukas and Schmid, M.}, title = {LP Based Global Minimization Of Peak Base Reaction Force of Maneuvering Robots}, abstract = {A method for computing the optimal control to minimize a robot's peak base reaction force, while avoiding obstacles, is presented. It contains the manipulator dynamics, initial and final conditions and obstacle constraints. Using the assumption that minimal peak base reaction force control is equal to time-optimal control, an iterative approach is used to find the path and control that globally minimizes the robots peak base reaction force. The conditions for optimality are derived and incorporated into an algorithm which uses linear programming to solve the given problem. Equations describing the system dynamics and the obstacle position are mapped into the center of mass space, a convenient space for path planning. The method is demonstrated for a general maneuver in the center of mass space and for a two-link manipulator which includes obstacle constraints.}, year = {2003}, address = {Austin/Texas, USA} } @Inproceedings { bblb_03, author = {Burgkart, Rainer and Brossmann, C. and Layer, M. and Bartels, E. and Dreer, J. and Schweikard, Achim and Gradinger, Reiner}, title = {New method for an intuitive surgical planning system for 3d correction-osteotomies of bony deformations}, year = {2003}, isbn = {978-1586033200}, volume = {11}, publisher = {IOS Press}, address = {Amsterdam} } @Inproceedings { Schweikard2003a, author = {Schweikard, Achim and Burgkart, Rainer and Burkhardt, S.}, title = {Bestimmung der Gradientenst{\{\dq}a}rken von MR-Sequenzen mit Hilfe von Kalibrierk{\{\dq}o}rpern}, year = {2003}, address = {Erlangen} } @Article { brsb_03, author = {Burkhardt, S. and Roth, Michael and Schweikard, Achim and Burgkart, Rainer}, title = {A new system for completely MR-based computer assisted orthopaedic surgery}, year = {2003}, journal = {International Congress Series 1256}, volume = {1256}, pages = {1342} } @Inproceedings { bgrs_03, author = {Burgkart, Rainer and Gottschling, Heiko and Roth, Michael and Schweikard, Achim and Regenfelder, F.}, title = {Intraoperative planning and computer assisted navigation of complex multi-planar correction osteotomies at the proximal femur using a standard c-arm fluoroscopy}, year = {2003}, address = {Marbella, Spain} } @Inproceedings { Hanne2002, author = {Hanne, Robert and Hilbig, Matthias and Schweikard, Achim}, title = {Lineare Optimierung in der Strahlentherapie}, year = {2002}, address = {Leipzig} } @Inproceedings { brs_02, author = {Bartels, E. and Roth, Michael and Schweikard, Achim}, title = {Roboterunterst{\{\dq}u}tzte Brachytherapiespickung}, year = {2002}, address = {Leipzig} } @Inproceedings { Nakamura2002, author = {Nakamura, S. and Gruhn, R. and Binder, Harald}, title = {Recognition of Non-Native Speech Using Dynamic Phoneme Lattice Processing}, abstract = {Robustness of speech reconizers to non-native speech input is a difficult problem with rising importance. This paper introduces an approach which deals with the dynamic application of pronunciation rules to a phoneme-lattice. These rules are generated in a separate step. The task is the robust recognition of English spoken by Japanese for hotel reservation, using the Wall-Street-Journal (WSJ) for baseline acoustic modeling.}, year = {2002}, address = {Yokohama, Japan} } @Inproceedings { grs_02, author = {Golias, D. and Riesner, Stefan and Schweikard, Achim}, title = {Online-Verfolgung von Strukturen in Ultraschallbilder}, year = {2002}, address = {Leipzig} } @Article { ss_02, author = {Schwarzer, F. and Schweikard, Achim}, title = {On the Complexity of One-Shot Translational Separability}, abstract = {The problem of deciding whether 2- or 3-dimensional objects can be separated by a sequence of arbitrary translational motions is known to have exponential lower bounds. However, under certain restrictions on the type of motions, polynomial time bounds have been shown. An example is finding a subset of the parts that is removable by a single translation. In this case, the main restriction is that all selected parts are required to be removed in the same direction and with the same velocity. It was an open question whether the polynomial time bound can be achieved if more than a single velocity is allowed for the moving parts. In this paper, we answer this question by proving that such 'multi-handed' separability problems are NP-hard.}, year = {2002}, issn = {0020-0190}, journal = {Information Processing Letters}, volume = {83}, pages = {187-194}, number = {4} } @Article { hhs_02, author = {Hilbig, Matthias and Hanne, Robert and Schweikard, Achim}, title = {MMRT-Inverse Planning based on Linear Programming}, year = {2002}, journal = {Zeitschrift f{\{\dq}u}r Medizinische Physik}, volume = {12}, pages = {89-96} } @Inproceedings { Burgkart2002, author = {Burgkart, Rainer and Schweikard, Achim and Burkhardt, S.}, title = {Korrektur objektinduzierter geometrischer Verzeichnungen in Kernspinbildern}, year = {2002}, address = {Leipzig} } @Book { Burkhardt2002, author = {Burkhardt, S. and Burgkart, Rainer and D{\{\dq}o}tter, M. and Roth, Michael and Schweikard, Achim}, title = {Korrektur von geometrischen Verzeichnungen bei MRI-Aufnahmen vom Femur}, year = {2002}, publisher = {Springer Verlag}, series = {Tagungsband Bildverarbeitung f{\{\dq}u}r die Medizin} } @Techreport { Schweikard02, author = {Schweikard, Achim and Shiomi, Hiroya and Doetter, M. and Roth, Michael and Berlinger, Kajetan and Adler Jr., John R.