单边核磁共振仪中射频线圈的优化  

Optimization of RF coil in single-sided NMR system

作　　者：籍勇亮[1] 何为[2] 吴高林[1] 王谦[1] 李龙[1] 孟凯凯[2] 徐征[2] 

机构地区：[1]国网重庆市电力公司电力科学研究院,重庆401123 [2]重庆大学电气工程学院输配电装备及系统安全与新技术国家重点实验室,重庆400044

出　　处：《电工电能新技术》2015年第9期75-80,共6页Advanced Technology of Electrical Engineering and Energy

基　　金：国家自然科学基金资助项目(51107150;51377182)

摘　　要：射频线圈是核磁共振系统中实施射频激励和接收核磁共振信号的核心结构,其性能直接决定了核磁共振信号的质量。针对单边核磁共振系统信噪比差的缺点,提出以空间均匀性和信噪比为优化参数的平面矩形螺旋线圈的优化方法。优化方法分为两步:1以射频磁场的均匀分布范围为优化目标,通过改变平面螺旋线圈的结构参数,运用毕奥-沙伐定律对RF线圈磁场进行计算,确定与目标区域匹配的线圈的基本结构。2以线圈的信噪比为优化目标,使用有限元仿真软件计算在步骤1中已确定的各种线圈的交流电阻,进而得到信噪比,从中选出信噪比最高的线圈。结果表明,最优的平面矩形螺旋线圈结构参数为:布线面积为17.2mm×17.2mm,线宽和线间距均为0.5mm,总匝数为10匝,均分在2mm厚电路板的双面,每个面上5匝;该射频线圈不仅能保证与主磁场B0均匀区域相匹配的激励区域,而且从信噪比测量实验可知,该线圈在目标区域内具有最好的信噪比。RF coil is used to transmit and receive signals in nuclear magnetic resonance （NMR） system, whose performances largely determine the signal quality. By considering the low signal-to-noise ratio （SNR） of single-sided NMR system, we optimized the planar rectangular spiral RF coil based on its spatial uniformity and SNR. The optimization method was divided into two steps. （1） The optimization goal was based on the uniform area of the RF magnetic field. We changed the structure parameters of the planar rectangular spiral RF coil. The RF field was calculated by Biot-Savart Law. The structures of RF coils, which fit the uniform area of the main magnetic field, were determined. （2） The optimization goal was the coils＇ SNR. The AC resistance of the coils gained in step （1） was found by the finite element simulation software. Thereby, these coils＇ SNR was obtained. At last, a coil, which has a high SNR in sensitive area, was selected. The result shows： the final RF coil has a wiring area of 17.2mm × 17.2mm and 10 turns, with 5 turns on each face of a 2mm thick printed circuit board （PCB）. The lead width and the adjacent distance are both 0. 5mm. This coil not only has a sensitive area which fits the uniform area of the main magnet, but also possesses a high SNR from the SNR measurement experiment.

关 键 词：单边核磁共振 射频线圈 空间均匀性 信噪比 

分 类 号：TM153[电气工程—电工理论与新技术]