量研学術機関リポジトリ「QST-Repository」は、国立研究開発法人 量子科学技術研究開発機構に所属する職員等が生み出した学術成果（学会誌発表論文、学会発表、研究開発報告書、特許等）を集積しインターネット上で広く公開するサービスです。 Welcome to QST-Repository where we accumulates and discloses the academic research results(Journal Publications, Conference presentation, Research and Development Report, Patent, etc.) of the members of National Institutes for Quantum and Radiological Science and Technology.
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Biodosimetry is one of convenient, cost-effective methods for measurement of radiation exposure. We discuss di-centric analysis, which is an estimation procedure of radiation dosage by counting number of di-centric chromosomes in cells of an exposed individual. In the di-centric analysis we have to make our own standard response curve by using learning data prior to applying test-data. The learning data are constructed by exposing cells to several fixed dosages and counting di-centric chromosomes. One of long-standing problems in di-centric analysis is whether random effects should be accounted in the analysis. In our study, we tried to dissect random effects from the counting data by using counting data constructed by using cells taken from 13 individuals. In di-centric analysis for low dosage we usually assume quadratic response curve, where Poisson intensity of counting per cell is a quadratic function of the dosage. We investigated separation of random effects and fixed effects from the estimated response curves of each individual. We adopted a Bayesian hierarchical model and estimated fixed and random effects by using MCMC. We found random effects are relatively small and thus we can expect fixed effects can be estimated precisely. Our result suggests that we have to prepare better standard response curve by estimating fixed effects by using large learning data.
RANDOM EFFECTS IN MEASUREMENT OF RADIATION EXPOSURE BY BIODOSIMETRY
