MRI Gradient Coil Series Shielding for Eddy Current Reduction
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Solution Overview
Problem
Current gradient coils in MRI apparatuses fail to effectively suppress eddy currents caused by leakage of edge magnetic fields at the axial ends, which degrades imaging quality and increases noise.
Innovation Solution
A gradient coil design comprising a main coil layer and a shielding coil layer, where X and Y end shielding coil sets are connected in series with the respective main coil sets and disposed outside the imaging region to form opposing magnetic fields, reducing edge magnetic fields and thus eddy currents.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If end shielding coil sets are added to block edge magnetic fields, then image quality is improved and noise is reduced, but device complexity increases
Solution Approach 1:
The end shielding coil sets are connected in series with their corresponding main coil sets, merging the shielding function into the existing gradient coil structure. This series connection integrates multiple functions (gradient field generation and edge field suppression) into a unified system, reducing the number of independent power supplies and control circuits needed.
Solution Approach 2:
The gradient coil system is designed with multi-functionality: the same coil structures serve both as gradient field generators and as shielding elements. The end shielding coil sets, when connected in series with the main coil sets, simultaneously contribute to gradient field formation and edge magnetic field suppression, maximizing the utility of each component.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution effectively blocks edge magnetic fields, improving image quality and reducing noise by minimizing eddy current generation in peripheral ferromagnetic structures.
Implementation Method 1
The X end shielding coil set is connected in series with the X main coil set and used to form a shielding magnetic field in the opposite direction to the X direction. The Y end shielding coil set is connected in series with the Y main coil set, and used to form a shielding magnetic field in the opposite direction to the Y direction.
Implementation Method 2
In the process of the gradient field being switched on and off, eddy currents will be generated in the metal interior of metal components in the MRI apparatus, affecting the imaging quality. The gradient coil can block edge magnetic fields at the two axial sides of the main coil layer to reduce the generation of eddy currents in peripheral ferromagnetic structures.
Data Source
AI summary
A gradient coil for an MRI apparatus is disclosed, comprising a main coil layer and a shielding coil layer. The shielding coil layer is arranged around the main coil layer, which includes an X, Y, and Z main coil set, and an X and Y end shielding coil set. The X end shielding coil set is connected in series with the X main coil set and used to form a shielding magnetic field in a direction opposite to the X direction. The Y end shielding coil set is connected in series with the Y main coil set and used to form a shielding magnetic field in the opposite direction to the Y direction. In the Z direction, the X end shielding coil set and Y end shielding coil set are disposed outside an imaging region enclosed by the main coil layer.