Furhang E E, Chui C S, Lovelock M
Department of Medical Physics, Memorial Sloan-Kettering Cancer Center, New York, New York 10021, USA.
Med Phys. 1995 May;22(5):525-30. doi: 10.1118/1.597553.
Mean mass energy absorption coefficient ratios of acrylic, polystyrene, and water to air, were calculated using Monte Carlo generated energy spectra. The energy spectra were calculated for 4- to 50-MV x-ray beams, from machines using flattening filters and scanning beams. The validity of these spectra was verified by comparing the measured ionization ratios with the calculated values. The agreement was found to be within 1.9%. For beams of energy below 6 MV, our estimates of the mean mass energy absorption coefficient ratios agree well with those recommended by the TG-21 protocol. For higher energy beams, the discrepancy increases to about 3%. It was found that the discrepancy is attributable to the different spectra used in these calculations.
使用蒙特卡洛生成的能谱计算了丙烯酸、聚苯乙烯和水与空气的平均质能吸收系数比。能谱是针对4至50兆伏的X射线束计算的，这些射线束来自使用均整滤波器的机器和扫描束。通过将测量的电离比与计算值进行比较，验证了这些能谱的有效性。发现两者的一致性在1.9%以内。对于能量低于6兆伏的射线束，我们对平均质能吸收系数比的估计与TG-21协议推荐的值吻合良好。对于更高能量的射线束，差异增加到约3%。发现差异归因于这些计算中使用的不同能谱。
