JPH02274231A - Magnetic resonance imaging device - Google Patents

Abstract

PURPOSE:To obtain enough lighting and keep a subject free from uneasy feeling by forming a plurality of plastic optical fibers like filaments, arranging a light emission means made of the optical fibers having a flawed clad part in a space for placing a subject and introducing light to the light emission means. CONSTITUTION:A static magnetic field generation means contains a superconducting wire and a cooling media in a double cylindrical vessel 10, and generates a high strength magnetic field at an axial intermediate position in an inner cylindrical space 11. A subject is introduced along an axial direction within an inner cylinder with a top plate 14 for a device. Also, a plurality of plastic optical fibers are formed like filaments and two light emission means 12 comprising the fibers having a flawed clad portion are arranged in the aforesaid space. In addition, light sources 13 (total of 4 sources) are respectively provided at each light emission means and both light receiving ends of a light guide 15, in order to introduce light to the light emission means. Furthermore, a reflecting plate 16 and a diffusion sheet 17 are arranged on the plastic optical fiber 12a for the improvement of the directivity of leak light. According to the aforesaid construction, side leak light available as plane illumination can be introduced from the clad portion of the light emission means arranged within the space for the subject, and the space can be made light.

Description

[Detailed Description of the Invention] [Aims of the Invention @] (Industrial Application Field) The present invention provides a device for generating a static magnetic field, a gradient magnetic field generating means, and a means for transmitting an excitation magnetic field and receiving an induced signal. The present invention also relates to a magnetic resonance imaging apparatus in which a space for arranging a subject is provided, and a magnetic field is generated in the space by each of the means described above.

(Prior art) Magnetic resonance (MR: n+agnetie resOn)
anee ) phenomenon is a phenomenon in which an atomic nucleus with non-zero spin and magnetic moment placed in a static magnetic field resonantly absorbs and emits only electromagnetic waves of a specific frequency, and this atomic nucleus has an angular frequency ω0 shown in the following formula. , (ωo=2πshi0.
It resonates at the Larmor frequency).

ω0 γH0 Here, γ is the gyromagnetic ratio specific to the type of atomic nucleus,
Further, H is the static magnetic field strength.

A device that performs biological diagnosis using the above principle processes the electromagnetic waves (magnetic resonance signals: echo signals and FID signals) of the same frequency as above that are induced after the above-mentioned resonance absorption, and calculates nuclear density, vertical Relaxation time constant TI, transverse relaxation time constant T2.
Diagnostic information that reflects information such as flow and chemical shift, such as slice images of a subject, can be obtained non-invasively.

Collecting diagnostic information by magnetic resonance can excite all parts of a subject placed in a static magnetic field and collect signals, but there are limitations in the equipment configuration and clinical requirements for imaging images. Therefore, the actual device is designed to excite a specific region and collect its signals.

In such a magnetic resonance imaging apparatus, a superconducting magnet, a normal conducting permanent magnet, or a combination thereof is used as the static magnetic field generating means. and,
A portion of the static magnetic field region generated by the static magnetic field generating means is a diagnosable region, where the subject is placed, and serves as an imaging possible region. This is because the static magnetic field in the diagnosable region must necessarily be a high-intensity magnetic field of several thousand to gauss, and the magnetic field uniformity must be several ppm, due to the principles of magnetic resonance phenomena. be.

Therefore, a static magnetic field generating means consisting of a superconducting magnet, a normal conducting magnet, or a permanent magnet, or a combination thereof, has dimensions of several meters and weighs several tons to several tons or more. It has become.

For example, a static magnetic field generating means made of a superconducting magnet is one in which a superconducting wire and a refrigerant are housed in a double cylindrical container with both openings closed. The magnetic field uniformity is designed to generate a high intensity magnetic field of several ppm.

The axial length of the inner cylinder space is about 2 meters. That is, the subject is introduced into this inner cylinder space having an axial length of 2 meters along the axial direction. Then, a region of the subject located at an axially intermediate position where a high-intensity magnetic field with a magnetic field uniformity of several ppm is generated in the inner cylinder space becomes an imageable region.

(Problems to be Solved by the Invention) In the above-mentioned example, the static magnetic field generating means is made up of a superconducting magnet, but in other examples as well, the subject introduction space has a length in meters. This length is extremely long compared to an X-ray CT scanner device, which is often compared as a tomographic imaging device. this is,
As mentioned above, this is for reasons such as obtaining a necessary magnetic field.

In this way, in the magnetic resonance imaging apparatus, the space in which the patient's name is introduced has a length measured in meters, so the inside of the space is dimly lit. Moreover, when the subject enters the room, -
The layer becomes darker. Additionally, the scan time of a magnetic resonance imaging device is several minutes.

Since the scanning time lasts for several tens of minutes, subjects who are placed in a dark space during this long scanning period feel anxious.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a magnetic resonance imaging apparatus that does not cause a subject to feel anxious.

[Structure of the Invention] (Means for Solving the Problems) The present invention has a structure in which the following means are taken to solve the above problems and achieve the objects.

