To observe the bladder injury in the three-dimensional conformal radiation therapy of spontaneous ca-nine benign prostatic hyperplasia, and to provide a basis for clinical, eight qualified BPH male canine models which were (7-15) year-old were chosen. The prostate directly exposed to 3-DCRT. The whole prostate of per animal was the target and sorrounded by 90% isodose curve, and was subjected to irradiation of 6 MV X-ray by 2 Gy per time and the total dose of 14 Gy. The bladder volume and dose of irradiation were measured with DVH. 1month after irradiation, the exposured bladder next to the prostate and non-irradiated regions of the bladder ( as control) were taken as biopsy. The bladder biopsy for optical microscopy, scanning and transmission electron mi-croscopy. It is resulted that after irradiation, no significant change of urinating occurred, and drugs, treatment were not given. According to RTOG acute radiation injury standard, the damage were evaluated as grade 0 to 1. Com-pared with the pre-irradiation, it could be seen by optical microscopy obvious necrosis, disorganization, suspension off of the epithelial cells and hole left behind the partial detachment of the epithelial cells, the disordered muscle and bare fiber. It could be seen by transmission electron microscope; the connection of damaged, epithelial cells detached, proliferation of collagen fibrils and radiation fibroblasts. It is conclused the pathological change of radio-cystitis such as necrosis and shedding of epithelial cells, collagen proliferation, and radiation fibroblasts occurred after irradiation in the dose lower than the currently accepted thresholds.%观察三维适形放射治疗犬自发性前列腺增生中膀胱损伤,为临床提供依据.选择(7-15)岁雄性合格BPH动物模型8只.应用立体定向放射治疗前列腺.勾画整个前列腺为靶区,以90％的等剂量曲线包绕靶区,单次剂量2 Gy,每周照射5次,共7次,总剂量14 Gy.应用DVH图测定膀胱受照体积与剂量.照射后1月分别取与前列腺紧邻受到照射的膀胱、未照射区域的膀胱(作为对照)标本.分别应用光镜、扫描电镜和透射电镜观察膀胱组织形态的变化.结果照射后排尿无明显改变,未给予药物等处理,按照RTOG急性放射损伤标准评价,损伤为(0-1)级.与照射前比较,照射后膀胱切片HE染色光镜下可见:细胞坏死明显,排列紊乱,细胞悬浮脱落,局部有细胞脱落后遗留的空穴；平滑肌紊乱；纤维裸露.透射电镜下可见膀胱上皮细胞连接破坏,间距增大,细胞脱落,胶原原纤维增生,出现放射性成纤维细胞.结论放射性膀胱炎的上皮细胞脱落、胶原增生、出现放射性成纤维细胞等组织病理改变.在低于目前公认的照射剂量阈值时即已经出现.
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