Establishment of a Radiation Dose–Response Calibration Curve Using a Rapid Cytokinesis-block Micronucleus Assay for Dose Assessment of Medical Radiation Equipment

Dicentric chromosome analysis (DCA) has limitations in its use for the evaluation of the radiation dose upon the development of medical radiation equipment due to its time/labour-consuming procedure and the requirement of highly trained experts. Therefore, we aimed to construct a dose-response curve using a semi-automatic cytokinesis-block micronucleus (CBMN) analysis method that can be easily analysed and utilised by anyone. CHO-K1 cells were exposed to gamma rays at various doses (0-4 Gy). For the CBMN assay, the bi-nucleated cells were selected and captured, and micronuclei (MN) scoring was automatically performed using the Metafer4 system. The MN scores were manually confirmed and corrected by analysts. Using the frequency distributions of MN according to the radiation dose, the dose-response calibration curve was generated using Dose Estimate v5.2 software. The equation of dose-response calibration curve is Y = 0.0299 (±0.0057) + 0.1502 (±0.0151) × D + 0.0111 (±0.0048) × D². The goodness-of-fit parameters were also calculated (chi-squared [<i>χ</i> ²] = 39.45, degrees of freedom = 5, <i>p</i> = 0.0000). The semi-automated CBMN assay consist of two steps: the automated MN capture/scoring step and the manual confirmation/correction step. Using an established dose-response calibration curve and the procedure of the semi-automated CBMN assay, the dose-estimation of gamma-irradiated (0.5 or 2 Gy) CHO-K1 cells were performed by two analysts individually, and it was inter-compared to verify the accuracy, the results showed that the estimated doses were a good fit the applied doses of radiation. The CBMN assay using CHO-K1 cells can be easily used as a biodosimetry tool for dose assessment of medical radiation equipment due to the advantage of being simple, easy, and quick to measure the dose.