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Journal Articles

Construction of a voxel phantom based on CT data for a Japanese female adult and its use for calculation of organ doses from external electrons

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.

Journal Articles

Dose calculation using Japanese voxel phantoms for diverse exposures

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.

Journal Articles

Evaluation of S values for beta-ray emitters within the urinary bladder

Kinase, Sakae; Zankl, M.*; Funabiki, Jun*; Noguchi, Hiroshi; Saito, Kimiaki

Journal of Nuclear Science and Technology, 41(Suppl.4), p.136 - 139, 2004/03

The present study was performed to evaluate S values to the urinary bladder wall for several beta-ray emitters such as $$^{14}$$C, $$^{24}$$Na, $$^{32}$$P, $$^{60}$$Co, $$^{89}$$Sr, $$^{90}$$Sr, $$^{90}$$Y, $$^{91}$$Y, $$^{137}$$Cs, $$^{147}$$Pm and $$^{204}$$Tl for a MIRD 5 type phantom using Monte Carlo simulation. S values were also evaluated on the adult voxel phantoms developed at JAERI and were compared with those for the MIRD 5 type phantom. Furthermore, each of the S values was compared with those derived from the simple assumption (ICRP 30). Consequently, it was found that the absorbed dose to the urinary bladder wall for those radionuclides are not one-half of the absorbed dose in bladder content and largely depend on the mass of the urinary bladder wall. S values derived from the simple assumption were found to be conservative for beta-ray emitters within the urinary bladder.

Journal Articles

Evaluation of S values for beta-ray emitters in voxel phantoms

Kinase, Sakae; Zankl, M.*; Funabiki, Jun*; Noguchi, Hiroshi; Saito, Kimiaki

KEK Proceedings 2003-15, p.45 - 52, 2004/02

no abstracts in English

Journal Articles

Evaluation of specific absorption fractions in voxel phantoms using Monte Carlo simulation

Kinase, Sakae; Zankl, M.*; Kuwabara, Jun; Sato, Kaoru; Noguchi, Hiroshi; Funabiki, Jun*; Saito, Kimiaki

Radiation Protection Dosimetry, 105(1-4), p.557 - 563, 2003/09

 Times Cited Count:26 Percentile:84.61(Environmental Sciences)

There exists a need to calculate specific absorbed fractions (SAFs) in voxel phantoms for internal dosimetry. For this purpose, an EGS4 user code for calculating SAFs using voxel phantoms was developed on the basis of an existing EGS4 user code for external dosimetry (UCPIXEL). In the developed code, the transport of photons, electrons and positrons in voxel phantoms can be simulated, particularly the transport simulations of secondary electrons in voxel phantoms can be made. The evaluated SAFs for the GSF Child voxel phantom using the developed code were found to be in good agreement with the GSF evaluated data. In addition, SAFs in adult voxel phantoms developed at JAERI were evaluated using the developed code and were compared with several published data. It was found that SAFs for organ self-absorption depend on the organ masses and would be affected by differences in the structure of the human body.

Journal Articles

Analyses of absorbed dose to tooth enamel against external photon exposure

Takahashi, Fumiaki; Yamaguchi, Yasuhiro; Iwasaki, Midori*; Miyazawa, Chuzo*; Hamada, Tatsuji*; Funabiki, Jun*; Saito, Kimiaki

Radiation Protection Dosimetry, 103(2), p.125 - 130, 2003/01

 Times Cited Count:4 Percentile:32.21(Environmental Sciences)

Absorbed dose to tooth enamels against external photon exposure was examined by the Electron Spin Resonance (ESR) dosimetry using tooth samples placed in a realistic physical phantom. Dose to teeth region was also measured with thermo-luminescence dosimeters (TLDs). A voxel-type phantom was constructed from CT images of the physical phantom. Monte Carlo calculations with this voxel-type phantom were performed to analyse the results of the experiments. The obtained data in this study were compared to the enamel doses, which were calculated with a modified MIRD-type and already given in a previous paper. The results suggested that the conversion factors from enamel dose to organ doses obtained by the modified MIRD-type phantom are to be applicable for retrospective individual dose assessments by the ESR dosimetry. The analysis, however, indicated that the size and figure of the head can affect the enamel dose for low photon energy region below 100keV.

