JPH05237071A - Manufacture of gradient coil for nmr imaging apparatus - Google Patents

Abstract

PURPOSE:To achieve a shortening of production time by building up layers of gradient coil continuously impregnating a glass robing with a resin or a non-magnetic conductive paint to eliminate the need for work of loading or unloading a bobbin in the course of a process. CONSTITUTION:A glass roving 2 is impregnated with a resin of a container 4 through a nozzle 3, and wound on a rotating mandrel 16 while applying a tension thereon. Then, the roving is impregnated with a non-magnetic conductive paint of the container 5 instead of the resin through the nozzle 3 and wound on the rotating mandrel 16 while applying a tension thereon to form an RF shield layer. Gradient coil elements of axes of (x), (y) and (z) are set in three layer on the layer obtained. The glass roving 2 is impregnated with a resin of a container 4 instead of the non-magnetic conductive paint through the nozzle 3 and wound on the rotating mandrel 16 while applying a tension thereon. A gradient coil layer is produced by the hardening of the resin and this eliminates the need of work for loading or unloading a bobbin in the course of a process thereby achieving a shortening of time.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement in a method for manufacturing a gradient coil for an NMR imaging apparatus by a filament winding method.

[0002]

2. Description of the Related Art When an atomic nucleus is placed in a static magnetic field, the atomic nucleus precesses at an angular velocity proportional to a constant that differs depending on the strength of the magnetic field and the type of atomic nucleus. Magnetic resonance occurs when a high-frequency rotating magnetic field of the above-mentioned frequency is applied to the axis perpendicular to this static magnetic field, and a group of specific nuclei having the above constant causes a level transition by a high-frequency magnetic field satisfying the resonance condition, Move to a high energy level orbit. After the resonance, nuclei excited to a higher level return to a lower order and emit energy. The NMR imaging device is a device for observing the nuclear magnetic resonance phenomenon caused by the specific atomic nuclei and taking a tomographic image of the subject. This NMR imaging device has a gradient coil which produces a gradient magnetic field together with a magnet which produces a static magnetic field. The gradient coil applies a magnetic field having a different strength depending on the position of the subject in the body axis direction in order to specify the position at which the tomographic image of the subject is taken. This gradient coil is generally formed along the wall surface of a cylindrical bobbin, and an RF coil (high-frequency coil) for creating a high-frequency rotating magnetic field is placed in the hollow part of the gradient coil, and the subject is placed in the RF coil. ing.

FIG. 2 is a constitutional view showing a gradient coil. FIG. 2 (a) is a front view and FIG. 2 (b) is a sectional view taken along the line XX '. The gradient coil 10 includes a bobbin 11 made of a rigid body made of FRP and a copper foil sheet (R
A member forming a shield for the F coil 14),
Gradient coil elements for each of the x, y, and z axes (not shown)
And a gradient coil layer 13 which is wound and fixed on the copper foil 12 in three layers.

The gradient coil having such a structure is manufactured by the following procedure. (1) A hobbin having a predetermined wall thickness is made by the filament windowing method. The filament winding method is a method of forming a tubular body by impregnating a glass roving (thread-shaped glass fiber) 15 with a resin in advance and winding it around a rotating mandrel 16 while applying tension in the apparatus shown in FIG. Is. In this manner, a cylindrical rigid body having a desired size, that is, a bobbin, having a hollow portion is produced. (2) Remove the bobbin from the device and attach the copper foil sheet to the surface of the bobbin. (3) Again, the bobbin was attached to the apparatus, the gradient coil elements of each axis of x, y and z were installed in three layers on the copper foil sheet, the mandrel was rotated, and the glass roving impregnated with the resin was tensioned. Wrap while hanging. The gradient coil element is fixed by curing the resin and the gradient coil layer 1
3 is made.

A gradient coil is manufactured by the above steps.

[0006]

However, in the conventional method for manufacturing the gradient coil, the bobbin is detached from the apparatus and reattached in the middle of the process, so that the manufacturing time is long and the cost is high. There was a problem to say.

The present invention has been made in view of the above problems, and an object of the present invention is to realize a low-cost gradient coil manufacturing method by eliminating the need for bobbin removal and mounting work during the process. is there.

[0008]

SUMMARY OF THE INVENTION The present invention which solves the above-mentioned problems is a filament winding method for forming a cylindrical object by winding a glass roving around a rotating mandrel while applying tension to the mandrel. The first step of making a bobbin by impregnating the glass roving before winding with a resin, and impregnating the glass roving with a non-magnetic conductive paint instead of the resin and winding it.
From the second step of forming the F shield layer and the third step of arranging the gradient coil element on the RF shield layer and impregnating glass roving with resin in place of the non-magnetic conductive paint to form a winding gradient coil layer. It is characterized by becoming. Further, the present invention is characterized in that the step of forming the RF shield layer is first performed, the step of forming the bobbin is performed, and the step of forming the gradient coil layer is finally performed by the filament winding method.