}, title = {Fiducial-Less Compensation of Breathing Motion in Lung Cancer Radiosurgery}, year = {2002}, series = {University of L{\{\dq}u}beck (Germany), Technisch-Naturwissenschaftliche Fakult{\{\dq}a}t}, number = {A-02-23}, tags = {MCRT}, note = {timestamp=2006.11.22} } @Techreport { Schwarzer2002, author = {Schwarzer, F. and Joskowicz, Leo and Schweikard, Achim}, title = {Efficient linear unboundedness testing: Algorithm and applications to assembly planning}, year = {2002}, address = {Jerusalem, Israel}, series = {Technical Reports Leibniz Center} } @Inproceedings { Dötter2002, author = {D{\{\dq}o}tter, M. and Roth, Michael and Schweikard, Achim}, title = {Dreidimensionale Navigation in der Orthopaedie ohne praeoperative tomographische Aufnahmen}, year = {2002}, address = {Leipzig} } @Inproceedings { Burkhardt02, author = {Burkhardt, S. and Schweikard, Achim and Burgkart, Rainer}, title = {Determination and correction of the susceptibility induced geometric distortions in MRI}, year = {2002}, address = {Grenoble}, note = {timestamp=2006.11.22} } @Article { hhkz_02, author = {Hilbig, Matthias and Hanne, Robert and Kneschaurek, Peter and Zimmermann, Frank and Schweikard, Achim}, title = {Design of an inverse planning system for radiotherapy using linear optimization}, abstract = {Our approach shows that inverse planning for intensity-modulated beams in radiotherapy can be solved efficiently by the mathematical method of linear optimization. The completeness property of this method guarantees that calculated treatment plans fulfill the dose constraints given by the oncologist. Techniques developed by our group can also avoid the possible infeasibility caused by a physically impossible dose distribution. In contrast to other optimization methods, the simplex algorithm used for linear optimization allows a very high optimization speed, i.e., very short planning cycles. These preconditions were integrated in the development of the software system MIPART ({\dq}Munich Inverse Planning And Radiotherapy Treatment{\dq}). The object-oriented software architecture of MIPART achieves a maximum of extensibility and flexibility. Our clinical tests show that MIPART can be easily integrated in the clinical routine in spite of the complexity of data in the field of intensity-modulated radiotherapy. Moreover, qualitatively better treatment plans can be generated than in conventional treatment planning, especially in complicated cases.}, year = {2002}, journal = {Zeitschrift f{\{\dq}u}r Medizinische Physik}, volume = {12}, pages = {89-96}, number = {2}, keywords = {computer-assisted; English Abstract; Humans; Imaging; Models; Phantoms; Radiotherapy Dosage; Radiotherapy Planning; Research Design; Theoretical} } @Inproceedings { bmgn_01, author = {Binder, Norbert and Markov, K. and Gruhn, R. and Nakamura, S.}, title = {Speech - Non-Speech Separation with GMMs}, abstract = {The separation of speech and non-speech events is an important problem for speech recognition .This paper investigates a separation method based on likelihood ratio using speech and non-speech Gaussioan Mixture models (GMM). The evaluation is done on the SPINE database}, year = {2001}, address = {Oita, Japan} } @Inproceedings { hhks_01c, author = {Hilbig, Matthias and Hanne, Robert and Kneschaurek, Peter and Schweikard, Achim}, title = {Verarbeitung von Dosis-Volumen-Constraints bei der inversen Bestrahlungsplanung mit linearer Optimierung}, year = {2001}, address = {Berlin} } @Inproceedings { bdrs_01, author = {Burgkart, Rainer and D{\{\dq}o}tter, M. and Roth, Michael and Schweikard, Achim}, title = {CT-less three-dimensional fluoroscopic navigation for femur head surgery}, year = {2001}, DOI = {10.1002/igs.1009}, volume = {6}, address = {Davos, CH}, series = {Computer Aided Surgery}, pages = {54}, number = {1}, file_url = {https://doi.org/10.1002/igs.1009} } @Inproceedings { hhks_01b, author = {Hilbig, Matthias and Hanne, Robert and Kneschaurek, Peter and Schweikard, Achim}, title = {Inverse radiotherapy treatment planning for intensity-modulated beams using the linear programming method}, year = {2001}, address = {San Francisco} } @Inproceedings { hhks_01, author = {Hanne, Robert and Hilbig, Matthias and Kneschaurek, Peter and Schweikard, Achim}, title = {Einfluss von geometrischen Parametern der Behandlungsstrahlen auf die Gewebe-Dosisbelastung bei der IMRT}, year = {2001}, address = {Hamburg} } @Inproceedings { Schwarzer2001, author = {Schwarzer, F. and Schweikard, Achim}, title = {C-Space Defragmentation for General Translational Assembly Planning}, year = {2001}, pages = {1537-1542} } @Misc { sa_00, author = {Schweikard, Achim and Adler Jr., John R.}, title = {Apparatus and method for compensating respiratory and patient motion during treatment}, year = {2000}, note = {US Patent 6,144,875} } @Article { ssj_00, author = {Schwarzer, F. and Schweikard, Achim and Joskowicz, Leo}, title = {Efficiently Testing for Unboundedness and Applications in Assembly Planning}, year = {2000}, journal = {International Journal of Robotics Research}, volume = {19}, pages = {817-834}, number = {9} } @Inproceedings { hhks_00, author = {Hilbig, Matthias and Hanne, Robert and Kneschaurek, Peter and Schweikard, Achim}, title = {Inverse Planung f{\{\dq}u}r IMRT auf der Basis von Linearer Programmierung}, year = {2000}, address = {M{\{\dq}u}nchen} } @Inproceedings { sa_00a, author = {Schweikard, Achim and Adler Jr., John R.