超椭圆柱面梯度线圈设计

发布时间：2018-07-03 12:22

本文选题：梯度线圈 + 流函数　；参考：《物理学报》2014年23期

【摘要】：超椭圆柱设计表面能够减小线圈与目标的距离,提高空间利用率,扩大成像区域的有效范围.提出利用流函数法及柱面的可展性在超椭圆柱面上设计核磁共振成像系统中的梯度线圈.根据Biot-Savart定律建立磁场强度与流函数的表达式,采用最小二乘法和Tikhonov正则化方法构造了双目标设计函数.利用柱面的可展性提高了基于分片离散流函数计算电磁场的数值精度,通过L-曲线方法实现了正则参数的合理选取.通过引入适当的流函数边界约束条件,把梯度线圈的优化问题转化为适定线性方程组的直接求解问题.通过数值算例验证了超椭圆柱面展开求解方法的正确性.优化结果显示,在满足线性度误差小于5%的设计约束下,该方法在设计超椭圆柱面线圈驱动电流分布的同时有效控制了梯度线圈的能耗.
[Abstract]:The design surface of the hyperelliptic column can reduce the distance between the coil and the target, improve the space utilization ratio and expand the effective range of the imaging area. The gradient coils in nuclear magnetic resonance imaging system are designed on hyperelliptic cylinders by using the current function method and the developability of cylinders. Based on Biot-Savart 's law, the expression of magnetic field intensity and current function is established, and the two-objective design function is constructed by using least square method and Tikhonov regularization method. The numerical accuracy of electromagnetic field calculation based on piecewise discrete flow function is improved by using the developability of cylinder, and the reasonable selection of regular parameters is realized by the L- curve method. By introducing appropriate boundary constraints of flow function, the optimization problem of gradient coils is transformed into a direct solution of linear equations. A numerical example is given to verify the correctness of the hyperelliptic cylindrical expansion method. The optimization results show that this method can effectively control the energy consumption of gradient coils while designing the driving current distribution of hyperelliptic cylindrical coils under the design constraint of less than 5% linearity error.
【作者单位】：中国科学院长春光学精密机械与物理研究所;中国科学院大学;弗莱堡大学医学院放射与医学物理系;
【基金】：国家自然科学基金(批准号:51275504) 吉林省科技发展计划(批准号:20140519007JH) 欧盟研究署‘RANGEMRI’启动项目(批准号:282345)资助的课题~~
【分类号】：TM55

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