Varian 2300 C／D直线加速器高能电子束铅挡野输出因子的测定与分析

目的：探讨Varian 2300 C/D直线加速器高能电子束射野输出因子变化规律。方法：用电离室法实测在各种能量下对四种限光筒的不同铅挡野的射野输出因子。结果：铅挡野输出因子随射野边长及限光筒大小变化没有明显的规律；铅挡野输出因子与能量有关。结论：射线能量、限光铜和铅挡野大小时输出因子的影响较大，临床应用时需要针对性地精确测量。

The measurement andanalysis of output factor of lead block fields for high energy electron beam of Varian2300 C/D linear accelerator

Purpose: To analyses the variation regularity of output factor of lead block fields for high energy electron beam of Varian 2300 C/D linear accelerator. Methods: Output factors of lead block fields were measured for four standard applicators under various electron beam energy. Results: The variations of output factor with field side or with applicators size were no obvious regularity; Output factor of lead block fields was related to standard applicators size and lead block fields side; Output factor of lead block fields was related to electron beam energy. Conclusion: Electron beam energy, standard applicator size andlead block fields side had a obvious influence upon output factor. The accurate measurement should be performed for use electron beam energy in the clinic.