}, title = {Motion Tracking for Respiratory Motion in Radiosurgery}, abstract = {Respiratory motion is difticult to track with conventional radiotherapy ayhtems. To track a moving target, the beam source or the patient would have to be moved in real-time during treatment. Safety margins currently used in radiation therapy increase the radiation dose by a very large amount. An accurate tracking method for following the motion of the tumor is of utmost clinical relevance. We investigate methods to compensate for respiratory motion using robotic radiosurgery with a modified Cyberknife system. Thus. the therapeutic beam is moved by a robotic arm. and follows the moving target tumor. To determine the precise position of the moving target we combine infrared trackin g with synchronized X-ray imaging. Infrared emitters are used to record the motion of the patient's skin surface. The position of internal gold fiducials is computed repeatedly during treatment. via computer image processing. Thus, stereo X-ray imaging is used during treatment to determine the precise spatial location of the implanted gold markers via automated image analysis. Using stereo X-ray imaging, precise marker positions can be established once every IO seconds. External markers (placed on the patient's skin) can be tracked automatically with optical methods at very high speed. Updated positions can be reported to the control computer more than 60 times per second. External markers alone cannot adequately reflect internal displacements caused by breathing motion. Large external motion may occur together with very small internal motion. and vice versa. In addition the direction of the visible external motion may deviate substantially from the direction of the target motion. We correlate the motion between external and internal markers. to predict the placement of the internal target in time periods between X-ray imaging. Although the infrared tracking is combined with X-ray imaging, it is not necessary to detect to position of the infrared emitters in an X-ray image. Time-stamps permit the simultaneous positions of both marker types to be established. and can therefore be used to determine respiratory motion patterns. These motion patterns are patient-specific, and can be updated durin g treatment. Experiments show that robotic tracking is ?dst and reliable enough to track the moving internal target. Clinical trials confirm our hypothesis that internal motion and external motion can indeed be correlated to predict internal motion with very high accuracy and reliability.}, year = {2000}, DOI = {10.1016/S0360-3016(00)80126-1}, volume = {48}, address = {Boston, MA}, series = {International Journal of Radiation Oncology, Biology, Physics}, pages = {166}, number = {3, Supplement 1}, file_url = {https://doi.org/10.1016/S0360-3016(00)80126-1} } @Inproceedings { omgb_00, author = {Ozhasoglu, C. and Murphy, Martin J. and Glosser, Greg and Bodduluri, Mohan and Schweikard, Achim and Forster, Kenneth M. and Martin, D. P. and Adler Jr., John R.}, title = {Real-Time Tracking of the Tumor Volume in precision radiotherapy and body radiosurgery -- a novel approach to compensate for respiratory motion}, year = {2000}, publisher = {Elsevier}, address = {San Francisco, CA}, editor = {Lemke, H. U. and Kiyonari, Inamura and Kunio, Doi and Vannier, Micheal W. and Farman, Allan G.}, pages = {691-696} } @Inproceedings { schw_00, author = {Schweikard, Achim}, title = {Robotergest{\{\dq}u}tzter Atmungsausgleich f{\{\dq}u}r die Strahlentherapie}, year = {2000}, address = {M{\{\dq}u}nchen} } @Article { sgbm_00, author = {Schweikard, Achim and Glosser, Greg and Bodduluri, Mohan and Murphy, Martin J. and Adler Jr., John R.}, title = {Robotic Motion Compensation for Respiratory Movement during Radiosurgery}, abstract = {Tumors in the chest and abdomen move during respiration. The ability of conventional radiation therapy systems to compensate for respiratory motion by moving the radiation source is inherently limited. Since safety margins currently used in radiation therapy increase the radiation dose by a very large amount, an accurate tracking method for following the motion of the tumor is of the utmost clinical relevance. We investigate methods to compensate for respiratory motion using robotic radiosurgery. Thus, the therapeutic beam is moved by a robotic arm, and follows the moving target tumor. To determine the precise position of the moving target, we combine infrared tracking with synchronized X-ray imaging. Infrared emitters are used to record the motion of the patient's skin surface. A stereo X-ray imaging system provides information about the location of internal markers. During an initialization phase (prior to treatment), the correlation between the motions observed by the two sensors (X-ray imaging and infrared tracking) is computed. This model is also continuously updated during treatment to compensate for other, non-respiratory motion. Experiments and clinical trials suggest that robot-based methods can substantially reduce the safety margins currently needed in radiation therapy.}, year = {2000}, DOI = {10.3109/10929080009148894}, journal = {Journal of Computer-Aided Surgery}, volume = {5}, publisher = {Wiley-Liss}, pages = {263-277}, number = {4}, tags = {MCRT}, file_url = {https://doi.org/10.3109/10929080009148894}, note = {timestamp=2007.03.01} } @Misc { s_99b, author = {Schweikard, Achim}, title = {Method to Control Radiation Apparatus for the Treatment of Tumors}, year = {1999}, note = {US Patent Application 09/103,533} } @Inproceedings { rbbc_99, author = {Roth, Michael and Brack, Ch. and Burgkart, Rainer and Czopf, A. and G{\{\dq}o}tte, H. and Schweikard, Achim}, title = {Multi-View contourless registration of bone structures using a single calibrated flouroscope}, year = {1999}, publisher = {Lemke, H.R., Vannier, M. Inamura, K. (ed.)