2021 年 56 巻 3 号 p. 133-144
The International Commission on Radiological Protection (ICRP) has published a report of ICRP Publication 147. This publication has consolidated and expanded the concept of effective dose developed by ICRP. Effective dose has been used as a valuable tool for use in the optimization of protection and retrospective demonstration of compliance for regulatory purpose. The use of equivalent dose should be discontinued to avoid confusion of the same unit of Sievert between effective dose and equivalent dose and to set the limits on organ/tissue doses to prevent tissue reactions. The ICRP has considered effective dose an approximate indicator of possible risk of stochastic effects at low doses below 100 mSv. The estimate of effective dose can be used for comparing medical exposures among different diagnostic modalities including computed tomography and nuclear medicine. However, it is emphasized that use of effective dose is not substitute for the risk of a specific individual/organ since there is an uncertainty of the risk estimate due to low doses and simplified concept using tissue weighting factors that are averaged across all ages and both genders for hypothetical populations. The present article provides a brief summary and commentary of the key issues on the report. The concept of detriment behind calculation of tissue weighting factors in effective dose is reviewed.
