JP2003052661A - RF coil and method of manufacturing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an RF coil which has the same function of transmitting and / or receiving RF signals as a conventional RF coil, has a simple structure, and is therefore low in manufacturing cost and can be mass-produced. I will provide a. SOLUTION: A coil portion is formed by winding a conductor of the thin film filament flatly, and further, a capacitance means installed in a winding circuit of the coil portion is connected to a conductor of the thin film filament. A part of them is overlapped with a small gap between them, or a part of the conductor of the thin film filament is formed in an interdigital shape at its ends and flat on the same plane with a small gap between them. It is formed by arranging it opposite to. By applying a resin film-shaped insulating coating to the coil unit and the capacitance means manufactured by the above method,
An RF coil which is flat and thin as a whole and which can have appropriate flexibility depending on the material of the insulating coating is obtained.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a coil for an MRI apparatus, and more particularly to a coil for transmitting and / or receiving an RF signal.
The present invention relates to an RF coil and a manufacturing method thereof.

[0002]

2. Description of the Related Art Typical MRI (Magnetic Resonance Imag)
ing: In a magnetic resonance imaging apparatus, a subject (subject) is placed inside a cylindrical magnet that generates a static magnetic field.
It is put on a bed or the like and inserted. A coil called a gradient magnetic field coil for generating a gradient magnetic field is further present between the cylindrical magnet and the subject, which is also supported by a cylindrical container or the like. In this situation, RF (Radio Frequenc
y) A coil called a coil transmits a rotating magnetic field to a target site of a subject (transmission of an RF signal), and when the transmission of the magnetic field is stopped, RF energy having a resonance frequency re-radiated from the target site is transmitted. Similarly, the image information of the target portion is obtained by receiving the RF coil (receiving the RF signal).

As mentioned above, the term "coil" is used both for gradient field coils and RF coils, and also for coils formed by loops of conductors, but unless stated otherwise below. A coil is an RF coil.

The transmission coil and the reception coil used in the MRI apparatus include those for both transmission and reception, as well as those for transmission and reception only. The types are saddle type and bird cage type. There are various types such as a surface coil type, but most of them have a structure in which a so-called coil-shaped loop is formed of a conductor and are casing together with other necessary electric parts and the like in plastic or the like.

Among the RF coils, there are some RF coils whose shape can be adjusted according to the outer diameter of each inspection target site such as the head and limbs of the subject to improve the image quality. Japanese Patent Application 3
The flexible birdcage coil described in Japanese Patent Laid-Open No. 178148 is an example thereof, but in the flexible birdcage coil as well, the conductor portion forming the loop remains rigid (rigid). In addition, in recent years, attempts have been made to perform MR imaging under surgery, but the coil used at that time also has holes in the inner circumference of the loop so that the affected area can be accessed. The casing remains rigid, and therefore most of the loops and their casings are also thick.

[0006]

As described above, when the variable structure for adjusting the shape is incorporated, the structure becomes complicated, or the casing is strengthened for durability, as a matter of course, Increasing manufacturing costs are inevitable. In addition, a thick and rigid casing may cause damage to the subject when it comes into contact with the subject's body during use, or may lead to deterioration of work efficiency and accuracy of surgery when used for surgery. There is a nature.

Further, when the above-mentioned coil is used under surgery, the coil may be contaminated with blood of a subject, and in general, after use, the coil is sufficiently disinfected against the contamination.・ If sterilization is not performed, there is a risk of nosocomial infection, but if the structure of the coil is complicated, disinfection and sterilization will take much time.

Therefore, according to the present invention, the RF coil is easy to handle, has the same function as the conventional coil, but has a simple structure, therefore the manufacturing cost is reduced, and the RF coil is also disposable (disposable). And a method for manufacturing the same.

[0009]

In order to solve the above-mentioned problems of the prior art and to achieve the object of the present invention, the RF coil of the present invention is a coil portion in which a thin film wire conductor is wound flat. And a resin film-like insulating coating for covering the coil portion.