}, address = {Paris} } @Book { Brack1999, author = {Brack, Ch. and Roth, Michael and Burgkart, Rainer and Schweikard, Achim}, title = {Radiological Navigation in Orthopedic Surgery}, year = {1999}, publisher = {Steinkopf-Verlag} } @Inbook { cmmh_99, author = {Chang, Steven D. and Murphy, Martin J. and Martin, D. P. and Hancock, Stephen L. and Doty, James and Adler Jr., John R.}, title = {Radiosurgery}, year = {1999}, volume = {3}, publisher = {Karger Medical and Scientific Publishers}, address = {New York}, editor = {Kondziolka, Douglas}, pages = {23-33} } @Inbook { Schweikard1998, author = {Schweikard, Achim and Adler Jr., John R. and Murphy, Martin J. and Hancock, Stephen L.}, title = {Image-Guided Stereotactic Radiosurgery: The Cyberknife}, year = {1998}, publisher = {Barnett, G., Roberts, D., Guthrie, B. (ed.), McGraw Hill}, tags = {MCRT}, note = {Motion Compensation in Radiosurgery} } @Article { sba_98, author = {Schweikard, Achim and Bodduluri, Mohan and Adler Jr., John R.}, title = {Planning for camera-guided robotic radiosurgery}, abstract = {Radiosurgery is a treatment for brain tumours and other lesions which employs a moving beam of photon radiation. In robotic radiosurgery, the radiation source is moved by a six degree-of-freedom robotic arm. A treatment planning system for robotic radiosurgery was developed. This planning system combines collision avoidance techniques and geometric algorithms for finding appropriate robot paths and beam activation profiles. The following design goals characterize our application: 1) ability to generate conformal 3D dose distributions; 2) transparency of the planning process; and 3) full use of the motion flexibility provided by the robotic arm. The new planning system is in clinical use in several leading medical institutions. Results obtained from the studies suggest that highly conformal distributions can be generated in a very effective way}, year = {1998}, issn = {1042-296X}, DOI = {10.1109/70.736778}, journal = {IEEE Transactions on Robotics and Automation}, volume = {14}, pages = {951-962}, number = {6}, file_url = {https://doi.org/10.1109/70.736778}, note = {timestamp=2006.11.22} } @Inbook { d_98, author = {Dietmaier, P.}, title = {The Stewart-Gough Platform of General Geometry can have 40 Real Postures: Analysis and Control}, year = {1998}, isbn = {978-90-481-5066-3}, DOI = {10.1007/978-94-015-9064-8_1}, publisher = {Springer Netherlands}, editor = {Lenar{\v{c}}i{\v{c}}, Jadran and Husty, Manfred L.}, pages = {7-16}, file_url = {https://doi.org/10.1007/978-94-015-9064-8_1} } @Inbook { asmh_98, author = {Adler Jr., John R. and Schweikard, Achim and Murphy, Martin J. and Hancock, Stephen L.}, title = {Image-guided neurosurgery: clinical applications of surgical navigation}, year = {1998}, publisher = {Quality Medical Publishing}, address = {St. Louis, MO}, editor = {Barnett, Gene H. and Roberts, David and Guthrie, Barton L.}, pages = {193-204}, note = {timestamp=2008.04.23} } @Inproceedings { Schwarzer1998, author = {Schwarzer, F. and Bieberbach, F. and Schweikard, Achim and Joskowicz, Leo}, title = {Efficiently testing for unboundedness and m-handed assembly}, year = {1998}, DOI = {10.1109/iros.1998.727456}, volume = {2}, pages = {1164-1169vol.2}, file_url = {https://doi.org/10.1109/iros.1998.727456}, note = {timestamp=2007.02.16} } @Article { ss_98a, author = {Schweikard, Achim and Schwarzer, F.}, title = {Detecting Geometric Infeasibility}, abstract = {The problem of deciding whether one or more objects can be removed from a set of other planar or spatial objects arises in assembly planning, computer-aided design, robotics and pharmaceutical drug design. In this context, it will be shown that certain D-dimensional arrangements of hyperplanes can be analyzed in the following way: only a single connected component is traversed, and the arrangement is analyzed as an arrangement of surface patches rather than full hyperplanes. In special cases, this reduction allows for polynomial time bounds, even if the boundary of the set of reachable placements has exponential complexity. The described techniques provide the basis for an exact method for translational assembly planning with many degrees of freedom. Experiments obtained with an implementation suggest that problems with random planning methods, which are related to the choice of internal parameters can be avoided with this exact method. In addition, unsolvability can be established and the program can be applied to the verification of symbolic rules describing the geometry.}, year = {1998}, issn = {0004-3702}, DOI = {10.1016/S0004-3702(98)00076-9}, journal = {Artificial Intelligence}, volume = {105}, series = {TU M{\{\dq}u}nchen}, pages = {139-159}, number = {1-2}, keywords = {Arrangement computation in D dimensions; Assembly planning; Complete algorithms; Geometric reasoning; Motion planning}, file_url = {https://doi.org/10.1016/S0004-3702(98)00076-9}, note = {timestamp=2007.02.16} } @Inproceedings { bbrs_98, author = {Brack, Ch. and Burgkart, Rainer and Roth, Michael and Schweikard, Achim}, title = {Accurate Navigation and Camera Calibration in Orthopeadic Surgery}, year = {1998}, publisher = {Lemke, H.U., Vannier, M., Inamura, K. (ed.)}, address = {Tokyo} } @Techreport { Bieberbach1997, author = {Bieberbach, F. and Schwarzer, F. and Joskowicz, Leo and Schweikard, Achim}, title = {Efficiently Testing for Linear Unboundedness and m-handed Assembly Planning}, year = {1997}, series = {TU M{\{\dq}u}nchen}, note = {Technischer Report TUM I-9750, Informatik} } @Inproceedings { Schweikard1997b, author = {Schweikard, Achim and Schwarzer, F.