MR磁场对一体化PET/MR系统灵敏度的影响  

The influences of MR magnetic field on the sensitivity of integrated PET/MR system

作　　者：崔亚莹 白玫[1] CUI Ya-ying;BAI Mei(Department of Medical Engineering,Xuanwu Hospital Capital Medical University,Beijing 100053,China;不详)

机构地区：[1]首都医科大学宣武医院医学工程处,北京100053

出　　处：《中国医学装备》2021年第7期6-9,共4页China Medical Equipment

基　　金：国家重点研发计划(2016YFC1307201)“适宜临床使用的抑郁障碍客观诊断指标体系的构建”;国家重点研发计划数字诊疗装备研发专项课题(2016YFC0103909)“PET/MR在神经系统疾病中的高级临床应用”。

摘　　要：目的:研究核磁共振(MR)射频线圈及不同强度的主磁场对一体化正电子发射断层扫描(PET)/MR系统灵敏度的影响。方法:利用基于蒙特卡罗工具的文本工程通用架构(GATE)软件建立GE Signa PET/MR仿真模型,在有无射频线圈的情况下选取不同强度磁场,依据美国电器制造商协会(NEMA)NU2-2012标准对系统灵敏度进行测量,分析不同强度磁场及射频线圈对一体化PET/MR系统灵敏度的影响;并与体模实验结果对比,验证仿真实验的准确性。结果:仿真实验与体模实验结果偏差<3%;磁场从0 T增加到7 T,系统灵敏度最多降低4%;同等静磁场条件下,射频线圈的存在使系统灵敏度降低20.57%~23.5%。当时间分辨率为2.25 ns、能窗下限为300 keV时,将能量分辨率从20%优化为11%,系统灵敏度提升0.5%;当时间分辨率为2.25 ns、能窗下限为450 keV时,将能量分辨率从20%优化为11%,系统灵敏度提升16.2%。在能量分辨率为11%时,将能窗下限从450 keV降低到300 keV时,系统灵敏度提高21.2%;能量分辨率为20%时,将能窗下限从450 keV降低到300 keV时,系统灵敏度提高40.2%。当时间分辨率从2.25 ns优化至0.4 ns时,系统灵敏度整体高于时间分辨率为2.25 ns时的灵敏度,但提高程度在1%左右。结论:磁场增大PET的系统灵敏度有所降低,但程度较小;射频线圈会大幅度降低PET的系统灵敏度。降低能量阈值,优化时间分辨率以及能量分辨率有助于提高系统灵敏度。Objective:To study the influences of magnetic resonance radio frequency(MR RF)coil and mainly magnetic fields with different strengths on the sensitivity of integrated positron emission tomography/magnetic resonance(PET/MR)system.Methods:Generic architecture of text engineering(GATE)software based on Monte Carlo tool was adopted to establish GE Signa PET/MR simulation model so as to select the sizes of different magnetic field.The sensitivity of this system was measured according to NU2-2012 standard of national electrical manufacturers association(NEMA).And then,the influences of magnetic field with different strengthen and RF coil on the sensitivity of integrated PET/MR system were further analyzed.The accuracy of simulation experiment was verified by comparing with the results of phantom experiment.Results:The results deviation between simulation experiment and phantom experiment was less than 3%,and the sensitivity of system decreased 4% at most when the magnetic field was increased from 0T to 7T.Under the same condition of static magnetic field,the RF coil reduced the sensitivity of system from 20.57%-23.5%.The energy resolution was optimized from 20% to 11% and the sensitivity of system was increased 0.5% when the time resolution was 2.25 ns and the lower limit of energy window was 300keV.And the energy resolution was optimized from 20% to 11% and the sensitivity of system was increased 16.2% when the time resolution was 2.25 ns and the lower limit of energy window was 450keV.The lower limit of energy window was reduced from 450 keV to 300 keV and the sensitivity of system was increased 21.2% when energy resolution was 11%.And the lower limit of energy window was reduced from 450 keV to 300 keV and the sensitivity of system was increased 40.2% when energy resolution was 20%.When the time resolution was optimized from 2.25ns to 0.4ns,the sensitivity of system was overall higher than that of the time resolution of 2.25ns,but the degree of improvement was approximately 1%.Conclusion:The sensitivity of the PET

关 键 词：正电子发射断层扫描(PET) 核磁共振(MR) 文本工程通用架构(GATE) 主磁场 射频线圈 灵敏度 

分 类 号：R318.6[医药卫生—生物医学工程]