JP6619417B2 - Magnetic resonance imaging system - Google Patents

Description

  The present invention relates to a magnetic resonance imaging apparatus (hereinafter referred to as an MRI (Magnetic Resonance Imaging) apparatus).

An MRI apparatus is an apparatus that measures and images an NMR signal generated by spins of nuclei constituting a tissue of a subject (for example, a human body). Since the obtained image is used for medical purposes such as diagnosis, a high-quality image is required. Since the intensity of the NMR signal generated by the nuclear spin is proportional to the intensity of the static magnetic field in the measurement region, the resolution of images such as tomographic images can be improved by increasing the intensity of the static magnetic field. For this reason, a superconducting magnet capable of generating a high-intensity magnetic field is used as a static magnetic field generator of an MRI apparatus.

A superconducting magnet uses a superconducting coil cooled to a temperature at which it transitions to a superconducting state. The superconducting coil is formed by winding a superconducting wire around a coil bobbin, and the gap between the superconducting wires is filled with resin and hardened. The superconducting coil transitions to a superconducting state when, for example, liquid helium is used as a refrigerant and is cooled to 4.2 Kelvin, which is the boiling point of liquid helium. The superconducting coil is supplied with a current for generating a static magnetic field after cooling, and in a state where the generated magnetic field strength reaches the rated magnetic field strength, a circuit called a superconducting switch is closed to a closed loop state in which a permanent current flows. Become. In this way, a superconducting state in which a predetermined permanent current continues to flow is maintained, and the static magnetic field is maintained at the rated magnetic field strength.

When a phenomenon occurs in which a part of the superconducting coil transitions from the superconducting state to the normal conducting state (quenching) for some reason while the superconducting coil is maintained in the superconducting state, a large amount of liquid helium is consumed. Therefore, in order to start up the superconducting magnet again, it is necessary to re- inject liquid helium, and a large loss occurs in terms of human and time. For this reason, it is important to suppress the occurrence of quenching.

  Regarding the occurrence of quench, for example, as described in Patent Document 1, the superconducting wire of the superconducting coil moves several μm due to some disturbance in the permanent current mode in which the permanent current is maintained, or the superconducting wire is moved. If the resin to be hardened is cracked, local heat generation occurs. When the temperature of the superconducting wire rises above the critical temperature due to the heat generation, a quench occurs in which a part of the superconducting coil transitions from the superconducting state to the normal conducting state.

As a method for suppressing the occurrence of quenching, for example, Patent Document 1 presumes that the cause of superconducting wire movement or resin cracking is “aging” of the superconducting coil.
Based on this estimation, we proposed to accelerate the secular change of the internal structure of the superconducting coil in advance by repeating excitation and demagnetization of the superconducting magnet or passing an overcurrent. It is stated that it is possible to suppress the occurrence of a sudden quench during a period in which a permanent current over a period of time is maintained.

  Patent Document 2 proposes a structure capable of suppressing the occurrence of quenching as a structure of a coil bobbin for winding a superconducting coil in an open-type MRI apparatus that can reduce a sense of blockage to a subject. .

JP 2006-324411 A International Publication No. 2014/050621

  It is difficult to confirm whether or not the method proposed in Patent Document 1 described above that accelerates the secular change in advance and suppresses quenching can achieve sufficient results. It would be desirable to allow quench suppression in a more reliable manner. Further, the MRI apparatus using the coil bobbin proposed in Patent Document 2 has various problems in terms of productivity.

  An object of the present invention is to provide an MRI apparatus with excellent productivity that can reduce the occurrence of quenching.

An MRI apparatus that solves the above-described problem includes a pair of superconducting magnets that are arranged to face each other with an imaging space in which a static magnetic field is to be formed therebetween, a gradient magnetic field generator, and an RF pulse irradiation coil. Each of the superconducting magnets includes a main coil, a shield coil for suppressing the leakage magnetic field of the main coil, and a coil bobbin. When the Z axis is defined in the direction of opposing arrangement, the main coil is Z at the center. An annular shape having an axis, opposed to the imaging space to hold the main coil, and further disposed along the imaging space side of the main coil to support the main coil, and the Z axis of the support plate An inner peripheral side support member for fixing the side to the coil bobbin, and an outer peripheral side support member for fixing the outer peripheral side of the support plate opposite to the Z axis of the support plate to the coil bobbin. The main coil is placed between And, characterized in that.

