Mandour M A, Harder D
Strahlentherapie. 1978 May;154(5):328-32.
The scattering foil widely used for field flattening in electron therapy produces a distortion of the electron spectrum which significantly reduces the slope of the descending part of the depth dose curve. It is already known that this effect can be drastically reduced by replacing the scattering foil by a two-foil scatterer. The second foil, fit with a radial thickness profile, acts as a compensator, attenuating the central part and enhancing the peripheral part of the beam by electron scattering. Calculations of the optimal foil combinations and radial thickness profiles are presented and numerical values of smooth (Gaussian) and three-step profiles for various field sizes are provided. The results are applicable to a variety of electron energies and scattering foil materials.
在电子治疗中广泛用于射野平坦化的散射箔会使电子能谱发生畸变，这会显著降低深度剂量曲线下降部分的斜率。众所周知，用双箔散射体替代散射箔可大幅减小这种效应。第二个箔片具有径向厚度分布，起到补偿器的作用，通过电子散射衰减射束的中心部分并增强其周边部分。文中给出了最佳箔片组合和径向厚度分布的计算结果，并提供了不同射野尺寸下平滑（高斯）和三步分布的数值。这些结果适用于多种电子能量和散射箔材料。