}, title = {General Translational Assembly Planning}, year = {1997}, address = {Albuquerque, New Mexico, USA}, pages = {162-169} } @Inproceedings { Schweikard1997a, author = {Schweikard, Achim}, title = {Resolution-Complete Inverse Planning in Radiosurgery}, year = {1997}, publisher = {Lemke, H.U., Vannier, M. Inamura, K. (ed.)}, address = {Berlin}, pages = {361-368} } @Article { Gosse1997, author = {Goss{\'e}, F. and Brack, Ch. and G{\{\dq}o}tte, H. and Roth, Michael and R{\{\dq}u}hmann, O. and Schweikard, Achim and Vahldiek, M.}, title = {Robot-assisted knee endoprosthesis}, abstract = {With the development of powerful computer systems, computer-assisted medical diagnosis and therapy have become common over the last 10 years. Even in the surgical field, computer- and robotic-assisted techniques are becoming practical but are not yet used on a daily basis. In the orthopaedic field, computer and robotic assistance is used in planning and performing demanding three-dimensional osteotomies, setting pedicle screws in the spine and milling the femoral medullary canal in total hip replacement. This article introduces a computer- and robotic-assisted system for performing arthroplasty in total knee replacement procedures.}, year = {1997}, journal = {Der Orthop}, volume = {26}, pages = {258-266}, number = {3}, keywords = {Computer Simulation; computer-assisted; Costs and Cost Analysis; English Abstract; Humans; image processing; Knee Joint; Knee Prosthesis; Osteotomy; Patient Care Planning; Preoperative Care; Quality Control; Robotics; Tomography; X-Ray Computed}, note = {timestamp=2006.11.22} } @Article { gbgr_97, author = {Goss{\'e}, F. and Brack, Ch. and G{\{\dq}o}tte, H. and Roth, Michael and R{\{\dq}u}hmann, O. and Schweikard, Achim and Vahldiek, M.}, title = {Roboterunterst{\{\dq}u}tzung in der Knieendoprothetik}, abstract = {Mit der Entwicklung sehr leistungsf{\{\dq}a}higer Kleincomputer hat der Einzug von computerunterst{\{\dq}u}tzten Systemen in vielen Bereichen der operativen Medizin begonnen. In der Orthop{\{\dq}a}die werden diese Systeme zur Unterst{\{\dq}u}tzung bei komplexen Korrekturosteotomien, bei Pedikelbohrungen an der Wirbels{\{\dq}a}ule sowie bei der Implantation von H{\{\dq}u}ftendoprothesensch{\{\dq}a}ften eingesetzt. Es wird ein System zur computerunterst{\{\dq}u}tzten Planung und intraoperativen Unterst{\{\dq}u}tzung in der Knieendoprothetik vorgestellt.}, year = {1997}, journal = {Der Orthop}, volume = {26}, pages = {258-266} } @Article { sa_97, author = {Schweikard, Achim and Adler Jr., John R.}, title = {Robotic radiosurgery with noncylindrical collimators}, abstract = {In radiosurgery, a moving beam of radiation acts as an ablative surgical instrument. Conventional systems for radiosurgery use a cylindrical radiation beam of fixed cross section. The radiation source can be moved only along simple, standardized paths. A new radiosurgical system based on a six-degree-of-freedom robotic arm has been developed to overcome limitations of conventional systems. We address the following question: Can dose distributions generated by robotic radiosurgery be improved by using noncylindrical radiation beams? This includes static noncylindrical collimators and collimators of adaptable cross section. Geometric methods for planning the shape of the beam in addition to planning beam motion are developed. Design criteria considered in this context are treatment time, radiation penumbra, and transparency of interactive treatment planning. An experimental evaluation compares distributions generated with our new radiosurgical system using cylindrical beams to distributions generated with beams of adaptable, noncylindrical shapes.}, year = {1997}, journal = {Journal of Computer-Aided Surgery}, volume = {2}, pages = {124-134}, number = {2}, keywords = {Comparative Study; Computer Simulation; computer-assisted; Equipment Design; Humans; Intracranial Arteriovenous Malformations; Online Systems; Particle Accelerators; Patient Care Planning; Radiation Dosage; Radiopharmaceuticals; Radiosurgery; Robotics; Therapy; Time Factors}, note = {timestamp=2006.11.22} } @Inproceedings { rbsg_96, author = {Roth, Michael and Brack, Ch. and Schweikard, Achim and G{\{\dq}o}tte, H. and Moctezuma, J. and Goss{\'e}, F.}, title = {A New Less Invasive Approach to Knee Surgery using a Vision-Guided Manipulator}, abstract = {We describe new methods for on-line image processing and calibration in the context of a vision-guided robotics system for orthopaedic knee surgery: During knee surgery, e.g. insertion of knee implants, bone material of the femur and the tibia has to be removed. Conventionally, surgeons use templates to guide a hand-held saw. Therefore accuracy is limited by the surgeon's skills and dexterity. The proposed system uses a saw mounted on a guiding device fixed on a manipulator's hand. During surgery the hand is guided to preoperatively planned cutting planes. Hence the surgeon freely moves the saw to remove bony material, only limited by the guiding device keeping the movement within the cutting plane. This approach combines the robot's high accuracy with the surgeon's expertise and is therefore expected to provide safety, high overall accuracy and lower complication rates.}, year = {1996}, publisher = {ASME Press}, pages = {731-738} } @Article { sw_95, author = {Schweikard, Achim and Wilson, R. H.