永磁磁共振成像装置主磁体设计方法研究  

Study on the design of main magnet body for permanent-magnet magnetic resonance imaging device

作　　者：李霞[1,2] 徐文龙[1] 徐冰俏[1] 陶贵生[1,2] 

机构地区：[1]中国计量学院信息工程学院,浙江杭州310018 [2]浙江大学生仪学院,浙江杭州310027

出　　处：《中国计量学院学报》2011年第3期273-276,共4页Journal of China Jiliang University

基　　金：国家自然科学基金资助项目(No.30900332);浙江省科技厅项目(No.2010C14010)

摘　　要：针对小动物磁共振成像分析仪,进行双柱型永磁小磁体的设计,要求静磁场强度为0.5 T,磁场不均匀度小于25×10-6.考虑磁路漏磁情况及磁阻现象,采用磁路设计中常用的磁路方法,进行永磁磁体结构的初始设计;利用有限元方法对初始的模型进行磁场数值分析;改变匀场环的形状和尺寸,观察空隙中磁力线的走向改变,分析匀场环的改变对成像区磁场均匀度的影响.利用Ansys有限元软件对匀场环的尺寸进行了优化计算,当匀场环内径大约为外径的1/3时,成像区不均匀度提高一个数量级.结果表明永磁磁体的磁路设计方法和有限元数值计算合理,可以满足成像要求.A small two-column type permanent-magnet magnet body of magnetic resonance imaging(MRI) for small animals was designed,the magnetic field strength of which was required for the 0.5T and the magnetic field inhomogeneity was less than 25×10-6.Considering the magnetic flux leakage and reluctance,the primitive permanent magnet structure was designed using the commonly used magnetic circuit methods and the magnetic field was numerically analyzed using finite element method.The distribution of magnetic field lines in air gap was investigated with the change of the shape and size of the shim ring,and the magnetic field homogeneity in the imaging area was influenced by the change of shim ring.The optimized shim-ring was obtained using the Ansys finite element software and the inhomogeneity of imaging region was improved when the inner diameter of the shim ring was about 1/3 of the outer.The results show that the magnetic circuit design method of permanent magnet and finite element method numerical calculation is reasonable to satisfy the imaging requirements.

关 键 词：永磁磁共振成像 磁路方法 有限元方法 均匀性 

分 类 号：TB9-55[一般工业技术—计量学]