Preferably, in order to limit the rise in the potential of the coil portion, capacitance means is installed in the winding circuit of the coil portion.

In order to form the coil portion into a flat thin film shape, the capacitance means preferably overlaps a part of the conductors of the thin film filament with a slight gap therebetween to form the gap portion. It is formed by sandwiching an insulator between.

Further, the capacitance means forms a part of the conductor of the thin film filament in an interdigital shape with its ends being on the same plane with a slight gap sandwiching an insulator. It can also be configured by arranging them so as to face each other.

Further, it is preferable that the RF coil has a certain degree of flexibility so as to fit the shape of the target region for RF imaging.

The method of manufacturing an RF coil according to the present invention comprises the steps of flatly winding a thin wire conductor to form a coil portion, and coating the coil portion with a resin film-like insulating coating. .

In the step of forming the coil portion, the coil portion may be formed by etching.

According to the present invention, the coil portion of the RF coil is
Since the coil part is thin and the structure is simple by forming the thin film wire conductor including the capacitance means, it is possible to apply a film-like insulating coating to the coil part. This leads to a reduction in manufacturing cost and enables mass production.

Further, when the RF coil itself is in the form of a thin film with the above structure, it is light and not bulky, so that it is easy to handle, and there is little risk of damage to the subject even when contact with the subject occurs. Discomfort to the subject can also be reduced.

[0018]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the accompanying drawings.

First Embodiment FIG. 1 is a perspective conceptual view showing an RF coil 1 according to a first embodiment of the present invention. The RF coil 1 includes a coil portion 3 formed by flatly winding a conductor such as copper formed on a thin film wire, and the coil portion 3 existing for connecting to the MRI apparatus main body. It is constituted by a resinous film-like coating 2 which covers the entire coil portion 3 except the end portion 4. At this time, the coating 2 is made of, for example, flame-retardant vinyl chloride or Kobazol (manufactured by Kobayashi Co., Ltd.).

In order to actually function the RF coil 1 as an RF coil, a conductive cord or the like (not shown) is further connected to the end portion 4 and the conductive cord is connected to an external RF system.
As the connection destination in the external RF system, either the transmitter and / or the receiver of the RF signal can be appropriately selected depending on the purpose of transmitting and / or receiving the RF coil 1.

In the RF coil used for surgery etc.,
As shown in FIG. 1, a hole is generally present in the central portion for accessing the affected area. Since the internal coil portion 3 of the RF coil 1 is formed in a flat thin film shape, the coating 2 for covering the RF coil 1 can be formed in a thin film shape, as shown in FIG. Compared with the conventional general RF coil 50 in which the coil case 10 that is the casing of the coil portion is rigidly formed of plastic or the like, the perspective view of the appearance of which is shown, the entire coil has a flat thin film shape. The point is that it is formed.

Since the RF coil 1 having such a structure has a simple structure, if the FOV (Field of View) is determined by the target site of the subject,
In accordance with this, for example, only by changing the winding diameter of the coil portion 3, it is possible to inexpensively mass-produce a large number of coils dedicated to each part. Further, since it is thin, it can be made lighter, and it is easy to carry and handle during use.

Furthermore, the coating 2 can be manufactured by changing its material and thickness depending on the application. Therefore, for example, in a coil for the head, a soft coating gives flexibility to some extent to improve the image quality according to the shape of the head, and when contact with the subject occurs. It is possible to prevent damage to the subject,
On the contrary, the holding can be facilitated by applying a rigid coating to some extent.

Further, considering that the coil is used under surgery, the RF coil 1 of the present embodiment,
Not only is there a hole in the center, but it is also thin, so it is easy to access the affected area, which leads to improved work efficiency and accuracy in surgery. In addition, even if the coil is contaminated by the blood of the subject during surgery, the mass-produced and inexpensive coil can easily take disposable usage into consideration, and disinfect / sterilize the coil. You can save time and trouble.

