基于目标场法和CST仿真的低场磁共振射频线圈设计  

Design of a radiofrequency coil for low-field magnetic resonance imaging by target-field method combined with CST simulation

作　　者：张勋 胡亮亮 屈正 徐进章[1] ZHANG Xun;HU Liangliang;QU Zheng;XU Jinzhang(School of Electrical Engineering and Automation,Hefei University of Technology,Hefei 230000,China;School of Instrument Science and Opto-electronics Engineering,Hefei University of Technology,Hefei 230000,China;School of Nuclear Science and Technology,Lanzhou University,Lanzhou 730000,China)

机构地区：[1]合肥工业大学电气与自动化工程学院,安徽合肥230000 [2]合肥工业大学仪器科学与光电工程学院,安徽合肥230000 [3]兰州大学核科学与技术学院,甘肃兰州730000

出　　处：《中国医学物理学杂志》2021年第6期743-748,共6页Chinese Journal of Medical Physics

基　　金：国家自然科学基金(81527802)。

摘　　要：根据临床对人体肺部磁共振成像的需要,设计一种用于肺部0.06 T低场磁共振成像的^(3)He射频线圈。通过预先设定感兴趣区域(ROI)及其内部的目标磁场,运用目标场法逆向求解ROI内产生目标磁场所需的源电流密度分布,流函数获取射频线圈理想绕组。然后利用CST软件建模简化线圈绕组,场路协同仿真研究负载射频线圈在不同品质因数(Q值)下的射频场B_(1)和特定吸收率(SAR)分布等性能指标。仿真实验结果表明,通过改变射频电路的电容值可调整线圈的Q值,线圈Q值越大,单位功率信号激励下产生的B_(1)场强越高,SAR值越高,传输效率越低,而B_(1)场均匀性不受影响,一直保持在近90%。通过射频线圈仿真,验证了目标场法联合CST仿真设计方法的可行性,可推广至高频射频线圈设计。According to the clinical needs of human lung MRI,a ^(3)He radiofrequency(RF)coil was designed for 0.06 T lowfield magnetic resonance imaging of the lung.By predefining the region of interest and its internal target magnetic field,the inverse solution of source current density distribution of the target magnetic field generated in the region of interest is obtained using target-field method;and the ideal winding of the RF coil is determined by stream function.Then,CST software is employed to model and simplify the coil winding,and field-circuit co-simulation is applied to study the performance indicators of load RF coil,such as RF field(B_(1))and specific absorption rate distribution under different quality factors(Q factors).The simulation results show that the Q factor of the coil can be adjusted by changing the capacitance value of the RF circuit.As Q factor of the coil get larger,there are higher B_(1) field intensity generated under the excitation of the unit power signal,higher specific absorption rate and lower transmission efficiency,while B_(1) field uniformity is not affected by Q factor and always keeps at nearly 90%.The feasibility of the design by target-field method combined with CST simulation is verified by RF coil simulation,and the proposed method can be promoted to high-frequency RF coil design.

关 键 词：低场磁共振成像 射频线圈 目标场法 CST软件 场路协同仿真 品质因数 

分 类 号：R318[医药卫生—生物医学工程] O441.4[医药卫生—基础医学]