JPH02277439A - magnetic resonance imaging device - Google Patents

Abstract

PURPOSE:To decrease vibrational energy generated in a coil and to obtain an MRI with little noises by integrating a bobbin and an inclined magnetic field coil in a body through a viscoelastic body between them. CONSTITUTION:An outer peripheral face of a bobbin 17 is applied with an adhesive 19 and a place on the face of the adhesive 19 where an X coil 14 is positioned is adhered with a rubber 18. The X coil 14 is positioned on this rubber 18 as a base through an adhesive 19. Furthermore, the surroundings of the rubber 18 and the X coil 14 are coated with the adhesive 19 and a rubber 18 is adhered covering the surroundings of the X coil 14 and a bobbin 17. In addition, a rubber 18 is adhered on the whole face of the inner periphery of the bobbin 17 through an adhesive material 19. In addition, another X-coil, a Y-coil and a Z-coil are positioned on rubbers similarly constituted as bases. As the coils are fixed through rubbers like this, vibrations of the coils are absorbed as frictional energies in the rubbers.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a magnetic resonance imaging apparatus (hereinafter referred to as MRI), and particularly to a portion of a gradient magnetic field coil that provides position information to nuclear magnetic resonance signals.

[Conventional technology]

Gradient magnetic field coils that provide positional information to nuclear magnetic resonance signals (hereinafter referred to as NMR signals) used to form images are extremely large because they are configured to accommodate a lying patient. .

Specifically, the outer periphery of a cylindrical non-conductive pipe that accommodates a patient is placed in the x and y directions, respectively, with its central axis in the Z direction.
, a gradient magnetic field coil for generating gradient magnetic fields in the z direction is fixed to a rigid body such as a metal screw.

[Problem to be solved by the invention]

However, in conventional MRI, the main focus is on fixing the coil with a rigid body, and no consideration is given to absorbing the vibrational energy generated in the coil, and it is only possible to contain the vibration. there were.

For this reason, the psychological anxiety for patients was greatly favorable.

Therefore, an object of the present invention is to reduce the vibration energy generated in the coil and provide an MHI with less noise.

[Means to solve the problem]

In order to achieve such an object, the present invention provides a magnetic resonance imaging apparatus equipped with a magnetic field generating device formed by winding a gradient magnetic field coil around a bobbin that accommodates a patient, in which a magnetic field generator is provided with a These are integrated through a viscoelastic material.

Further, the present invention provides a magnetic resonance imaging apparatus including a magnetic field generating device formed by winding a gradient magnetic field coil around a bobbin for storing a patient, wherein the bobbin is made of a viscoelastic material. laminated in the radial direction through
It was created as a unified whole.

Furthermore, the present invention provides a magnetic resonance imaging apparatus including a magnetic field generating device formed by winding a gradient magnetic field coil around a bobbin that accommodates a patient, in which a viscoelastic body is interposed between the bobbin and the gradient magnetic field coil. The bobbin is made by stacking a plurality of bobbins having the same central axis in the radial direction and integrating them.

, [Function] In the MHI configured as described above, noise is generated from the gradient magnetic field coil, but in the path from the noise source to the bobbin, that is, the patient storage area, between the gradient magnetic field coil and the bobbin, or There is a viscoelastic body interposed within the bobbin, and noise as vibration energy is absorbed by this viscoelastic body.

Therefore, the vibration energy generated in the coil is reduced,
MRI with less noise can be obtained.

〔Example〕

An embodiment of the MHI according to the present invention will be described below with reference to the drawings.

FIG. 2 is a block diagram showing this embodiment.

A subject 3 is placed in a static magnetic field space 2 generated by a magnet 1, and a transmitter 4 for generating a high-frequency magnetic field to cause a nuclear magnetic resonance phenomenon and an irradiation coil 5 driven by the transmitter 4 are inspected. Place it near person 3.

