中文摘要：

利用不同能量的各项同性点源对铁和铅两种靶物质进行照射，使用蒙特卡罗程序实现模拟计算。根据模拟结果讨论了测量系统几何条件（点源、靶物质和探测点的相对位置及探测半径）及轫致辐射对积累因子的影响情况，通过各自影响因素的贡献值不同，说明对辐射防护屏蔽进行设计时，应综合考虑各项参数，更合理地设计屏蔽系统。

英文摘要：

Point sources with different energies were used to irradiate target materials of iron and lead, with simulated calculation made by Monte Carlo code. On the basis of the results of simulation, the influence of geometrical condition of measuring system （point source, relative position of target material and detector, radius of detection） and bremsstrahlung on build-up factor value are discussed. With different values of contributing factors, it is indicated that design of the shielding system should be more reasonable than before, while considering all parameters in comprehensive fashion.