Training Center for Engineering Practices, Northwestern Polytechnical University, Xi'an, Shaanxi, China.
Dongguan Sanhang Civil-military Integration Innovation Institute, Dongguan, Guangdong, China.
Technol Health Care. 2022;30(S1):315-328. doi: 10.3233/THC-THC228030.
High installation and operating cost have limited applications for many circumstances. In practice, primary and shielding coils cannot insert into the magnet pole simultaneously owing to deficient workspace for the planar permanent MRI systemsOBJECTIVE: To minimize eddy currents induced in the resist-eddy current plates and pole piece when the gradient coil current switches on and off rapidly.
A theoretical framework that have minimum power dispassion and magnetic energy with eddy plate is proposed for a planar gradient coil. The mirror image of the magnetostatic model is substituted into the stream function for designing a minimum power dispassion planar gradient coil. A finite-difference is used to formulate the coil distribution that makes magnetic field similar to the required magnetic field for gradient coil design.
A coil designed with actively shielded was simulated and compared with the designed gradient coils using mirror image theory and piece pole effect. According to the numerical evaluation of the x and z coils, the operating currents in the cases were reduced to 34.4% using magnetostatic mirror-image method to replay the active shielding. Moreover, there was a significant improvement on the shielding effect when added to resistive eddy current plate.
Using the magnetostatic mirror image theory and mirror-image model, the current density function that could not only gives the minimum power dissipation and magnetic energy with the presence of the eddy plate and pole piece effect, but also provides excellent coil performance compared with active shielding solution.
高安装和运营成本限制了许多情况下的应用。在实践中，由于平面永磁 MRI 系统的工作空间不足，初级和屏蔽线圈不能同时插入磁极。
当梯度线圈电流快速开关时，最小化在抗涡流板和磁极中感应的涡流。
为平面梯度线圈提出了一种具有最小功率损耗和磁能的涡流板理论框架。将静磁场模型的镜像代入流函数中，设计最小功率损耗的平面梯度线圈。使用有限差分来制定与梯度线圈设计所需磁场相似的线圈分布。
对带有主动屏蔽的线圈进行了模拟，并与使用镜像理论和片极效应设计的梯度线圈进行了比较。根据对 x 和 z 线圈的数值评估，使用静磁场镜像法重新生成主动屏蔽，将操作电流降低到 34.4%。此外，在添加电阻涡流板时，屏蔽效果有显著提高。
使用静磁场镜像理论和镜像模型，可以得到不仅在存在涡流板和磁极效应时具有最小功率损耗和磁能的电流密度函数，而且与主动屏蔽解决方案相比，还提供了出色的线圈性能。
