Continuation of Validation of Biological Dosimetry Analysis through International Networks

Biological dosimetry is an essential tool for estimating radiation dose received by an individual when physical dosimetry is lacking or in dispute, or as a complement when it is available. Currently, the dicentric chromosome assay (DCA) is the tool of choice for biological dosimetry, however, the assay is labor-intensive and time-consuming, therefore, strategies have been developed to increase its throughput for potential applications with radiation mass casualties. One such strategy is to develop biological dosimetry networks, both national and international to increase throughput when limited capacities of a single nation may be overwhelmed or insufficient for dose estimation for a large number of individuals. In a previous study, we evaluated the validity and accuracy of the DCA among five geographically dispersed cytogenetic biological dosimetry laboratories, in which dose estimates were provided after 1000 metaphases were analyzed. In a follow-up study, we tested the DCA in an abbreviated form using triage quality dose estimations from network laboratory partners, where doses were estimated by analyzing 20, 30, and 50 cells (or 30 dicentrics) per sample. The results from both these studies indicated that the dose estimates made were in good agreement with the applied doses and were adequate to provide valuable information for treatment. However, these dose estimates were made from calibration curves generated in each laboratory using blood samples that had all been irradiated with the same exposure system as the blinded samples. In an emergency situation, dose estimates will be made using calibration curves already existing in each laboratory and therefore, laboratories within one network will have calibration curves produced from different radiation sources. To validate this situation, dose estimates from the above described study will be re-analysed with dose estimates made based on pre-existing gamma radiation calibration curves in each laboratory. These estimates will be made using full 1000 metaphase spread scoring as well as triage quality scoring and compared to actual doses applied to the samples.EPRBioDose 201