Dose estimation with the calibration of dose-response curve of micronucleus in human peripheral lymphocytes induced by 50MeV proton beams

Background: The purpose of this paper is to establish an easy and reliable biodosimeter protocol to evaluate the biological effects of proton beams. Materials and Methods: Human peripheral blood lymphocytes were irradiated using proton beams (LET: 34.6 keV μm−1), and the chromosome aberrations induced were analyzed using cytokinesis-blocked (CB) micronucleus (MN) assay. To determine the efficiency of MN assay in estimating the doses received by 50MeV proton beams and to monitor predicted dose of victims in accidental exposure, here we have evaluated the performance of MN analysis in a simulated situation after exposure with proton beams. Peripheral lymphocytes were irradiated by 50MeV proton beams up to 6Gy and analyzed by Giemsa staining of CB MN assay. Results: The detected MN was found to be a significant dose-effect curve in the manner of dose-dependent increase after exposure with proton beams in vitro. When plotting on a linear scale against radiation dose, the line of best fit was Y=0.004+(1.882x10-2±9.701x10-5) D+(1.43x10-3±1.571x10-5)D2. Our results show a trend towards increase of the number of MN with increasing dose. It was linear-quadratic and has a significant relationship between the frequencies of MN and dose (R2= 0.9996). The number of MN in lymphocyte that was observed in control group is 5.202±0.04/cell. Conclusion: Hence, this simple protocol will be particularly useful for helping physicians to decide medical therapy for the initial treatment of victims with rapid and precise dose estimation after accidental radiation exposure. Also it has potential for use as a valuable biomarker to evaluate the biological effectiveness for cancer therapy with proton beams. Iran. J. Radiat. Res., 2011 8(4): 231-236