Validation of a radiobiological model for low-dose-rate prostate boost focal therapy treatment planning

Abstract

Purpose: Low-dose-rate brachytherapy using iodine-125 seeds is a highly efficacious treatment for low-risk prostate cancer. We propose a bioeffect model may be used to target an ablative dose to the tumor with a lower, therapeutic dose to low-risk regions to maintain high rates of tumor control with reduced toxicity. We report on the validation of the model and derivation of the optimal cutpoint value of tumor control probability (TCP) that predicts for freedom from biochemical failure. Methods and Materials: The TCP was calculated from postimplant dosimetry data for 423 prostate cancer patients from three Australian institutions. To apply the model, the prostate was mathematically divided i..