Towards high-accuracy head-tracking for radiation therapy

Type of publication:  Artikel in einem Konferenzbericht
Buchtitel: Varian Research Partnership Symposium
Jahr: 2013
Monat: März
Seiten: accepted
Verlag: Varian Research Partnership Symposium
Ort: Atlanta, GA, USA
Organisation: Varian Medical
Abriss: 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.
Autoren: Stüber, Patrick
Wissel, Tobias
Jauer, Philipp
Wagner, Benjamin
Bruder, Ralf
Schweikard, Achim