JP4521311B2 - Magnetic resonance imaging system - Google Patents

Description

  The present invention relates to a magnetic resonance imaging apparatus (hereinafter referred to as “MRI apparatus”), and more particularly, to an open-type MRI apparatus that has less occlusion on a subject.

  An example of a conventional MRI apparatus is described in Patent Document 1. In the MRI apparatus described in Patent Document 1, in order to make it difficult for magnetic field fluctuations due to external excitation to occur, the coil container containing the super-electric coil is contained in the vacuum container and supported by the inner wall of the vacuum container with a support rod. . Further, the upper and lower coil containers are mechanically and thermally connected by the first connecting pipe.

Japanese Patent Laid-Open No. 2002-159466 (page 9, FIG. 1)

  In the MRI apparatus described in Patent Document 1, since the vacuum vessel is cantilevered with respect to the installation floor surface, the upper vacuum is mainly caused by the bending of the second connecting pipe that connects the vacuum vessels. The container vibrates. When the vacuum vessel vibrates, the coil vessel connected to the vacuum vessel also vibrates. Since the lower coil container is regulated by the floor surface, the amplitude of the lower coil container is smaller than the amplitude of the upper coil container. As a result, a relative displacement occurs between the superconducting coils accommodated in the upper and lower coil containers. When relative displacement occurs between the upper and lower superconducting coils, the magnetic resonance image deteriorates. In particular, when the static magnetic field strength and the gradient magnetic field strength are increased to improve the image quality, the vibration of the gradient magnetic field coil used to increase the magnetic field strength affects the magnetic resonance image.

  In order to solve the above problems, an MRI apparatus of the present invention includes a superconducting coil, a coil container that houses the superconducting coil, a heat shield that covers the coil container, and a vacuum container that houses the coil container and the heat shield, The coil container has an upper coil container, a lower coil container, and a coil container connecting portion, the vacuum container has an upper vacuum container and a lower vacuum container, and the coil container is supported from the lower vacuum container and is an upper vacuum container. And a temporary fastening mechanism for temporarily fastening the vacuum vessel and the heat shield.

  According to the present invention, since the lower vacuum vessel having a smaller vibration than the upper vacuum vessel supports the coil vessel, the vacuum vessel vibration due to the external excitation of the gradient magnetic field coil vibration and the installation floor vibration propagates to the superconducting coil. Can be suppressed. Further, it is possible to prevent the superconducting coil from vibrating and deteriorating the MR image.

  Furthermore, by having a mechanism for temporarily fastening the vacuum vessel and the heat shield (or coil vessel), the lower vacuum vessel supports the coil vessel and the coil vessel is free from the upper vacuum vessel. Even so, the strength capable of withstanding an impact load during transportation or the like can be maintained.

  The MRI apparatus irradiates a subject placed in a uniform static magnetic field with electromagnetic waves and detects a nuclear magnetic resonance signal generated from the subject. Then, the detected nuclear magnetic resonance signal is image-processed to obtain a magnetic resonance image representing the physical properties of the subject. In order to provide position information of the nuclear magnetic resonance signal, a gradient magnetic field is applied in a manner superimposed on the static magnetic field.

  An MRI apparatus that generates a static magnetic field in the vertical direction is more open to the subject than an MRI apparatus that generates a magnetic field in the horizontal direction, but it is difficult to generate a static magnetic field and reduce a leakage magnetic field. Yes. On the other hand, in an MRI apparatus that generates a static magnetic field in the vertical direction, it is necessary to increase the magnetic field strength to obtain a high-quality image. However, the image quality is greatly affected by external vibration or the like. Therefore, in the present invention, the vibration of the vacuum vessel due to external excitation of gradient magnetic field coil vibration and installation floor vibration is suppressed from propagating to the superconducting coil. In addition, by having a mechanism for temporarily fastening the vacuum vessel and the heat shield (or coil vessel), the lower vacuum vessel supports the coil vessel and the coil vessel is free from the upper vacuum vessel. However, the strength that can withstand an impact load during transportation or the like can be maintained.

