Mesh-type reference Korean phantoms (MRKPs) for adult male and female for use in radiation protection dosimetry

Abstract

In the present study, to overcome the dosimetric limitations of the previous voxel-type reference Korean computational phantoms due to their limited voxel resolutions (i.e. on the order of millimeters) and the nature of voxel geometry, a pair of new reference Korean phantoms, called mesh-type reference Korean phantoms (MRKPs), were developed for the adult male and female in a high-quality/fidelity mesh format. The developed phantoms include all target and source regions required for effective dose calculation, even micrometer-scale target and source regions of the respiratory and alimentary tract organs, skin, urinary bladder, and eye lens. The developed phantoms, which are in either the polygon-mesh (PM) format or the tetrahedral-mesh (TM) format as necessary, can be directly used in several general-purpose Monte Carlo codes (e.g. Geant4, MCNP6, and PHITS) without voxelization. In order to understand the dosimetric impact of the new phantoms, the dose coefficients (=fluence-to-effective dose conversion coefficients) were calculated for photons and electrons with energies ranging from 10 keV to 10 GeV for the anterior-posterior (AP) irradiation geometry and compared with those of the previous voxel-type reference Korean phantoms. The results demonstrate that the effective dose coefficients of the MRKPs were generally similar to those of the previous voxel-type reference phantoms for photons; however, for electrons, significant differences were observed at energies lower than 1 MeV that were mainly due to the explicit definition of the 50 µm-thick radiosensitive target layer in the skin of the new mesh phantoms.