1987 Fiscal Year Final Research Report Summary
Experimental studies on the dosimetry and biological effects of neutrons
| Project/Area Number |
60304096
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| Research Category |
Grant-in-Aid for Co-operative Research (A)
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| Allocation Type | Single-year Grants |
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| Research Field |
放射線5生物学
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| Research Institution | HIROSHIMA UNIVERSITY |
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Principal Investigator |
YOKORO Kenjiro Research Institute for Nuclear Medicine and Biology, Hiroshima University, 原爆放射能医学研究所, 教授 (70034618)
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| Co-Investigator(Kenkyū-buntansha) |
NAKANISHI Takashi Faculty of Science, Kanazawa University, 理学部, 講師 (00019499)
KOSAKO Toshiso Research Center for Nuclear Science and Technology, University of Tokyo, 原子力研究センター, 助教授 (50114476)
NIWA Ohtsura Research Institute for Nuclear Medicine and Biology, Hiroshima University, 原爆放射能医学研究所, 助教授 (80093293)
SAWADA Shozo Research Institute for Nuclear Medicine and Biology, Hiroshima University, 原爆放射能医学研究所, 教授 (60034625)
ITO Akihiro Research Institute for Nuclear Medicine and Biology, Hiroshima University, 原爆放射能医学研究所, 教授 (60034633)
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| Project Period (FY) |
1985 – 1987
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| Keywords | Reassessment of atomic bomb radiation dosimetry / Cause of death among A-bomb survivors / Risk assessment of neutronsin man / RBE of neutrons / TLD dosimetry / Carcinogenicity in man and animals |
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| Research Abstract |
The purposes of this research project are 1) to develop and apply the technologies for radiation dose estimation of atomic bombs detonated in both Hiroshima and Nagasaki in 1945, 2) to compare the dose-effect relationship among A-bomb survivors based on a newly established dosimetry system (DS86) with that of previous one (T65D) and 3) to investigate the effects of neutrons in various biological systems in both man and rodents using a 252-Cf source being located at Hiroshima Univ. Res. Inst. Nucl. Med. Biol., and to assess RBEs of neutrons on those systems. The results obtained from the 3 years' study are summarized as follows (1) The measurement of gamma-ray peaks of radioactive 154-Eu, 152-Eu and 60-Co in exposed rocks and stones induced by the hit of neutrons, and TLD measurement for gamma-rays in the exposed tiles in this study project have contributed much to the establishment of the new dosimetry system, DS86. (2) It was found to be difficult to estimate the RBE of neutrons emitted from A-bombs since the component of neutrons has been shown to be very small in DS86. However, at a RBE of 10, risk estimates are increased 30% for nonleukemia and 80% for leukemia than those evaluated from the previous T65D dosimetry (3) The RBEs of fission neutrons emitted from a 252-CF source were tested in various bilogical systems such as DNA dmage, cell lethality, teratogenic and carcinogenic effects in rodents. In all systems tested so far, it was clearly shown that neutrons are more effective than HTO beta-rays of 60-Co, 137-Cs gamma-rays, and RBEs were estimated to be about 2-20 according to the biological systems. Through these studies, it was indicated that A-bomb dosimetries and basic biological investigations should be continued for the accurate evaluation of the biological effects of neutrons.
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[Publications] Yokoro, K., Niwa, O., Hamada, K., Kamiya, K., Seyama, T. & Inoh, A.: "Carcinogenic and co-carcinogenic effects of radiation in rat mammary carcinogenesis and mouse T-cell lymphomagenesis: a review." International Journal of Radiation Biology. 51. 1069-1080 (1987)
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「研究成果報告書概要(欧文)」より
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[Publications] Hasai, H., Iwatani, K., Shizuma, K., Hoshi, M., Yokoro, K., Sawada, S., Kosako, T. & Morishima, H.: "Europium-152 depth profile of a stone bridge pillar exposed to the Hiroshima atomic bomb: 152-Eu activates for analysis of the neutron spectrum." Health Physics. 53. 227-239 (1987)
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「研究成果報告書概要(欧文)」より
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[Publications] Kato, K., Yamamoto, M., Kumamaru, T., Yuroku, Y., Habara, M., Aoyama, T. & Yoshizawa, Y.: "Europium isolation from silicate rock samples exposed to Hiroshima atomic bomb neutrons." Analytical Sciences. 3. 493-497 (1987)
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「研究成果報告書概要(欧文)」より
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