Towards clinical application of RayStretch for heterogeneity corrections in LDR permanent 125-I prostate brachytherapy

Purpose: RayStretch is a simple algorithm proposed for heterogeneity corrections in low-dose-rate brachytherapy. It is built on top of TG-43 consensus data, and it has been validated with Monte Carlo (MC) simulations. In this study, we take a real clinical prostate implant with 71 125I seeds as reference and we apply RayStretch to analyze its performance in worst-case scenarios. Methods and Materials: To do so, we design two cases where large calcifications are located in the prostate lobules. RayStretch resilience under various calcification density values is also explored. Comparisons against MC calculations are performed. Results: Dose-volume histogram-related parameters like prostate D90, rectum D2cc, or urethra D10 obtained with RayStretch agree within a few percent with the detailed MC results for all cases considered. Conclusions: The robustness and compatibility of RayStretch with commercial treatment planning systems indicate its applicability in clinical practice for dosimetric corrections in prostate calcifications. Its use during intraoperative ultrasound planning is foreseen