楔形角、线倾角及其测量

WEDGE ANGLE LINE-OBLIQUE ANGLE AND ITS MEASUREMENT

本文提出沿着等剂量线倾斜方向，等距地在同深度测量三点剂量，根据这三点剂量推导出楔形角和线顺角的方法，计算公式为：式中α为射线入射角，Ｋ是三点剂量及射束轴上百分深度量的函数。文中比较了本法和三维水箱扫描法所得楔形角大小．二者十分一致。在楔形角测量中、作者发现钴－６０γ线楔形角随深度有明显改变，故建议在使用楔形滤板前，应作必要的校测。

The doses at three points along the oblique direction of isodose line at the same depth aremeasured.The wedgeangle and the line-oblique angle are derived from these doses measured according to the following formula:The wedge angles calculated by above formula were compared with these measured by 3-D water-scanner phantom,It was found that the results were very closed,this confirmed the correctness of the for-mula.It is recommended that the wedge angles may be measured before its use,because the wedge anglesvaries greatly tissue with the depth.