en Radiation Biology Radiation Biology تحقيق بديع Original Research <p><strong>Background:</strong> Exposure to ionizing radiation is known to induce oxidative stress followed by damage to critical biomolecules like lipids, proteins and DNA through radiolysis of cellular water. Since radiation has been widely used as an important tool in therapy of cancer, the detailed investigation regarding the DNA damage and repair kinetics would help to predict the radiation sensitivity of cells. The present study is focused on quantification of DNA damage and repair kinetics of human peripheral blood lymphocytes after 8 MeV pulsed electron beam irradiation in vitro. <strong>Materials and Methods:</strong> DNA damage and repair kinetics in human blood cells were studied using alkaline comet assay. The dose-response curves for the dose range of 0-5 Gy were established using 8 MeV electron beam. Repair kinetics was studied by incubating the cells from 0 to 90 min at 37&deg;C after irradiation. For quantification of DNA damage, percentage Tail DNA, Tail length, Tail moment and Olive Tail moment were used as a comet parameter.<strong> Results and Conclusion:</strong> The study reveals that, induction of DNA damage by 8 MeV pulsed electron beam is near linear with a negligible negative quadratic component at high doses. This small quadratic component is attributed to high dose rate during the pulsed irradiation. The DNA repair halftime and mean repair time for human blood lymphocytes were found to be varying between 9.29 - 23.78 min and 13.41 - 34.31 min respectively. The repair rate is found to be maximum in initial 15 minutes and almost constant after 60 min.</p> DNA damage, DNA repair kinetics, alkaline comet assay, Microtron accelerator, pulsed electron beam 213 220 http://ijrr.com/browse.php?a_code=A-10-1-564&slc_lang=en&sid=1 K. Rajesha Nairy 790031947532846009808 790031947532846009808 No Depatment of studies in Physics, Mangalore University, Mangalagangotri-574 199, India N.N. Bhat 790031947532846009809 790031947532846009809 No Radiological Protection and Advisory Division, Bhabha Atomic Research Center, Mumbai-400 085, India P. Joseph 790031947532846009810 790031947532846009810 No Depatment of studies in Physics, Mangalore University, Mangalagangotri-574 199, India G. Sanjeev 790031947532846009811 790031947532846009811 No Depatment of studies in Physics, Mangalore University, Mangalagangotri-574 199, India N. Yerol narayanay@yahoo.com 790031947532846009812 790031947532846009812 Yes Depatment of studies in Physics, Mangalore University, Mangalagangotri-574 199, India