基于Geant4的微型透射式X射线管中背散射电子对出射光束影响  

Influence of backscattered electrons on exit beam of miniature transmission X-ray tube using Geant4

作　　者：董浪 王明[1,2] 孙甜甜 代伟 张磊 李国栋 张庆贤 谷懿[1,2] 曾国强[1,2] DONG Lang;WANG Ming;SUN Tiantian;DAI Wei;ZHANG Lei;LI Guodong;ZHANG Qingxian;GU Yi;ZENG Guoqiang(College of Nuclear Technology and Automation Engineering,Chengdu University of Technology,Chengdu 610059,China;Applied Nuclear Technology in Geosciences Key Laboratory of Sichuan Province,Chengdu University of Technology,Chengdu 610059,China)

机构地区：[1]成都理工大学核技术与自动化工程学院,成都610059 [2]地学核技术四川省重点实验室成都理工大学,成都610059

出　　处：《核技术》2024年第4期58-65,共8页Nuclear Techniques

基　　金：国家自然科学基金(No.12105030);四川省教育厅科研基金项目(No.2022NSFSC1185);四川省青年科技创新研究团队项目(No.2021JDTD0018)资助。

摘　　要：X射线管工作时,管内会产生大量的背散射电子。在X射线管内电场的作用下,背散射电子会被电场拉回到阳极靶上,并产生额外的X射线,最终对出射光束质量产生不利影响。背散射电子的分布与X射线管的特性(管电压和靶材料)密切相关。因此,本文将从透射式X射线管中背散射电子的分布规律出发,系统讨论靶材料和管电压引起的背散射电子变化以及其对出射光束质量的影响。首先,在Geant4代码中建立了透射式X射线管的物理模型,并将计算结果与文献数据进行对比验证;其次,开展了不同管电压与靶材料对X射线管中背散射电子分布的影响分析;最后,探究了在管电压作用下背散射电子对出射光束质量的影响。结果显示:当考虑电场时,X射线管的出射光束半高全宽(Full Width at Half Maxima, FWHM)、光子产额和特征峰产额会有所增加,表明背散射电子会对出射光束的质量产生一定的影响。结果同时显示:对出射光束质量影响程度最高主要是第一代和第二代被电场拉回的背散射电子。当管电压发生改变时,背散射电子对出射光束质量的影响程度也会改变,管电压越大,背散射电子对X射线管出射光束质量的影响也越明显。本研究结果为未来开展微型透射式X射线管的数值仿真计算提供参考。[Background]When an X-ray tube operates,a large number of backscattered electrons are generated inside the tube.Under the influence of the electric field inside the X-ray tube,these backscattered electrons are pulled back to the anode target by the electric field,generating additional X-rays,which ultimately have a negative impact on the quality of the emitted beam.[Purpose]This study aims at the distribution rules of backscattered electrons in transmission X-ray tubes,and the changes in backscattered electrons caused by target materials and tube voltages as well as their impact on the outgoing beam quality.[Methods]Firstly,Geant4 was used to establish the physical model of the transmission X-ray tube,and the theoretical calculations were compared with experimental data to verify the accuracy of the calculation program.Then,C,Si,Cu,Ag,and W were selected as anode target materials,and the influences of different electric field strengths and these target materials on the distribution of backscattered electrons in the X-ray tube were analyzed in details.Finally,the influence of the backscattered electrons on the outgoing beam quality under the effect of tube voltage was investigated.[Results]The full width at half maximum,photon yield,and characteristic peak yield of the outgoing beam of the X-ray tube increase when considering the electric field,indicating that the backscattered electrons have effect on the outgoing spectrum quality.Simultanously,the backscattered electrons pulled back by the electric field in the first and second generations predominantly affect the outgoing beam quality.A change in the tube voltage alters the extent of influence of the backscattered electrons on the outgoing beam quality,and a larger tube voltage leads to a more obvious influence of the backscattered electrons on the outgoing beam quality of the X-ray tube.[Conclusions]The distribution of inside backscattered electron is closely related to the characteristics of the X-ray tube,including the tube voltage and target material.The re

关 键 词：透射式X射线管 背散射电子 管电压 靶材料 GEANT4 

分 类 号：TL99[核科学技术—核技术及应用]