Biodosimetric Strategy for Radiation Emergency Medicine in Japan

Biological dosimetry, based on the study of chromosomal aberrations, has become a routine component of accidental dose assessment. Exposed dose of a patient with suspected overexposure can be estimated from chromosomal aberration yield of peripheral blood lymphocytes by applying the yield to an appropriate dose-response curve. In the radiation emergency medicine field, it is practically important that there is no strict time-limit for blood collection after the accidental exposure. In the National Institute of Radiological Sciences of National Institutes for Quantum and Radiological Science and Technology (QST-NIRS), some biodosimetric methods have been well-prepared: 1) cell-fusion mediated prematurely condensed dicentric chromosome assay (PCDC) for triage dose assessment, 2) dicentric chromosome assay (DCA) for more precise dose assessment within one month after the accidental exposure, 3) three-color fluorescence in situ hybridization (FISH) analysis for retrospective dose assessment. The biological dosimetry was useful to support medical management in cases of restoration workers of the Fukushima Daiichi Nuclear Power Station accident (March 2011) and workers of the JAEA Plutonium Fuel Research Facility (Oarai, June 2017). Prompt measures are taken for biological dosimetry of mass casualty accidents/incidents: 1) domestic, regional, and global networking (including standardization and harmonization of protocols and human resource development), 2) development of chromosome analysis methods by using automated image-capturing systems (microscopy and flow cytometry), 3) development of image-analysis softwares.NCT ASIA PACIFIC JAPAN 201