Quickscan dicentric chromosome analysis for radiation biodosimetry

The dicentric chromosome assay (DCA) is the gold-standard assay for accurately estimating unknown radiological doses to individuals following radiological or nuclear accidents. However in a mass-casualty scenario, this assay is not well suited for providing timely dose estimates due to its time- and expertise-intensive nature. In Canada, two approaches are being developed in an attempt to increase triage-quality biological dosimetry throughput. These are 1) increasing the number of trained personnel capable of conducting the DCA, and 2) evaluating alternative biodosimetry approaches or DCA variations. In a recent exercise, a new scoring technique (termed DCA QuickScan) was evaluated as an alternative rapid-scoring approach. Triage-quality conventional DCA and DCA QuickScan analysis were based upon scoring a minimum of 50 metaphase cells or 30 dicentrics by 9-15 scorers across four laboratories. Dose estimates for the conventional DCA were found to be within 0.5 Gy of the actual dose for 83% of the unknown samples, while DCA QuickScan dose estimates were within 0.5 Gy for 80% of the samples. Of the dose estimates falling 0.5 Gy or more outside the actual dose, the majority were dose over-estimates. It was concluded that the DCA QuickScan approach can provide critical dose information at a much faster rate than the conventional DCA without sacrificing accuracy. Future studies will further evaluate the accuracy of the DCA QuickScan method.