Abstract
Purpose: To evaluate the importance of annual intercomparisons for maintaining the capacity and capabilities of a well-established biodosimetry network in conjunction with assessing efficient and effective analysis methods for emergency response.Materials and methods: Annual intercomparisons were conducted between laboratories in the Canadian National Biological Dosimetry Response Plan. Intercomparisons were performed over a six-year period and comprised of the shipment of 10–12 irradiated, blinded blood samples for analysis by each of the participating laboratories. Dose estimates were determined by each laboratory using the dicentric chromosome assay (conventional and QuickScan scoring) and where possible the cytokinesis block micronucleus (CBMN) assay. Dose estimates were returned to the lead laboratory for evaluation and comparison.Results: Individual laboratories performed comparably from year to year with only slight fluctuations in performance. Dose estimates using the dicentric chromosome assay were accurate about 80% of the time and the QuickScan method for scoring the dicentric chromosome assay was proven to reduce the time of analysis without having a significant effect on the dose estimates. Although analysis with the CBMN assay was comparable to QuickScan scoring with respect to speed, the accuracy of the dose estimates was greatly reduced.Conclusions: Annual intercomparisons are necessary to maintain a network of laboratories for emergency response biodosimetry as they evoke confidence in their capabilities.
Highlights
Biological dosimetry has been employed for many years as a method for estimating the dose of ionizing radiation received by an individual
Typical results from an intercomparison from a single year are shown in Figure 1(A–C) for conventional DCA (CDCA), QuickScan dicentric chromosome assay (DCA) and cytokinesis block micronucleus (CBMN) assays
One way to maintain the capacity and capability of a network is through annual intercomparisons which evaluate the abilities and expertise within the network and allow for an opportunity to test protocols and practice procedures
Summary
Biological dosimetry has been employed for many years as a method for estimating the dose of ionizing radiation received by an individual. The DCA is very sensitive due to a low and stable background dicentric frequency (0.5–1 per 1000 metaphase spreads) (IAEA 2011) and is specific to damage from ionizing radiation. Using this assay, dose levels as low as 0.1–0.2 Gy can be detected when 500–1000 metaphase spreads are analyzed, but this requires many hours of analysis (IAEA 2001). In a mass casualty event, where medical treatment would be administered only to those receiving more than 2.0 Gy, this level of sensitivity is not required (Sullivan et al 2013) In these situations, the sensitivity of the assay can be reduced by decreasing the number of metaphase cells scored which subsequently greatly reduces the time required for analysis. Standard triage DCA analysis consists of analyzing only 50 metaphase spreads, providing a threshold of detection of 1–2 Gy; still adequate to guide treatment of acute radiation syndrome (ARS) (Lloyd 1997, Lloyd et al 2000, Voisin et al 2001, International Organization for Standardization [ISO] 2008)
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