title: Analysis of effects of posture on organ doses by internal photon emitters using voxel phantoms.
abstract: In order to clarify the effects of posture on absorbed doses in organs due to internal exposures, specific absorbed fractions (SAFs) for monoenergetic photons from 0.01 to 4 MeV were calculated using two Japanese adult male phantoms, JM2 (upright) and JM (supine), whose designs were based on CT images of two postures obtained from the same person. Differences in the SAFs of JM2 and JM are within a factor of 2 in most cases although significant differences in SAFs exist in several combinations of source and target organs for low energy photons. Organ doses due to photons from the intake of unit activity of eight radionuclides (126Ba, 128Ba, 133Ba, 130Cs, 131Cs, 178W, 179W and 190W) with different biokinetics and decay characteristics were calculated from the SAFs of JM2 and JM. It was found that the organ doses in the testes, bone marrow, lower large intestine wall, lungs and stomach wall, which are important for calculating effective dose, in the two postures roughly agree, the maximum difference being 14%. These results indicate that the impact of posture on the organ doses and effective doses from internal photon emitters is not significant.
authors.affiliation: Nuclear Science and Engineering Directorate, Japan Atomic Energy Agency, 2-4 Shirakata-Shirane, Tokai-mura, Naka-gun, Ibaraki-ken 319-1195, Japan. sato.kaoru@jaea.go.jp
authors.forename: Kaoru
authors.initials: K
authors.lastname: Sato
authors.forename: Akira
authors.initials: A
authors.lastname: Endo
mesh_terms: D001822:Body Burden; D006801:Humans; D007700:Kinetics; D008297:Male; D015233:Models, Statistical; D009010:Monte Carlo Method; D019047:Phantoms, Imaging; D017785:Photons; D011187:Posture; D011829:Radiation Dosage; D011868:Radioisotopes / Q000494:pharmacology; D011874:Radiometry / Q000379:methods*; D011877:Radionuclide Imaging / Q000379:methods; D014018:Tissue Distribution; D014915:Whole-Body Counting / Q000379:methods
chemical_list: D011868:Radioisotopes