Estimation of Photon and Electron Specific Absorbed Fractions for Selected Organs of a Human Voxelizedphantom Using GATE Monte Carlo Package

Abstract

Background: The specific absorbed fraction (SAF) of energy is an essential element of internal dose assessment. Objectives: Here we report a set of SAFs calculated for selected organs of ahuman computational phantom. Materials and Methods: The Monte Carlo transport code GATE version 6.1 was used to simulate monoenergetic photons and elec- trons with energies ranging from 10 keV to 2 MeV. The particles were emitted from three source organs: the kidneys, liver, and spleen. SAFs were calculated for three target regions in the body (kidneys, liver, and spleen) and compared with the results obtained using MCNP4B and GATE/GEANT4 Monte Carlo codes. For most photon energies, the self-irradiation was higher and cross-irradiation was lower in the results obtained using GATE than those obtained usingMCNP4B. Results: The results showed generally good agreement for photons and high-energy electrons, with discrepancies within -2 3%. Nevertheless, significant dierences were found for cross-irradiation of photons of lower energy and electrons of higher energy due to statistical uncertainties larger than 10%. The comparisons of SAF values for the human voxel phantom did not show significant dierences; furthermore, the results demonstrated the usefulness and applicability of the GATE Monte Carlo package for voxel level dose calculations in non-uniform media. Conclusions: The present SAF calculation for the Zubal voxel phantom is validated by comparison with the results obtained using other Monte Carlo codes.