A design method of a flat shim coil
A technology of shim coils and design methods, which is applied in magnetic resonance measurement and other directions, can solve problems such as inhomogeneity of the main magnetic field, and achieve the effect of improving uniformity and eliminating inhomogeneous magnetic field components
Active Publication Date: 2021-09-03
INNOVATION ACAD FOR PRECISION MEASUREMENT SCI & TECH CAS
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[0004] In order to solve the problem of the inhomogeneity of the main magnetic field of the flat magnet system (such as: permanent magnet, conventional electromagnet, superconducting magnet, etc.), the patent of the present invention proposes a design method of a flat shim coil for magnetic resonance imaging. The shimming coil designed by this method can eliminate the inhomogeneous magnetic field components of each order of the main magnetic field of the flat-plate MRI magnet system, and improve the uniformity of the main magnetic field (such as figure 1 shown)
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[0039] In order to facilitate those of ordinary skill in the art to understand and implement the present invention, the present invention will be described in further detail below in conjunction with the examples. It should be understood that the implementation examples described here are only used to illustrate and explain the present invention, and are not intended to limit the present invention.
[0040] The invention will be used to offset Correlated inhomogeneity components of the coil and are used to cancel The plate shim coil groups of related inhomogeneous components are respectively defined as the first plate shim coil group and the second plate shim coil group, and the two groups of the first plate shim coil group and the second plate shim coil group 2 A design method of a planar shim coil for magnetic resonance imaging is introduced by using a flat plate shim coil as a design example. Both the first planar shim coil group and the second planar shim coil group can...
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The invention discloses a design method of a flat-plate type shim coil. Firstly, grid division is performed on the coil plane; target points are selected on the target spherical surface; current density flow functions of grid nodes and finite grid node current density are established. Differential relationship; set the magnetic field strength of the target point; establish a system of equations between the current density flow function of the grid node and the axis direction component of the magnetic field strength of the target point; construct a combined constraint function of power consumption and local uniform distribution, obtain the constraint matrix, and use Tikhonov regularization The specific value of the current density flow function of the grid node is solved by the method of transformation; according to the equipotential line of the distribution of the current density flow function of the grid node on the corresponding coil circular plane, the winding mode of the shim coil is obtained by arranging the equipotential value . The invention can effectively eliminate the inhomogeneous magnetic field components of each order of the main magnetic field introduced by the flat-plate magnet system due to manufacturing errors, thereby improving the uniformity of the main magnetic field of the flat-plate magnet system.
Description
technical field [0001] The invention relates to a design method of a planar shim coil applied to a planar magnet. Background technique [0002] According to different working principles and application fields, magnetic resonance instrument systems can be divided into nuclear magnetic resonance (NMR) instruments, magnetic resonance imaging (MRI) instruments, and electron paramagnetic resonance (EPR) instruments. Magnets are the most important components of magnetic resonance instrument systems. One of the components of the magnetic resonance instrument, the performance of the magnetic resonance instrument depends largely on the main magnetic field B of the magnet 0 The higher the uniformity of the main magnetic field of the magnet, the higher the signal-to-noise ratio and resolution of the NMR signal obtained by the NMR instrument, and the higher the quality of the MRI image obtained by the MRI instrument. [0003] Ideally, the main magnetic field strength of the MRI equipme...
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IPC IPC(8): G01R33/34
CPCG01R33/34
Inventor 陈方樊萌刘朝阳张志冯继文陈俊飞陈黎程鑫鲍庆嘉汪慧娟王佳鑫杨李泽
Owner INNOVATION ACAD FOR PRECISION MEASUREMENT SCI & TECH CAS