}, title = {Assembly sequences for polyhedra}, abstract = {The problem of finding sequences of motions for the assembly of a given object consisting of polyhedral parts arises in assembly planning. We describe an algorithm to compute the set of all translations separating two polyhedra withn vertices inO(n4) steps and show that this is optimal. Given an assembly ofk polyhedra with a total ofn vertices, an extension of this algorithm identifies a valid translation and removable subassembly in O(k2n4) steps if one exists. Based on the second algorithm, a polynomial-time method for finding a complete assembly sequence consisting of single translations is derived. An implementation incorporates several changes to achieve better average-case performance; experimental results obtained for simple assemblies are described.}, year = {1995}, issn = {1432-0541}, DOI = {10.1007/BF01189068}, journal = {Algorithmica}, volume = {13}, pages = {539-552}, number = {6}, keywords = {Arrangement computation in the plane; Assembly planning; Separating polyhedra}, file_url = {https://doi.org/10.1007/BF01189068}, note = {timestamp=2007.02.16} } @Inbook { Schweikard1995a, author = {Schweikard, Achim and Adler Jr., John R.}, title = {Bloodless Robotic Surgery}, year = {1995}, publisher = {St. Martin's Press}, pages = {123-129} } @Book { c_95, author = {Adler Jr., John R. and Schweikard, Achim}, title = {Future health: computers and medicine in the twenty-first century}, year = {1995}, isbn = {0-312-12602-6}, publisher = {St. Martin's Press, Inc.}, address = {New York, NY, USA}, editor = {Pickover, Clifford A.}, pages = {123-129}, tags = {MCRT}, note = {Motion Compensation in Radiosurgery} } @Inbook { astl_95, author = {Adler Jr., John R. and Schweikard, Achim and Tombropoulos, Rhea and Latombe, J.-C.}, title = {Modelling and Planning for Sensor-based Intelligent Robot Systems}, abstract = {We describe a radiosurgical system based on a novel medical linear accelerator of particularly light weight, a six degree-of-freedom robotic arm and an online x-ray vision system. The system introduces a class of radiosurgical procedures, termed non-stereotactic, or image-guided radiosurgery. A treatment planning subsystem based on new paradigms for inverse planning was developed in an interdisciplinary project at Stanford University in conjunction with Accuray Inc., Santa Clara. Four patients have been treated with a fully integrated system prototype at Stanford University Medical Center. The new system has the potential for revolutionary changes in radiosurgery by allowing for high accuracy targeting, fractionated treatment and highly conformal radiosurgical treatment of non-spherical lesions. Furthermore, it is expected that image-guided procedures will replace radiotherapeutical methods for many extra-cranial lesions.}, year = {1995}, DOI = {10.1142/9789812797773\_0028}, volume = {21}, publisher = {World Scientific Publishers Co.}, series = {Series in Machine Perception and Artificial Intelligence}, editor = {Bunke, H. and Kanade, Takeo and Noltemeier, H.}, pages = {460-470}, file_url = {https://doi.org/10.1142/9789812797773\_0028} } @Inbook { Schweikard1995b, author = {Schweikard, Achim and Bodduluri, Mohan and Tombropoulos, Rhea and Adler Jr., John R.}, title = {Planning, Calibration and Collision Avoidance for Image-Guided Radiosurgery}, year = {1995}, publisher = {Elsevier}, address = {Amsterdam} } @Inproceedings { sta_95, author = {Schweikard, Achim and Tombropoulos, Rhea and Adler Jr., John R.}, title = {Robotic Radiosurgery with Beams of Adaptable Shapes}, abstract = {In radiosurgery, a moving beam of radiation acts as an ablative surgical instrument. Conventional systems for radiosurgery use a cylindrical radiation beam of fixed cross-section. The radiation source can only be moved along simple standardized paths. A new radiosurgical system based on a six degree-of-freedom robotic arm has been developed to overcome limitations of conventional systems. We address the following question: Can dose distributions generated by robotic radiosurgery be improved by using non-cylindrical radiation beams of adaptable cross-section? Geometric methods for planning the shape of the beam in addition to planning beam motion are developed. Design criteria considered in this context are: treatment time, radiation penumbra as well as transparency of interactive treatment planning. An experimental evaluation compares distributions generated with our new radiosurgical system using cylindrical beams to distributions generated with beams of adaptable shapes.}, year = {1995}, volume = {905}, publisher = {Springer}, address = {Nice, France}, series = {Lecture Notes in Computer Science}, editor = {Ayache, Nicholas}, pages = {138-149}, tags = {TP} } @Misc { s_95, author = {Schweikard, Achim}, title = {Treatment Planning Apparatus and Method for Radiosurgery and Radiation Therapy}, year = {1995}, note = {US Patent 5,458,125} } @Inproceedings { stka_94, author = {Schweikard, Achim and Tombropoulos, Rhea and Kavraki, L. and Adler Jr., John R. and Latombe, J.-C.