Translocation dose-response curve for ¹³⁷Cs γ-rays: Dose validation at various dose rate and changing dose rate...

A Fluorescence In-Situ Hybridization (FISH) based translocation dose-response curve has been constructed for biodosimetry application in our nuclear establishment at Kalpakkam, India. Peripheral blood sample from a healthy male donor (27 years) was exposed to nine different doses (0.1 Gy-5 Gy) of ¹³⁷Cs γ-rays (100 mGy/min) in an automated calibration facility with a linear distancing system and subjected to FISH assay using chromosome 1, 2 and 4 specific fluorescent probes. Validation of the dose-response curve was done following three different approaches i) by blind test method ii) using blood samples exposed to γ doses (0.5, 1 & 2 Gy) at different dose rates (124, 23 & 10 mGy/min) and iii) with blood samples exposed to 0.5, 1 & 2 Gy γ doses at changing dose rates (increasing and decreasing dose rates). Results showed that a predefined dose-response curve constructed at a particular acute dose rate can be used for dose estimation in exposures involving varying dose rates and changing dose rate scenarios.