MRI Bus-Bar Conductor Routing to Minimize Lorentz Force
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Solution Overview
Problem
In magnetic resonance imaging (MRI) systems, bus-bar conductors experience significant vibrations and electrical discharges due to the Lorentz force caused by the strong magnetic field, leading to mechanical shaking, acoustic noise, and white pixel artifacts in images.
Innovation Solution
The bus-bar conductors are designed to be disposed along paths that minimize the Lorentz force by being parallel to the magnetic field lines or extending to the fringe region of the magnetic field, reducing the impact of the magnetic field on the conductors and minimizing vibrations and electrical discharges.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the bus-bar conductors are extended closer to the magnet's iso-center for coupling to the gradient coil, then the coupling efficiency is improved, but the Lorentz force and vibrations increase
Solution Approach 1:
The bus-bar conductors are routed along the longitudinal axis of the magnet core (extending in the z-direction) rather than radially outward, changing the spatial dimension of conductor placement. This dimensional change allows the conductors to reach the gradient coils while minimizing exposure to the strong radial magnetic field components that generate Lorentz force.
Solution Approach 2:
The patent applies different routing strategies for different sections of the bus-bar conductors. The conductors are positioned to follow magnetic field lines in regions of strong magnetic field intensity, while extending linearly to fringe regions where field strength decreases, optimizing the local quality of magnetic field interaction along the conductor length.
2Productivity
If the bus-bar conductors are extended closer to the magnet's iso-center for coupling to the gradient coil, then the coupling efficiency is improved, but the acoustic noise and mechanical shaking increase
Solution Approach 1:
By routing conductors along the longitudinal axis rather than radially, the patent changes the spatial arrangement to reduce Lorentz force-induced vibrations, thereby minimizing acoustic noise generation while maintaining coupling efficiency.
Solution Approach 2:
The patent converts the potentially harmful effect of extended conductor length into a benefit by strategically routing conductors through regions where they experience minimal Lorentz force, transforming what could be a source of vibration and noise into an efficient current transmission path.
3Productivity
If the bus-bar conductors are extended closer to the magnet's iso-center for coupling to the gradient coil, then the coupling efficiency is improved, but the electrical discharge and image artifacts increase
Solution Approach 1:
The longitudinal routing of bus-bar conductors along the magnet core axis reduces intermittent contacts between filaments and joints by eliminating sharp bends and stress points, thereby preventing electrical discharges that would cause image artifacts.
Solution Approach 2:
The patent optimizes the local geometry of conductor joints and connections by positioning them in regions of minimal magnetic field stress, ensuring reliable electrical contact and preventing the metal-to-metal intermittent contacts that generate electrical discharge and white pixel artifacts.
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 configuration reduces vibrations and acoustic noise, minimizes electrical discharges, and improves image quality by reducing white pixel artifacts, resulting in a more stable and effective MRI system operation.
Implementation Method 1
The parts of the bus-bar conductors proximate to the magnet core are subjected to a strong Lorentz force due to the magnetic field.
Data Source
AI summary
A magnetic resonance imaging system is disclosed. The magnetic resonance imaging system includes a magnet core that generates a magnetic field including a plurality of magnetic field lines. The magnetic resonance imaging system also includes a plurality of gradient coils disposed along the magnet core and a plurality of gradient amplifiers. Further, the magnetic resonance imaging system includes a plurality of bus-bar conductors coupling a corresponding gradient coil of the plurality of gradient coils and a corresponding gradient amplifier of the plurality of gradient amplifiers. The plurality of bus-bar conductors is disposed along at least one of a first path extending along the plurality of magnetic field lines and a second path extending along a substantially linear direction from the corresponding gradient coil to a fringe region of the magnetic field to reduce an effect of Lorentz force on the plurality of bus-bar conductors.