Estimation and Evaluation of Tissue Inhomogeneity Effect on Dose Distribution for High Dose Rate Iridium 192 Source Using Monte Carlo Simulation and Film Dosimetery

Abstract

The aim of this work was to present a theoretical analysis of how phantom dimensions and tissue heterogeneities in interstitial brachytherapy affect on dose distributions. This work was carried out using Gafchromic film measurement and Monte Carlo simulation for 192Ir source. Results show that treatment planning systems (TPS) which consider the patient geometry as homogeneous medium, lead to a dose underestimation up to 8.2% for lung and an overestimation up to 9% for bone. These values depend on the thickness and distance from the source. Thus, TPSs currently in use for clinical brachytherapy cannot consider the effect of tissue heterogeneity on dose distribution.