en Radiation Biology Radiation Biology تحقيق بديع Original Research <strong>Background:</strong> In megavoltage radiotherapy rooms, ordinary concrete is usually used due to its low construction costs, although higher density concrete are sometimes used, as well. The use of high-density concrete decreases the required thickness of the concrete barrier hence, its disadvantage is its high cost. In a nuclear reactor, neutron radiation is the most difficult to shield. A method for production of economic high-density concrete with appropriate engineering properties would be very useful. <strong>Materials and Methods:</strong> Galena (PbS) mineral was used to produce of a high-density concrete. Galena can be found in many parts of Iran. Two types of concrete mixes were produced. The water-to-concrete (w/c) ratios of the reference and galena concrete mixes were 0.53 and 0.25, respectively. To measure the gamma radiation attenuation of Galena concrete samples, they were exposed to a narrow beam of gamma rays emitted from a cobalt-60 therapy unit. <strong>Results:</strong> The Galena mineral used in this study had a density of 7400 kg/m3. The concrete samples had a density of 4800 kg/m3. The measured half value layer thickness of the Galena concrete samples for cobalt- 60 gamma rays was much less than that of ordinary concrete (2.6 cm compared to 6.0 cm). Furthermore, the galena concrete samples had significantly higher compressive strength (500 kg/cm2 compared to 300 kg/cm2). <strong>Conclusion:</strong> The Galena concrete samples made in our laboratories had showed good shielding/engineering properties in comparison with all samples made by using high-density materials other than depleted uranium. Based on the preliminary results, Galena concrete is maybe a suitable option where high-density concrete is required in megavoltage radiotherapy rooms as well as nuclear reactors. High-density concrete, galena, shielding, megavoltage radiotherapy. 143 146 http://ijrr.com/browse.php?a_code=A-10-1-249&slc_lang=en&sid=1 S.M.J. Mortazavi mmortazavi@sums.ac.ir 79003194753284600850 79003194753284600850 Yes M.A. Mosleh-Shirazi 79003194753284600851 79003194753284600851 No M.R. Maheri 79003194753284600852 79003194753284600852 No H. Yousefnia 79003194753284600853 79003194753284600853 No S. Zolghadri 79003194753284600854 79003194753284600854 No A. Haji-pour 79003194753284600855 79003194753284600855 No