| 毛玲丽,刘春波,裴曦,徐榭.实时MRI引导放射治疗中边缘磁场对电子枪束流特性的影响[J].中国医学影像技术,2019,35(3):433~438 |
| 实时MRI引导放射治疗中边缘磁场对电子枪束流特性的影响 |
| Impact of MRI fringe magnetic field on radiation beam characteristics of electron guns in real time MRI-guided radiotherapy |
| 投稿时间：2018-07-12 修订日期：2018-11-26 |
| DOI：10.13929/j.1003-3289.201807094 |
| 中文关键词: 电子枪 边缘磁场 平行配置 放射疗法 磁共振成像 |
| 英文关键词:electron gun fringe magnetic field in-line configuration radiotherapy magnetic resonance imaging |
| 基金项目:国家自然科学基金面上项目（11575180）、国家重点研发计划（2017YFC0107500）、安徽省重点研究与开发计划（1804a09020039）。 |
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| 中文摘要: |
| 目的 观察实时MRI引导放射治疗（MRIgRT）系统中MR边缘磁场对电子枪束流特性的影响。方法 以电磁场仿真软件模拟平行配置MRIgRT系统中1.5T MR不同边缘磁场下Varian 600C电子枪和Litton L2087电子枪的束流特性。结果 2款电子枪在磁场中的整体表现一致。随磁感应强度增大，Litton L2087和Varian 600C电子枪电流分别缓慢增加至无磁场时的2.72%和1.93%。电子枪阳极出口处电流在经历初始稳定水平后开始减少，达到最小值后电流缓慢增加，电流损失最大分别可达80.25%和73.48%；高场强处，束流半径出现周期性变化；束流均方根发射度存在波动。结论 平行配置的MRIgRT系统中，边缘磁场会对电子枪束流轨迹产生影响，导致大量电流损失，均方根发射度变化巨大。 |
| 英文摘要: |
| Objective To investigate the impact of MR fringe magnetic field on the electron beam characteristics of the electron gun in the MRI-guided radiotherapy (MRIgRT). Methods Electromagnetic field analysis software was used to simulate the beam characteristics of both Litton L2087 electron gun and Varian 600C electron gun under different magnetic field strengths for the in-line MRIgRT configuration. Results Two electron guns exhibited qualitatively similar behavior in the fringe magnetic field. As field strength increased, the current emitted by the cathode increased slowly, which could increase up to 2.72% and 1.93% from the original value without external magnetic field for Litton L2087 and Varian 600C electron gun, respectively. The current at the anode exit started to decrease after the initial plateau, and after reaching a minimum value, the current started to increase slowly, and the current loss could reach up to 80.25% and 73.48% of the initial value, respectively. At high values of the field strength, the beam radius changed periodically. Beam root mean square emittance fluctuated under different magnetic field strengths. Conclusion For in-line MRIgRT configuration, the fringe magnetic field can affect the trajectory of the beam and cause a large amount of current loss in the electron gun, and the beam RMS emittance varies greatly. |
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