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虽然最近的一些恶性脑肿瘤间质内近距离放射治疗的研究已经显示出良好的临床效果相比，传统的治疗，正常的大脑反应，这种治疗方式的生物学数据是稀缺的。因此，我们建立了一个正常大鼠脑组织间质照射的模型系统，并从组织学上研究了正常脑组织的影响。头部固定在立体定位架上，聚乙烯导管（外径= 1.2将含有一对Ir-192粒子或伪粒子的植入体（长5 mm）垂直植入右半球。用Ir-192粒子进行辐照，每个粒子长度为3 mm，平均放射性为0.5 mCi或1.0 mCi，在7-10天内，将100戈伊或200戈伊的辐照剂量分别输送到距导管轴3 mm处的参考点。用假种子进行假处理。 关于我们 照射后12周。照射后即刻，在照射超过400戈伊的区域观察到凝固性坏死，并且渗出的水肿液已沿着胼胝体扩散，并伴有反应性星形胶质细胞。照射后4周，在坏死组织中观察到小的钙化灶，并且在坏死周围的照射半球中也观察到明显的脱髓鞘。照射后12周内，照射剂量小于200戈伊的区域未见坏死灶扩大，在血脑屏障通透性实验中，于处死前15 min静脉注射HRP（100 mg/kg）。照射后即刻通透性增加最为广泛，超过50戈伊照射区可见HRP血管外蓄积。电子显微镜显示脑毛细血管内皮细胞胞饮增多，星形细胞突起受损。综上所述，这些结果表明，间质照射后，照射超过50戈伊的区域血脑屏障受损，照射低于200戈伊的区域未观察到凝固性坏死。少

Although some recent studies of interstitial brachytherapy of malignant brain tumors have shown good clinical results comparing conventional therapy alone, the biological data of normal brain response to this treatment modality are scarce. Therefore, we have developed a model system for interstitial irradiation using normal rat brain, and then studied the effects on normal brain tissue histologically.Adult female SD rats were subjected to this study. With the head fixed in stereotaxic frame, a polyethylene catheter (O.D.=1.2 mm, 5 mm length) containing a pair of Ir-192 seeds or dummy seeds, was implanted in right hemisphere perpendicularly. Irradiation was performed with Ir-192 seeds of 3 mm length each with a mean activity of 0.5 mCi or 1.0 mCi, during 7-10 days, the radiation dose of 100 Gy or 200 Gy delivered to the reference point, at a 3 mm distance from the axis of the catheter, respectively. Sham treatment was performed with dummy seeds.Animals were sacrificed at immediately, 4 … More and 12 weeks after irradiation. Immediately after irradiation, coagulative necrosis was observed in the region irradiated more than 400 Gy and extravasated edema fluid had spread along the corpus callosum with reactive astrocytes. Four weeks after irradiation, small calcified foci were observed in the necrotic tissue and demyelination was also observed marked in the irradiated hemisphere around the necrosis. Within 12 weeks after irradiation, the necrotic lesion was not enlarged and not seen in the area had irradiated less than 200 Gy.In blood-brain barrier permiability study, HRP (100 mg/kg) was given intravenously 15 minutes before sacrifice. Increased permiability was most widespread at immediately after irradiation, extravascular accumulation of HRP was seen in the area had irradiated more than 50 Gy. Electron microscopy showed increased pinocytosis of the endothelium of cerebral capillary and impaired astrocytic processes.In summary these findings suggest that after interstitial irradiation, blood-brain barrier is impaired in the region irradiated more than 50 Gy and coagulative necrosis is not obserbed in the area irradiated less than 200 Gy. Less