Korean adult male voxel model KORMAN segmented from magnetic resonance images

A voxel model of Korean adult male, KORMAN, was developed by processing whole-body magnetic resonance (MR) images of a healthy volunteer who represents an approximately average Korean in height and weight. Layer by layer the MR images were semi-automatically segmented and indexed using a graphic software and digitizer to construct data arrays consisting of 250 x 120 x 170 voxels of a size of 2 x 2 x 10 mm3. To assess the utility of the model, some illustrative dosimetric calculations were made to obtain organ absorbed doses and effective doses to the KORMAN placed in broad parallel photon fields with energies ranging from 0.05 to 10 MeV. The results were compared with those based on the medical internal radiation dose (MIRD)-type models given in ICRP74. The effective doses of ICRP74 were higher than those of KORMAN with percent differences ranging from 6% (LLAT, 10 MeV) to 30% (PA, 0.05 MeV). Significant differences of more than 40% were observed in organ absorbed doses for some organs including bone surface (AP), stomach (PA), and testes (LAT) for low photon energy. These are mainly caused by difference in trunk thickness between MIRD-type model and KORMAN, and differences in organ positions in the body.