  According to the present invention, it is possible to obtain an MRI apparatus that can reduce the occurrence of quenching and has excellent productivity.

Explanatory drawing explaining the whole structure of one Embodiment of this invention Sectional view of the MRI main body of the embodiment shown in FIG. Explanatory drawing explaining the structure of the coil bobbin shown in FIG. Explanatory drawing showing the method of manufacturing the main coil shown in FIG. 2 and FIG. Explanatory drawing explaining other embodiment of this invention. Explanatory drawing explaining further another embodiment of this invention. Explanatory drawing explaining the manufacturing method of the main coil shown in FIG. Explanatory drawing explaining further another embodiment of this invention.

1. Introduction An embodiment of the present invention will be described with reference to the drawings as appropriate. In addition, the structure which attached | subjected the same code | symbol in drawing to refer performs a substantially similar effect | action, and there exists a substantially similar effect. In order to avoid duplication of explanation, repeated explanation regarding the configuration of the same reference numerals is omitted. Further, the following embodiments not only solve the problems of the invention described above and achieve the effects of the invention described above, but also solve problems other than the problems of the invention described above, and exhibit effects other than the effects described above.

2. Description of Overall Configuration of MRI Apparatus 100 According to One Embodiment of the Present Invention The overall configuration of the MRI apparatus 100 according to one embodiment of the present invention will be described with reference to FIG. The MRI apparatus 100 mounts the control device 110, the MRI main body 200 having the wide opening 202 formed to place the subject 102 and the imaging space 204 formed in the center of the opening 202, and the subject 102 A couch 180 having a top plate 182 for performing the above.

  The control device 110 includes an input / output device 120 for performing an operation for capturing an MRI image, inputting necessary data, or displaying necessary information including the captured image. A processing device 130 that performs control related to the entire apparatus 100, performs necessary arithmetic processing or image processing, stores necessary data in a storage device (not shown), or reads data from the storage device, and imaging operation Therefore, an imaging control device 140 that controls and drives each device provided in the MRI main body 200 is included. The input / output device 120 includes a display device 122 for displaying information including images, and an input device 124 for performing operations and inputting information. Although the MRI main body 200 and the bed 180 are also provided with input / output devices, the description and explanation thereof are omitted.

The MRI main body 200 will be described in detail. An upper superconducting magnet 300 and a lower superconducting magnet 302 are provided in the vertical direction, and these are supported by a column 206 and a column 208. The positions of the support pillars 206 and the support pillars 208 do not need to be determined in particular, but in this embodiment, they are provided opposite to each other with the imaging space 204 as an example. For example, the positions of the columns 206 and 208 may be shifted in the opposite direction of the bed 180.

  In order to help understand the explanation of the MRI main body 200, in this specification, the center of the imaging space (observation region) 204 is the origin, the body axis direction of the subject 102 is the X axis, and the left and right faces across the imaging space 204 Then, a rectangular coordinate is set with the direction of the column 206 and column 208 provided as the Y axis and the height direction as the Z axis. The Y axis is a direction perpendicular to the X axis and indicates the horizontal direction, and the Z axis is a direction perpendicular to the X axis and the Y axis and indicates the height direction.

  The bed 180 can place the subject 102 to be examined and move the subject 102 to an appropriate position. The subject 102 placed on the top plate 182 can move in the Z-axis direction that is the height direction and can move in the X-axis direction that is the body axis direction. Furthermore, since the MRI main body 200 has a wide opening 202, it can move in the Y-axis direction, which is the horizontal direction. The bed 180 may also have a structure that has wheels and can move in a state where the subject is placed.

