JPH03965Y2 - - Google Patents

Description

[Detailed explanation of the invention] (a) Industrial application field This invention is a nuclear magnetic resonance imaging device (hereinafter referred to as NMR-
(referred to as CT).

(b) Prior Art In NMR-CT, it is necessary to form a highly uniform static magnetic field. Static magnetic field generators that create such static magnetic fields are generally
As seen on pages 254 to 257 of Vol. 41, No. 7 (7, 1983), normal conducting magnets, superconducting magnets, or permanent magnets are used.

A device using a normal conducting magnet consumes a large amount of power, and also generates heat due to the application of a large current, which requires a cooling device to prevent the temperature from rising, resulting in a large device. Furthermore, in devices using superconducting magnets, liquid helium or liquid nitrogen must be periodically replenished to maintain the superconducting state, which poses problems in maintaining the device.

The solution to these problems is to use permanent magnets. In such a case, there is no need for a cooling device or replenishment of liquid helium, etc., making the device very economical in terms of maintenance.

By the way, this type of nuclear magnetic resonance imaging device using permanent magnets includes an exterior body having a first opening for insertion of a subject formed on the side surface, a pair of permanent magnets, and a structure that magnetically couples the magnets and is almost sealed. a static magnetic field generating means comprising a magnetic yoke having a space and a second opening for inserting a subject formed on a side surface thereof, and disposed within the exterior body such that the second opening is positioned opposite to the first opening; and the second opening. A cylindrical body inserted approximately horizontally into a static magnetic field generator and having an end facing the first opening has been prototyped.

By the way, the installation environment of this kind of static magnetic field generator,
For example, the presence of steel frames under the floor, ceiling, etc. may adversely affect the uniformity of the magnetic field. In order to deal with this problem, it is conceivable to configure the upper and lower permanent magnets in the prototype example so that their positions can be adjusted in the vertical direction together with the upper yoke and the lower yoke.

If such position adjustment is performed, it becomes impossible to set the height of the structural center of the static magnetic field generating device and the center height of the cylindrical body in a predetermined relationship, and it becomes impossible to place the center of the subject within a uniform magnetic field. When adjusting the height of the cylindrical body to deal with this problem, the first opening of the exterior body and the opening of the cylindrical body become misaligned, resulting in the disadvantage that in some cases the subject cannot be inserted into the cylindrical body. .

(c) The problem that the idea aims to solve The present invention solves the above drawbacks.

(d) Means for Solving the Problems The present invention has the first opening diameter of the exterior body larger than the inner diameter of the cylindrical body, and the first opening diameter for inserting the subject having a diameter substantially equal to the inner diameter of the cylindrical body. The above-mentioned problem is solved by providing a cover body having three openings and adjustable in position so as to cover the first opening of the exterior body, and means for adjusting the position of the cylindrical body.

(e) Effect By using the above means, the position of the cylindrical body is adjusted by the position adjustment means, the center of the cylindrical body and the structural center of the static magnetic field generator are set in a desired relationship, and the position of the cover body is adjusted to the position of the cylindrical body. By making adjustments in accordance with the position adjustment of the shaped body, the first opening and the third opening can be made to match, thereby eliminating the above-mentioned drawbacks.

(F) Embodiment An embodiment of the present invention will be described with reference to FIGS. 1 to 5. Reference numeral 1 denotes an exterior body made of a non-magnetic material such as FRP, wood, etc., which consists of a top plate 2 and four side plates 3a, 3b, 3c, and 3d surrounding the top plate 2, and two opposing side plates. (Also referred to as front and back)
Rectangular first openings 4a and 4b for inserting a subject (human body) are provided in the openings 3a and 3b so as to face each other. The first openings 4a, 4b are formed to face second openings 6a, 6b of the static magnetic field generating device 5, which will be described later. 7 is a device installation surface.

The static magnetic field generating device 5 is disposed within the exterior body 1 and has the following configuration. That is, 8a and 8b are a pair of upper and lower disk-shaped permanent magnets made of rare earth magnet material;
9A and 9B are disc-shaped upper and lower yokes made of a magnetic material that are arranged in contact with one surface of each of the permanent magnets and fix the magnets 8A and 8B; 10 is electromagnetically connected to the upper and lower yokes; The upper yoke 9A and the lower yoke 9B are arranged so as to seal the openings at the upper and lower ends of the cylindrical side yoke made of a magnetic material, thereby forming a magnetic circuit with each of these yokes. A strong static magnetic field (for example,
0.2T) is formed. Also, side yoke 10
has a pair of circular openings 6a and 6b arranged opposite each other for insertion of a subject into the static magnetic field. Reference numerals 11A and 11B are a pair of pole pieces that are disposed opposite to each other on the other surfaces of the permanent magnets 8A and 8B to improve the uniformity of the static magnetic field.

12A... is means for adjusting the vertical position of the upper yoke 9A, and each means is screwed into a seat 13A made of a non-magnetic material fixed to the inner surface of the side yoke 10 and a screw hole 14A of the upper yoke 9A which can be slid up and down on the side yoke 10. It consists of a non-magnetic screw 15A whose lower end is supported in contact with the seat 13A, and by changing the degree of engagement of the screw 15A, the height of the upper yoke 9A is adjusted, and accordingly it is fixed to the upper yoke 9A. The heights of the permanent magnet 8A and the pole piece 11A are adjusted to change the magnetic flux distribution. 12B... is a means for adjusting the vertical position of the lower yoke 9B, and includes a screw made of a non-magnetic material that is screwed into a seat 13B fixed to the side yoke 10 and a screw hole 14B of the lower yoke 9B which can be slid up and down on the side yoke 10. 1
5B, and the height of the lower yoke 9B is adjusted by adjusting the screwing degree of this screw 15B.