A first embodiment of an MRI apparatus according to the present invention will be described with reference to FIGS. FIG. 1 is a longitudinal sectional view of an MRI apparatus, FIG. 2 is a perspective view thereof, FIG. 3 is a diagram for explaining a vibration mode, and FIG. 4 is an enlarged view of a fastening portion between an upper vacuum vessel and an upper heat shield.

  The MRI apparatus is obtained from a superconducting magnet apparatus, gradient magnetic field coils (hereinafter referred to as “GC”) 101a and 101b, a high-frequency coil, a bed 98 for placing a subject on the imaging space 99, and a subject. An image reconstruction device that forms a nuclear magnetic resonance image based on the magnetic resonance signal, a power supply device that supplies power to a superconducting magnet device, a GC, a high-frequency coil, and the like, and a control device that controls the MRI apparatus. The superconducting magnet device surrounds the coil container, the superconducting coils 11a and 11b arranged facing each other in the vertical direction across the imaging space 99, the coil containers 21a and 21b accommodating the superconducting coils 11a and 11b together with the refrigerant. And cryostats 51a and 51b including vacuum vessels 41a and 41b each having a built-in coil vessel and a heat shield and kept inside a vacuum, and vacuum vessels 41a and 41b, It is comprised from the vacuum vessel connection pipes 61 and 62 which connect and arrange | position a cryostat so that it may mutually oppose. The GC applies a gradient magnetic field superimposed on a static magnetic field, and gives position information of a nuclear magnetic resonance signal. The GCs 101a and 101b adopt a structure with a vacuum vessel attached. The high frequency coil irradiates electromagnetic waves.

  The superconducting coils 11 a and 11 b are wound in an annular shape and generate a uniform vertical static magnetic field in the imaging space 99. Superconducting coils 11a and 11b are accommodated in annular coil containers 21a and 21b, and are immersed in a refrigerant such as liquid helium stored in coil containers 21a and 21b. The superconducting coils 11a and 11b are cooled to a temperature exhibiting superconducting characteristics, and the cooling temperature is maintained. The coil container 21a is built in the vacuum container 41a, and the coil container 21b is built in the vacuum container 41b.

  Between the coil container 21a and the vacuum container 41a, and between the coil container 21b and the vacuum container 41b, heat shields 31a and 31b are provided for suppressing radiant heat from entering the coil container. The heat shields 31a and 31b are formed so as to cover the coil containers 21a and 21b. The refrigerant in the coil containers 21a and 21b and the heat shields 31a and 31b are cooled by a refrigerator (not shown).

  The coil containers 21a and 21b arranged up and down across the imaging space 99 are supported with a predetermined distance apart in the vertical direction using the coil container connecting pipes 22 and 23. The coil containers 21a and 21b are mechanically and thermally connected by the coil container connecting pipes 22 and 23.

  Tubular heat shield connection pipes 32 and 33 for connecting the heat shields 31a and 31b are disposed on the outer peripheral portions of the coil container connection pipes 22 and 23, respectively. The heat shield connecting pipes 32 and 33 support the heat shields 31a and 31b with a predetermined distance apart in the vertical direction. The coil containers 21a and 21b and the coil container connecting pipes 22 and 23 are covered by the heat shields 31a and 31b and the heat shield connecting pipes 32 and 33, thereby preventing heat from entering the coil containers 21a and 21b from the outside.

  The members constituting the superconducting magnet device such as the vacuum vessels 41a and 41b, the heat shields 31a and 31b, the coil vessels 21a and 21b, the vacuum vessel connecting pipes 61 and 62, and the heat shield connecting pipes 32 and 33 are mainly made of stainless steel or A non-magnetic metal material such as an aluminum alloy is used.

