Comparison of TG‐43 dosimetric parameters of brachytherapy sources obtained by three different versions of MCNP codes

Abstract

Monte Carlo simulations are widely used for calculation of the dosimetric parameters of brachytherapy sources. MCNP4C2, MCNP5, MCNPX, EGS4, EGSnrc, PTRAN, and GEANT4 are among the most commonly used codes in this field. Each of these codes utilizes a cross‐sectional library for the purpose of simulating different elements and materials with complex chemical compositions. The accuracies of the final outcomes of these simulations are very sensitive to the accuracies of the cross‐sectional libraries. Several investigators have shown that inaccuracies of some of the cross section files have led to errors in 125I and 103Pd parameters. The purpose of this study is to compare the dosimetric parameters of sample brachytherapy sources, calculated with three different versions of the MCNP code — MCNP4C, MCNP5, and MCNPX. In these simulations for each source type, the source and phantom geometries, as well as the number of the photons, were kept identical, thus eliminating the possible uncertainties. The results of these investigations indicate that for low‐energy sources such as 125I and 103Pd there are discrepancies in normalgLfalse(rfalse) values. Discrepancies up to 21.7% and 28% are observed between MCNP4C and other codes at a distance of 6 cm for 103Pd and 10 cm for 125I from the source, respectively. However, for higher energy sources, the discrepancies in normalgLfalse(rfalse) values are less than 1.1% for 192Ir and less than 1.2% for 137Cs between the three codes.PACS number(s): 87.56.bg

Monte-Carlo techniques for radiotherapy applications II: equipment and source modelling, dose calculations and radiobiology

“…While the majority of this overview has focussed on external beam radiotherapy and associated imaging, it is worth noting that Monte-Carlo calculation techniques have been widely used to model the dosimetry of brachytherapy. Many of the Monte-Carlo codes have capabilities for defining the geometries and sources used in brachytherapy, including EGSnrc and its egs_brachy user code, 50 MCNP 51,52 and GEANT4• [53][54][55] For those without GEANT4 experience, brachytherapy simulation capabilities are also offered through the more user-friendly TOPAS and GATE toolkits. 56,57 As part of the Monte-Carlo collection in this journal, Dagli et al compared three different dose calculation algorithms for clinical HDR brachytherapy.…”