论文部分内容阅读
放射治疗中降低剂量率会导致放射剂量削减现象,造成疗效减弱效应。主要成因是低剂量率射线照射后细胞内损伤修复快;延长照射时间则细胞再增殖加多;以及照射期间细胞周期反复运转,周期内各时相细胞放射敏感性的差异所造成的影响。 一、细胞放射敏感性是剂量率的函数 1972年Hall指出:脉冲加速器可达到10~7Gy/min,超高剂量率造成局部耗氧,放射敏感性降低;10~7～Gy/min内,细胞放射敏感性最高;低于
Reduced dose rates in radiation therapy can lead to radiation dose reductions, resulting in a diminished efficacy. The main cause is the fast repair of intracellular damage after low-dose-rate irradiation; the prolonged irradiation time increases the proliferation of cells; and the effect of repeated cell cycle rotation during irradiation, and the difference in radiosensitivity of cells at various phases of the cycle. 1. Radiosensitivity of cells is a function of dose rate. Hall pointed out in 1972 that pulsed accelerators can reach 10~7 Gy/min. Ultra-high dose rates cause local oxygen consumption and radiosensitivity decreases; within 10~7~Gy/min, cells Highest radiosensitivity; below