Techniques to Minimize the Dosimetric Impact of Intrafractional Motion with Improved Treatment Accuracy and Efficiency on a C-arm Medical Linear Accelerator

Abstract

Stereotactic radiosurgery is a high-dose therapeutic technique for treating cranial lesions. To ensure that treatment is safe and effective several techniques are employed, namely: (1) Image guidance to ensure accurate patient positioning (e.g. pre-treatment cone-beam computed tomography); (2) Use of immobilization devices (e.g. invasive frames or non-invasive thermoplastic masks) that fixate the patient to the treatment couch during therapy. Despite these efforts, intra-fraction motion on the order of several millimetres or degrees can occur that could impact target coverage, and dose received to healthy tissues. This work aims to quantify the dosimetric impact of motion during radiosurgery and develop two methodologies for addressing motion: 1) megavoltage (MV) imaging with region of interest (ROI) apertures to detect and correct for motion with couch translations. 2) Dynamic couch trajectories to minimize treatment distances during delivery which could improve treatment efficiency, potentially minimizing the magnitude and/or frequency of motion.