Numerical optimization of intra-operative RF coil for open vertical-field MRgFUS using hybrid MoM/FDTD method

The numerical optimization of a special organ-oriented RF coil for the open vertical field magnetic resonance guided focused ultrasound system is reported. The hybrid MoM/FDTD method is used modeling the RF coil. The numerical simulation of the current distribution on the RF coil with complicated structure was fulfilled by MoM, and the electromagnetic field simulation considering of the full tissue-coil interactions within the region of the oriented organ was evaluated by FDTD. The Huygence equivalent box with six surfaces interconnects the two hybrid methods, the MoM method and the FDTD method, smoothly. After several iterations, the final solutions are convergence and the RF coil is optimized furthest to compensate the low sensitivity at vertical field. The magnetic distribution of B₁ field is much improved compared with the previous published results.