Arthur G
Department of Medical Physics, Westmead Hospital, NSW.
Australas Phys Eng Sci Med. 1994 Mar;17(1):43-8.
The variation of wedge factor with field size was measured for a range of square and rectangular fields for 45 degrees and 60 degrees wedges. Measurements were performed on accelerators with both externally mounted wedges, the Varian 600C of nominal energy 6MV and internally mounted wedges, the Philips SL75/5 of nominal energy 6MV and the Philips SL25 of nominal energy 25MV. Analysis of the results confirm previous investigations reported in the literature of the variation of wedge factor with field size and in particular the significantly greater variation for internally mounted wedges. A wedge factor for a rectangular field based on the wedge factor of the open field equivalent square gives a maximum error of 1.5%. A wedge factor for a rectangular field based on the wedge factor of the square field of equal area reduces the maximum error to 0.5% for all three accelerators. Analysis of results reported in the literature show a similar reduction.
针对一系列方形和矩形射野，测量了45度和60度楔形滤过板的楔形因子随射野大小的变化。测量在配有外部安装楔形滤过板的加速器（标称能量为6MV的Varian 600C）、内部安装楔形滤过板的加速器（标称能量为6MV的飞利浦SL75/5和标称能量为25MV的飞利浦SL25）上进行。结果分析证实了文献中先前报道的楔形因子随射野大小的变化情况，特别是内部安装楔形滤过板时变化显著更大。基于等效方形开野楔形因子的矩形射野楔形因子，最大误差为1.5%。基于等面积方形射野楔形因子的矩形射野楔形因子，对所有三台加速器而言，最大误差降至0.5%。文献报道的结果分析显示出类似的降低情况。
