Design and optimization of a permanent Mmagnet for small-sized MRI based on particle swarm Optimization algorithm

The main magnet, an important part of an MRI system, is used to produce the static magnetic field in the imaging area. In a permanent MRI magnet, there is a widespread end effect that causes a non-uniform magnetic field distribution and affects the imaging quality. In this paper, we have designed an H-type permanent magnet for small-sized MRI applications; in particular, the novel design has been realized by adding a shimming ring outside the pole piece to improve the magnetic field uniformity. Particle swarm optimization (PSO) algorithm is used to solve the complex and nonlinear optimization problems. The simulation results show that the magnet optimized by the proposed method generates a homogeneous magnetic field that can be easily implemented in practice and at a low cost