That is, the invention according to claim 1 includes static magnetic field generating means,
A gradient magnetic field generating means, means for transmitting an excitation magnetic field and receiving an induced signal are provided, and a space for placing a subject is provided,
In a magnetic resonance imaging apparatus in which a magnetic field is generated in the space by each of the above means, a light emitting means formed by scratching the cladding part of a plurality of plastic optical fibers formed in a strip shape is arranged in the space, and The invention according to claim 2 is characterized in that the light emitting means is provided with a means for introducing light, and the invention according to claim 2 is characterized in that the light emitting means is colored. , characterized in that at least one of a reflecting member and a diffusing member is arranged on the surface of the light emitting means, and
The invention according to claim 4 is characterized in that the light emitting means is sandwiched between a reflecting member and a diffusing member. From the cladding part of the light emitting means placed in the examiner placement space,
Side light leakage that can be used as surface illumination instead of spot illumination can be obtained, and the space can be brightened, and since the light emitting means is in the form of a strip, the installation space is small and the space for placing the subject is not narrowed. . Further, according to the invention according to claim 2, it is preferable that the light emitting means is colored, for example, milky white, because it provides milky white planar illumination light that soothes the subject's mood. Furthermore, according to the third aspect of the invention, since at least one of a reflecting member and a diffusing member is disposed on the surface of the light emitting means, light leakage directionality can be improved. Further, according to the invention according to claim 4, since the light emitting means is sandwiched between a reflecting member and a diffusing member, the light leakage directionality can be further improved compared to the invention according to claim 3. can.

(Embodiment) An embodiment of the magnetic resonance imaging apparatus according to the present invention will be described below with reference to FIGS. 1 and 2.

FIG. 1 is a perspective view showing the tM configuration of a static magnetic field generating means made of, for example, a superconducting magnet and a light emitting means disposed in the static magnetic field generating means, which are the main parts of the magnetic resonance imaging apparatus of this embodiment, and FIG. ~ Figures 4 show details of the light emitting means of the same embodiment, Figure 2 is a perspective view of a plastic optical fiber ribbon or tape as the light emitting means, and Figure 3 (a)
) is a diagram showing the occurrence of side light leakage of a ribbon or tape of a plastic optical fiber, viewed from the stretching direction of the ribbon or tape, and Figure 3(b) is a diagram showing the occurrence of side light leakage of a ribbon or tape of the same plastic optical fiber. 4 is a diagram showing a light emitting means formed by pasting a reflecting plate and a diffusing plate on the surface of a plastic optical fiber ribbon or tape in order to improve the directionality of light leakage. .

As shown in FIG. 1, the static magnetic field generating means made of, for example, a superconducting magnet is constructed by housing a superconducting wire and a refrigerant (not shown) in a container 10 formed by a double cylindrical body with both openings closed. At an axially intermediate position of the inner cylindrical space 11, a high-strength magnetic field with a magnetic field uniformity of several ppm is installed. It is designed to generate a ff fa field. The axial length of the inner cylinder space 11 is
It is about 2 meters long. That is, a subject (not shown) is introduced into the inner cylinder space 11 having an axial length of 2 meters along the axial direction. And the inner cylinder space 11
The magnetic field uniformity is at an axial intermediate position where a high intensity magnetic field of several ppm is generated (not shown). , i & the examiner's site becomes the imaging possible area.

In addition, for example, two light emitting means 12 formed by scratching the cladding part of a plurality of plastic optical fibers formed in a strip shape, for example, a ribbon or tape, are inserted into the space 1.
1, and in order to introduce light into these two light emitting means 12, a light source 13 is connected to the light receiving end of the light guide 15 via a light guide 15 connected to the light receiving end of the light emitting means 12. It is set up. In this case, one light emitting means 12. Light at both light receiving ends of the light guide 15? fA13 is provided, and a total of four lights [13
is used. Further, reference numeral 14 denotes a top plate for placing a subject that is taken in and out of the inner tube space 11 that serves as a space for placing a subject.

Here, details of the light emitting means 12 will be explained with reference to FIGS. 2 to 4. As shown in FIG. 2, the light emitting means 12 can be formed into a ribbon or tape-like strip shape by arranging a large number of plastic optical fibers in parallel.

Here, one of the plastic optical fibers is designated 12a.
The occurrence of side light leakage in one plastic optical fiber is shown in Fig. 3(a) as seen from the stretching direction of the ribbon or tape, and in Fig. 3(b) as seen from the end face direction of the ribbon or tape. explain. That is, the plastic optical fiber 12a has a core 12a1 and a cladding 12a.
2, and by roughening a part of the surface of the cladding 12a2, the roughened surface scatters light and changes the reflection angle, leaking light to the outside and forming a plastic optical fiber. It is known that light leakage can be obtained from the side surface of 12a.

Furthermore, in order to improve the light leakage directionality, as shown in FIG. 4, a configuration can be adopted in which a reflecting plate 16 and a diffusion sheet 17 are arranged on the plastic optical fiber 12a. Here, a white plate or an aluminum plate (foil) can be used as the reflection plate 16, and by providing this reflection plate 16, the diffusion effect can be improved and light leakage can be made efficient. Further, as the diffusion sheet 17, cellophane or the like can be used. By providing this diffusion sheet 17, a diffusion effect can be achieved, and the amount of emitted light can therefore be made more uniform.

