A polygon-surface reference Korean male phantom (PSRK-Man) and its direct implementation in Geant4 Monte Carlo simulation

Abstract

Even though the hybrid phantom embodies both the anatomic reality of voxel phantoms and the deformability of stylized phantoms, it must be voxelized to be used in a Monte Carlo code for dose calculation or some imaging simulation, which incurs the inherent limitations of voxel phantoms. In the present study, a voxel phantom named VKH-Man (Visible Korean Human-Man), was converted to a polygon-surface phantom (PSRK-Man, Polygon-Surface Reference Korean-Man), which was then adjusted to the Reference Korean data. Subsequently, the PSRK-Man polygon phantom was directly, without any voxelization process, implemented in the Geant4 Monte Carlo code for dose calculations. The calculated dose values and computation time were then compared with those of HDRK-Man (High Definition Reference Korean-Man), a corresponding voxel phantom adjusted to the same Reference Korean data from the same VKH-Man voxel phantom. Our results showed that the calculated dose values of the PSRK-Man surface phantom agreed well with those of the HDRK-Man voxel phantom. The calculation speed for the PSRK-Man polygon phantom though was 70-150 times slower than that of the HDRK-Man voxel phantom; that speed, however, could be acceptable in some applications, in that direct use of the surface phantom PSRK-Man in Geant4 does not require a separate voxelization process. Computing speed can be enhanced, in future, either by optimizing the Monte Carlo transport kernel for the polygon surfaces or by using modern computing technologies such as grid computing and general-purpose computing on graphics processing units programming.