Validation of<scp>GEANT4</scp>, an object-oriented Monte Carlo toolkit, for simulations in medical physics

TLDR

GEANT4 is an object‑oriented Monte Carlo toolkit developed by a global collaboration that simulates particle transport through matter. The study aims to validate GEANT4 for medical physics by performing a series of benchmark simulations. Results were compared with published data from MCNP, EGS4, and EGSnrc, with additional experimental comparisons where possible, across multiple geometries, source types, particle species, and energies. In heterogeneous media discrepancies up to 5 % were observed, while in homogeneous media GEANT4 matched EGSnrc against experiment and depth‑dose differences were below 4 %, indicating GEANT4 is a promising low‑energy medical physics tool.

Abstract

GEANT4 (GEometry ANd Tracking 4) is an object-oriented Monte Carlo simulation toolkit that has been developed by a worldwide collaboration of scientists. It simulates the passage of particles through matter. In order to validate GEANT4 for medical physics applications, different simulations are conducted. The results are compared to published results based on three Monte Carlo codes widely used in medical physics: MCNP, EGS4, and EGSnrc. When possible, the simulation results are also compared to experimental data. Different geometries are tested (multilayer and homogeneous phantoms), different sources considered (point-source and broad parallel beam), and different primary particles simulated (photons and electrons) at different energies. For the heterogeneous media, there are notable differences between the Monte Carlo codes reaching up to over 5% in relative difference. For the monoenergetic electrons in a homogeneous medium, the difference between GEANT4 and the experimental measurements is similar to the difference between EGSnrc and the experimental measurements; for the depth-dose curves, the difference expressed as a fraction of the peak dose is always smaller than 4%. We conclude that GEANT4 is a promising Monte Carlo simulation toolkit for low-energy medical applications.