电离辐射可以破坏人类细胞的增殖能力。但处于乏氧状态下的乏氧细胞却具有拮抗放射细胞毒的作用。在有氧存在的情况下,辐射的杀伤率比乏氧条件下的杀伤率高2.5-3倍。例如在常态空气下,哺乳动物细胞的放射剂量—反应曲线的斜率要比严重乏氧条件下的剂最—反应曲线陡3倍。由于实体恶性肿瘤中血管床是有缺陷 Ionizing radiation can destroy the proliferation of human cells. However, hypoxic cells in the hypoxic state can antagonize radiation cytotoxicity. In the presence of oxygen, the killing rate of radiation is 2.5-3 times higher than that under hypoxic conditions. For example, in normal air, the slope of the radiation dose-response curve of mammalian cells is three times steeper than the agent-response curve under severe hypoxia. The vascular bed is defective due to solid malignancy