序癌的放射治疗之所以不一定成功,可能是因为肿瘤中存在缺氧细胞之故,这种缺氧细胞对射线有很强的抵抗力。为此,人们试用中子、π介子等生物效果不太受氧影响的粒子束来代替原来的射线,但由于这些粒子束的产生需要大型加速器,故限制了它们的使用。在这种情况下,化学防护剂和化学致敏剂并用的方法受到了重视。化学防护剂是使正常组织得到保护,从而使更多的射线作用于肿瘤细胞。致敏剂是有选择地使缺 Precursor radiotherapy is not necessarily successful because it may be due to the presence of hypoxic cells in the tumor. This hypoxic cell is very resistant to radiation. For this reason, people try neutrons, pions, and other biological effects that are less affected by oxygen to replace the original ray, but because these particle beams require large accelerators, their use is limited. In this case, the method of using a chemical protectant together with a chemical sensitizer has received attention. Chemical protectants protect normal tissues so that more radiation can act on tumor cells. Sensitizers are selectively deficient