ABSTRACT
Objective To establish the rabbit model of radiation-induced lung injury (RILI) for the study of CT perfusion. Methods Forty-eight New Zealand rabbits were randomly divided into two groups, 36 rabbits in test group were administered with 25 Gy of single fractionated irradiation in the whole unilateral lung, and the other 12 rabbits in control group were sham-irradiated. All rabbits were sacrificed at 1, 6, 12, 24, 48, 72 h, and 1,2, 4, 8, 16, 24 week after irradiation respectively, then six specimens were extracted from upper, middle and lower fields of bilateral lungs, respectively. The pathological changes were observed with light and electron microscopies. The expression of TNF-α and TGF-β1 in local lung tissue was detected by immunohistochemistry. Results In test group, RILI occurred at early stage,characterized by acute inflammatory reaction, and featured by the progressing fibrosis at later stage. The expression of TNF-α and TGF-β1 1 and 72 h post-irradiation were statistically different between test and control groups (t = 3.04-14. 95,P ＜ 0. 05 ). Thickness of alveolar wall, density of pulmonary interstitium 12 h of post-irradiation, amount of fibroblast and fibrocyte from interstitium 24 h post-irradiation were statistically different between two groups ( t = 4.44-39. 78, P＜ 0.05 ), and correlated with the time postirradiation (r = 0. 821, 0. 872, 0. 682). There was statistical differences among the relative amount of collagen fibers at time points post-irradiation in test group ( F = 100.31, P ＜0.05), while no difference in control group ( F= 1.00, P ＜ 0.05 ). The relative amount of collagen fibers was statistically different between two groups 72 h post-irradiation (t = 3.07-45.18, P＜0.05 ), and correlated with the time postirradiation (r = 0.993 ). Conclusions Stable and reliable rabbit model of RILI could be established through single fractionated irradiation in whole unilateral lung with 25 Gy of high-energy X-rays, which may simulate the occurrence and development of evolution of RILI.