Effective wedge angles with a universal wedge.
Effective wedge angles with a universal wedge.
复制标题
具有通用楔块的有效楔角。
DOI：
10.1088/0031-9155/30/9/010
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发表时间：
1985
影响因子：
3.5
通讯作者：
Siddon,RL
中科院分区：
文献类型：
--
作者：
Petti,PL;Siddon,RL
一些最近设计的X射线产生加速器配备有单个内置楔子，并且通过以适当的比例组合开放(非楔形)场和楔形场来获得不同的“有效”楔角。本文描述了一种根据两个分量场的测量等剂量分布来确定这些比例的技术。作者将飞利浦 SL/75 6 MV 加速器的数据与两个现有的理论模型进行了比较。在一种模型中，光束通过有效楔角和标称楔角的正切之比进行加权，在所检查的有效楔角和方形视场尺寸范围内，与数据的一致性在 3 度以内。第二种更简单的模型，其中梁直接通过楔角的比率进行加权，导致误差高达 11 度。结果表明，这两个模型都是精确理论解的近似值，可以用一个自由参数来表示。该参数可以在物理上解释为开放场和楔形场的中心轴深度-剂量曲线的斜率之比。
Some recently designed X-ray producing accelerators are equipped with a single built-in wedge, and different'effective'wedge angles are obtained by combining an open (unwedged) and a wedged field in the appropriate proportions. This paper describes a technique for determining these proportions from measured isodose distributions of the two component fields. The authors' data for the Philips SL/75 6 MV accelerator are compared with two existing theoretical models. One model, in which the beams are weighted by the ratio of the tangents of the effective and nominal wedge angles, agrees with the data to within 3 degrees over the range of effective wedge angles and square field sizes examined. The second and simpler model, in which the beams are weighted by the ratio of the wedge angles directly, results in errors of as much as 11 degrees. It is shown that both of these models are approximations to an exact theoretical solution which may be formulated in terms of one free parameter. This parameter may be interpreted physically as the ratio of the slopes of the central-axis depth-dose curves for the open and wedged fields.