Magnetic Field Shielding Apparatus for MRI Cryostat Stray Field Management
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Solution Overview
Problem
MRI systems face operational instability due to stray fields from gradient coil assemblies causing eddy currents and temperature rises in superconducting coil assemblies, leading to flux jumps and volatilization of cooling media.
Innovation Solution
A magnetic field shielding apparatus is integrated into the cryostat, utilizing conductive shielding components and shielding cylinders to shield the superconducting coil assembly from stray fields, reducing eddy currents and maintaining a stable temperature.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If gradient coil assembly generates gradient magnetic field, then MRI imaging function is enabled, but stray field causes eddy current and temperature rise in superconducting coil assembly
Solution Approach 1:
A magnetic field shielding apparatus is introduced as an intermediary component between the gradient coil assembly and the superconducting coil assembly. The shielding apparatus includes a conductive shielding component and a shielding cylinder that intercept and redirect stray magnetic fields, preventing them from reaching the superconducting coil assembly and generating eddy currents, thus resolving the temperature rise issue while maintaining MRI imaging functionality
2Productivity
If gradient coil assembly operates, then gradient magnetic field is formed for imaging, but stray field causes flux jump and quench in superconducting coil assembly
Solution Approach 1:
The magnetic field shielding apparatus serves as a protective intermediary that filters and redirects stray magnetic fields before they can interact with the superconducting coil assembly. The conductive shielding component and shielding cylinder work together to create a magnetic field barrier, preventing flux jumps and quench events that would compromise the reliability of the superconducting coil assembly while allowing the gradient coil assembly to operate normally for imaging
3Device complexity
If no magnetic field shielding is provided, then device complexity is low, but eddy current causes cooling medium volatilization and operational instability
Solution Approach 1:
The magnetic field shielding apparatus is designed as a relatively simple structural addition to the MRI system. The conductive shielding component can be arranged on the cryostat, and the shielding cylinder is positioned around the superconducting coil assembly. This moderate increase in device complexity effectively prevents eddy currents and the associated cooling medium volatilization, ensuring operational stability with a manageable structural enhancement
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 eliminates eddy currents and temperature rises, ensuring the normal and stable operation of MRI systems by shielding the superconducting coil assembly from stray fields, thereby preventing flux jumps and volatilization of cooling media.
Implementation Method 1
A stray field generated by the gradient coil assembly may generate an eddy current on coils of the superconducting coil assembly
Implementation Method 2
The stray field of the gradient coil assembly may generate an eddy current on the coils of the superconducting coil assembly
Data Source
AI summary
The present disclosure relates to systems and methods for magnetic resonance imaging (MRI). The systems may include a gradient coil assembly configured to form a gradient magnetic field. The systems may also include a cryostat including a superconducting coil assembly and a magnetic field shielding apparatus arranged on/in a component of the cryostat. The superconducting coil assembly may be configured to form a main magnetic field. The magnetic field shielding apparatus may be configured to shield the superconducting coil assembly from a stray field of the gradient coil assembly. The magnetic field shielding apparatus may include a conductive shielding component, a shielding cylinder, or a combination thereof.