Dicentric assay: Inter-laboratory comparison in Indian laboratories for routine and triage applications

• This is the first Inter-Laboratory Comparison (ILC) study from India on Dicentric Chromosomal Assay (DCA) for both routine and triage biodosimetry applications.
• No significant difference in the in vitro dose response curve parameters (slope, intercept and curvature) between labs.
• Validation of calibration curves was done by blind trial method using samples exposed to different doses of X-rays and gamma rays.
• Triage analysis was done by scoring 20, 50 and 100 metaphases for dose determination.
• Scoring 20 metaphases is adequate to detect radiation exposure of 2 Gy and 50 metaphases is sufficient to determine radiation exposures of as low as 0.5 Gy.
• The feasibility of formation of biodosimetry network in India which is essential especially when the country is aiming at capacity building in nuclear energy is demonstrated.

An Inter-Laboratory Comparison (ILC) study on Dicentric Chromosome Assay (DCA) was carried out between two Indian biodosimetry labs. Human peripheral blood samples exposed to 10 different doses of X-rays up to 5 Gy were shared between the labs to generate calibration data. Validation of calibration curves was done by dose estimation of coded samples exposed to X- or gamma radiation. Reliability of the DCA data for triage application was evaluated by scoring 20, 50 and 100 metaphases in the dose range of 0.5–3.0 Gy. No significant difference was observed between labs regarding the established calibration data as well as the DCA triage dose assessments. Scoring of 20 metaphases (MP) was adequate to detect radiation exposure of >2 Gy whereas 50 MP were sufficient to determine exposures of 0.5 Gy. Both labs performed the DCA in a reliable manner and made the first step in setting up a biodosimetry network in India.