Cytogenetic biodosimetry of an accidental exposure of a radiological worker using multiple assays

A technician involved in the maintenance of X-ray equipment visited the occupational medicine service with complaints of skin lesions, apparently caused by an accidental exposure three months earlier. To estimate the dose received by the technician in the accident, biodosimetry was performed 6 and 18 months post-exposure with the dicentric and micronucleus assays. Part of the latest blood sample was also used for retrospective dosimetry by fluorescence in situ hybridisation (FISH) analysis for translocations. The data obtained 6 and 18 months post-exposure indicate that both dicentrics and micronuclei disappear with a half-time of 1 y. After correction for delayed blood sampling, dose values of 0.75 Gy (95% confidence limits 0.56-1.05 Gy) from dicentrics and 0.96 Gy (95% confidence limits 0.79-1.18 Gy) from micronuclei were obtained. FISH analysis of translocations resulted in a dose estimate of 0.79 Gy (95% confidence limits 0.61-0.99 Gy). The satisfactory agreement between the three cytogenetic endpoints supports the use of the micronucleus assay for triage purposes in the case of large scale radiological accidents and provides further evidence for the valid use of FISH for translocations as a reliable retrospective biological dosimeter.