Variation of Internal Doses Caused by Differences in Physical Characteristics between the Average Japanese and the ICRP’s Reference Man Which Is Based on the Standard Data of Caucasians in the Dosimetric Methodology in Conformity to the 2007 Recommendations

This paper describes a systematic analysis of the variation of internal doses derived from differences in physical characteristics in a dosimetric methodology fully based on the 2007 Recommendations of the International Commission on Radiological Protection (ICRP), including biokinetic models revised recently. Effective dose coefficients were estimated for the intakes of radionuclides reflecting the average physical characteristics of the adult Japanese, and compared with those provided by the ICRP, which have been evaluated using the physical constitution of the standard adult Caucasian (ICRP reference phantoms). Japanese dose coefficients were calculated using a dataset of specific absorbed fractions for the average adult Japanese, which was prepared by modification of the existing data with additional radiation transport calculations, combined with the current nuclear decay data and biokinetic models of ICRP. Comparison was made on 1339 conditions of intakes for 284 nuclides, which showed discrepancies in dose coefficients ranging from −37% to 44%. However, the discrepancies were smaller than 10% in 78% of all conditions. The extent of the variation in the dose coefficients will be acceptable for using the ICRP’s dose coefficients for the purpose of radiation protection for the Japanese.

本文系统性分析了完全基于国际放射防护委员会（International Commission on Radiological Protection, ICRP）2007年建议书建立的剂量学方法中，由物理特性差异引发的内照射剂量变化，其中涵盖近期修订的生物动力学模型（biokinetic models）。本研究针对反映日本成年人群平均物理特征的放射性核素摄入场景，估算了有效剂量系数（effective dose coefficients），并与基于标准成年高加索人群物理体质（ICRP参考体模，ICRP reference phantoms）评估得到的ICRP官方剂量系数进行对比。日本人群的剂量系数通过针对日本成年平均人群的特定吸收分数（specific absorbed fractions）数据集计算得到：该数据集通过对现有数据进行修正并补充辐射输运计算（radiation transport calculations），结合当前核衰变数据（nuclear decay data）与ICRP生物动力学模型构建而成。本次对比覆盖了284种核素的1339种摄入场景，结果显示剂量系数的差异范围为-37%至44%。但在全部场景中，78%的场景其剂量系数差异幅度小于10%。就剂量系数的变异程度而言，在针对日本人群开展辐射防护的工作中，采用ICRP剂量系数具备可接受性。