The coil containers 21a, 21b and the heat shields 31a, 31b are supported by the vacuum containers 41a, 41b via the support members 71-76. In the present embodiment, the lower heat shield 31b is directly supported by the lower vacuum vessel 41b via the support members 75 and 76. Here, the heat shield is not directly supported with respect to the upper vacuum vessel 41a, and is in a free state with respect to the upper vacuum vessel 41a. And the coil container which accommodates a superconducting coil is supported by the heat shield. Therefore, the coil container is also free with respect to the upper vacuum container 41a. In this way, the lower vacuum vessel, which has less vibration than the upper vacuum vessel, supports the coil vessel, so that the vacuum vessel vibration due to external excitation of gradient magnetic field coil vibration and installation floor vibration is prevented from propagating to the superconducting coil. it can.

As in the present embodiment, support members 71 and 73 may be provided between the upper coil container 21a and the upper heat shield 31a. In this case, the upper coil container 21a and the upper heat shield 31a are integrated by the support members 71 and 73, and the rigidity of the coil container 21a and the heat shield 31a is increased. As a result, excitation of the coil container due to vibration propagating through the support member is suppressed.

  Moreover, the heat insulation distance by a support member can be enlarged by not connecting a vacuum vessel and a coil container directly like this Example, but connecting a vacuum vessel and a coil container via a heat shield.

  In this embodiment, the vacuum vessel and the coil vessel are connected via the heat shield, but the coil vessel may be directly supported by the lower vacuum vessel 41b. That is, if the coil container can be made free with respect to the upper vacuum container 41a, it is possible to suppress the propagation of the vacuum container vibration due to the gradient magnetic field coil vibration or the like to the superconducting coil.

  Furthermore, the connection between the vacuum container and the coil container includes the indirect connection between the vacuum container and the coil container through the above-described heat shield, and the direct connection between the vacuum container and the coil container through no heat shield. And may be combined.

  A rod shape is used as the shape of the support members 71 to 76. As the shape of the support member, a single cylindrical shape, a multi-cylindrical shape or the like can be used in addition to the rod shape. In order to insulate the coil container and the heat shield from the vacuum container, the support member is made of a nonmagnetic material having a low thermal conductivity. For example, a fiber reinforced synthetic resin material such as a glass fiber reinforced epoxy resin can be used. If the heat insulation performance is the same, the rod and single cylinder are cheaper than the multiple cylinder. However, in the case of a rod shape and an end cylindrical shape, it is necessary to further increase the distance between connections.

  In this embodiment, the coil container is supported on the vacuum container by the support members 71, 72, and 75 that support the coil container in the vertical direction and the support members 73, 74, and 76 that support the coil container in the horizontal direction. You may support using the supporting member supported in the diagonal direction. Further, the support members 71 to 76 are arranged at intervals in the circumferential direction.

  The heat shield is held at a temperature between room temperature, which is the temperature of the outer peripheral portion of the vacuum vessel, and a superconducting temperature at which the coil vessel is cooled by the refrigerant. Therefore, a large temperature gradient is generated in the support members 71 to 76. The heat shield is preferably held between 60K and 70K. Therefore, considering the heat penetration from the support member, the heat capacity of the heat shield, and the refrigeration capacity of the refrigerator, so that the heat shield is maintained at this temperature, the mounting position, shape, number, and cross-sectional area of the support member Etc. The number of support members and the cross-sectional area of the support members are preferably as large as possible from the viewpoint of strength, but are preferably as small as possible from the viewpoint of suppressing heat penetration into the coil container. The length of the support member is preferably shorter from the viewpoint of strength, but the longer one is desirable from the viewpoint of suppressing heat penetration into the coil container.

  Next, the operation of the MRI apparatus will be described below. The vacuum vessels 41a and 41b vibrate due to external vibration such as GC vibration or installation floor vibration. The state of this vibration is exaggerated and shown in FIG. In the MRI apparatus, the vibration of the lower vacuum container 41b is restricted by the installation floor surface, and is smaller than the vibration of the upper vacuum container 41a. There is almost no vibration on the bottom surface of the lower vacuum vessel 41b, and it can be considered that the bottom vacuum vessel 41b is restrained by its own weight. That is, the bottom surface of the vacuum vessel 41b is ideally a node for vibration.

