Kofler Cameron, Domal Sean, Satoh Daiki, Dewji Shaheen, Eckerman Keith, Bolch Wesley E
Medical Physics Graduate Program, College of Medicine, University of Florida, Gainesville, FL, USA.
Nuclear Science and Engineering Center, Japan Atomic Energy Agency, Tokai-mura, Japan.
Radiat Environ Biophys. 2019 Nov;58(4):477-492. doi: 10.1007/s00411-019-00812-2. Epub 2019 Sep 5.
The system of protection established by the International Commission on Radiological Protection (ICRP) provides a robust framework for ionizing radiation exposure justification, optimization, and dose limitation. The system is built upon fundamental concepts of a reference person, defined in ICRP Publication 89, and the radiation protection quantity effective dose, defined in ICRP Publication 103. For external exposures to radionuclide-contaminated soil, values of the organ dose rate coefficient (Gy/s per Bq/m) and effective dose rate coefficient (Sv/s per Bq/m) have been computed by several authors and national laboratories using ICRP-compliant reference phantoms-both stylized and voxelized. These coefficients are of great value in post-accident exposure assessments as seen in Japan following the 2011 Fukushima Daiichi nuclear power station disaster. Questions arise, however, among the general public regarding the accuracy of organ and effective dose estimates based upon reference phantom methodologies, especially for those individuals with height and/or total body mass that differ modestly or even substantially from the nearest age-matched reference person. In this pilot study, this issue is explored through use of the extended 351-member UF/NCI hybrid phantom library in which values of organ and detriment-weighted dose rate coefficients are computed for sex/height/mass-specific phantoms, and systematically compared to their values of the effective dose rate coefficient computed using corresponding reference phantoms. Results are given for monoenergetic photons, and then for some 33 different radionuclides, with all dose rate coefficient data provided in a series of electronic annexes. For environmentally relevant radionuclides such as Sr, Sr, Cs, and I, percent differences between the detriment-weighted dose rate coefficient computed using non-reference and the effective dose rate coefficient computed using reference phantoms vary only ± 5% for young children approximated by the reference 1-year-old phantom. With increased body size and age, the range of percent differences in these two quantities increases to + 7% to - 14% for the reference 5-year-old, to + 10% to - 27% for the reference 10-year-old, to + 33% to - 31% for the reference 15-year-old, and to + 15% to - 40% for male and female adults.
国际放射防护委员会（ICRP）建立的防护体系为电离辐射照射的正当性判断、优化及剂量限制提供了一个强大的框架。该体系基于ICRP第89号出版物中定义的参考人的基本概念以及ICRP第103号出版物中定义的辐射防护量——有效剂量。对于外部暴露于放射性核素污染土壤的情况，一些作者和国家实验室使用符合ICRP标准的参考体模（包括理想化体模和体素化体模）计算了器官剂量率系数（每贝可勒尔每平方米戈瑞每秒）和有效剂量率系数（每贝可勒尔每平方米希沃特每秒）的值。在2011年福岛第一核电站灾难后的日本，这些系数在事故后照射评估中具有重要价值。然而，普通公众对基于参考体模方法的器官和有效剂量估计的准确性存在疑问，特别是对于那些身高和/或总体质量与最接近的年龄匹配参考人相比有适度甚至显著差异的个体。在这项初步研究中，通过使用扩展的包含351个成员的佛罗里达大学/美国国立癌症研究所混合体模库来探讨这个问题，在该库中计算了针对性别/身高/体重特定体模的器官和危害加权剂量率系数，并系统地将其与使用相应参考体模计算的有效剂量率系数的值进行比较。给出了单能光子的结果，然后是约33种不同放射性核素的结果，所有剂量率系数数据都在一系列电子附录中提供。对于诸如锶、铯和碘等与环境相关的放射性核素，使用非参考体模计算的危害加权剂量率系数与使用参考体模计算的有效剂量率系数之间的百分比差异，对于由参考1岁体模近似的幼儿仅在±5%范围内变化。随着体型和年龄的增加，这两个量的百分比差异范围对于参考5岁儿童增加到+7%至 -14%，对于参考10岁儿童增加到+10%至 -27%，对于参考15岁儿童增加到+33%至 -31%，对于成年男性和女性增加到+15%至 -40%。
