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目的观察高剂量率(HDR)192Ir后装照射犬外周血管、神经病理反应,为HDR后装放疗应用于骨与软组织恶性肿瘤保肢术提供放射剂量耐受阈参考。方法健康普通犬12条,常规外科手术沿犬股神经血管束放置施源器,术后经3次HDR后装放射,每种剂量1条犬,总剂量分别为15、30、45、60、75、90Gy,照射长度1.0cm,照射后10、60d活体取材,经光镜和透射电镜进行组织学观察,自身对侧血管神经束作对比。结果照射后10d,大血管主要表现为内膜病变;照射后60d,剂量达到45Gy时,出现明显的不同程度血管增生和管腔狭窄。神经照射后改变,15Gy组变化不明显;30Gy以上组变化明显:急性期出现不同程度脱髓鞘,髓鞘和轴突崩解脱失等改变;慢性期神经萎缩明显。结论HDR后装放疗引起外周血管明显病理变化的剂量为45Gy;而30Gy足以引起明显的神经病理变化。建议临床治疗控制在总剂量30Gy以下,贴近神经处酌减剂量。
Objective To observe the peripheral vascular and neuropathological responses of high dose rate (HDR) 192Ir post-irradiation dogs and to provide reference for radiation dose tolerance for HDR post-radiotherapy for limb salvage in patients with bone and soft tissue malignancies. Methods Twelve dogs were randomly divided into two groups. One hundred and eight dogs were randomly divided into three groups: one was a normal dog, and the other was a total dose of 15, 30, 45, 60, 75,90Gy, irradiation length 1.0cm, 10,60days after irradiation, the samples were taken from the body. The histological observation was made by light microscope and transmission electron microscopy. Results At 10 days after irradiation, the major vessels showed endometrial lesions. At 60 days after irradiation, the number of blood vessels hyperplasia and stenosis were significantly different at 45 Gy doses. Changes in nerve irradiation, 15Gy group did not change significantly; 30Gy more obvious changes in the group: the acute stage of varying degrees of demyelination, myelin and axon disintegration loss and other changes; chronic atrophy. Conclusions The dose of HDG after radiotherapy is 45 Gy in peripheral blood vessels. However, 30 Gy is sufficient to cause obvious neuropathological changes. Proposed clinical treatment control in the total dose of 30Gy, close to the nerve at the discretion of the dose.