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Sato, Kaoru; Noguchi, Hiroshi; Emoto, Yutaka*; Koga, Sukehiko*; Saito, Kimiaki
Journal of Nuclear Science and Technology, 46(9), p.907 - 913, 2009/09
A Japanese adult female voxel ((
)lume pi(
)) phantom (the JF phantom) was developed using CT images of a healthy female volunteer. The height (152cm) and weight (44kg) of JF are smaller than the averages of Japanese adult female. The voxel size of JF is 0.98
0.981mm
. Therefore, the shapes of small or complicated organs such as thyroid and stomach wall are realistically reproduced. The shapes of female specific organs such as ovaries and uterus are also distinctly represented. These suggest that the JF phantom will enable to evaluate accurately organ doses due to diverse exposures to Japanese adult females.
Saito, Kimiaki; Koga, Sukehiko*; Ida, Yoshihiro*; Kamei, Tetsuya*; Funabiki, Jun*
Hoken Butsuri, 43(2), p.122 - 130, 2008/06
A voxel phantom for a Japanese female adult was developed according to CT data. The developed phantom Onago has a slightly larger size than the Asian Reference Man, Female (ARMF). The organ doses and effective doses for external electrons were calculated with the developed phantom in the energy range of 1 MeV through 10 GeV, and compared with those for a Japanese male voxel phantom Otoko and with those for a MIRD phantom. The organ doses show some typical tendencies which are common for all phantoms, but in some cases the absolute values of organ doses differ largely according to phantom. The maximum difference observed between the voxel phantoms and the MIRD-type phantom was a factor of fifty for the individual organ dose and a factor of two for the effective dose. This suggests the necessity of sophisticated phantoms and detailed investigation using the phantoms to find out the realistic reference organ doses and the fluctuations for external electron exposures.
Sato, Kaoru; Noguchi, Hiroshi; Endo, Akira; Emoto, Yutaka*; Koga, Sukehiko*; Saito, Kimiaki
Radiation Protection Dosimetry, 127(1-4), p.205 - 208, 2007/11
Times Cited Count：13 Percentile：66.15(Environmental Sciences)Calculation of specific absorbed fractions (SAFs) used in internal dosimetry requires a human phantom. However, radiation exposure occurs under various postures, which may affect the shape and location of organs. Therefore, it is important to clarify the effect of posture on SAFs. In the present study, a voxel phantom was developed on the basis of CT images in upright posture, and the difference of SAFs between supine and upright postures was investigated. The authors developed the voxel phantom of Japanese adult in supine posture named JM for the evaluation of SAFs of Japanese adult male. The subject, who was employed for the construction of JM, was selected as a volunteer again to obtain the CT images. The developed voxel phantom in upright posture was named JM2. The voxel size of JM2 is 0.98mm0.98mm1mm, which is the same as that of JM. The fine voxels reproduce the shape and location of organs in the body realistically. It is possible to compare directly the change in the shape and location of organs due to the postures between JM and JM2, since the CT images for construction of the both phantoms were obtained from the identical person. This paper describes the physical characteristics of JM and JM2 and discusses the impact of posture on SAFs for photons in selected organs.
Sato, Kaoru; Noguchi, Hiroshi; Emoto, Yutaka*; Koga, Sukehiko*; Saito, Kimiaki
Radiation Protection Dosimetry, 123(3), p.337 - 344, 2007/02
Times Cited Count：39 Percentile：91.43(Environmental Sciences)A Japanese adult male voxel (volume pixel) phantom (hereinafter referred to as the JM phantom) was constructed on the basis of CT images of a healthy Japanese adult male volunteer. Body characteristics of the JM phantom were compared with those of a voxelized MIRD5 type phantom and a Japanese adult male voxel phantom which was previously developed. The voxel size of the JM phantom is 0.980.981 mm. The shapes of organs of the JM phantom, even for small or complicated organs, such as thyroid and stomach, are more realistically reproduced as compared with the previous Japanese voxel phantom (voxel size: 0.980.9810 mm). Photon self-absorbed fractions for brain, kidneys, spleen, pancreas, thyroid and urinary bladder wall of JM were evaluated and were compared with those of the other phantoms. In consequence, it was suggested that the mass, shape and thickness of organs are important factors for the determination of self-absorbed fractions.
Saito, Kimiaki; Sato, Kaoru; Kinase, Sakae; Noguchi, Hiroshi; Funabiki, Jun*; Takagi, Shunji*; Sato, Osamu*; Emoto, Yutaka*; Koga, Sukehiko*
Proceedings of Monte Carlo 2005 Topical Meeting (CD-ROM), 14 Pages, 2005/00
The voxel phantoms for Japanese male and female adults developed from CT data have been utilized for radiation protection purposes. User codes based on the EGS4 Monte Carlo program have been constructed to calculate external and internal exposures for photons and electrons. The calculated doses were compared with those using stylized MIRD type and other phantoms. The difference for external dose is not simply explained by the difference in body size, but the positions of organs were found to be an important factor to determine the doses. In internal exposure, the positional relations among organs drastically affect the specific absorption fractions, if the source and target organs are different. The simple approximation which has been used by ICRP to evaluate the dose at the boundary of two different media was found to give S values being too conservative. These calculated data shows the usefulness of realistic voxel phantoms combined with the Monte Carlo calculations.
Saito, Kimiaki; Wittmann, A.*; Koga, Sukehiko*; Ida, Yoshihiro*; Kamei, Tetsuya*; Funabiki, Jun*; Zankl, M.*
Radiation and Environmental Biophysics, 40(1), p.69 - 76, 2001/04
Times Cited Count：91 Percentile：90.02(Biology)no abstracts in English
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
Sato, Kaoru; Noguchi, Hiroshi; Emoto, Yutaka*; Koga, Sukehiko*
no journal, ,
no abstracts in English
