JPH0736644Y2 - Gradient magnetic field coil for MRI apparatus - Google Patents

Description

[Detailed description of the device] [Industrial applications]

The present invention relates to an MRI apparatus used for medical diagnosis, and particularly to improvement of a gradient magnetic field coil thereof.

[Prior art]

The MRI apparatus includes a main magnetic field coil that generates a uniform static magnetic field and a gradient magnetic field coil that generates a gradient magnetic field that is superimposed on the static magnetic field. This gradient magnetic field coil requires three types in order to generate gradient magnetic fields Gx, Gy, Gz having gradients in the respective directions of three orthogonal axes (x, y, z directions). Conventionally, these three types of gradient magnetic field coils (Gx coil, Gy coil, Gz coil) are generally wound around a cylindrical bobbin made of GFRP (glass fiber reinforced plastic) or phenol with a rectangular copper wire for electrical use. Is manufactured. That is, for example, as shown in FIG.
The Gx coil 2 is formed on the upper side, and the Gy coil 3 is further formed on it. At the time of fixing the coil, a measure to reduce the noise of the gradient magnetic field coil by interposing the cushioning material 6 made of a vibration-proof rubber or the like between the bobbin 1 and the Gx coil 2 and between the Gx coil 2 and the Gy coil 3. I am trying. That is, the gradient magnetic field can be switched at high speed, and when the current is applied to or cut off from the coils 2, 3 etc. within a strong main magnetic field (generally 0.2 to 2 terraces), the coil 2,
Since a strong radial force is applied to 3 and the like to generate noise, the cushioning material 6 is inserted to reduce the noise.

[Problems to be solved by the device]

However, the conventional structure has a problem that a satisfactory result cannot be obtained in terms of noise prevention. That is, bobbin 1
When manufacturing and assembling the coils 2, 3 and the like, shape errors of the cylindrical bobbin 1, shape errors of the coils 2, 3, etc., thickness errors of the cushioning material 6, and assembly errors are unavoidable. As shown in Fig. 4, a slight gap 8
Cannot occur. Therefore, due to a large force applied to the coils 2 and 3 at the time of switching the current flowing through the gradient magnetic field coil, the coils 2 and 3 and the like are deformed / moved in the gap 8 and collision between the coils 2 and 3 or the bobbin 1 occurs. , Noise is generated. It is an object of the present invention to provide a gradient magnetic field coil for an MRI apparatus that has a simple structure and can sufficiently suppress noise.

[Means for Solving the Problems]

To achieve the above object, in the gradient magnetic field coil of the MRI apparatus according to the present invention, when forming the coil on the bobbin, a heating foam material is interposed between the bobbin and the coil and the heating foaming. The material is heated to foam and harden.

[Action]

When forming the coil on the bobbin, a heating foam material is interposed between the bobbin and the coil and between the coils, and the heating foam material is heated to foam and harden. After the curing, no gap is formed between the bobbin and the coil and between the coil and the coil, and the bobbin and the coil are firmly fixed by being bonded to the heating foam material. By thus fixing the coil with the heated foam material without any gap, the coil does not move even if a force is applied when the current is applied to or cut off from the coil. Therefore, it is possible to prevent the coil from colliding with the bobbin when the power supply to the coil is turned on and off, and to prevent the coil from colliding with each other, and it is possible to effectively suppress the generation of noise, and to prevent the noise of the subject. The burden can be reduced.

【Example】

Next, an embodiment of the present invention will be described with reference to the drawings. As shown in FIG. 1, four saddle-shaped Gx coils 2 are first formed on the surface of a cylindrical bobbin 1 made of GFRP (or phenol), for example. On top of that, also 4
One saddle-shaped Gy coil 3 is formed, and two solenoid-shaped Gz coils 4 are mounted on the saddle-shaped coil 3. The plurality of fixing members 5 are these coils 2,
This is for firmly fixing 3, 4 to the bobbin 1.
The upper side of FIG. 1 is in a state in which the Gy coil 3, the Gz coil 4 and the like are removed, and only the Gx coil 2 is visible. Gx coil 2 and Gy coil 3 look like a ladder in the figure. Between these bobbin 1 and Gx coil 2, and between Gx coil 2
Between the Gy coil 3 and the heating foam material 9 as shown in FIG.
Is intervened. A space 7 is provided between the Gy coil 3 and the Gz coil 4. That is, the Gz coil 4 is fixed so that the space 7 is maintained by the fixing material 5. The heat-foamable material 9 is a resin such as foamed polyethylene that foams when heated and increases in volume and then hardens. A gap may be formed during assembly as shown in FIG.
After assembly, the heated foam material 9 expands by heating and enters between the bobbin 1 and the coil 2 and between the coil 2 and the coil 3 without any gap as shown in FIG. Will be done. In the above embodiment, the cushioning material 6 may be used together even when the heated foam material 9 is used, and in the above, between the bobbin 1 and the coil 2 and between the coil 2 and the coil 3. Although the heating foam material 9 is interposed, the heating foam material 9 may be interposed between the bobbin 1 and the fixing material 5, between the coils 2, 3, 4 and the fixing material 5, and the like. Needless to say.

[Effect of device]

According to the gradient magnetic field coil of the MRI apparatus of the present invention, when forming a coil on the bobbin, a heating foam material is interposed between the bobbin and the coil, and the heating foam material is heated to foam. After heating, foaming and curing, there is no gap between the bobbin and the coil and between the coil and the coil because it is cured.
Since the bobbin and coil are bonded to the heated foam material and firmly fixed, the coil does not deform or move when the coil is powered on and off, and noise is reduced and the burden on the subject. Can be reduced. Moreover, since the coil is not deformed, the accuracy of the generated gradient magnetic field is also improved. Furthermore, even if there is an error in the outer diameter of the bobbin, the shape of the coil, or the like, and a gap is created, the gap can be filled, which facilitates manufacturing. Further, since the heating foam material is interposed, and the heating foam material is heated and foamed to be cured, the manufacturing process is not complicated, and the noise is reduced without increasing the cost. It is possible to improve accuracy and ease of manufacturing.

[Brief description of drawings]

FIG. 1 is a side view showing a partially cutaway portion of a gradient magnetic field coil according to an embodiment of the present invention, FIG. 2 is a sectional view taken along the line AA of FIG. 1, and FIG. An enlarged enlarged sectional view and FIG. 4 are enlarged sectional views of a conventional example. 1 ... Bobbin, 2 ... Gx coil, 3 ... Gy coil, 4 ...
... Gz coil, 5 ... Fixing material, 6 ... Buffer material, 7 ... Space, 8 ... Gap, 9 ... Heating foam material.

Claims (1)

[Scope of utility model registration request] 1. A gradient magnetic field coil for an MRI apparatus comprising a coil formed on a bobbin, wherein a heating foam material is interposed between the bobbin and the coil, and the heating foam material is heated to foam. Characterized by being cured
Gradient field coil for MRI equipment.