}, title = {Treatment planning for a radiosurgical system with general kinematics}, abstract = {In radiosurgery a beam of radiation is used as an ablative surgical instrument to destroy brain tumors. Treatment planning consists of computing a sequence of beam configurations for delivering a necrotic dose to the tumor, without damaging healthy tissue or particularly critical structures. In current systems, kinematic limitations severely constrain beam motion. This often results in inappropriate dose distributions. A new radiosurgical system has been implemented to overcome this disadvantage. In this system, a compact radiation source of high energy is moved by a 6-der robotic arm. We describe algorithms for computing a motion with specified characteristics for this new system. Treatment plans used at test sites with earlier systems are compared to plans computed with the described algorithms. The experience reported shows that full kinematic flexibility combined with treatment planning algorithms allows for better protection of healthy tissue and higher dosage in tumors.}, year = {1994}, DOI = {10.1109/robot.1994.351344}, address = {San Diego, CA, USA}, pages = {1720-1727}, file_url = {https://doi.org/10.1109/robot.1994.351344}, note = {timestamp=2006.11.22} } @Inproceedings { Moctezuma1994b, author = {Moctezuma, J. and Bernasch, J. and Lohmann, G. and Schweikard, Achim and Goss{\'e}, F.}, title = {Robotic surgery and planning for corrective femur osteotomy}, year = {1994}, DOI = {10.1109/iros.1994.407490}, volume = {2}, pages = {870-877vol.2}, file_url = {https://doi.org/10.1109/iros.1994.407490}, note = {timestamp=2006.11.22} } @Inproceedings { Moctezuma1994a, author = {Moctezuma, J. and Goss{\'e}, F. and Bernasch, J. and Lohmann, G. and Schweikard, Achim}, title = {Robotic Femur Osteotomy}, year = {1994}, pages = {870-877} } @Inbook { Schweikard1994a, author = {Schweikard, Achim and Tombropoulos, Rhea and Adler Jr., John R. and Latombe, J.-C.}, title = {Planning for Image-Guided Radiosurgery}, year = {1994}, publisher = {AAAI Press}, address = {Menlo Park}, pages = {96-101}, note = {Papers from the 1994 AAAI Spring Symposium} } @Inproceedings { sbta_94, author = {Schweikard, Achim and Bodduluri, Mohan and Tombropoulos, Rhea and Adler Jr., John R.}, title = {Planning, calibration and collision-avoidance for image-guided radiosurgery}, abstract = {In radiosurgery a moving beam of radiation is used as an ablative surgical instrument to destroy brain tumors. A new camera-guided system capable of tracking patient motion during treatment has been built. The radiation source is moved by a six degree-of-freedom robotic arm. In addition to offering a more cost effective, less invasive, and less painful treatment, the robotic gantry allows for arbitrary spatial motion of the radiation source. Based on this feature we can treat non-spherical lesions with accuracies unachievable with classical radiosurgical systems. The system introduces a new class of radiosurgical procedures, called non-stereotactic, or image-guided radiosurgery. At the heart of these procedures are algorithms for planning both a treatment and the corresponding beam motion, given the geometric description of the tumor shape and relative locations in the particular case}, year = {1994}, DOI = {10.1109/iros.1994.407492}, volume = {2}, address = {M{\{\dq}u}nchen}, pages = {854-861}, file_url = {https://doi.org/10.1109/iros.1994.407492}, note = {timestamp=2006.11.22} } @Inproceedings { Adler1994, author = {Adler Jr., John R. and Schweikard, Achim and Tombropoulos, Rhea and Latombe, J.-C.}, title = {Image-Guided Robotic Radiosurgery}, year = {1994}, address = {Shadyside Hospital, Pittsburgh}, pages = {291-297} } @Article { Henke1994aatis, author = {Henke, Maria and Roes, Stefanie}, title = {Ein Rendezvous mit OSCAR --- Untersuchung der Bahnbewegungen von Satelliten}, year = {1994}, journal = {Praxisheft 2 f{\{\dq}u}r Amateurfunk und Elektrotechnik in Schule und Freizeit}, pages = {66-72} } @Inproceedings { Schweikard1994b, author = {Schweikard, Achim and Adler Jr., John R.}, title = {New Collimation Methods for Radiosurgery}, year = {1994}, address = {Shadyside Hospital, Pittsburgh}, pages = {298-305} } @Inproceedings { sal_93a, author = {Schweikard, Achim and Adler Jr., John R. and Latombe, J.-C.}, title = {Motion planning in stereotaxic radiosurgery}, abstract = {Stereotaxic radiosurgery, which uses a beam of radiation as an ablative surgical instrument to destroy brain tumors, is considered. The beam is produced by a linear accelerator moved by a mechanical gantry. Radiation is concentrated by crossfiring at the tumor from multiple directions. Because access to and exit from the tumor is obstructed along some directions by critical brain structures (e.g., brainstem, optic nerves), planning the path of the beam is often difficult and time-consuming. A computer-based planner that assists the surgeon in generating a satisfactory path, given the spatial distribution of the brain tissues obtained with medical imaging, is described. Experimental results with the planner are presented, including a comparison with manually generated paths}, year = {1993}, DOI = {10.1109/robot.1993.292092}, journal = {IEEE Transactions on Robotics and Automation}, volume = {9}, pages = {909-916}, number = {6}, file_url = {https://doi.org/10.1109/robot.1993.292092}, note = {timestamp=2006.11.22} } @Inproceedings { mgbl_93, author = {Moctezuma, J. and Goss{\'e}, F. and Bernasch, J. and Lohmann, G. and Schweikard, Achim}, title = {Planungsverfahren und kameragef{\{\dq}u}hrte Handhabungsger{\{\dq}a}te f{\{\dq}u}r H{\{\dq}u}ftgelenkosteotomien}, year = {1993}, address = {Langen} } @Article { s_92a, author = {Schweikard, Achim}, title = {A simple path search strategy based on calculation of free sections of motions}, year = {1992}, journal = {Engineering Applications of Artificial Intelligence}, volume = {5}, pages = {1-10}, number = {1} } @Inproceedings { Wilson1992, author = {Wilson, R. H. and Schweikard, Achim}, title = {Assembling polyhedra with single