医用直线加速器楔形因子与射野依赖性研究

THE VARIATION OF WEDGE FACTORS WITH FIELD SIZE ON LINEAR ACCELERATORS

楔形因子（ＷｅｄｇｅＦａｃｔｏｒＷＦ）随射野大小变化在放疗照射剂量确定中是非常重要的参量变化规律。不同加速器其机头设计不同则ＷＦ不同。笔者对两台加速器（ＰＨＩＬＩＰＳＳＬ７５和ＶＡＲＩＡＮＣＬ１８００）ＷＦ随射野变化关系进行了研究，发现ＶＡＲＩＡＮＣＬ１８００ＷＦ随射野改变＜±１％，ＰＨＩＬＩＰＳＳＬ７５则ＷＦ随射野变化有±７％的改变。类比于总散射因子（Ｓｐ，ｃ）的定义，我们定义因子Ｓｗ来表征楔形板因子对射野大小的依赖关系。

The variation of the wedge factor (WF)with field size play an important role,which determinesthe radiction output in treatments using wedge filters.The design of such filters varied considerably from onemanufacturer to another.We investigated two different wdeges,Varian CL-1800 and Philips SL75,and found dif-rized the variation of WF with field size in Sw.