Inter-laboratory comparison to validate the dicentric assay as a cytogenetic triage tool for medical management of radiation accidents

Radiation accidents with exposure of human beings can assume huge dimensions concerning occurring health impairments and essential medical resources such as personnel, patient care management and appropriate medical facilities. Particularly in mass-casualty events, a rapid sorting and allocation of victims to treatment is needed and their classification in medical treatment groups has to be conducted as fast as possible. For triage purposes several approaches can be considered. Clinical signs and symptoms are extremely helpful in estimating radiation effects on an organ-based level, whereas the assessment of radiation effects based on cytogenetic biodosimetry tools is the alternative approach. For both systems there are pros and cons with respect to the usefulness for specific applications, such as individual cases versus mass-casualty screening or whole- versus partial-body exposures. Among the biodosimetry tools the dicentric chromosome assay (DCA) is considered as the “gold standard” for biodosimetry after an acute radiation exposure. Recently, steady progress in standardization and harmonization of the DCA has occurred, in order to enable the validated performance of the DCA in the frame of cooperative response of biodosimetry networks during a large scale radiological scenario. Using the DCA in triage mode which allows the stratification of radiation exposed victims into broad 1.0 Gy categories only 20-50 metaphase cells per subject are scored instead of the 500-1000 scored for routine analysis. Our data show that there are significant differences between the dicentric yields after 1.0 Gy and 3.0 Gy γ-ray ex vivo exposure of blood suggesting this assay as suitable for the distinction between high and low dosed exposed individuals. These preliminary findings indicate the usefulness of the DCA also for therapeutic decision making.