工业钼靶X射线光机能谱的蒙特卡罗模拟

利用蒙特卡罗模拟程序EGSnrc,构建出工业钼靶X射线光机模型,进行了28 keV的电子束经过钼靶产生的光子在光机各组件中的传输模拟,得到距源焦点50 cm处, 射野半径为5 cm平面上的粒子相空间文件,通过对相空间文件分析得到粒子注量、能谱分布、角分布、平均能量等信息,模拟计算了过滤材料和管电压对钼靶X射线谱分布的影响。钼过滤下钼靶X射线的平均能量小于铑过滤,但对较高能量部分的影响要大于铑过滤;随着管电压的升高,钼靶光机的光子产生效率呈上升趋势,平均能量增加。25,28,30,35 kV 4组辐射质条件下,钼靶X射线能谱的平均能量分别为16.0,16.6,17.0,17.8 keV,与实验测量值接近,相对误差在1%以内。

Monte Carlo Simulation for X-ray Spectrum on Industrial Molybdenum Target Units

The Monte Carlo simulation program EGSnrc is adopted to simulate components of industrial X-ray mammography target units and the transportation process for photons which is produced by 28 keV electron beam bombarding a molybdenum target . The particle phase space files which is gained on a plane away the focus at 50 cm and a radius 5 cm radiation field.The information, like particle fluence, energy spectrum distribution, angular distribution, average energy and so on,can be obtained by the analysis of the phase space files. Simulated the molybdenum target X-ray spectrum distribution is affected by filter material and tube voltage. The mean energy of molybdenum filtration is less than rhodium filter, but the impact of higher energy part is greater than the rhodium filter, with tube voltage increasing, the effective production rate of photon and the mean energy are all increased.Under the four groups radiation quality conditions, the mean energy of mammography X-ray spectra are each 16.0, 16.6, 17.0, 17.8 keV, and close to the experimental measurements, the relative error in less than 1%.