中文摘要：

放疗计划系统中的光予剂量计算一般先基于均匀水模进行，然后根据人体组织密度的非均匀性，利用修正算法，将均匀水模的剂量分布修正到真实人体．在不同组织交界面处，非均匀修正的精度较差．本研究利用蒙特卡洛程序对人体非均匀组织的几种组合情况进行模拟，获得非均匀组织对光子吸收剂量的影响，为发展精确的剂量修正方法提供基础．

英文摘要：

The general calculation method of photon dose distribution in a radiation therapy planning system is carried out based on the homogeneous water phantom. The actual dose distribution on the human body is obtained by the correction algorithm according to the inhomogeneous characteristic of tissue density. The correction precision is low in the different tissue interfaces. The combinations of human inhomogeneous tissue are simulated with Monte Carlo program in this study, the influence of photon absorbed dose in the different tissue interfaces are obtained, which provides a foundation for the development of an accurate correction method for photon dose distribution.