Monte Carlo模拟对放疗中电子反散射谱的研究

Investigation of spectral characteristics of electron backscattering effect in radiotherapy with Monte Carlo code

电子束治疗腮、耳垂等敏感处肿瘤时,经常需要挡铅以保护正常组织,由此产生电子的反散射效应。本文用蒙特卡罗程序模拟了10MeV临床电子束谱随深度的变化;给出了多种散射体的反散射谱平均能量与基本电子谱平均能量的比值随平均束能量的变化曲线。并从能谱的观点,对反散射效应强弱随深度的变化关系作了定性分析,得到与文献一致的结论。

The Pb slab is often used to protect normal tissues against beam damage in electron beam treatment of sensitive tumors. The spectral characteristics of a 10 MeV clinic electron beam as a function of the depth are simulated using Monte Carlo code MCNP4C. The simulation results show the relationship between the mean beam energy and the ratio of the mean energy of the backscattered spectra to that of the primary spectra. The similar characteristics are obtained for several scattering materials. The variation in the backscattering effect intensity with the depth is also qualitatively analyzed in viewpoint of the energy spectrum, and the consistent conclusions with the published literature are deduced.