As a method of manufacturing the RF coil 1, for example,
As shown in the conceptual cross-sectional view of the coil portion 3 and the coating 2 in FIG. 6A, the coil portion 3 manufactured in a loop in another process is placed on the coating 2 serving as a base, and the coating 2 is further applied from above.
May be attached with an adhesive or the like, or may be fused by heat or the like. Further, as shown in FIG. 6B, a coil portion 3 is formed by etching or the like on a conductor such as copper that is integrally formed by being attached to the coating 2 that serves as a base portion, and then, as described above. It is also conceivable to attach the cover 2 as a cover by any method.
It is assumed that the coating 2 has durability such as pressure resistance and chemical resistance depending on the situation of use.

Second Embodiment Referring to FIG. 2, an RF coil 2 according to a second embodiment of the present invention.
A perspective conceptual view of 0 is shown. The RF coil 20 according to the second embodiment is characterized in that it includes a capacitance section 5 that is generally used in the winding circuit of the coil section 3 to limit an increase in the potential of the coil section. There is.

The function of the capacitance section will be briefly described with reference to FIG. 2. When the capacitance section is present in the coil section 3, the capacitance increases as the capacitance section 5 increases. The capacity per unit can be increased. Then, for example,
In FIG. 2, the first coil portion 30 resulting from the division by the two capacitance portions 5 comes into contact with the body of the subject, and thus the subject and the first coil portion 30. Even if the electric potential of the first coil piece 30 is lowered because a capacitance is formed between the
Due to the effect that the capacitances of the respective capacitance units 5 are increased, the stability of the entire circuit of the coil unit 3 can be maintained.

In the conventional RF coil, as the capacitance portion, as shown in FIG. 5 (b), the dimensions are about 5 mm in length and width and 2 mm in height on the coil portion 60 which is a circuit. In many cases, the chip capacitor 7 is mounted. Since the rigid casing is applied to the chip capacitor 7, the coil case 10 for casing the coil portion 60 including the chip capacitor 7 also includes
There is no choice but to have a thickness equal to or higher than the height of the chip capacitor 7.

Therefore, in the present embodiment, in order to make the coil thin, the capacitance means is formed not by using the chip capacitor but by the pattern of the conductor itself forming the coil portion 3. The method of forming the electrostatic capacitance means by the pattern of the conductor itself will be briefly described with reference to the drawings. For example, as shown in FIG.
When viewed from the side, the first coil piece 30 and a part of the second coil piece 30 ', both of which are made of a conductor such as copper, are overlapped with each other with a slight gap therebetween. When it is formed, the capacitance is generated in the overlapping portion, and the capacitance means 5a is obtained. In the RF coil, an RF signal having a high frequency on the order of megahertz is generally used, so that the capacitance means can be obtained with such a simple structure. By constructing the electrostatic capacitance means 5a by the above method, the coil portion 3 can be formed thin, and by providing the resin film-like coating 2 on the coil portion 3, the electrostatic capacitance means is provided and an electric circuit is provided. It is possible to manufacture a thin RF coil while having high stability.

Also in the RF coil of the second embodiment, the first
Similar to the RF coil of the embodiment, by connecting a conductive cord (not shown) or the like connected to the end portion 4 of the coil portion 3 to a transmitter and / or a receiver of an external RF RF signal, And / or can be used as an RF coil for reception.

The number of the capacitance means depends on the balance between the performance required for the coil and the manufacturing cost.
It is set appropriately.

Further, as shown in FIG. 3 (b),
The insulator 6 may be sandwiched in the space between the coil pieces 30 and 30 ′ to form the capacitance means 5 b having an increased capacitance.

Furthermore, in order to eliminate even a slight thickness due to the gap between the coil pieces 30 and 30 ', it is conceivable to form the capacitance means with the configuration shown in FIG. Figure 4
FIG. 4 is a top view of the electrostatic capacitance portion of the coil portion 3 of the thin film wire, but in FIG. 4, the capacitance means 5c has the coil portion pieces 40, 40 ′ formed in an interdigital shape.
Are arranged on the same plane so as to face each other with a slight gap therebetween. By using the capacitance means 5c configured in this way, a coil having a substantially perfect planar shape but high electrical circuit stability can be obtained. Further, as in the case of the capacitance means 5b, the thin film insulator 8 is provided in the gap between the coil pieces 40 and 40 '.
The capacity may be increased by sandwiching.

