术中近距离照射犬肝组织的病理学观察

目的 了解高剂量率^192Ir放射源在不同照射剂量、不同观察时间对正常犬肝组织的放射反应，为临床开展近距离治疗肝癌提供病理学参考。方法 选用健康的普通犬6只，常规外科程序开腹，在肝左叶平行插入两根钢针，针间距1．5cm，参考点距放射源中轴外1cm；照射剂量为10、20和30Gy，每种剂量一只犬分别在照射后20和60d活杀，并从照射中心始向外1，2，3和4cm依次取材，观察组织学改变；自身肝组织作对比。结果 大体检查：除照射后60d、照射10Gy一只犬外，所有犬在照射中心均可见坏死灶；显微镜下：照射后20d的病理主要改变是急性坏死和炎性反应；在照射后60d、照射20Gy以上，出现肝细胞损伤和纤维组织增生明显。结论 临床近距离放疗肝癌时，单次量最好在10Gy以下，照射2—3次，总量在30Gy以下为宜；对肿瘤周边欠缺的剂量给予体外照射。

Responses of canine liver tissue to intraoperative brachytherapy

Objective To investigate responses of normal liver tissue to high-dose-rate 192Ir source at different irradiation doses and time phases to provide pathological reference for brachytherapy of liver cancer in clinical practice. Methods Six dogs received routine surgical procedure. Two steel needles were implanted in parallel into the left lobe. The length was 1.5 cm and reference distance 1 cm apart from the source. The irradiation doses were 10, 20 and 30 Gy, respectively. The dogs were killed 20 and 60 days later. The samples of liver tissue were extracted outward from the center for 1, 2 and 3 cm in order. The right lobe was used as the control. Results There was necrosis in the irradiation center in all dogs but one receiving 10 Gy irradiation for 60 days. Microscopic examination showed that the major tissue changes were acute necrosis and inflammatory responses in 20 days. Liver cell damage and fiber tissue proliferation were found in 60 days when the irradiation dose >20 Gy. Conclusions When the irradiation dose is over 20 Gy, severe necrosis of liver tissue appears. Therefore, it is suitable that the irradiation dose is less tan 10 Gy and given for 2-3 fractions during brachytherapy of liver cancer. Meanwhile, the total dose should be less than 30 Gy.