[0009]

The layers of the gradient coil are continuously formed while the glass roving is appropriately impregnated with the resin or the non-magnetic conductive paint. There is no need to remove and install bobbins during the process. Therefore, the time can be shortened and the manufacturing cost can be reduced.

[0010]

Embodiments of the present invention will now be described in detail with reference to the drawings.

FIG. 1 is a diagram showing the construction of an apparatus for carrying out the method of the present invention. The apparatus main body of FIG. 1 has the same configuration as that shown in FIG. 3, and here, the peripheral portion of the mandrel 16 is shown. 1 is a bobbin formed on the mandrel 16, 2 is glass roving, 3 is a nozzle installed at a predetermined position, 4 is a container containing polyester resin or epoxy resin, and 5 is non-magnetic conductive paint. The container 6 is a glass roving material roll. Nozzle 3 is connected to the mouth of container 4 or 5 and glass roving 2
It is configured to be impregnated with resin or non-magnetic conductive paint.

The gradient coil in such a device is manufactured in the following steps. (1) A hobbin having a predetermined wall thickness is made by the filament windowing method. The glass roving 2 is impregnated with the resin in the container 4 through the nozzle 3, and the glass roving 2 is wound around the rotating mandrel 16 while applying tension. By hardening the resin, a cylindrical bobbin having a hollow portion is produced. (2) Next, the non-magnetic conductive paint of the container 5 is impregnated into the glass roving 2 through the nozzle 3 in place of the resin, and the RF shield layer is wound while applying tension to the mandrel 16 that rotates the glass roving 2. Form. (3) After the RF shield layer is formed, three layers of gradient coil elements of x, y, and z axes are provided on the RF shield layer, and the glass roving 2 is replaced with the non-magnetic conductive paint in the container 4. Resin is impregnated through the nozzle 3, and the glass roving 2 is wound around the rotating mandrel 16 while applying tension. The hardening of the resin fixes the gradient coil elements and creates a gradient coil layer.

The gradient coil is manufactured by the above steps,
There is no need to remove and install the bobbin during the process.

The present invention is not limited to the above embodiment. For example, the RF shield layer may be formed on the inner wall of the bobbin, that is, the step of first forming the RF shield layer on the mandrel and the step of forming the bobbin and the step of forming the gradient coil layer may be provided.

[0015]

As described above, according to the present invention, each layer of the gradient coil is continuously formed while appropriately impregnating the glass roving with the resin or the non-magnetic conductive coating material. A low-cost gradient coil can be realized without the need for bobbin removal / installation work on the way.

[Brief description of drawings]

FIG. 1 is an explanatory view of an apparatus for carrying out the method of the present invention.

FIG. 2 is a configuration diagram showing a gradient coil.

FIG. 3 is an explanatory diagram of a filament windowing method.

[Explanation of symbols]

 1, 11 ... Bobbin 2 ... Glass roving 3 ... Nozzle 4 ... Container containing resin 5 ... Container containing non-magnetic conductive paint 6 ... Material roll of glass roving 10 ... Gradient coil 12 ... RF shield layer 13 ... Gradient coil Layer 14 ... RF coil

─────────────────────────────────────────────────── ───Continued from the front page (51) Int.Cl. ⁵ Identification code Office reference number FI Technical display location H01F 7/20 C 7135-5E 8203-2G G01R 33/22 N

Claims (2)

[Claims] 1. A filament winding method for winding a glass roving around a rotating mandrel while applying tension to form a cylindrical object, wherein the glass roving before being wound at a predetermined position is impregnated with a resin and bobbins. A second step of forming an RF shield layer by impregnating a glass roving with a non-magnetic conductive paint impregnated with glass roving instead of the resin, and arranging a gradient coil element on the RF shield layer; A method for producing a gradient coil for an NMR imaging apparatus, comprising a third step of forming a gradient coil layer by impregnating glass roving with a resin instead of a non-magnetic conductive paint and winding the resin. 2. A filament winding method for winding a glass roving around a rotating mandrel while applying tension to form a cylindrical object, wherein a non-magnetic conductive paint is applied to the glass roving before being wound at a predetermined position. A first step of impregnating to form an RF shield layer, a second step of impregnating glass roving with resin in place of the non-magnetic conductive paint to form a bobbin, and disposing a gradient coil element on the bobbin, A method for producing a gradient coil for an NMR imaging apparatus, comprising a third step of forming a gradient coil layer by impregnating glass roving with resin.