【摘要】 根据IAEATRS 457报告提出的CT电离室校准方法,建立了RQT8辐射质,运用蒙特卡罗模拟程序EGSnrc得到RQT 8辐射质下距源焦点95 cm处,射野半径为5 cm的平面上的注量谱及角分布,以此构造校准模型,并研究了附加光阑的长度、倒角对校准CT电离室的影响。建立的参考辐射质半值层偏差为1.4%,附加光阑在长度为50 mm倒角为80°时散(透)射最小,总体达到了CT电离室校准、测试和国际比对的要求。更多还原

【Abstract】 Based on the calibration method in the IAEA TRS 457 report,RQT 8 radiation quality was established.The spectra and angular distributions for RQT 8 radiation quality was performed by Monte Carlo simulation software EGSnrc with the distance of 95 cm,radius of 5 cm between tube focal spot and recording planar,which constructing the model of CT chambers calibration field.The effection of calibration CT chambers was studied under additional aperture with different length as well as angle edges.The result shows that the deviation of established Half-value Layer for reference radiation quality no more than 1.4%,the scattering and transmission is the least when the width of additional apertures is 50 mm and the opening angle is 80°,all of which is reaching on the requirements of calibration,testing and international comparison for CT chambers.更多还原