Updated computational performance evaluation of ICRP mesh-type reference computational phantoms using PHITS, Geant4, MCNP6.3, and EGSnrc

The International Commission on Radiological Protection (ICRP) has adopted mesh-type reference computational phantoms (MRCPs) for the calculation of new reference dose coefficients following the forthcoming general recommendations. In the present study, the computational performance of adult and pediatric MRCPs was systematically evaluated using recently updated Monte Carlo radiation transport codes, including PHITS (version 3.31), Geant4 (version 11.01.p02), MCNP6.3, and EGSnrc (version 2025a). Performance evaluation included initialisation time, memory usage, computation time, and multi-threading efficiency for photon, electron, and neutron transport under selected external exposure scenarios. Among the evaluated codes, EGSnrc exhibited the longest initialisation time, approximately 8-9 times longer than PHITS. Nevertheless, the absolute time remained within a few minutes. In terms of memory usage, PHITS and EGSnrc required the least memory (