  In the present embodiment, since the lower vacuum container 41b with small vibration supports the coil container (via the heat shield), vibration propagating from the vacuum container to the coil container can be suppressed. Therefore, it is possible to suppress the vibration of the vacuum vessel from propagating to the superconducting coil housed in the coil vessel. As a result, a good nuclear magnetic resonance image can be obtained. The effect becomes remarkable by supporting the heat shield 31b (indirectly supporting the coil container 21b) from the bottom surface of the lower vacuum container 41b serving as a vibration node. Therefore, it is preferable to support the heat shield or the coil container from the bottom surface of the lower vacuum container 41b which becomes a vibration node.

  In this embodiment, the outer peripheral surface of the lower heat shield 31b is supported by the lower vacuum vessel 41b by the support member 75. Thereby, the overturning moment of a coil container can be enlarged compared with the case where it supports on an internal peripheral surface. As a result, the stability of the MRI apparatus is increased. Considering the space at the installation position, the inner peripheral surface of the lower heat shield 31b and the lower vacuum vessel 41b may be connected.

Further, the connection position of the support member of the lower vacuum vessel 41b is not limited to the bottom surface, and may be a side surface. However, when supporting from the side surface of the lower vacuum vessel 41b, it is preferable to bring the support position closer to the bottom surface of the lower vacuum vessel 41b. The reason is that the bottom surface of the lower vacuum vessel 41b is ideally a vibration node, and the vibration of the side surface increases as the distance from the bottom surface increases. That is, as the connection position moves away from the bottom surface, vibration that propagates to the coil container increases. In order to suppress the vibration of the side surface, the rigidity of the side surface may be increased.

In this embodiment, the vacuum containers 41a and 41b arranged on the upper and lower sides are connected by the two vacuum container connecting pipes 61 and 62. However, one or three vacuum containers 41 and 62 are generated if the openability is not impaired and sufficient supporting force is generated. You may connect with more than this vacuum vessel connecting pipe 4.

  In this embodiment, the coil container and the heat shield are not connected to the upper vacuum container 41a. However, in an actual MRI apparatus, a refrigerator, a liquid helium injection pipe, and the like are attached to the upper vacuum container 41a. Accessories are connected to the coil container and heat shield. Even in such a case, accessories such as a refrigerator are vibration-insulated in the vacuum vessel via the bellows, so the effect is not impaired.

  Here, in the MRI apparatus in which the coil container and the heat shield are not connected to the upper vacuum container 41a as in this embodiment, the superconducting coil, the coil container, the heat shield, and their own weights are added by the support members 71 to 76. Must support. Furthermore, the support member, the heat shield, and the like need to be strong enough to withstand the impact load during transportation. In the following, an MRI apparatus capable of avoiding damage to the support member and the heat shield due to impact during transportation will be examined.

  In order to maintain the positions of the superconducting coil, the coil container, the heat shield, the vacuum container, and the like, it is necessary to keep each positional relationship sound by the support member. Further, these supports are required to have high heat insulation performance. Here, as already described, in order to generate a gradient magnetic field in the MRI apparatus, a pulsed current is passed through the GC. Since GC is in a static magnetic field, Lorentz force acts on the conductor of GC through which current flows, and induces vibration in GC. This GC vibration is transmitted to a static magnetic field generation source via a support structure member or the like, and vibrates the static magnetic field generation source. The static magnetic field fluctuates in time due to the vibration of the static magnetic field generation source, and as a result, the MRI image is adversely affected. Therefore, in the present embodiment, a structure is adopted in which the vacuum vessel to which the GC is attached and the heat shield are connected only by the lower vacuum vessel 41b close to the restraining end, and the GC vibration is not easily transmitted to the static magnetic field generation source. However, a heat shield / coil container support using only the lower vacuum container 41b results in a support system that is close to a cantilever. Therefore, when receiving an impact such as transportation, the heat shield may be deformed by falling down, and an excessive load may be generated on the support member due to bending or axial force. Therefore, an MRI apparatus that can sufficiently suppress the deformation of the heat shield and the support member due to the impact of transportation or the like was examined.

