MRI Gradient Coil Vibration Isolation Using Elastic Seals

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Solution Overview

Problem

Conventional magnetic resonance imaging (MRI) systems face limitations in silencing noise from vibrations of the gradient coil, as the hermetically-sealed container used to reduce air-borne noise does not effectively eliminate noise propagated through solids, and the gantry design can impede the feeling of openness for the subject.

Innovation Solution

The implementation of loop-shaped, hollow elastic members are placed between the magnetostatic field magnet and the gradient coil, and between the gradient coil and the bore tube, to create hermetically-sealed spaces that can be evacuated, reducing vibration propagation through both air and solids, and adjusting internal pressures to enhance sealing and flexibility.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Object-affected harmful factors

If a hermetically-sealed container is used to evacuate air around the gradient coil, then air-borne noise is reduced, but noise propagated through solids remains and the gantry length increases

Engineering Contradiction:

Improveair-borne noiseVSAvoidgantry length

Core Design Contradiction:

Object-affected harmful factorsVSLength of stationary object

Solution Approach 1:

The hermetically-sealed container is divided into multiple segments along the gradient coil axis, with each segment sealed by elastic members at its ends. This segmentation allows the container to be compressed axially, shortening the gantry length while maintaining the noise-reducing vacuum environment.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Elastic members are used as hermetic seals at the ends of each container segment. These flexible elastic members can be compressed axially along with the container, enabling the gantry to be shortened without compromising the hermetic seal or the vacuum environment needed for noise reduction.

Inventive Principle:

Principle #30Flexible shells and thin films

2Stability of the object's composition

If the gradient coil is fixed rigidly to reduce vibrations, then positioning stability is improved, but vibration noise is transmitted to the gantry structure

Engineering Contradiction:

Improvecoil positioning stabilityVSAvoidvibration noise transmission

Core Design Contradiction:

Stability of the object's compositionVSObject-generated harmful factors

Solution Approach 1:

A vibration isolation member is introduced as an intermediary between the gradient coil and the gantry structure. This intermediary component absorbs and dampens vibrations from the gradient coil, preventing them from being transmitted to the gantry structure while maintaining proper positioning stability.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The vibration isolation member provides beforehand cushioning by being pre-installed between the gradient coil and the gantry structure. This cushioning element is positioned in advance to absorb and attenuate vibrations before they can propagate to the gantry, reducing vibration noise transmission.

Inventive Principle:

Principle #11Beforehand cushioning (Prior cushioning)

3Reliability

If the hermetically-sealed container is made rigid to maintain sealing, then sealing reliability is improved, but flexibility for compression is reduced

Engineering Contradiction:

Improvesealing reliabilityVSAvoidcompression flexibility

Core Design Contradiction:

ReliabilityVSAdaptability or versatility

Solution Approach 1:

Inventive Principle:

Principle #30Flexible shells and thin films

Solution Approach 2:

The hermetically-sealed container is designed with flexible elastic members that allow dynamic compression along the axial direction. This dynamic design enables the container to be compressed for gantry shortening while maintaining the hermetic seal through the elastic deformation of the sealing members.

Inventive Principle:

Principle #15Dynamics

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 significantly improves the silencing capability by reducing noise propagation through solids and air, while shortening the gantry length to enhance the subject's feeling of openness during MRI procedures.

Implementation Method 1

an elastic member that is loop-shaped and hollow, is disposed in at least one selected from: a space between an inner circumferential side of the magnetostatic field magnet and an outer circumferential side of the gradient coil; and a space between an inner circumferential side of the gradient coil and an outer circumferential side of the bore tube, and thereby seals the space hermetically

Methodology Applied

Scientific EffectElasticity: Elasticity

Data Source

PatentUS9885767B2Magnetic resonance imaging apparatus

Publication Date: 2018.02.06 TOSHIBA MEDICAL SYST CORP

AI summary

A magnetic resonance imaging apparatus includes: a magnetostatic field magnet that is formed in the shape of a cylinder and generates a magnetostatic field in a space inside the cylinder; a gradient coil that is formed in the shape of a cylinder, is disposed in the cylinder of the magnetostatic field magnet, and applies a gradient magnetic field to the magnetostatic field; a bore tube that is formed in the shape of a cylinder and is disposed in the cylinder of the gradient coil; and an elastic member that is loop-shaped and hollow, is disposed in at least one selected from: a space between an inner circumferential side of the magnetostatic field magnet and an outer circumferential side of the gradient coil; and a space between an inner circumferential side of the gradient coil and an outer circumferential side of the bore tube, and thereby seals the space hermetically.