MRI Magnetic Field Adjustment Implement for Shield Room Uniformity
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Solution Overview
Problem
The challenge is to maintain the uniformity of the static magnetic field in MRI apparatuses, especially when a high magnetic field MRI with a superconducting magnet is placed in a shield room designed for older MRI systems with permanent magnets, leading to magnetic field leaks and non-uniformity due to the placement of iron shields.
Innovation Solution
A magnetic field adjustment implement, including a cancel coil and a placing unit, is positioned outside the magnet to improve the uniformity of the static magnetic field by canceling the influence of nearby metal objects and iron shields, allowing for effective magnetic field uniformity even in constrained spaces.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If a high magnetic field MRI apparatus with a superconducting magnet is placed in a shield room designed for older permanent magnet systems, then the magnetic field intensity is improved, but magnetic field uniformity deteriorates due to magnetic field leaks and the need for additional iron shields
Solution Approach 1:
A magnetic field adjustment implement is introduced as an intermediary device between the superconducting magnet and the shield room walls. This implement includes magnetic field adjustment units positioned at specific locations to counteract the non-uniform magnetic field caused by the shield room structure, thereby restoring field uniformity without reducing the high field intensity
Solution Approach 2:
The magnetic field adjustment units can be moved to different positions and orientations, and their magnetic properties can be adjusted to optimize the compensation effect. By changing the parameters of the adjustment implement (position, orientation, magnetic strength), the system adapts to the specific shield room geometry and achieves uniform field distribution
2Object-generated harmful factors
If iron shields are placed on the shield room wall to prevent magnetic field leaks, then magnetic field containment is improved, but magnetic field uniformity deteriorates due to turbulent field distribution
Solution Approach 1:
The iron shields that cause field non-uniformity are not removed, but their harmful effect is converted into a beneficial one. The magnetic field adjustment units are positioned to specifically counteract the field disturbances created by the iron shields, transforming the shields from a source of problems into an acceptable structural element that provides both containment and allows for field uniformity through active compensation
Solution Approach 2:
The magnetic field adjustment units act as intermediaries between the iron shields and the imaging space. They absorb and compensate for the field disturbances generated by the shields, allowing the shields to perform their containment function while maintaining field uniformity in the imaging region
3Area of stationary object
If the distance between the static magnetic field magnet and the shield room wall is reduced to fit in narrow spaces, then space utilization is improved, but magnetic field uniformity deteriorates due to increased influence from nearby metal structures
Solution Approach 1:
The magnetic field adjustment implement serves as a mediator that enables close positioning of the magnet to the shield room wall. By placing adjustment units in the gap between the magnet and the wall, the system compensates for the increased magnetic interaction with nearby metal structures, allowing space-efficient installation while maintaining field uniformity
Solution Approach 2:
The magnetic field adjustment units are strategically positioned at specific locations where field non-uniformity is most pronounced. Rather than uniformly adjusting the entire field, the system applies localized compensation at critical points, efficiently counteracting the adverse effects of close wall proximity
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 solution enhances the uniformity of the static magnetic field, reduces magnetic field leaks, and enables the placement of high magnetic field MRI systems in narrower shield rooms, improving image quality and operational efficiency.
Implementation Method 1
A magnetic field adjustment implement, including a cancel coil and a placing unit, is positioned outside the magnet to improve the uniformity of the static magnetic field by canceling the influence of nearby metal objects and iron shields
Implementation Method 2
In a recent MRI apparatus, a super conductive magnet is used as a static magnetic field magnet. Therefore, it is possible to form a high magnetic field more than or equal to 1.5 [T] (tesla) in an imaging space
Implementation Method 3
a thickness and the like of a piece of iron are adjusted so that isomagnetics of 5 [G] (gauss; 1 [G]=1×10−4 [T]) do not leak from a shield room when an MRI apparatus having a super conductive magnet is placed in the shield room
Data Source
AI summary
According to one embodiment, a magnetic field adjustment implement for a magnetic resonance imaging apparatus includes a magnetic field adjustment unit and a placing unit. The magnetic field adjustment unit is configured to improve a uniformity of a static magnetic field formed by a magnet of the magnetic resonance imaging apparatus. The static magnetic field is formed under an influence of a circumstance in a shield room in which the magnet is placed. The magnetic field adjustment is placed outside the magnet. The placing unit is configured to place the magnetic field adjustment unit outside the magnet.