title: Retrospective Biodosimetry of an Occupational Overexposure-Case Study.
abstract: In 2014, Health Canada was approached by the Canadian Nuclear Safety Commission to conduct biodosimetry for a possible overexposure 4 y prior to assessment. Dose estimates were determined by means of two cytogenetic assays, the dicentric chromosome assay (DCA) and translocations as measured by the fluorescent in situ hybridization (FISH). As dicentrics are considered to be unstable over time, the results of the DCA were adjusted to account for the time elapsed between the suspected exposure and sampling. The frequency of damage was then compared to Health Canada's calibration curves, respectively, to calculate dose. In addition, the translocation data were corrected for age-related increases in background. With a half-life of 36 months for dicentric chromosomes taken into consideration, the dose estimates from both assays were in agreement. Due to the uncertainty in the half-life of dicentrics, the FISH assay is considered to be more reliable as a technique for retrospective biodosimetry.
authors.affiliation: Consumer and Clinical Radiation Protection Bureau, Health Canada, 775 Brookfield Road, PL 6303B, Ottawa,  Canada ON K1A 1C1  Lindsay.Beaton@hc-sc.gc.ca.
authors.forename: L A
authors.initials: LA
authors.lastname: Beaton-Green
authors.affiliation: Canadian Nuclear Safety Commission, 280 Slater Street, Ottawa,  Canada ON K1P 5S9.
authors.forename: T
authors.initials: T
authors.lastname: Barr
authors.affiliation: Public Health England Centre for Radiation, Chemical and Environmental Hazards, Chilton, Didcot, Oxon OX11 0RQ, UK.
authors.forename: E A
authors.initials: EA
authors.lastname: Ainsbury
authors.affiliation: Consumer and Clinical Radiation Protection Bureau, Health Canada, 775 Brookfield Road, PL 6303B, Ottawa,  Canada ON K1A 1C1.
authors.forename: R C
authors.initials: RC
authors.lastname: Wilkins
mesh_terms: D000328:Adult; D001681:Biological Assay / Q000379:methods*; D016022:Case-Control Studies; D002478:Cells, Cultured; D002869:Chromosome Aberrations / Q000528:radiation effects*; D020732:Cytogenetic Analysis / Q000379:methods*; D006801:Humans; D017403:In Situ Hybridization / Q000379:methods*; D008297:Male; D016273:Occupational Exposure / Q000032:analysis*; D011829:Radiation Dosage; D000069079:Radiation Exposure / Q000032:analysis*; D018788:Radioactive Hazard Release; D011874:Radiometry / Q000379:methods*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity