基于梯度电感约束和图形处理单元加速算法的磁共振双平面自屏蔽梯度线圈设计方法

Designing method of magnetic resonance biplane self-shielding gradient coil based on gradient inductance constraint and graphic processing unit acceleration algorithm

目的针对MRI梯度线圈自感和互感引起涡流抑制梯度磁场快速变化、影响梯度切换率及成像时间问题,提出一种有效解决方案。方法采用梯度电感最小化和梯度磁场自屏蔽等约束条件,结合目标场点法建立数学模型,求解双平面梯度线圈的绕线分布,以减小梯度线圈的磁场能量,降低涡流等对梯度线圈性能的影响。为缩短数值计算软件对以上复杂数学模型矩阵求解的运算时间,采用图形处理单元(GPU)加速算法实现梯度线圈的设计计算。结果采用最小化梯度电感能有效降低涡流影响,实现磁场自屏蔽,具有良好的梯度切换率,可改善梯度线圈整体性能。结论采用双平面梯度线圈新型目标场点法算法能实现梯度电感最小化和梯度磁场自屏蔽梯度线圈设计。

Objective To purpose an effective solution of reducing MRI time when rapid change and gradient switching rate of gradient magnetic field are restrained by eddy current caused by self induction and mutual inductance of gradient coil in MR system.Methods With the constraints of gradient inductance minimization and gradient magnetic field self-shielding,a mathematical model was established by combining the target field point method to solve the winding distribution of the double-plane gradient coil,so as to reduce the magnetic field energy of the gradient coil and the eddy current on the performance of the gradient coil.At the same time,in order to shorten the operation time of solving the above complex mathematical model matrix by MATLAB software,graphic processing unit(GPU)acceleration algorithm was used to realize the calculation of gradient coil.Results By minimizing gradient inductance,eddy current effect could be effectively reduced,the magnetic field self-shielding could be realized,the gradient switching rate was good,and the overall performance of the gradient coil could be improved.Conclusion The new target field point method for biplane gradient coil is effective and feasible,which can realize minimization of gradient inductance and designing self-shielding gradient coil of gradient magnetic field.