基于FEM/FDTD混合方法设计射频线圈

Design of head birdcage coil based on FEM/FDTD method in low magnetic field

核磁共振成像系统中的射频线圈是发射信号的核心部分,主要研究在0. 23T磁共振成像系统中头部射频线圈的设计和分析方法,为适应系统要求选择低通鸟笼线圈。利用Comsol及Matlab软件对线圈建模仿真,通过有限元(Finite Element Method,FEM)及时域有限差分(Finite Difference Time Domain)混合方法进行电磁场仿真分析,提出了分布式电容的优化方案,提高了线圈的磁场均匀度,磁通圆度等参数,符合系统设计的要求。混合方法使用较少的内存提高了计算精度与速度,为大型复杂射频线圈设计提供了仿真思路。

The radio frequency coil in the magnetic resonance imaging system is the core part for transmitting signal. The main research is the design and analysis of the head RF coil in the O. 23T magnetic resonance imaging system. The low - pass birdcage coil is selected to meet the system requirements. By using Comsol and Matlab software to simulate the coil, the finite element method（Finite Element Method, FEM） and the finite difference time domain （Finite Difference Time Domain） hybrid method were used to simulate the electromagnetic field. The optimized scheme of distributed capacitance was proposed, improving the coil magnetic field uniformity, magnetic flux circularity and other parameters to meet the system design requirements. The hybrid method used less memory to improve the calculation accuracy and speed, and provided simulation ideas for the design of large and complex RF coils.