医用直线加速器楔形因子与深度依赖性研究

THE DEPTH DEPENDENCE OF WEDGE FACTORS

目的：确定楔形因子（ＷｅｄｇｅＦａｃｔｏｒＷＦ）随射野大小变化对于放射治疗中吸收剂量的影响。材料与方法：笔者在ＳＩＥＭＥＮＳＭＥＶＡＴＲＯＮ１２（以下简称ＳＩＥＭＥＮＳ）直线加速器上对ＷＦ随水体模中测量深度变化关系进行了测量研究，使用配有０．６ｃｃ电离室的３５７０剂量仪作为剂量测量仪。结果与结论：通过测量发现在体模内最大剂量点到体模内２０ｃｍ范围内ＷＦ随测量深度变化最大有６％的改变。而ＷＦ与体模表面下１０ｃｍ处测得的ＷＦ相比最大有３％的偏差。

Purposes The variation of the wedge factor (WF) with field size was determined. This variation is very important in dose calculations for radiation therapy. Material and methods The WF was measured with different depth in water phantom on Siemens Mevatron 12, using 0.6cc chamber and 3570 dosemeter. Result and conclusion The WF measured at depths between points of maxium doseage and 20cm under surface in water phantom are within 6%, and compared with WF measured at 10cm WF variations are under 3%.