Optimization and Design of Multi-ring Pole Pieces for Small-sized Permanent Magnetic Resonance Imaging Magnet

摘要

In magnetic resonance imaging (MRI) system, the main magnet creates a static magnetic field, which largely determines the final imaging quality. Pole pieces of pure-iron are commonly used to improve the field homogeneity in the imaging region. In this work, we attempt to design a novel configuration of multi-ring pole pieces for a small animal MRI system. Based on the model of a small H-type permanent magnet, the magnetic field is calculated using the finite element method, which considers the nonlinearity of the ferromagnetic materials. The pole piece was designed with the particle swarm optimization (PSO) algorithm. The results show that, the optimal multi-ring pole pieces can effectively reduce the uniformity about 10-20 ppm (10(-6)), with a better performance compared with the flat and traditional onering pole piece configuration.