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目的:探讨电子束深度剂量曲线的测定方法,为临床选择电子束治疗方案提供物理基础.方法:在电子直线加速器上分别测量6、9、12、15、18、21MEV六档标称能量,经φ3、φ4、φ5圆形及固定10*10CM限光筒后输出的电子束深度电离曲线.采用E0＝2.33R50,I及E0＝0.818+1.935R50,I+0.040(R50,I)2分别计算平均入射能量E0,并推导出利用SW,A、PU或CE从百分深度电离量直接计算百分深度剂量的公式.结果:所引用二种E0计算公式的差异在2.1％之内,该差异对参考点剂量及深度剂量曲线几乎没有影响.通过对所获得深度剂量曲线与深度电离曲线的比较看到:其85％峰值深度R85,D及半峰值深度R50,D均大于深度电离曲线上的对应值,且该差别随平均入射能量的增加而加大.结论:深度剂量曲线应在测得深度电离曲线后,经计算平均入射能量E0,查出对应深度的SW,A、PU或CE,进而由百分深度电离量求得.“,”Objective: Our aim was to investigate a method for drawing the electron beam depth dose curve from depth ionization curve. Methods: We Measured the depth ionization curve from a Siemens Primus accelerator with 345 and 1010 cm applicators at a nominal energy of 6 to 21 MeV.The formula 0=2.33R50,i and 0=0.818+1.935R50,i+0.040(R50,i)2 were used to calculate the mean injection energy, respectively. We derived relative dose at a depth R from relative ionizatio...