| Project/Area Number |
06680511
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| Research Category |
Grant-in-Aid for General Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Research Field |
環境影響評価(含放射線生物学)
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| Research Institution | KYUSHU UNIVERSITY |
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Principal Investigator |
UEHARA Shuzo Kyushu University School of Health Sciences, Professor, 医療技術短期大学部, 教授 (90038927)
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| Co-Investigator(Kenkyū-buntansha) |
HOSHI Masaharu Hiroshima University Research Institute for Nuclear Medicine and Biology, Profes, 原爆放射能医学研究所, 教授 (50099090)
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| Project Period (FY) |
1994 – 1995
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| Project Status |
Completed (Fiscal Year 1995)
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| Budget Amount *help |
¥1,200,000 (Direct Cost: ¥1,200,000)
Fiscal Year 1995: ¥600,000 (Direct Cost: ¥600,000)
Fiscal Year 1994: ¥600,000 (Direct Cost: ¥600,000)
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| Keywords | In-vivo measurement / ^<90>Sr in bone / Beta-ray emitter / Bremsstrahlung / Body phantom / Photon detector / Monte Carlo Simulation |
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| Research Abstract |
1) Since 1960's there are a number of experimental works on the external measurement of ^<90>Sr+^<90>Y bremsstrahlung generated by their beta-rays using the whole-body counter installed NaI (Tl) crystal. Quantitative evaluation of the bremsstrahlung yield of ^<90>Sr+^<90>Y has been undertaken using an in-house Monte Carlo code SR90. The optimum organ and the condition for the external measurement of bremsstrahlung using a single detector was investigated under more realistic environment contaminated by the other sources such as ^<137>Cs and ^<40>K.
2) Body organs consisted of a large volume bone and also thin skin such as leg, waist and head are considered to be the candidates for the present purpose. As the results of calculations, waist and head were inappropriate because they contain large volume inner soft tissue. Leg phantom approximated by the coaxial cylinder consisted of bone and skin was investigated varying the bone diameter and skin thickness.
3) The photon spectrum entering the detector window having 200 mm diameter was obtained. A factor, signal-to-noise ratio s/n, was introduced to judge quantitatively the optimum condition for in-vivo measurements.
s/n = <@D7I(<@D190@>D1Sr[1])(/)I(<@D1137@>D1Cs[1]+<@D140@>D1K[70])@>D7
in which I means the intensity between 30 and 160 keV in the calculated spectrum for the sources with activities in units of Bq kg^<-1> designated in the bracket. In comparison with s/n ratio for various conditions of leg phantom, the best value was obtained for the case of large bone (50 mm diameter) covered with thin skin (1 mm).
4) A possibility of a new and simple method for in-vivo measurement of beta-emitter is suggested by combining the present calculations with the conventional measurements.
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