An Improved Passive Shimming Design Method

Abstract

Passive shimming technology can make the uniformity of DSV region of MRI system meet the imaging requirements. In this paper, the dichotomy method is introduced to improve the OTMF algorithm, so that it can quickly get the minimum shimming sheet laying scheme under the lowest magnetic field inhomogeneity, and greatly reduce the iteration time. Based on Improved OTMF algorithm by Dichotomy, this paper continues to study the influence of the number of shimming trays, the number of pockets in each shimming tray, the size of the shimming pieces, and the spacing between the shimming pieces on the shimming effect through DOE test design method and Monte Carlo simulation test method, and gives the best shimming design scheme for a 1.5T MRI superconducting magnet. This scheme has been proved to reduce the inhomogeneity of the magnetic field at 20cm DSV from 1199.2373ppm to 0.57ppm. The shimming design method introduced in this paper has certain guiding significance in exploring the factors affecting the passive shimming effect and shimming design.