Real Field Simulating and Passive Shimming of a Permanent magnet for MRI

摘要

A method of shape optimization combined with finite element analysis is applied to simulate the real magnetic field with deviation in a permanent magnet for magnetic resonance imaging (MRI) device. Based on the real field the passive shimming is carried out to elevate the homogeneity of the field in a large imaging space. With the improved genetic algorithm and Hook-Jeeves method as the searching tools, the size and locations of the ferromagnetic shimming pieces could be readily determined, and the high uniformity of the magnetic field is approached using the method proposed in this paper.