16 is a non-magnetic and magnetically permeable material, such as FR
A cylindrical body for inserting a subject made of P., which is inserted approximately horizontally into the device 5 through the second openings 6a, 6b of the side yoke 10, with both ends facing and close to the first openings 4a, 4b. Ru. The outer surface shape of this cylindrical body 16 in a longitudinal section is formed into an elliptical shape smaller than the second openings 6a and 6b, and the cylindrical body 16
It is possible to move up and down within a and 6b. The inner shape of the longitudinal section of the cylindrical body 16 is determined by the NMR signal detection probe (not shown) and the outer shape of the subject inserted into the probe, and is approximately the same (same) as the third openings 17a and 17b described later. ) is formed into an elliptical shape.

18a and 18b are the static magnetic field generator 5 and the exterior body 1
A support device made of a non-magnetic material that supports both ends of the cylindrical body 16 and is located between, for example, a pair of L-shaped supports 19 and 20 and a connecting body that connects them, as shown in FIG. 21, 22, and a receiver 25 that is vertically slidable in slide grooves 23, 24 formed at the top of the support columns 19, 20 and supports the cylindrical body 16, and a receiver 25 that is screwed onto the connecting body 22 and is received at the tip. It is composed of screws 26, 26 made of non-magnetic material that support the body 25, and the screw 2
It also constitutes a vertical position adjustment means that changes the height of the cylindrical body 16 by changing the height of the tips of the screws 26 and 26 depending on the screwing degree of the screws 6 and 26.

27a and 27b are the first openings 4a and 4 of the exterior body 1.
The cover body is attached to part b by non-magnetic screws 28 so as to cover it, and has third openings 17a and 17b for inserting the subject at approximately the center, and a mounting hole 29 for inserting the screws 28. By making the holes vertically long, the vertical mounting positions of the cover bodies 27a and 27b can be adjusted. The size of the cover bodies 27a, 27b is determined by themselves so that the first openings 4a, 4
Make it large enough to cover b.

In the above configuration, the static magnetic field is adjusted by rotating the screws 15A and/or the screws 15B and changing the positions of the upper yoke 9A and/or the lower yoke 9B. With this position adjustment, screw 2
6 and 26 to change the height of the cylindrical body 16, the structural center of the static magnetic field generator 5 (pole piece 1
The height of the center axis of the cylindrical body 16 is kept in a predetermined relationship with respect to the height of the central point between 1A and 11B (where the magnetic field is highly homogeneous), and the center of the subject inside the cylindrical body 16 is is aligned with the center of the structure, and the subject is placed in a highly uniform magnetic field.

Then, as the height of the cylindrical body 16 is adjusted, the screw 28
... and slide the cover bodies 27a and 27b up and down to open the end opening of the cylindrical body 16 and the third opening 17a,
17b, and then screw in and fix the screws 28. By doing this, the subject is placed in the third opening 1.
It can be easily inserted into the cylindrical body 16 through 7a and 17b without any trouble. Moreover, the first openings 4a, 4
Although the diameter of b is large, the first openings 4a, 4
b and the third openings 17a, 17b are covered by cover bodies 27a, 27b, and the cylindrical body 1
Foreign matter is prevented from entering the exterior body 1 from between the end portion of the housing 6 and the first openings 4a, 4b, and the appearance is improved.

Note that the present invention is not limited to the above-mentioned embodiments, and the configurations of the cover body and the vertical adjustment means for the cylindrical body can be modified in various ways.

(g) Effects According to the present invention configured as described above, by adjusting the position of the cylindrical body using the cylindrical body position adjustment means, the subject can be placed in a highly uniform magnetic field, and the cylindrical body can be placed in a highly uniform magnetic field. By adjusting the position of the cover body in conjunction with the position adjustment of the cylindrical body, the test subject can be inserted into the cylindrical body without any trouble, and other effects are great.

[Brief explanation of the drawing]

Figures 1 to 5 all show one embodiment of the present invention, with Figure 1 being a longitudinal sectional view, Figure 2 being a perspective view with the static magnetic field generator removed, Figure 3 being a side view, and Figure 3 being a side view. 4 is a sectional view of the main part taken along the line -- in FIG. 3, and FIG. 5 is a perspective view of the main part. 1... Exterior body, 4a, 4b... First opening, 5...
...Static magnetic field generator, 6a, 6b...Second opening, 8
A, 8B... Permanent magnet, 9A, 9B, 10... Yoke, 16... Cylindrical body, 17a, 17b... Third
Opening, 18a, 18b...support device (vertical position adjustment means), 27a, 27b...cover body.

Claims (1)

[Scope of utility model registration request] An exterior body with a first opening for inserting a subject formed on a side surface, a pair of permanent magnets, and the magnets are magnetically coupled to form a nearly sealed space, and a second opening for inserting a subject is formed on a side surface. a static magnetic field generating device disposed within the exterior body such that a second opening is located opposite to the first opening, and the second
and a cylindrical body inserted into the static magnetic field generator approximately horizontally from the opening and having an end facing the first opening, the first opening having a diameter larger than the inner diameter of the cylindrical body; , a cover body having a third opening for inserting a subject having a diameter substantially equal to the inner diameter of the cylindrical body, and the cover body is attached to the first opening of the exterior body so as to be adjustable in position so as to cover the first opening; A nuclear magnetic resonance imaging apparatus comprising a position adjustment means.