translations}, year = {1992}, DOI = {10.1109/robot.1992.220106}, series = {Stanford University, Dept. of Computer Science}, pages = {2392-2397vol.3}, number = {CS-91-1387}, file_url = {https://doi.org/10.1109/robot.1992.220106}, note = {timestamp=2007.02.16} } @Article { s_92, author = {Schweikard, Achim}, title = {Real zero isolation for trigonometric polynomials}, abstract = {An exact and practical method for determining the number, location, and multiplicity of all real zeros of the trigonometric polynomials is described. All computations can be performed without loss of accuracy. lThe method is based on zero isolation techniques for algebraic polynomials. An efficient method for the calculation of the coefficients of a corresponding algebraic polynomial is stated. The complexity of trigonometric zero isolation depending on the degree and the coefficient size of the given trigonometric polynomial is analyzed. In an experimental evaluation, the performance of the method is compared to the performance of recently developed numeric techniques for the approximate determination of all roots of trigonometric polynomials. The case of exponential or hyperbolic polynomials is treated in an appendix.}, year = {1992}, issn = {0098-3500}, DOI = {10.1145/131766.131775}, journal = {ACM Transactions on Mathematical Software}, volume = {18}, pages = {350-359}, number = {3}, file_url = {https://doi.org/10.1145/131766.131775} } @Inproceedings { Schweikard1992, author = {Schweikard, Achim and Adler Jr., John R. and Latombe, J.-C.}, title = {Wegbestimmung in der Stereotaktischen Bestrahlungchirurgie}, year = {1992}, address = {Karlsruhe}, pages = {326-336} } @Article { s_91, author = {Schweikard, Achim}, title = {Trigonometric polynomials with multiple roots}, year = {1991}, journal = {Information Processing Letters}, volume = {39}, pages = {231-236}, number = {5} } @Techreport { Wilson1991a, author = {Wilson, R. H. and Adler Jr., John R. and Latombe, J.-C.}, title = {Motion Planning for Stereotaxic Radiosurgery}, year = {1991}, publisher = {MIT Press}, address = {Cambridge (Mass.)}, series = {Stanford University, Dept. of Computer Science}, pages = {693-706}, note = {Techn. Report STAN-CS-92-1441} } @Article { s_91a, author = {Schweikard, Achim}, title = {Polynomial time collision detection for manipulator paths specified by joint motions}, abstract = {An exact collision detection algorithm is described and analyzed. The time bound considers the complexity of the solids, the number of joints, and the number of distinct collision configurations. A bound for the number of collision configurations can be taken directly from the input data. The algorithm is based on an exact treatment of trigonometric expressions. The representation of trigonometric constants is discussed. Since all computations are exact, the distances between objects can be arbitrarily small. It is shown that collision detection can be performed in polynomial time. Other measures for the complexity of a motion with respect to collision detection could be based on minimal distances between objects. In this case smaller distances lead to increased computing time}, year = {1991}, DOI = {10.1109/70.105397}, journal = {IEEE Transactions on Robotics and Automation}, volume = {7}, pages = {865-870}, number = {6}, file_url = {https://doi.org/10.1109/70.105397}, note = {timestamp=2006.11.22} } @Techreport { Schweikard1990a, author = {Schweikard, Achim}, title = {A Hyperplane Strategy for Multi-Dimensional Motion Planning}, year = {1990}, series = {Fachbereich Informatik, Technische Universit{\{\dq}a}t Berlin}, number = {90-30}, note = {Technischer Bericht} } @Article { s_90, author = {Schweikard, Achim}, title = {Ein iteratives Verfahren zur Bestimmung {\{\dq}u}berschneidungsfreier Teilst{\{\dq}u}cke von Bewegungen}, year = {1990}, issn = {0178-0026}, journal = {Robotersysteme}, volume = {6}, pages = {245-252}, number = {4}, keywords = {Algorithms; Planning; Robotics; Trajectory} } @Techreport { Schweikard1990b, author = {Schweikard, Achim}, title = {Square-Free Trigonometric Polynomials}, year = {1990}, series = {Fachbereich Informatik, Technische Universit{\{\dq}a}t Berlin}, number = {90-12}, note = {Technischer Bericht} } @Techreport { Schweikard1989b, author = {Schweikard, Achim}, title = {AdaIR - Ein Programmiersystem zur Steuerung von Industrierobotern in Ada}, year = {1989}, series = {Fachbereich Informatik, Technische Universit{\{\dq}a}t Berlin}, number = {89-3}, note = {Technischer Bericht} } @Techreport { Schweikard1989a, author = {Schweikard, Achim}, title = {Real zero isolation for trigonometric and exponential polynomials}, year = {1989}, series = {Fachbereich Informatik, Technische Universit{\{\dq}a}t Berlin}, number = {89-21}, note = {Technischer Bericht} } @Article { sh_88, author = {Schweikard, Achim and Hommel, G.}, title = {Berechnung erreichbarer Effektorstellungen f{\{\dq}u}r Handhabungsger{\{\dq}a}te mit weniger als sechs Freiheitsgraden}, year = {1988}, journal = {Robotersysteme}, volume = {4}, pages = {177-182} } @Inproceedings { Schweikard1988b, author = {Schweikard, Achim}, title = {Exact Collision Detection For Simultaneously Working Robot Manipulators}, year = {1988}, pages = {335-340}, note = {timestamp=2006.11.22} } @Techreport { Schweikard1988a, author = {Schweikard, Achim}, title = {Exakte und geschlossene Verfahren zur Kollisionserkennung f{\{\dq}u}r parallel arbeitende Roboterarme}, year = {1988}, series = {Fachbereich Informatik , Technische Universit{\{\dq}a}t Berlin}, number = {88-7}, note = {Technischer Bericht} }