en Radiography Radiography Original Research Original Research <p dir="ltr" style="text-align: justify"><strong>Background: </strong>Critical macromolecules of cells such as DNA are in exposure to damage of free radicals that induced from the interaction of ionizing radiation with biological systems. Selenium and vitamin-E are natural compounds that have been shown to be a direct free radical scavenger. The aim of this study was to investigate the radioprotective effect of selenium and vitamin-E separately and synergistically against genotoxicity induced by 6MV x-rays irradiation in blood lymphocytes.</p> <p dir="ltr" style="text-align: justify"><strong>&nbsp; Methods</strong>: Fifteen volunteers were divided into three groups include A, B and C. These groups were given selenium (800IU), vitamin-E (100mg) and selenium (400IU) + vitamin-E (50mg), respectively. Peripheral blood samples were collected from each group before (0hr) and 1, 2 and 3hr after selenium and vitamin-E administration (separately and synergistically). Then the blood samples were irradiated to 200cGy of 6MV x-rays. After that lymphocyte samples were cultured with mitogenic stimulation to determine the chromosomal aberrations with micronucleus assay in cytokinesis-blocked binucleated cells.</p> <p dir="ltr" style="text-align: justify"><strong>&nbsp; Results</strong>: The lymphocytes in the blood samples collected at one hr after ingestion selenium and vitamin-E, exposed in vitro to x-rays exhibited a significant decrease in the incidence of micronuclei, compared with control group at 0hr. The maximum protection and decrease in frequency of micronuclei (50%) were observed at one hr after administration of selenium and vitamin-E synergistically.</p> <p dir="ltr" style="text-align: justify"><strong>&nbsp; Conclusion</strong>: The data suggest that ingestion of selenium and vitamin-E as a radioprotector substance before exposures may reduce genetic damage caused by x-rays irradiation.</p> 6MV, X-rays, Selenium, Vitamin-E, Lymphocyte, Micronucli. 469 475 http://mjiri.iums.ac.ir/browse.php?a_code=A-10-1-999&slc_lang=en&sid=1 Aram Rostami rostamy_1969@yahoo.com 200319475328460022384 200319475328460022384 No Department of Medical Physics, Faculty of Medicine, Iran University of Medical Sciences, Tehran, Iran. Seyed Akbar Moosavi seyedmoos@gmail.com 200319475328460022385 200319475328460022385 No Department of Lab Sciences, School of Allied Medicine, Iran University of Medical Sciences, Tehran, Iran. Vahid Changizi changizi@sina.tums.ac.ir 200319475328460022386 200319475328460022386 Yes Department of Technology of Radiology and Radiotherapy, School of Allied Medicine, Tehran University of Medical Sciences, Tehran, Iran. Ali Abbasian Ardakani a.ardekani@live.com 200319475328460022387 200319475328460022387 No Department of Medical Physics, Faculty of Medicine, Iran University of Medical Sciences, Tehran, Iran.