Abstract

Radiotherapy treatment of cancer is designed to deliver a lethal dose to a tumour, while minimising collateral damage to surrounding healthy tissue. The prescribed dose is typically administered in thirty to forty treatment sessions, over a period of about fifty days. Patients are carefully positioned at each session, to ensure that the tumour is accurately targeted. Possible changes in the position and shape of nearby healthy organs are not taken into account, so that the dose to these organs can be different from the dose originally planned. The interdisciplinary VoxTox project aims to track actual doses at the level of volume elements (voxels), and to correlate with short-and long-term side effects (toxicity). This can potentially lead to improved treatment strategies, which increase survival probabilities, and reduce long-term side-effects. The initial focus is on prostate cancer, where the main treatment risk is damage to the rectum.

This seminar presents dose-tracking methodologies being developed in the VoxTox project, making use of low-resolution images from computed-tomography scans performed at treatment time to guide patient positioning. Progress is reported in areas that include: uncertainty estimates for locating the rectum though manual and automated image segmentation; biomechanical modelling to understand the movement of material elements; dose recalculations, taking into account changes in material distributions at each treatment session.