Cytogenic investigations of serious overexposures to an industrial gamma radiography source.

This paper describes the sequence of events, medical aspects and dose estimations for two radiographers and their driver who were seriously exposed to an iridium-192 industrial radiography source that became detached from its wind-out cable. The men came to medical attention about 1 month later by which time all three were severely leucopenic and one had skin burns on both hands. Doses were estimated by (i) physics calculations combined with their accounts of the event. (ii) the levels of depression of their blood neutrophils, (iii) electron spin resonance on tooth enamel and (iv) blood lymphocyte chromosomal analyses by the conventional dicentric and the fluorescence in situ hybridisation methods. Intercomparison of these methods for estimating doses showed a good level of agreement. In brief, the averaged whole body dose for the most seriously exposed man was about 2.5-3.0 Gy and for the others it was 1.0-2.0 Gy.

Novel data set for retrospective biodosimetry using both conventional and FISH chromosome analysis after high accidental overexposure.

Blood samples of ten Chernobyl and one non-Chernobyl victims were analysed both by conventional cytogenetics and by fluorescence in situ hybridization (FISH) using a cocktail of chromosomes 2, 3 and 8. The analysed group comprised men acutely irradiated mainly in 1986 and aged 26-47 years at the time of first blood sampling. All of them displayed acute radiation syndrome of varying severity. Chromosome analysis of the earliest blood samples was carried out by conventional scoring of unstable aberrations with the number of metaphases analysed per individual ranging from 35 to 300. Estimated individual doses ranged from 0.85 to 9.8 G y. After a 10 year delay, i.e. in 1996, blood samples were analysed both by conventional scoring of unstable aberrations and by FISH measurements of stable ones. Usually about 500 metaphases per individual were scored. Estimated by the FISH-method individual translocation (tc + ti) frequencies ranged from 2.2 to 116.8 per 100 cells full genome equivalent. Based on three different published dicentric dose response, in vitro curves individual doses were calculated from the earliest dicentric frequencies. A dose response curve for truly persisting translocations (tc + ti) was estimated over the range 1-10 Gy.