Development and implementation of a Monte Carlo frame work for evaluation of patient specific out- of - field organ equivalent dose

The aim of this study was to develop and implement a Monte Carlo framework for evaluaon of paent specific out-of-field organ equivalent dose (OED).
Dose calculaons were performed using a Monte Carlo-based model of Oncor linac and tomographic phantoms. Monte Carlo simulaons were performed using EGSnrc user codes. Dose measurements were performed using radiochromic films. Furthermore, the applicability of this framework was examined for a 3D conformal radiotherapy of breast.
Commissioning of the beam model was done by comparing the measured and calculated out-of-field dose values of several points in the physical and tomographic phantoms, respecvely. The maximum percentage difference was 17%, which was smaller than 30% acceptance criteria for Monte Carlo modeling. The maximum stascal uncertainty in out -of-field dose calculaon was 23%. Organ equivalent doses for out of field organs in 3D conformal radiotherapy of le1 breast varied from 2.4 cGy for right kidney to 134.6 cGy for the le1 humeral head.
The framework developed in this research is a valuable tool for calculang peripheral dose and out-of field paent specific OEDs, the quanes needed for calculang risk of secondary cancer inducon as a result of radiotherapy. This code can be used as a paent specific treatment plan opmizaon tool in order to select a treatment plan with the lowest risk of secondary cancer inducon.