简述了一个模拟质子、α粒子的蒙特卡罗径迹结构模型 ,考虑了质子、α粒子在水中输运时的电离、激发等非弹性散射机制 ,模拟计算了质子、α粒子在水蒸气 (密度为 1g cm3 )中的径迹 ,质子、α粒子的能量范围为 0 3— 5MeV u .考虑了产生的大量低能电子 (能量下限为 1eV)在水介质中的输运 .计算得到的射程、径向剂量等参数 ,与实验数据符合得较好 . In this paper, a Monte Carlo trajectory simulation model of proton and α particle is briefly introduced. The inelastic scattering mechanism such as ionization and excitation of proton and α particle in water is considered. Density of 1g cm3), the energies of the proton and α-particles range from 0 3 to 5 MeV u Considering the transport of a large number of low-energy electrons generated with a lower energy limit of 1 eV in an aqueous medium The calculated range, Radial dose and other parameters, in good agreement with the experimental data.