Optimized dicentric chromosome dose-response curves with centromere probes improve low-dose radiation biodosimetry.

Accurate biological dose assessment is critical in radiation emergencies, particularly in cases of low-dose exposure. The dicentric chromosome assay (DCA) is the gold standard for biodosimetry, but conventional Giemsa staining often presents challenges in identifying centromeres, especially in morphologically distorted metaphase cells. In this study, we constructed dose-response calibration curves using both Giemsa and centromere-fluorescence in situ hybridization (FISH) staining across two dose ranges (0-5 and 0-1 Gy) according to ISO 19238:2023 guidelines. The centromere-FISH-based curves demonstrated improved statistical validity, satisfying Poisson distribution requirements across all dose points and achieving lower minimum detectable doses of 47-94 mGy, compared to 87-127 mGy obtained with Giemsa staining. Furthermore, dose estimation of blinded samples showed higher accuracy and reliability using centromere-FISH-based curves, particularly at low-dose levels (0.05-0.2 Gy). These findings suggest that centromere-FISH staining enhances the sensitivity and accuracy of DCA, supporting its application as an effective method for biodosimetry following low-dose radiation exposure. Furthermore, we propose applying the 0-1 Gy or 0-5 Gy calibration curve to improve the estimation accuracy for low-dose exposure and enable flexible application in radiation exposure incidents.