Dynamic Model-Based Dose Calculations of Permanent Implant Prostate Brachytherapy

This thesis presents the development of a framework for performing dynamic model-based dose calculations in target organs exhibiting geometry changes during permanent implant brachytherapy. The framework is applied to investigate the dosimetric effect of edema during125I prostate brachytherapy. Dynamic dose distributions are accumulated from mapped dose distributions calculated using Monte Carlo (MC) simulations on treatment geometries predicted from post-implant images and clinically-observed models of edema. Ten unique edema resolution models are implemented for 120 patients. Clinical AAPM TG-43 and static MC dose calculations overestimate D90 values compared to dynamically-calculated dose distributions; these overestimations range from 5 to >30% depending on edema model and patient parameters,e.g., the presence of intraprostatic calcifications. Edema should be considered for accurate dose calculations of permanent implant prostate brachytherapy treatments.