3.Explanation of imaging operation by imaging controller 140 and MRI main unit 200
3.1 Configuration of Imaging Control Device 140 The processing device 130 sends an imaging command and a control signal to the imaging control device 140 in accordance with an imaging instruction, and generates a drive signal for causing an NMR phenomenon from the imaging control device 140 to the MRI body 200. send. In order to cause the NMR phenomenon, the MRI main body 200 generates the above-described superconducting magnets 300 and 302 for generating a static magnetic field, a gradient magnetic field generator for generating a gradient magnetic field, and a high-frequency magnetic field (hereinafter referred to as RF) pulse. An RF irradiation coil for irradiation is provided.

  It also has an NMR receiver coil for receiving NMR signals generated by the NMR phenomenon. The imaging control device 140 includes a sequencer 142 for controlling the imaging operation, an RF current supply device 144 that supplies a drive current for driving the RF pulse irradiation coil based on a control signal from the sequencer 142, and a gradient magnetic field generator. It has a gradient magnetic field power source 146 for driving, and a signal processing device 148 for processing NMR signals.

3.2 Description of Configuration of MRI Main Body 200 for Inducing NMR Phenomenon AA cross-sectional view of the MRI main body 200 shown in FIG. 1 taken along the Y axis in the Z-axis direction is shown in FIG. 1 and 2, the MRI main body 200 has a circular shape or a substantially circular outer shape centered on the Z axis, and an observation region for imaging the region of the subject 102 at the upper and lower central portions on the Z axis ( Imaging space) 204 is formed, and an opening 202 that is a wider space around the observation region 204 is formed. In order to obtain a clearer image, it is desirable to generate a uniform and strong magnetic field in the observation region 204. In order to generate a uniform and strong static magnetic field in the observation region 204, the MRI main body 200 is provided with an upper superconducting magnet 300 and a lower superconducting magnet 302.

A plane that passes through the origin of the rectangular coordinate system that is the center of the imaging space 204 and is perpendicular to the Z axis, that is, a plane that overlaps the Y axis is set as the symmetry plane 201. The upper superconducting magnet 300 and the lower superconducting magnet 302 are arranged to face each other and have a symmetrical relationship with respect to the symmetry plane 201.

An upper RF pulse irradiation coil 214 and a lower RF pulse irradiation coil 215 are provided so as to sandwich the observation region 204. Further, the upper gradient magnetic field generator 210 and the lower RF pulse irradiation coil 215 are disposed so as to sandwich the upper RF pulse irradiation coil 214 and the lower RF pulse irradiation coil 215. A side gradient magnetic field generator 211 is provided. Further, an upper superconducting magnet device 300 and a lower superconducting magnet 302 are provided so as to sandwich the upper gradient magnetic field generator 210 and the lower gradient magnetic field generator 211. Although not shown, an NMR receiving coil for receiving an NMR signal emitted by an NMR phenomenon close to the subject 102 in a space sandwiched between the upper RF pulse irradiation coil 214 and the lower RF pulse irradiation coil 215 is provided. Provided.

3.3 Description of Superconducting Magnet According to One Embodiment of the Present Invention In the MRI main body 200 shown in FIGS. 1 and 2, the upper superconducting magnet 300 and the lower superconducting magnet 302 that are a pair of superconducting magnets that generate a static magnetic field are included in the imaging space. They are arranged opposite to each other in the Z-axis direction across 204, and have a symmetric shape and configuration with respect to the symmetry plane 201. In the MRI apparatus 100 having such a structure, the opening 202 can be formed very widely, giving the subject 102 a feeling of opening and improving the workability of imaging. All of the MRI apparatuses 100 described below have such an open structure. As another method of the MRI apparatus 100, there is a method in which a cylindrical space is formed in the body axis direction of the subject and a static magnetic field is generated in the body axis direction of the subject. Such an MRI apparatus that generates a static magnetic field in the body axis direction is hereinafter referred to as a cylindrical MRI apparatus.