  In the MRI apparatus of the present embodiment, the upper vacuum vessel 41a and the upper heat shield 31a are temporarily fastened in order to suppress deformation of the heat shield and the support member due to an impact such as transportation. Specifically, the upper vacuum vessel 41a and the upper heat shield 31a are temporarily fastened by connecting the temporary fastening device 82 connected to the upper vacuum vessel 41a to the upper heat shield 31a. The temporary fastening device 82 has a T-shaped cross-sectional shape. The upper vacuum vessel 41a is provided with an opening, and the convex portion of the temporary fastening device 82 is inserted into the vacuum vessel through this opening. A recess is formed on the upper heat shield 31 a by the heat shield seat 81. The upper vacuum vessel 41a and the upper heat shield 31a are interposed via the temporary fastening device 82 by fitting the convex portion of the temporary fastening device 82 (the T-shaped | portion) into the recess formed on the upper heat shield 31a. Is temporarily concluded. The recesses formed on the temporary fastening device 82 and the upper heat shield 31a are combined to form a “temporary fastening mechanism”.

  In this way, in addition to the connection between the lower vacuum container 41b and the heat shield that are permanently installed, by temporarily connecting the upper vacuum container 41a and the upper heat shield 31a far from this connection position (floor side). Even if an impact is applied to the heat shield or the like during transportation, an impact load flows to the upper vacuum vessel 41a via the temporary fastening device 82, and deformation of the heat shield or the like can be suppressed.

  The temporary fastening device 82 is attached to the upper vacuum vessel 41a via a fastening block 86 and a bellows 83 during fastening. The fastening block 86 is fastened between the temporary fastening device 82 and the upper vacuum vessel 41a, and adjusts the level of the temporary fastening device 82 in the height direction. In consideration of the distance between the upper vacuum vessel 41a and the upper heat shield 31a, the length of the convex portion of the temporary fastening device 82, and the like, the fastening fixed block 86 having a predetermined length is selected. By using a fixed block longer than a predetermined length, the fastening between the upper vacuum vessel 41a and the upper heat shield 31a can be released.

  FIG. 4 is an enlarged view of a fastening portion between the upper vacuum vessel 41a and the upper heat shield 31a. The temporary fastening device 82 is fixed to the upper vacuum vessel 41a by a fastening screw 89 at the time of fastening through a fastening block 86 at the time of fastening. The temporary fastening device 82 can be fixed by fastening with a fixing screw 89 at the time of fastening, welding or adhesion.

  FIG. 5 is a view showing a fastening portion when the fastening of the temporary fastening device 82 is released. The MRI apparatus according to the present invention temporarily fastens the upper vacuum vessel 41a and the upper heat shield 31a when transported to a predetermined location, but releases the fastening after transported to the predetermined location. This is to make the coil container free with respect to the upper vacuum container 41a when using the MRI apparatus. The procedure for releasing the fastening of the temporary fastening device 82 is shown below. First, the fastening screw 89 at the time of fastening is removed from the temporary fastening device 82, the fastening block 86 at the time of fastening, and the upper vacuum vessel 41a. A jack is inserted between the temporary fastening device 82 and the upper vacuum vessel 41a, and the temporary fastening device 82 attracted to the vacuum vessel side by a vacuum force is pulled away from the upper vacuum vessel 41a. Next, the loose fixing block 86 is removed. Next, the temporary fastening device 82 is further lifted to a predetermined position by a jack. When the temporary fastening device 82 reaches a predetermined position, the fastening release fixing block 91 is installed between the temporary fastening device 82 and the upper vacuum vessel 41a. Thereafter, the jack is loosened to eliminate the gap between the fastening block 91 at the time of fastening release and the temporary fastening device 82, and the fastening screw 90 at the time of fastening release is tightened. Other than during transportation, etc., by releasing the fastening between the upper vacuum vessel 41a and the upper heat shield 31a, heat intrusion into the heat shield or the like due to contact heat transfer can be suppressed.

  By connecting the bellows 83 to the temporary fastening device 82 and the upper vacuum container 41a, it is possible to fix and release the fastening block 86 at the time of fastening and the fastening block 91 at the time of fastening release while maintaining the vacuum. Since the work can be performed with the vacuum held, the restoration work time at the transportation destination can be reduced as compared with the case where the vacuum is not held.

  According to the present invention, since the lower vacuum vessel, which has lower vibration than the upper vacuum vessel, supports the coil vessel, the vacuum vessel vibration due to external excitation of GC vibration or installation floor vibration propagates to the superconducting coil. Can be suppressed. Further, it is possible to prevent the superconducting coil from vibrating and deteriorating the MR image. Furthermore, even if the MRI has a mechanism for temporarily fastening the upper vacuum vessel and the upper heat shield, the lower vacuum vessel supports the coil vessel and the coil vessel is free from the upper vacuum vessel. It is possible to maintain the strength that can withstand impact loads during transportation.

  FIG. 6 is a diagram showing a second embodiment of the present invention, and shows an enlarged view near the fastening portion. In this embodiment, a shaft seal 85 is employed instead of the bellows 83 which is the vacuum seal mechanism of the first embodiment.

  Here, the shaft seal 85 has an O-ring shape. The material is composed of an elastic member such as rubber. The shaft seal 85 is connected to the inner surface of the opening of the upper vacuum vessel 41a. The inner surface of the shaft seal is in close contact with the outer periphery of the convex portion of the temporary fastening device 82. Even when the convex portion of the temporary fastening device 82 moves up and down, the inner surface of the shaft seal keeps in close contact with the outer periphery of the convex portion of the temporary fastening device 82. By providing such a shaft seal, like the bellows 83, it is possible to fix and release the fixing block 86 and the like during fastening while maintaining a vacuum.

  This embodiment also has the same effect as the first embodiment. Furthermore, by adopting the shaft seal 85 as the vacuum seal mechanism, even if the vacuum seal mechanism is damaged, it can be replaced more quickly than the bellows attached by welding, etc., and the MRI system can be restored. Can be shortened.

  FIG. 7 is a view showing a third embodiment of the present invention, and shows an enlarged view near the fastening portion. This embodiment employs an adjustment screw 84 in place of the jack used for level adjustment in the height direction of the temporary fastening device 82 in the first embodiment. By adopting the adjustment screw 84, the level adjustment in the height direction of the temporary fastening device 82 is facilitated.

FIG. 8 is a diagram illustrating a fastening portion when the fastening of the temporary fastening device 82 is released. The procedure for releasing the fastening of the temporary fastening device 82 is shown below. First, the fastening screw 89 at the time of fastening is removed from the temporary fastening device 82, the fastening block 86 at the time of fastening, and the upper vacuum vessel 41a. Next, the temporary fastening device 82 is pulled away from the upper vacuum vessel 41a by using an adjustment screw (by turning the adjustment screw so that the distance between the temporary fastening device 82 and the upper vacuum vessel 41a becomes longer). The fixing block 86 is removed when loosened. Using the adjusting screw, the temporary fastening device 82 is further lifted to a predetermined position. When the temporary fastening device 82 reaches a predetermined position, the fastening release fixing block 91 is installed between the temporary fastening device 82 and the upper vacuum vessel 41a. The adjustment screw is turned so that the distance between the temporary fastening device 82 and the upper vacuum vessel 41a becomes shorter, and the gap between the temporary fastening device 82 and the fastening block 91 at the time of fastening is eliminated. After that, the fastening screw 90 is fastened to the temporary fastening device 82, the fastening block 91 and the upper vacuum vessel 41a.

  This embodiment also has the same effect as the first embodiment. Furthermore, by employing the adjustment screw 84, fine adjustment of the height direction level of the temporary fastening device 82 becomes easier, and the time for fastening and releasing work of the temporary fastening mechanism can be shortened.

  FIG. 9 is a view showing a fourth embodiment of the present invention, and shows an enlarged view near the fastening portion. In this embodiment, the convex portion of the temporary fastening device 82 has a tapered structure whose diameter decreases conically as it goes to the tip. On the other hand, the concave portion formed on the upper heat shield 31 a has a taper structure corresponding to the convex portion of the temporary fastening device 82.

  This embodiment has the same effect as the first embodiment. Furthermore, in order to employ the taper structure in which the concave portion formed on the upper heat shield 31a and the convex portion of the temporary fastening device 82 are combined, the convex portion of the temporary fastening device 82 is provided in the concave portion formed on the upper heat shield 31a. Even if a slight misalignment occurs during fitting, it can be easily inserted.

  FIG. 10 is a diagram showing a fifth embodiment of the present invention. In this embodiment, a plurality of temporary fastening mechanisms in the first embodiment are arranged on the upper surface of the MRI apparatus. In the present embodiment, since a plurality of temporary fastening mechanisms are used, the load on each temporary fastening mechanism is reduced, and the shape of each temporary fastening mechanism can be reduced.

  FIG. 11 is a diagram showing a sixth embodiment of the present invention. In this embodiment, the temporary fastening mechanism in the first embodiment is arranged on the side of the MRI apparatus. In this embodiment, since the temporary fastening mechanism is arranged on the side of the MRI apparatus, an increase in the height direction of the MRI apparatus shape due to the installation of the temporary fastening mechanism can be avoided.

  FIG. 12 is a diagram showing a seventh embodiment of the present invention. In this embodiment, the temporary fastening mechanism in the first embodiment is arranged on the upper and side surfaces of the MRI apparatus. In the present embodiment, since a plurality of temporary fastening mechanisms are arranged on the upper surface and side surfaces, the entire MRI apparatus can be downsized even when the temporary fastening mechanisms are installed.

  In each of the above embodiments, the upper vacuum vessel 41a and the upper heat shield 31a are fastened using a temporary fastening mechanism. When the upper vacuum vessel 41a and the upper coil vessel 21a are fastened, it is necessary to form an opening in the upper heat shield 31a, but by fastening the upper vacuum vessel 41a and the upper heat shield 31a, the upper heat shield 31a. It is not necessary to form an opening in the opening and to close the hole of the opening after releasing the temporary fastening.

  On the other hand, the upper vacuum vessel 41a and the upper coil vessel 21a may be fastened. Alternatively, the upper vacuum vessel 41a, the upper heat shield 31a, and the upper coil vessel 21a may be fastened. In this case, since the upper vacuum vessel 41a and the upper coil vessel 21a can be directly fastened, the impact load during transportation can be distributed over a wider range.

Sectional drawing which shows the 1st Example of the MRI apparatus of this invention. The perspective view of the MRI apparatus of this invention. The figure explaining the vibration mode of the MRI apparatus of this invention. Sectional drawing which shows the 1st Example of the MRI apparatus of this invention. Sectional drawing which shows the 1st Example of the MRI apparatus of this invention. Sectional drawing which shows the 2nd Example of the MRI apparatus of this invention. Sectional drawing which shows the 3rd Example of the MRI apparatus of this invention. Sectional drawing which shows the 3rd Example of the MRI apparatus of this invention. Sectional drawing which shows the 4th Example of the MRI apparatus of this invention. Sectional drawing which shows the 5th Example of the MRI apparatus of this invention. Sectional drawing which shows the 6th Example of the MRI apparatus of this invention. Sectional drawing which shows the 7th Example of the MRI apparatus of this invention.

Explanation of symbols

11a, 11b ... superconducting coil, 21a, 21b ... coil container, 31a, 31b ... heat shield, 41a, 41b ... vacuum container, 71, 72, 73, 74, 75, 76 ... support member, 81 ... heat shield seat, 82 ... temporary fastening device.