As the method of forming the electrostatic capacitance means as described above, as in the case of forming the coil portion 3, a method of laminating a pre-manufactured coil portion piece with the coating 2 or a coil portion piece by etching or the like is used. A method of processing the can be considered.

In the attached drawings, a substantially circular RF coil having a hole in the center is drawn, but the outer shape of the RF coil in the present invention is not limited to the above-mentioned substantially circular shape. It may be square or curved, and 1
A phased array coil structure may be used in which a plurality of single coils each having one winding are combined and used. Further, not only the outer shape of the coil, but also the materials, sizes, constituting means, manufacturing methods, expressions, terms and the like referred to in the description of the above embodiments are examples for explanation, and the present invention is not limited thereto. Modifications are possible within the scope of the claims.

[0036]

As described above, according to the present invention, while having the same function of transmitting and / or receiving an RF signal as the conventional coil, the structure is simple and therefore mass production is possible. Thus, it is possible to provide an RF coil that is easy to carry and handle. The RF coil of the present invention can be used as an RF coil for MR imaging by using a megahertz-order RF signal.

[Brief description of drawings]

FIG. 1 is a perspective conceptual view of an RF coil according to a first embodiment of the present invention.

FIG. 2 is a perspective conceptual view of an RF coil according to a second embodiment of the present invention.

FIG. 3 (a) is a diagram for explaining an example of the capacitance means according to the second embodiment of the present invention.
(B) is a figure for demonstrating another example of the said electrostatic capacitance means.

FIG. 4 is a diagram for explaining still another example of the electrostatic capacitance means.

FIG. 5 (a) is a perspective view of a conventional RF coil, and FIG. 5 (b) is a diagram for explaining capacitance means in the conventional RF coil.

6 (a) and 6 (b) are cross-sectional conceptual views for explaining the method for manufacturing the RF coil of the present invention.

[Explanation of symbols]

1, 20, 50 ... RF coil, 2 ... Coating, 3 ... Coil part,
5 ... Capacitance section, 5a, 5b, 5c ... Capacitance means, 6,
8 ... Insulator, 7 ... Chip capacitor, 10 ... Coil case

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Tetsuji Tsukamoto             127, 4-7 Asahigaoka, Hino City, Tokyo             GE Yokogawa Medical System Co., Ltd.             Within F-term (reference) 4C096 AB42 AD10 CC08

Claims (8)

[Claims] 1. Use for transmitting and / or receiving RF signals
An RF coil, comprising: a coil portion in which a thin film wire conductor is flatly wound; and a resin film-like insulating coating for covering the coil portion. 2. The RF coil according to claim 1, further comprising electrostatic capacitance means for limiting a rise in potential of the coil portion in a winding circuit of the coil portion. 3. The capacitance means is formed by superposing a part of the conductors of the thin film filament with a slight gap therebetween and sandwiching an insulator in the gap portion. The RF coil according to claim 2. 4. The capacitance means forms a part of a conductor of the thin film filament in an interdigital shape with its ends being on the same plane with a slight gap sandwiching an insulator. The RF coil according to claim 2, wherein the RF coil is formed by arranging the RF coil so as to face each other flatly. 5. The frequency of an RF signal used for MR imaging and used is in the megahertz order.
4. The RF coil according to any one of 4. 6. The RF coil according to claim 1, wherein the RF coil has a certain degree of flexibility so as to conform to the shape of a target region for MR imaging. 7. A method of manufacturing an RF coil, comprising: a step of winding a thin-film filament conductor flat to form a coil part; and a step of thereafter covering the coil part with a resin film-like insulating coating. 8. An etching step of forming a coil portion into a shape in which a thin film wire conductor is flatly wound, and a step of subsequently covering the coil portion formed by the etching step with a resin film insulating coating. The method for manufacturing an RF coil according to claim 7, further comprising: