en Radiation Biology Radiation Biology تحقيق بديع Original Research <p><strong>Background:</strong> The&nbsp;trabecular&nbsp;bone&nbsp;changes&nbsp;in the tibia of C₃H/HeN&nbsp;mice&nbsp;were measured 12 weeks after whole body irradiation with various doses of&nbsp;fast&nbsp;neutrons&nbsp;(0-2.4 Gy) or ¹³⁷Cs-generated gamma-rays&nbsp;(0-6 Gy). <strong>Materials and Methods:</strong> Serum calcium, phosphorus, estradiol concentration and alkaline phosphatase activity were measured. Tibiae were analyzed using microcomputed tomography. Biomechanical property and osteoclast surface level were measured. Results: There was a significant relationship between the loss of bone architecture and the radiation dose, and the best-fitting dose-response curves were linear-quadratic. Mean relative biological effectiveness (RBE) values (Ref. gamma) of 2.05 and 2.33 were estimated for fast neutron irradiation in trabecular bone volume fraction and bone mineral density, respectively. There was a substantial reduction in osteoclast surface level in tartrate-resistant acid phosphatase-stained histological sections of tibial metaphyses in irradiated mice with high dose of neutrons. <strong>Conclusion:</strong> There was a significant relationship between the loss of bone architecture and the radiation dose. The difference of osteoclastic bone resorption may represent a contributor to the low RBE in high dose of irradiation level relative to that of low dose level.</p> Neutrons, trabecular bone, osteoclast, relative biological effectiveness 251 257 http://ijrr.com/browse.php?a_code=A-10-1-569&slc_lang=en&sid=1 Y. Yang 790031947532846009829 790031947532846009829 No College of Veterinary Medicine, Chonnam National University, Gwangju, Republic of Korea H.J. Lee 790031947532846009830 790031947532846009830 No Korea Institute of Radiological & Medical Science, Seoul, Republic of Korea H. Jang 790031947532846009831 790031947532846009831 No College of Veterinary Medicine, Chonnam National University, Gwangju, Republic of Korea J.H. Lee 790031947532846009832 790031947532846009832 No Ministry of Food and Drug Safety, Osong, Republic of Korea C. Moon 790031947532846009833 790031947532846009833 No College of Veterinary Medicine, Chonnam National University, Gwangju, Republic of Korea J.C. Kim 790031947532846009834 790031947532846009834 No College of Veterinary Medicine, Chonnam National University, Gwangju, Republic of Korea U. Jung 790031947532846009835 790031947532846009835 No Advanced Radiation Technology Institute, KAERI, Jeongeup, Republic of Korea S.K. Jo 790031947532846009836 790031947532846009836 No Advanced Radiation Technology Institute, KAERI, Jeongeup, Republic of Korea C.M. Kang 790031947532846009837 790031947532846009837 No Korea Institute of Radiological & Medical Science, Seoul, Republic of Korea S.H. Kim shokim@chonnam.ac.kr 790031947532846009838 790031947532846009838 Yes College of Veterinary Medicine, Chonnam National University, Gwangju, Republic of Korea