Claims (12)

An annular superconducting coil disposed vertically opposite to the coil container, a coil container for housing the superconducting coil, a heat shield formed so as to cover the coil container, and the coil container and the heat shield are accommodated. An MRI apparatus comprising a vacuum vessel,
The coil container includes an upper coil container and a lower coil container that are positioned above and below the imaging space, and a coil container connecting portion that connects the upper coil container and the lower coil container,
The vacuum container has an upper vacuum container formed so as to cover the upper coil container, and a lower vacuum container formed so as to cover the lower coil container,
The coil container is supported directly or indirectly from the lower vacuum container, and is free from the upper vacuum container.
A magnetic resonance imaging apparatus comprising a temporary fastening mechanism for temporarily fastening the vacuum vessel and the heat shield. An annular superconducting coil disposed vertically opposite to the coil container, a coil container for housing the superconducting coil, a heat shield formed so as to cover the coil container, and the coil container and the heat shield are accommodated. An MRI apparatus comprising a vacuum vessel,
The coil container includes an upper coil container and a lower coil container that are positioned above and below the imaging space, and a coil container connecting portion that connects the upper coil container and the lower coil container,
The vacuum container has an upper vacuum container formed so as to cover the upper coil container, and a lower vacuum container formed so as to cover the lower coil container,
The coil container is supported directly or indirectly from the lower vacuum container, and is free from the upper vacuum container.
The heat shield has an upper heat shield formed to cover the upper coil container,
A magnetic resonance imaging apparatus comprising a temporary fastening mechanism for temporarily fastening the upper vacuum vessel and the upper heat shield. An MRI apparatus comprising an annular superconducting coil disposed vertically opposite, a coil container that houses the superconducting coil, and a vacuum container that houses the coil container,
The coil container includes an upper coil container and a lower coil container that are positioned above and below the imaging space, and a coil container connecting portion that connects the upper coil container and the lower coil container,
The vacuum container has an upper vacuum container formed so as to cover the upper coil container, and a lower vacuum container formed so as to cover the lower coil container,
The coil container is supported directly or indirectly from the lower vacuum container, and is free from the upper vacuum container.
A magnetic resonance imaging apparatus comprising a temporary fastening mechanism for temporarily fastening the upper vacuum container and the upper coil container.   4. The magnetic resonance imaging apparatus according to claim 1, wherein the coil container is supported by the heat shield. The temporary fastening mechanism according to claim 1 or 2,
A temporary fastening device connected to the vacuum vessel and having a convex portion in the direction of the heat shield from the vacuum vessel;
Connected to the heat shield, and having a recess formed on the heat shield and at a position facing the protrusion.
A magnetic resonance imaging apparatus for temporarily fastening the vacuum vessel and the heat shield by inserting the convex portion into the concave portion. The temporary fastening mechanism according to claim 3,
A temporary fastening device connected to the vacuum vessel and having a convex portion from the vacuum vessel toward the coil vessel;
Connected to the coil container, and having a recess formed on the coil container at a position facing the protrusion.
A magnetic resonance imaging apparatus for temporarily fastening the vacuum vessel and the coil vessel by inserting the convex portion into the concave portion.   7. The magnetic resonance imaging apparatus according to claim 5, wherein the convex portion has a tapered structure whose diameter decreases in a conical shape toward the tip, and the concave portion has a tapered structure corresponding to the convex portion.   8. The magnetic resonance imaging apparatus according to claim 5, wherein the temporary fastening device is connected to the vacuum vessel via a block that adjusts a distance between the vacuum vessel and the temporary fastening device.   9. The temporary fastening mechanism according to claim 5, wherein the temporary fastening mechanism has an adjustment screw penetrating the temporary fastening device and having a tip thereof directed toward the outer surface of the vacuum vessel, and rotating the adjustment screw to rotate the adjustment screw. A magnetic resonance imaging apparatus for adjusting a distance between a vacuum container and the temporary fastening device.   The magnetic resonance imaging apparatus according to claim 1, wherein the temporary fastening mechanism is located on an upper surface of the upper vacuum container.   The magnetic resonance imaging apparatus according to claim 1, wherein the temporary fastening mechanism is located on a side surface of the upper vacuum container. The coil container is supported from the lower vacuum container according to any one of claims 1 to 11, wherein the coil container is supported directly or indirectly from an inner surface of the bottom surface of the lower vacuum container via a support member. Magnetic resonance imaging device.

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