Patient-Specific Collision Zones for 4π Trajectory Optimized Radiation Therapy

Abstract

This thesis presents a system that determined patient-specific collision zones (CZs) to enable safe and deliverable non-coplanar treatment trajectories for stereotactic body radiation therapy (SBRT) patients. Full body scans of patients in treatment position were acquired using an optical scanner, creating a library of scans to augment CT scans. This resulted in a patient model that was aligned with a model of the treatment LINAC, where both components were rotated to test for collisions. To test collision detection accuracy an end-to-end cranial test was performed. The buffer sized required during the registration process to achieve a sensitivity of one was determined via a registration accuracy test. Incorporating the patient-specific CZs, non-coplanar treatment plans were created and compared to clinical coplanar plans for SBRT lung patients (N = 8). A statistically significant change in the mean dose to the lungs was found. Our study indicated that determining patient-specific CZs can be accomplished enabling safe non-coplanar treatment plans.