The inventors examined in detail how the internal structure of the superconducting magnet of the MRI apparatus changes in the superconducting state. As a result, specific structural change which does not occur in the superconducting magnet apparatus of the cylindrical MRI apparatus, it was found that place in the superconducting magnet apparatus of the open type MRI apparatus 100.

For example, in the upper superconducting magnet 300 or the lower superconducting magnet 302 of the open MRI apparatus 100, the coil bobbin is easily deformed by the electromagnetic force acting on the main coil, and the main coil is likely to be distorted in accordance with the deformation of the coil bobbin. In the superconducting magnet device of the open type MRI apparatus 100, the upper and lower coil bobbins are connected at, for example, two locations, and this portion serves as a fulcrum so that the coil bobbin is easily deformed in three dimensions.

If the main coil is distorted as described above and this distortion becomes excessive, the resin impregnated to fill the gaps in the superconducting wire is cracked, or the superconducting wire moves and quenching is likely to occur. I understood. It has been found that the deformation of the coil bobbin occurs on the end plate of the coil bobbin, which is a plate-like member that holds the main coil from the opposing surface side of the pair of superconducting magnets . In addition to this, in the conventional open superconducting magnet apparatus, the main coil is directly wound around the coil bobbin.

For this reason, although it is necessary to manufacture a coil slot, since it becomes deep groove processing, there exists a subject which productivity falls. For this reason, conventionally, there is a tendency that the cost tends to be high. On the other hand, in the cylindrical superconducting magnet apparatus, the entire coil bobbin has an integral structure, and thus the above-described deformation does not occur. As described above, it has been found that the problems are greatly different between the cylindrical MRI apparatus and the open type MRI apparatus 100.

  In the present embodiment, the main coil is not wound directly on the coil bobbin, but the main coil is manufactured by winding a superconducting wire by another operation, and then the manufactured main coil is combined with the coil bobbin main body. By doing in this way, the structure of a coil bobbin can be simplified and productivity can be improved. More importantly, in this embodiment, by supporting the main coil at both ends, it is possible to suppress deformation of the main coil, and it is possible to reduce the deformation of the main coil and reduce the distortion of the main coil. Hereinafter, this embodiment will be specifically described with reference to the drawings.

4. Specific Structure of Superconducting Magnet Device According to One Embodiment of the Present Invention FIG. 2 is a cross-sectional view of the upper superconducting magnet 300 and the lower superconducting magnet 302 of the first embodiment, and FIG. 3 is an upper superconducting magnet. 2 is a cross-sectional perspective view of a coil bobbin used for 300 and a lower superconducting magnet 302. FIG. Incidentally coil bobbin used in the upper superconducting magnet 300 and the lower superconducting magnet 302 is in the form of a symmetrical, shows a coil bobbin of the upper superconducting magnet 300 as a representative, by using this coil bobbin, the upper superconducting magnet 300 and the lower superconducting magnets The operation and effect of the coil bobbin 302 will be described.

The superconducting magnet device has a pair of upper superconducting magnet 300 and lower superconducting magnet 302 that are opposed to each other across the imaging space 204, and these include a coupling mechanism 252 provided inside the column 206 and the column 208, respectively. They are connected by a connecting mechanism 254. The upper superconducting magnet 300 and the lower superconducting magnet 302 are symmetrical in shape and structure with respect to the plane of symmetry 201, and have the same effect and the same effect. Therefore, the upper superconducting magnet 300 will be mainly described. A description of the superconducting magnet 302 is omitted.

The upper superconducting magnet 300 and the lower superconducting magnet 302 have a circular shape centered on the Z axis shown in FIG. 2, and in the cross-sectional view shown in FIG. Shape. Each of the pair of upper superconducting magnet 300 and lower superconducting magnet 302 includes a main coil 310, a shield coil 320 for suppressing a leakage magnetic field of the main coil 310, and a coil bobbin 330. The coil bobbin 330 includes a cylindrical member 332 around which the main coil 310 is wound, and a support plate 362 that supports the main coil 310 from the symmetry plane 201 side so as to oppose electromagnetic force in the direction of the symmetry plane 201 acting on the main coil 310. And a supporting member 360 having the same.