Journal Articles

Analysis of absorbed dose to tooth enamel for ESR dosimetry

Takahashi, Fumiaki; Yamaguchi, Yasuhiro; Saito, Kimiaki; Iwasaki, Midori*; Miyazawa, Chuzo*; Hamada, Tatsuji*; Funabiki, Jun*

Journal of Nuclear Science and Technology, 39(Suppl.2), p.1314 - 1317, 2002/08

An analysis of dose to tooth enamel was carried out to develop a method that can predict the organdose and effective dose by the Electron Spin Resonance (ESR) dosimetry using teeth for external photon exposure. Absorbed dose to tooth enamel were obtained with Monte Carlo calculations using EGS4 code with a mathematical human model, which has a newly defined teeth-part. Experiments were also carried out to investigate the dose at the tooth area with a physical head phantom. The calculated doses to tooth enamel were, however, less than the measured doses with the TLDs for the case of photon incidence from the back of a human body. Then, a computational human model, called a “Voxel (Volume-pixel) type" phantom was constructed based upon a computed topography (CT) image of the physical head phantom used in the experiments.The additional Monte Carlo calculations were performed to verify the results in the experiments with the EGS4 in conjunction with user's code UCPIXEL and the Voxel type phantom.

Journal Articles

Construction of a computed tomographic phantom for a Japanese male adult and dose calculation system

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:90 Percentile:90.4(Biology)

no abstracts in English

Journal Articles

Evaluation of specific absorbed fractions in voxel phantoms using Monte Carlo simulation

Kinase, Sakae; Zankl, M.*; Kuwabara, Jun; Sato, Kaoru; Noguchi, Hiroshi; Funabiki, Jun*; Saito, Kimiaki

Radiation Risk Assessment Workshop Proceedings, p.118 - 127, 2001/00

There exists a need to calculate specific absorbed fractions (SAFs) in voxel phantoms for internal dosimetry. For the purpose, an EGS4 user code for calculating SAFs using voxel phantoms was developed on the basis of the EGS4 user code (UCPIXEL). In the developed code, the transport of photons, electrons and positrons in voxel phantoms can be simulated, particularly the transport simulations of secondary electrons in voxel phantoms can be made. The evaluated SAFs for the GSF "Child" voxel phantom using the developed code were found to be in good agreement with the GSF evaluated data. In addition, SAFs in voxel phantoms developed at JAERI were evaluated using the developed code and were compared with several published data. It was found that SAFs depend on the organ masses and would be affected by differences in the structure of the human body.

Oral presentation

Estimation of DNA damage spectrum induced by heavy ions by simulation

Watanabe, Ritsuko; Sato, Osamu*; Kubota, Asako*; Funabiki, Jun*; Saito, Kimiaki

no journal, , 

The purpose of this study is to estimate the yields and the configuration of DNA damages as well as the spatial distribution of the damages along to the tracks of heavy ions using the Monte Carlo simulation. A new Monte Carlo track structure code for any kind of ions from hydrogen to uranium has been developed and applied for simulation of the induction process of DNA damage. Induction of strand breaks and base damages were simulated with direct and the radical generation and diffusion using Monte Carlo methods for atomistic model of DNA. In our presentation, the framework of the developed track code for ions, OH radical yields, and the calculated DNA damage spectrum for selected types of ions for different energies will be shown and discussed by comparison with available experimental data.

Oral presentation

Simulation of DNA damage spectrum induced by heavy ions

Watanabe, Ritsuko; Sato, Osamu*; Kubota, Asako*; Funabiki, Jun*; Saito, Kimiaki

no journal, , 

The purpose of this study is to estimate the yields and the configuration of DNA damages as well as the spatial distribution of the damages along to the tracks of heavy ions using the Monte Carlo simulation. A new Monte Carlo track structure code for any kind of ions from hydrogen to uranium has been developed and applied for simulation of the induction process of DNA damage. In our presentation, the calculated DNA damage spectrum for some selected types of ions for different energies is shown and discussed by comparison with available experimental data.

Oral presentation

DNA damage spectrum estimated from track structure of heavy ions and its implications for biological consequences

Watanabe, Ritsuko; Sato, Osamu*; Kubota, Asako*; Funabiki, Jun*; Saito, Kimiaki

no journal, , 

The purpose of our study is to estimate the yields and the configuration of radiation-induced DNA damages and further to relate the estimated clustered DNA damage with biological consequences. We have developed the Monte Carlo simulation code system to estimate radiation-induced DNA damage spectrum which starts from detailed track structure by considering the direct and indirect actions in cellular environment for X-rays and heavy ions. In our presentation, the calculated DNA damage spectrum for heavy ions as C ions will be shown. Analysis on the contribution of energy deposition pattern, higher-order structure of DNA, direct and indirect action to the DNA damage spectrum will be also shown. The damage spectrum as a function of LET will be discussed with comparison with experimental data on LET-RBE relationship of cell death.

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