摘要
以立体定向放射外科治疗的４例临床病理改变为基础，探讨有关放射生物学效应。认为治疗后早期改变是血脑屏障紊乱和靶细胞超微结构改变，逐步转入水肿期、坏死期、吸收期及瘢痕期。在坏死期，自靶中心向外依次为坏死区、变性与反应区、水肿区，与ＣＴ或ＭＲＩ影像上表现的中央无强化区、强化环、周围低密度或长Ｔ１长Ｔ２水肿样信号区可能相对应。坏死是肿瘤细胞辐射损伤和血管效应相结合的结果。
he radiobiological effects of radiosurrgery were studied on the basis of 4 cases with clinical pathology. The early pathological changes after radiosurgical treatment include disruptions of blood-brain-barrier (BBB) and ultrastructural damages of target cells. Then the lesions develop to edema stage, necrotic stage, resorptive stage and the final stage of glial scar progressively. At the necrotic stage, there are the necrotic region, the degenerative and reactive region and edema region from the center of target volume to the surounding area, corresponding to the central area of nonenhancement on CT or MRI, enhancing ring on CT or MRI and area with low-density on CT or low-signal on T1WI and highsignal on T2WI, respectively. The edema-like areas surounding the lesions were caused predominantly by higher radiation doses. Single large fractioned radiosurgery can lead treatment volumn radiologic necrosis, regardless of early responding tissue and late responding tissue. Tumor necrosis is the result of radiatin damage of tumor cells combined with vascular effects.