  In this drawing, the cylindrical member 332 has a separate structure from the coil bobbin 330. The cylindrical member 332 is configured as a separate member from the coil bobbin 330. With the cylindrical member 332 separated from the coil bobbin 330, the cylindrical member 332 is used as an inner peripheral member of the coil and a superconducting wire is wound to superconduct The coil is formed, and thus the main coil 310 is manufactured as a separate operation. Thereafter, the main coil 310 manufactured using the cylindrical member 332 as an inner peripheral member is assembled to the coil bobbin 330. This eliminates the need to wind a superconducting wire directly around the coil bobbin 330. The support member 360 for fixing the main coil 310 to the coil bobbin 330 can be a member having an L-shaped cross section.

  The L-shaped support member 360 has a support plate 362 for supporting the main coil 310 and an outer peripheral side support member 361 for fixing the outer peripheral side of the support plate 362 to the end plate 334 of the coil bobbin 330. The outer peripheral side of the support plate 362 is fixed to the end plate 334 of the coil bobbin 330 by the outer peripheral side support member 361. The inner peripheral side which is the other end of the support plate 362 of the support member 360 having an L-shaped cross section is fixed to the end plate 334 of the coil bobbin 330 together via the cylindrical member 332. The cylindrical member 332 functions as an inner peripheral side support member for fixing the inner peripheral side of the support plate 362 of the support member 360 having an L-shaped cross section to the end plate 334 of the coil bobbin 330. The main coil 310 is held between the support plate 362 and the end plate 334 of the coil bobbin 330. 2 and 3, the support member 360 and the cylindrical member 332 are fixed to the coil bobbin 330 using the bolts 372, but they may be fixed using welding or the like.

When the main coil 310 is generating a magnetic field in a superconducting state, forces attracting each other act on the main coil 310 of the upper superconducting magnet 300 and the main coil 310 of the lower superconducting magnet 302. In this embodiment, the main coil 310 is fixed and supported on the inner side by the support plate 362 of the support member 360, the outer peripheral side of the support plate 362 is fixed to the coil bobbin 330 by the outer peripheral side support member 361, The peripheral side is configured to be fixed to the coil bobbin 330 via a cylindrical member 332 that acts as an inner peripheral side support member.

  Therefore, the main coil 310 arranged in a circle around the Z axis is supported by the support plate 362 of the support member 360 over the entire surface on the side of the symmetry plane 201. Further, the support member 360 is structured to be fixed to the end plate 334 of the coil bobbin 330 on both the outer peripheral side and the inner peripheral side in the radial direction of the main coil 310. Therefore, the surface of the support member 360 that supports the main coil 310 has a structure that is not easily distorted. That is, the support surface of the support plate 362 of the support member 360 that supports the main coil 310 can be prevented from being three-dimensionally distorted. Therefore, the main coil 310 is hardly distorted and can suppress the occurrence of quenching.

  The support member 360 described above is an annular member corresponding to the annular end plate 334. Since the end plate 334 and the support member 360 have an annular shape centered on the Z-axis, it is possible to prevent stress from being concentrated and to prevent distortion. Further, by making the cross section of the support member 360 L-shaped, twisting hardly occurs and the three-dimensional distortion can be suppressed.

As shown in FIG. 2, the superconducting magnet device used in the open-type MRI apparatus 100 has an upper superconducting magnet 300 and a lower superconducting magnet 302 that are paired in the vertical direction that is the Z direction across the imaging space 204. Is arranged. The upper superconducting magnet 300 and the lower superconducting magnet 302 form a stable static magnetic field having a highly accurate uniformity in the imaging space 204.

The inside of the refrigerant container 402 is filled with liquid helium, which is a cooling refrigerant, and coil bobbins 330 are provided at the upper and lower ends of the refrigerant container 402, respectively, and the coil bobbin 330 functions as a part of the refrigerant container 402. doing. A coil bobbin 330 for the upper superconducting magnet 300 and a coil bobbin 330 for the lower superconducting magnet 302 are supported by a coupling mechanism 252 and a coupling mechanism 254 that are arranged to face each other along the Y axis across the imaging space 204. Yes.

