Jette D
Med Phys. 1985 Mar-Apr;12(2):178-82. doi: 10.1118/1.595773.
The Fermi-Eyges theory of multiple scattering, applicable to charged-particle teletherapy beams, has been generalized to second order in small quantities representing deviations from the particles' initial lines of travel and direction. The second-order multiple-scattering theory provides increased accuracy, and in particular it takes into account the skewness of the particles' paths, in calculating dose. Only the assumptions and certain results of the second-order theory are presented in this communication, for the immediate use of other investigators. An application to rectangular fields shows that the second-order theory predicts one component of the buildup of electron central axis depth dose, which the (first-order) Fermi-Eyges theory cannot do. (The other major component of buildup, which is not yet incorporated into this theoretical work, is due to high-energy secondary electrons). Various approximate calculations of electron central axis depth dose are compared with the second-order calculation.
适用于带电粒子远距治疗束的费米-艾格斯多重散射理论，已推广到二阶，该二阶理论针对表示偏离粒子初始行进路线和方向的小量。二阶多重散射理论提高了计算剂量时的准确性，特别是它考虑了粒子路径的偏斜。本通讯仅介绍二阶理论的假设和某些结果，以供其他研究人员直接使用。对矩形射野的应用表明，二阶理论预测了电子中心轴深度剂量累积的一个分量，而（一阶）费米-艾格斯理论则无法做到这一点。（累积的另一个主要分量，尚未纳入本理论工作，是由高能二次电子引起的）。将电子中心轴深度剂量的各种近似计算与二阶计算进行了比较。
