37例经伽玛刀18mm准直器治疗的脑膜瘤和听神经瘤,计算其20％等剂量曲线内的体积,然后在周边剂量和等中心点数不变的情况下,重新用14mm准直器进行剂量计划。显示:中心剂量明显高于原中心剂量(P<0.001);与原20％等剂量曲线剂量相等的新等剂量曲线所包含的体积比原体积明显减少(P<0.001)。说明使用小准直器治疗大病灶时,中心剂量提高,但周围脑组织受照射的范围比大准直器减少。 Thirty-seven cases of meningioma and acoustic neuroma treated with Gamma Knife 18mm collimator were used to calculate the volume in the 20% isodose curve, and then the 14mm collimator was used again when the peripheral dose and isocenter points were unchanged. Dose plan. The center dose was significantly higher than the original center dose (P<0.001); the volume of the new isodose curve equal to the original 20% isodose curve dose was significantly reduced compared to the original volume (P<0.001). This shows that when using a small collimator to treat large lesions, the center dose increases, but the surrounding brain tissue is exposed to a smaller range than large collimators.