Development of CT voxel phantoms for Japanese

Sato, Kaoru; Noguchi, Hiroshi; Saito, Kimiaki; Emoto, Yutaka*; Koga, Sukehiko*

Radiation Risk Assessment Workshop Proceedings, p.102 - 110, 2001/00

For calculating doses due to radioactivity taken in a body, Specific Absorbed Fractions (SAFs) are used. In recent years, more realistic phantoms called voxel (volume pixel) phantoms have been developed on the basis of CT or MRI images of actual persons. The voxel phantoms can accurately describe sizes, shapes and locations of organs, which would affect SAFs. We are now developing Japanese adult voxel phantoms for internal dosimetry by using CT images. Until now, CT scans for three healthy Japanese male volunteers were performed under supine or upright positions to study the effect of body size and position on SAFs. The height and weight of the middle size man is almost coincident with the averages for Japanese adult. So far the development of voxel phantom has been almost finished for the middle size man (voxel-phantom-MM). The voxel size is 0.980.981.0 mm. It was found that even small size organs such as thyroid were realistically modeled. The result showed that voxel-phantom-MM had realistic structure which would enable us to calculate reliable SAFs