JPH032532B2 - - Google Patents

Description

[Detailed description of the invention] (a) Industrial application field The present invention relates to a nuclear magnetic resonance imaging apparatus (hereinafter referred to as NMR-
(referred to as CT).

(b) Prior art In nuclear magnetic resonance tomography (NMR-CT), which has recently been in the spotlight in the field of medical equipment, it is important to form a highly uniform static magnetic field.
As a means for forming this static magnetic field, a normal conducting magnet, a superconducting magnet, or a permanent magnet is used, as seen in pages 254 to 257 of Japan Clinical Practice Vol. 41, No. 7 (1983/7).

By the way, the device on which the present invention is based is equipped with a static magnetic field generator using permanent magnets. It consists of a magnetic yoke that magnetically couples the magnets and forms a nearly sealed space.

In this static magnetic field generating device, a large diameter coil for generating a gradient magnetic field must be provided within the space formed by the magnetic yoke. This coil needs to be provided so that it can be moved in and out of the space for adjustment and the like.

In order to meet these requirements, the opening for inserting the object to be imaged may be formed large enough to allow insertion of the coil. However, this has the disadvantage that leakage magnetic flux from the apertures increases and the uniformity of the static magnetic field is disturbed.

(c) Problems to be Solved by the Invention In view of the above-mentioned drawbacks, the present invention aims to make it possible to insert and remove the coil while maintaining the uniformity of the static magnetic field.

(d) Means for Solving the Problems The present invention comprises a pair of permanent magnets and a magnetic yoke having an opening for inserting an object to be imaged on the side surface and magnetically coupling the permanent magnets and forming a substantially sealed space. A nuclear magnetic resonance imaging apparatus equipped with a static magnetic field generator comprising: a nuclear magnetic resonance imaging apparatus comprising a static magnetic field generating device, characterized in that a pair of slits for inserting magnetic field generating coils are formed extending laterally from both ends of the opening; It is.

(e) Effect By the above means, the coil can be taken in and out of the space using the slit and opening, and the opening area of the slit for inserting the coil is small, so leakage magnetic flux is small.

(F) Embodiment FIG. 1 shows a perspective view of a static magnetic field forming means for a nuclear magnetic resonance tomography apparatus employing the present invention.
Reference numeral 1 denotes a yoke made of a cylindrical magnetic material, and a strong and highly uniform magnetic flux exists within this cylinder. Reference numeral 2 denotes an opening formed in the side wall of the yoke 1, and has a shape such that an object to be imaged, such as a human body, can enter the yoke 1. Reference numerals 3 and 3 denote slits extending laterally from the opening 2, and are used to insert the coil A for generating a gradient magnetic field inside the yoke 1. This coil A is, for example, “THE REVIEW OF
SCIENTIFIC INSTRUMENTS”
VOLUME32, NUMBER3 MARCH, 1961
It is formed in the shape shown in P241 to P250.

Figure 2 is a central vertical cross-sectional view of Figure 1, with 4,4
is a circular permanent magnet made of neomax made of an alloy of iron, boron, and neodymium, and is provided at the center of the upper and lower end walls 5, 5 of the yoke 1. These permanent magnets 4, 4 are powerful, and the magnetic field energy BH reaches a maximum of 35 to 37 megagauss Oersted. Pole pieces 6, 6 are attached to opposing surfaces of the permanent magnets 4, 4, and have the function of making the magnetic flux within the yoke 1 uniform. Reference numeral 7 denotes a resin sheet that is adhered to the surfaces of the pole pieces 6, 6, the exposed surfaces of the permanent magnets 4, 4, and the front and back surfaces of the upper and lower end walls 5, 5 of the yoke 1 via silicone grease, and has an adhesive surface on the surface. have. FIG. 3 shows an enlarged view of how this resin sheet 7 is adhered to, for example, a pole piece 6. Silicone grease 8 is applied to the surface of the pole piece 6, and the adhesive surface 9 is coated with the silicone grease 8. A resin sheet 7 is attached to the side. As the resin sheet 7 having the adhesive surface 9, for example, Micro Duster (trade name) manufactured by Mitsubishi Rayon Co., Ltd. is used. This micro duster uses plastic film with adhesive on the surface.
A large number of plastic films are stacked together, and if magnetic dust adheres to the adhesive surface 9, the magnetic dust can be completely removed by peeling off the plastic film one by one, and the adhesive surface 9 can be easily renewed. .

(g) Effects of the Invention According to the present invention configured as described above, the coil insertion opening can be formed by adding a pair of slits without enlarging the overall shape of the object insertion opening. As a result, leakage of magnetic flux can be suppressed to a minimum, disturbances to the uniformity of the magnetic field can be reduced, and a static magnetic field generating device with good performance can be provided.

[Brief explanation of the drawing]

FIG. 1 is a perspective view of a static magnetic field forming means for a nuclear magnetic resonance tomography apparatus employing the present invention, FIG. 2 is a central vertical sectional view of FIG. 1, and FIG. 3 is an enlarged sectional view of the main part of the structure of the present invention. It is. 1... Yoke, 4... Permanent magnet, A... Coil.

Claims (1)

[Claims] 1 Nuclear magnetic resonance equipped with a static magnetic field generating device consisting of a pair of permanent magnets and a magnetic yoke that has an opening on the side surface for insertion of an object to be imaged and magnetically couples the permanent magnets and forms a nearly sealed space. 1. A nuclear magnetic resonance imaging device, characterized in that a pair of slits for inserting magnetic field forming coils are formed extending laterally from both ends of the opening.