The superconducting magnet device having the upper superconducting magnet 300 and the lower superconducting magnet 302 has a vacuum vessel 406 having a vacuum inside to suppress heat conduction, and suppresses heat radiation inside the vacuum vessel 406. A shield plate 404 is provided. A refrigerant container 402 that fills the cooling refrigerant is provided inside the shield plate 404. The main coil 310 and the shield coil 320 are cooled by the refrigerant in the refrigerant container 402.

  For example, liquid helium is used as the refrigerant. As a superconducting wire used for the main coil 310 and the shield coil 320, for example, an alloy superconductor wire such as NbTi can be used. In the embodiment of FIG. 2, the main coil 310 is formed by winding the above-described superconducting wire around the cylindrical member 332 as described above, and the formed main coil 310 is then used as the coil bobbin 330 using the support member 360. To fix. The shield coil 320 is wound around the coil bobbin 330. The coil bobbin 330 is formed using, for example, a nonmagnetic metal such as SUS304 or an aluminum alloy.

The main coils 310 of the upper superconducting magnet 300 and the lower superconducting magnet 302 each generate a magnetic field having the same direction in the Z-axis direction, thereby forming a uniform static magnetic field in the imaging space 204. The shield coils 320 of the upper superconducting magnet 300 and the lower superconducting magnet 302 are provided in order to cancel out the leakage of the magnetic field generated by the main coil 310 to the outside, and are opposite to the main coil 310 in the Z-axis direction. Generate a magnetic field in the direction.

  As described above with reference to FIG. 3, the coil bobbin 330 has an annular shape centered on the Z axis. The annular coil bobbin 330 has a main coil bobbin support part 336 for supporting the main coil 310, a shield coil bobbin part 338 for supporting the shield coil 320, and a housing part 340. The main coil bobbin support part 336 The shield coil bobbin portion 338 and the housing portion 340 are integrated.

The housing part 340 connects and integrates the main coil bobbin support part 336 and the shield coil bobbin part 338, and functions to support them. The main coil bobbin support part 336 is arranged on the symmetry plane 201 side that is closest to the imaging space 204 by the casing part 340, and the main coil bobbin support part 336 and the lower superconducting magnet in the coil bobbin 330 of the upper superconducting magnet 300. The main coil bobbin support portion 336 of the coil bobbin 330 of 302 is opposed to each other with the plane of symmetry 201 interposed therebetween. On the other hand, the shield coil bobbin portion 338 is located farther from the imaging space 204 in the Z-axis direction than the main coil bobbin support portion 336.

  The main coil bobbin 350 includes a cylindrical member 332, a support plate 362 having an annular shape, and an end plate 334 having an annular shape. The main coil 310 is not directly wound around the main coil bobbin 350, but is wound and molded by another work using a winding jig as described below with reference to FIG. The jig is removed and fixed to the coil bobbin 330. By doing so, the shape of the support member 360 that supports the main coil 310 can have a structure and shape suitable for further reducing the distortion of the main coil 310. Productivity is also improved.

  This leads to suppression of distortion of the main coil 310, and quenching can be suppressed. The gap between the superconducting wires forming the main coil 310 is impregnated with resin to fix the superconducting wires. The structure shown in FIGS. 2 and 3 acts to reduce the stress applied to the resin impregnated in the gaps of the superconducting wires. This also leads to the effect of suppressing the occurrence of quenching.

  The inner peripheral portion of the end plate 334 of the coil bobbin 330 is fixed to the inner cylinder 342, and the outer peripheral portion of the end plate 334 is fixed to the shield coil bobbin portion 338. As a result, the end plate 334 functions to connect and integrate the main coil bobbin 350 and the shield coil bobbin portion 338.