A gradient magnetic field power supply 6 for applying a gradient magnetic field, and independently in three mutually orthogonal axes directions driven by the gradient magnetic field power supply 6,
The subject 3 has a gradient magnetic field coil 7 that generates a gradient magnetic field.
The transmitter 4 has a receiving coil 8 and a receiver 9 for detecting a resonance signal generated by the transmitter 4. Gradient magnetic field power supply6.
A processing device 11 has a sequence control unit 10 that controls the operation contents and timing of the receiver 9, and performs digitization of the signal from the receiver 9, image reconstruction processing, etc.
The image is displayed on the CRT display 12.

The subject 4 is placed on the bed 13 and placed within the magnetic field space 2 .

In the gradient magnetic field coil 7, the arrangement of the coils forming gradient magnetic fields in the x, y, and z directions is shown in FIGS. 3(a) and 3(b).
). FIG. 3(a) is a side view, and FIG. 3(b) is a view viewed from the axial direction.Z coils 16, 16', .15' is wound. Each Z coil 16.16
' are wound along the circumferential direction of the bobbin 17, respectively. Each of the X coils 14, 14' has a rectangular shape and is brought into contact with the left and right sides of the bobbin 17 at a wide angle of 120 degrees. Furthermore, each Y
The coils 15 and 15' have a rectangular shape and are brought into contact with the upper and lower surfaces of the bobbin at a wide angle of 120°.

Here, the X coils 14 and 14' are connected to each other so that current flows in the same direction and magnetic fields are generated in the same direction. Also, Y coil 15.15'
The same is true for the X coils 16 and 16'.

FIG. 1 is a sectional view showing a structure in which the X coil 14 contacts the bobbin 17. In the figure, an adhesive 19 is applied to the outer peripheral surface of the bobbin 17, and the
Rubber 18 is bonded to the location where the coil 14 is to be placed, and the X coil 14 is placed on this rubber 18 with an adhesive 19 interposed therebetween.

Further, an adhesive 19 is applied around the rubber 18 and the X coil 14, and the rubber 18 is applied to the X coil 14. Rubber 18 is attached to cover the bobbin 17.

Further, rubber 18 is also adhered to the entire inner circumference of the bobbin 17 via an adhesive 19.

Although FIG. 1 shows only the X coil 14, other X coils 14', Y coils 15, 15',
The X coils 16, 16' are similarly constructed and placed on the rubber 18 as a base.

In this way, by fixing the coil through rubber, the vibration of the coil becomes frictional energy within the rubber.
Absorbed.

In order to suppress the vibration of the coil and rapidly absorb frictional energy, a heavy rubber is desirable, and since the absorbed energy is released as heat, a rubber with good thermal conductivity is desirable.

This purpose can be achieved by mixing alumina oxide powder or the like into a heavy rubber with good thermal conductivity.

Also, coils 14.14', 15.15', 16°1
The three sides of the bobbin 17 that are not in contact with the bobbin 17 are also covered with the rubber 18, and the inside and outside of the bobbin 17 are also covered with the rubber 18, thereby making it possible to absorb vibrations and noise caused by the vibrations.

In the embodiment described above, the rubber 18 is interposed between the bobbin 17 and the X coil 14, but it goes without saying that any material so-called viscoelastic material may be used. For example, VEM material (manufactured by 3M Corporation) or Isodump NaC-1002 material (manufactured by EAR (USA)) is also suitable.

4(a) and 4(b) are configuration diagrams showing other embodiments of the present invention, and FIG. 4(a) is a cross-sectional view in the axial direction of the bobbin 17 (coils are omitted); Figure (b) is a diagram of the bobbin 17 viewed from the axial direction. Figures (a) and (b)
The bobbin 17 is made of, for example, glass fiber reinforced plastic (hereinafter referred to as GFRP), and has a double structure with the same central axis. The GFRP 22 located on the outside and the GFRP 23 located on the inside are bonded to each other with a viscoelastic body 25 made of the above-mentioned material interposed on their respective abutting surfaces to form a so-called laminated constraint vibration damping structure.

