MRI Gradient Coil Shim Tokens for Bore Space
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Solution Overview
Problem
The existing MRI apparatuses require a large number of shims to achieve uniformity in the static magnetic field, which increases the thickness of the gradient coil assembly, reducing the inner space of the MRI scanner bore.
Innovation Solution
Incorporating shim tokens between shim trays and cooling portions within the gradient coil assembly, allowing for targeted placement and optimization of shim tokens to improve magnetic field uniformity, thereby reducing the number of shims needed and maintaining or increasing the inner bore diameter.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a great number of shims is provided to increase the uniformity of the static magnetic field, then the uniformity of the magnetic field is improved, but the thickness of the gradient coil assembly increases
Solution Approach 1:
The patent introduces shim tokens that can be positioned in multiple spatial dimensions (radial, tangential, and axial positions) rather than simply increasing the number of shims in a single dimension. This allows precise magnetic field uniformity adjustment through multi-dimensional positioning of fewer shim tokens, thereby reducing the overall thickness of the gradient coil assembly while maintaining field uniformity.
Solution Approach 2:
The shim tokens are designed with different local properties (different positions, orientations, and configurations) to address specific local magnetic field non-uniformities. Each shim token can be independently positioned at optimal locations within the gradient coil assembly to correct local field variations, achieving overall field uniformity with fewer components rather than using many uniform shims throughout.
2Manufacturing precision
If a great number of shims is provided to increase the uniformity of the static magnetic field, then the uniformity of the magnetic field is improved, but the inner space of the bore is reduced
Solution Approach 1:
By utilizing multi-dimensional positioning of shim tokens (radial, tangential, axial coordinates) rather than increasing shim quantity in a single dimension, the patent achieves magnetic field uniformity correction with fewer components. This reduces the space occupied by the gradient coil assembly, thereby preserving more inner bore space for patient positioning.
Solution Approach 2:
The patent changes the parameters of the shim tokens (position, orientation, configuration) rather than simply increasing their number. By optimizing these parameters, the magnetic field uniformity is improved while minimizing the space required for the gradient coil assembly, thus maintaining a larger bore inner diameter.
3Manufacturing precision
If the thickness of the gradient coil assembly is increased to accommodate more shims, then the uniformity of the magnetic field is improved, but the inner diameter of the bore is reduced
Solution Approach 1:
The patent employs multi-dimensional positioning of shim tokens within the gradient coil assembly to achieve magnetic field uniformity correction without increasing the assembly's outer dimensions. By distributing shim tokens strategically in multiple spatial dimensions, the inner bore diameter is preserved while still achieving the required field uniformity.
Solution Approach 2:
Instead of increasing the number of shims which would require a thicker gradient coil assembly, the patent optimizes the parameters (position, orientation, configuration) of a smaller number of shim tokens. This approach maintains the gradient coil assembly thickness and preserves the bore inner diameter while achieving magnetic field uniformity.
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
This approach enhances the uniformity of the static magnetic field while minimizing the thickness of the gradient coil assembly, preserving or expanding the inner space of the MRI scanner bore, and reduces the number of shims required, facilitating easier replacement and maintenance.
Implementation Method 1
a main magnet forming a static magnetic field in a bore
Implementation Method 2
a gradient coil assembly which forms a magnetic field gradient in the static magnetic field
Implementation Method 3
the first shim token is provided between shim trays in a gradient coil assembly so that a distribution of the static magnetic field is uniform
Data Source
AI summary
The MRI apparatus includes a main magnet forming a static magnetic field in a bore, and a gradient coil assembly which forms a magnetic field gradient in the static magnetic field and includes a plurality of shim trays arranged therein at a predefined interval and at least one first shim token provided between the shim trays.