Of course, even if at least one of the reflection plate 16 and the diffusion sheet 17 is placed on the plastic optical fiber 12a, it is possible to improve the light leakage directionality to some extent.

As described above, according to this embodiment, from the cladding portion which is the side surface of the light emitting means 12 arranged in the subject arrangement space 11,
Side light leakage that can be used as planar illumination instead of spot illumination can be obtained, and the space 11 can be brightened, and the light emitting means 1
2 is in the form of a strip like a ribbon or tape, so the installation space is small, which is advantageous because it does not narrow the subject placement space 11.

Furthermore, it is preferable to color the light emitting means 12 in a milky white color, for example, because it provides milky white planar illumination light that softens the subject's mood. The same effect can be obtained by making the color of the light source 13 milky white.

Furthermore, since at least one of the reflection plate 16 and the diffusion sheet 17 is arranged on the surface of the light emitting means 12, the directionality of light leakage can be improved.

Further, since the light emitting means 12 is sandwiched between the reflection plate 16 and the diffusion sheet 17, the light leakage directionality can be further improved than the above-described one.

Of course, the subject placement space 11 is a magnetic field generation space and must not be contaminated with noise, but since the light emitting means 12 is a non-electrical element, it may not introduce noise.
It will not become a source of noise. Further, the magnetic field is not disturbed, and the operation of the light emitting means 12 etc. does not become abnormal due to the magnetic field. [Effects of the Invention] As described above, in the invention according to claim 1, the static magnetic field generating means, the gradient magnetic field generating means, In a magnetic resonance imaging apparatus, a magnetic resonance imaging apparatus is provided with means for transmitting an excitation magnetic field and receiving an induced signal, and a space for placing a subject is provided in which a magnetic field is generated by each of the means described above. A light emitting means formed by scratching the cladding part of a plurality of light emitting means formed in a strip shape is arranged in the space, and a means for introducing light into the light emitting means is provided, so that the light emitting means is arranged in the subject placement space. Side light leakage can be obtained from the cladding part of the light emitting means, which can be used as planar illumination instead of spot illumination, and the space can be brightened.
Since the light emitting means is in the form of a strip, the installation space is small, and the space for placing the subject can be kept small.

Further, in the invention according to claim 2, since the light emitting means is colored, for example, if the light emitting means is colored milky white, it becomes a milky white planar illumination light that softens the mood of the subject, which is clinically preferable. Become something.

Furthermore, in the invention according to claim 3, since at least one of a reflecting member and a diffusing member is disposed on the surface of the light emitting means, light leakage directionality can be improved.

Further, in the invention according to claim 4, since the light emitting means is sandwiched between a reflecting member and a diffusing member, the light leakage directionality can be further improved than in the invention according to claim 3.

Therefore, according to the present invention, it is possible to provide a magnetic resonance imaging apparatus that does not give a subject a sense of anxiety.

[Brief explanation of drawings]

FIG. 1 is a perspective view showing the configuration of a static magnetic field generating means made of a superconducting magnet, for example, and a light emitting means disposed in the static magnetic field generating means, which are essential parts of an embodiment of a magnetic resonance imaging apparatus according to the present invention. 2 to 4 show details of the light emitting means of the same embodiment, and FIG. 2 is a perspective view of a plastic optical fiber ribbon or tape as the light emitting means;
Figure 3(a) is a diagram showing the appearance of the side surface of the ribbon or tape of the plastic optical fiber, viewed from the stretching direction of the ribbon or tape, and Figure 3(b) is the side surface of the ribbon or tape of the plastic optical fiber. Figure 4 is a diagram showing the occurrence of the phenomenon seen from the end surface direction of the ribbon or tape. Figure 4 shows a reflection plate on the surface of the plastic optical fiber ribbon or tape in order to improve the light leakage directionality. It is a figure which shows the light emitting means formed by sticking a diffuser plate. 10... Container, 11... Inner cylinder space 11.12...
Light emitting means, 13... Light source, 14... Top plate for subject placement, 15... Light guide, 16... Reflector, 17
...Diffusion sheet. Applicant's agent Patent attorney Takehiko Suzue

Claims (4)

[Claims] (1) A static magnetic field generating means, a gradient magnetic field generating means, a means for transmitting an excitation magnetic field and receiving an induced signal are provided, and a space for placing a subject is provided, and a magnetic field is generated by each of the above means in the space. In the magnetic resonance imaging apparatus, a light emitting means formed by scratching the cladding portion of a plurality of plastic optical fibers formed into a strip is disposed in the space, and a means for introducing light into the light emitting means is provided. A magnetic resonance imaging device characterized by: (2) The magnetic resonance imaging apparatus according to claim 1, wherein the light emitting means is colored. (3) The magnetic resonance imaging apparatus according to claim 1, wherein at least one of a reflection member and a diffusion unit is disposed on the surface of the light emitting means. (4) The magnetic resonance imaging apparatus according to claim 1, wherein the light emitting means is sandwiched between a reflecting member and a diffusing member.