In the bobbin 17 configured in this way, the vibration energy conducted from the coil is reduced by the same sound reduction mechanism as described above in the bobbin 17 having a laminated constraint vibration damping structure. In addition, in such a laminated restraint type controlled vibration structure, the vibration damping time is significantly shortened (1/10 to 1710
Therefore, not only is the noise level significantly reduced (-20 to -30 phon), but also the synergistic effect is achieved by shortening the time for noise generation due to each pulsed impact of each gradient magnetic field. The noise level will be reduced accordingly.

Although FIGS. 4(a) and 4(b) show a two-layer bobbin structure, it goes without saying that a three-layer bobbin structure as shown in FIG. 5 will be even more effective.

In each of the above-mentioned examples, it is effective to use a heavy viscoelastic material, and it goes without saying that a metal oxide such as alumina oxide or an inorganic material may be mixed therein. do not have.

Further, the present invention has an embodiment shown in FIG. 1 and FIG.
) It goes without saying that it will be extremely effective if the embodiment shown in (b) is used simultaneously.

〔Effect of the invention〕

As is clear from the above explanation, in the MRI configured in this way, noise is generated from the gradient magnetic field coils.
In the path from this noise source to the bobbin, that is, the patient storage area, there is a viscoelastic body interposed between the gradient magnetic field coil and the bobbin or within the bobbin, and this viscoelastic body Noise as vibration energy will be absorbed.

Therefore, the vibration energy generated in the coil is reduced,
MHI with less noise can be obtained.

[Brief explanation of drawings]

Fig. 1 is a block diagram showing an embodiment of the MRI according to the present invention, showing the gradient magnetic field coil portion, Fig. 2 is a schematic block diagram of the MRI according to the present invention, and Figs. FIG. 4(a)<b) is a block diagram showing the winding mode of the gradient magnetic field coil of the MHI according to the invention. FIG. This is another embodiment of the bobbin. 7...Gradient magnetic field coil, 14...X coil, 17.
...Bobbin, 18...Rubber, 19...Adhesive.

Claims (1)

[Claims] 1. In a magnetic resonance imaging apparatus equipped with a magnetic field generating device formed by winding a gradient magnetic field coil around a bobbin that accommodates a patient, a viscoelastic body is interposed between the bobbin and the gradient magnetic field coil. A magnetic resonance imaging apparatus is characterized in that these are integrated. 2. A magnetic resonance imaging apparatus according to claim 1, wherein the gradient magnetic field coil is covered with a viscoelastic body. 3. In a magnetic resonance imaging apparatus equipped with a magnetic field generating device formed by winding a gradient magnetic field coil around a bobbin that accommodates a patient, the bobbin connects a plurality of bobbins having the same central axis in a radial direction via a viscoelastic body. A magnetic resonance imaging device characterized in that it is integrated by laminating two layers. 4. In a magnetic resonance imaging apparatus equipped with a magnetic field generating device formed by winding a gradient magnetic field coil around a bobbin that accommodates a patient, the bobbin and the gradient magnetic field coil are integrated with each other via a viscoelastic body. The magnetic resonance imaging apparatus is characterized in that the bobbin is a plurality of bobbins having the same central axis, stacked in the radial direction and integrated. 5. The magnetic resonance imaging apparatus according to claim 4, wherein the entire inner wall of the bobbin is coated with a viscoelastic material. 6. The magnetic resonance imaging apparatus according to any one of claims 1 to 5, characterized in that the viscoelastic body is made of heavy rubber. 7.Claim 6, wherein a metal oxide is mixed into a viscoelastic body.
The magnetic resonance imaging device described. 8. The magnetic resonance imaging apparatus according to claim 6, wherein aluminum oxide is mixed in the viscoelastic body. 9. The magnetic resonance imaging apparatus according to claim 6, wherein an inorganic substance is mixed into the viscoelastic body.