The main electromagnetic force acting on the main coil 310 provided on the main coil bobbin 350 of the upper superconducting magnet 300 is the repulsive force generated between the shield coil 320 supported by the same coil bobbin 330 and the imaging space 204. This is an attractive force generated between the main coil 310 fixed to the coil bobbin 330 of the lower superconducting magnet 302 arranged oppositely. For this reason, the electromagnetic force acting toward the symmetry plane 201 in the Z-axis direction becomes the main component of the electromagnetic force acting on the main coil 310. The main coils 310 of the upper superconducting magnet 300 and the lower superconducting magnet 302 are supported by the support plate 362 of the support member 360, respectively.

Each of the main coils 310 is supported by a support surface of a support plate 362 parallel to the symmetry plane 201, and the support surface has a structure that is not easily twisted. Therefore, the main coils 310 of the upper superconducting magnet 300 and the lower superconducting magnet 302 have a main structure. Generation of a three-dimensional twist in the coil 310 is suppressed. As a result, the occurrence of quenching is suppressed.

  The shield coil bobbin portion 338 includes an annular inner cylinder 344 and an outer cylinder 346, an annular end plate 348, and an annular end plate 352. The annular end plate 348 has an inner peripheral portion fixed to the inner cylinder 344. The outer peripheral portion and the outer cylinder 346 may be configured to be either connected or not. The same applies to the annular end plate 352. The shield coil 320 is wound in a space surrounded from four sides by an annular inner cylinder 344, an outer cylinder 346, an annular end plate 348, and an annular end plate 352. The gap between the superconducting wires is impregnated with resin to fix the superconducting wires.

  The casing 340 includes an inner cylinder 342 and an annular end plate 354 fixed to the end of the inner cylinder 342 opposite to the imaging space 204. An end plate 334 is fixed to the end of the inner cylinder 342 on the imaging space 204 side. The outer peripheral portion of the annular end plate 354 is fixed to the shield coil bobbin portion 338. Further, the inner cylinder 342 does not have to be cylindrical as long as it is a member having the same rigidity, and may be constituted by, for example, discretized ribs.

  Each part of the coil bobbin 330 is firmly fixed by welding or screwing. In addition, the coil bobbin 330 of the present embodiment is provided with an annular support plate 362 that supports the main coil 310 in the vertical direction that is the Z-axis direction. As shown in FIG. 3, the support plate 362 is provided integrally with a support member 360 having an L-shaped cross section, and the upper end is an end plate 334 of the main coil bobbin 350 or an annular end plate of the shield coil bobbin portion 338. It is firmly fixed to 348 by welding or bolts.

  A tip 364 of the support plate 362 on the side of the symmetry plane 201 is coupled to the cylindrical member 332, and the cylindrical member 332 is coupled to the end plate 334. The main coil 310 is surrounded by the support plate 362, the cylindrical member 332, and the end plate 334 of the support member 360. The support plate 362 prevents the coil from being deformed in the Z-axis direction. Similar to the coil bobbin 330, the support plate 362 is made of a nonmagnetic metal such as SUS304 or an aluminum alloy.

The main coil 310 of the upper superconducting magnet 300 and the main coil 310 of the lower superconducting magnet 302 are attracted to each other by a strong attractive force, but the symmetry plane 201 side and the lower superconducting magnet 302 of the main coil 310 of the upper superconducting magnet 300 are applied. Since the support plates 362 are respectively provided on the symmetry plane 201 side of the main coil 310 to support and fix the main coils 310, distortion of the main coil 310 is suppressed. The support plate 362 is fixed to the coil bobbin 330 on the Z-axis side via the cylindrical member 332, and the side far from the Z-axis of the support plate 362 is fixed to the end plate 334 or the annular end plate 348 by the outer peripheral support member 361.

Thus, since both sides of the support plate 362 are fixed to the end plate 334, the support plate 362 has a structure in which twisting is unlikely to occur. For this reason, it is possible to suppress the occurrence of distortion such as twisting in the main coil 310. As described above, the coil bobbin 330 and the support member 360 of the upper superconducting magnet 300 and the coil bobbin 330 and the support member 360 of the lower superconducting magnet 302 have a symmetric structure and shape with respect to the symmetry plane 201, and are exactly the same. It works and has an effect.

