【摘要】 目的:研究永磁微型核磁共振成像系统双平面梯度线圈产生梯度磁场的最大线性偏离与电流密度函数展开阶数、线圈的最大半径、双平面线圈间距及目标场点数等参数的关系。方法:根据改进的目标场法,利用Matlab仿真设计双平面梯度线圈,然后利用控制变量法,分别模拟计算出各个参数在不同取值情况下梯度磁场的最大线性偏离值,最后对得到的数据进行分析。结果:利用上述方法,获得了最大线性偏离值随着横、纵向梯度线圈中各个参数的改变而分别产生不同程度的变化。结论:通过对以上参数的合理取值可以获得满足梯度线性度和制造工艺的梯度线圈。另外,此研究也可推广到永磁MRI系统双平面匀场线圈。更多还原

【Abstract】 Objective To investigate the relationships between the maximum linear deviation(MLD) of gradient magnetic field at the design of biplanar gradient coils for mini-type permanent magnetic resonance imaging system and several parameters of coils, including the order of the current density expansion, the maximal radius of the coils, the gap between the biplanar coils and the number of the target field points. Methods According to the improved target field method, the biplanar gradient coils are designed by Matlab simulation. Then the MLD under different values of each parameter was calculated by control variable method, and the data were analyzed. Results Using the above-mentioned methods, the relationships between MLD and various parameters in transverse and longitudinal gradient coils were obtained. Conclusion The reasonable values of parameters can make the designed gradient coils meet the requirements for gradient linearity and manufacturing technique. This study can also be extended to the biplanar shimming coils on permanent magnetic resonance imaging system.更多还原