  Next, the outer structure of the coil bobbin 330 will be described. As shown in FIG. 2, the refrigerant container 402 is fixed to the inner peripheral side end 356 of the annular end plate 354 and the outer peripheral side end 358 of the annular end plate 352, and the annular end plate 352 of the coil bobbin 330 is fixed. The annular end plate 354 acts as a part of the outer peripheral wall of the refrigerant container 402. The inside of the refrigerant container 402 is filled with liquid helium as a refrigerant. Accordingly, a space filled with liquid helium is formed around the coil bobbin 330, and the main coil 310 and the shield coil 320 fixed to the coil bobbin 330 are cooled by the liquid helium as a refrigerant, and the superconducting state is maintained.

Coupling mechanism 252 with coupling mechanism 254 for coupling the upper superconducting magnet 300 and the lower superconducting magnet 302, a coil bobbin 330 of the upper superconducting magnet 300, and a connector stud for connecting the coil bobbin 330 of the lower superconducting magnet 302. The connecting mechanism 252 and the connecting mechanism 254 having connecting pillars are resistant to the attracting electromagnetic force acting between the main coil 310 and the shield coil 320 of the upper superconducting magnet 300 and the main coil 310 and the shield coil 320 of the lower superconducting magnet 302. Thus, the upper superconducting magnet 300 and the lower superconducting magnet 302 are supported. The periphery of the coupling mechanism 252 and the coupling mechanism 254 is covered with a refrigerant container 402, a shield plate 404, and a vacuum container 406. Each of the coupling mechanism 252 and the coupling mechanism 254 couples and supports the refrigerant container 402, the shield plate 404, and the vacuum container 406 of the superconducting magnet device that exist above and below.

For example, in the case of the structure described in Patent Document 2, although the deformation of the bobbin due to the electromagnetic force in the Z-axis direction of the main coil 310 is suppressed by the support member, the end plate of the main coil bobbin 350 is displaced and a large deformation occurs. easy. When the deformation occurs, coil distortion also occurs, and the resin between the conductors of the superconducting coil is broken or the conductors easily move.

In this embodiment, such deformation can be suppressed, and the occurrence of quenching can be further reduced. Patent Document 2, the main coil bobbin to constitute a slot, constituting the main coil wound directly superconducting wire in this portion. When trying to process the slot with the accuracy required for the superconducting coil of about ± 0.1 to 0.2mm, there is a big problem in productivity. Eventually production costs will increase.

  On the other hand, in the present embodiment, the main coil 310 shown in FIG. 2 or FIG. 3 is wound and molded using a jig in a separate operation, and the end plate 334 of FIG. It is configured to be attached. By doing so, it is possible to provide a structure with both ends fixedly supported against the Z-direction electromagnetic force acting on the main coil 310, to minimize deformation of the main coil 310, and to make the structure difficult to quench. it can.

  Further, slot processing is eliminated, and productivity is greatly improved. For example, the bobbin manufacturing cost can be reduced. A jig for separate work is required, but since the jig can be used many times, the impact of the cost is negligible during mass production. Note that the support plate 362 or the end plate 334 may have a structure that is partially cut away for attaching a power feeding member to the coil.

  In the above-described embodiment, the case where the main coil 310 and the shield coil 320 are made of a material that is in a superconducting state at the liquid helium temperature has been described. 402 and the shield plate 404 may be unnecessary. Further, the main coil 310 and the shield coil 320 can also be composed of a plurality of coils.

FIG. 4 is an explanatory diagram for explaining a production method of the main coil 310 described in FIG. 2 and FIG. As shown in FIG. 4 (A), the main coil 310 is not wound around the upper superconducting magnet 300, but is produced on the cylindrical member 332 separated from the coil bobbin 330 from both sides thereof. A jig 422 is applied, a superconducting wire is wound around the cylindrical member 332, and a resin for fixing the superconducting wire is poured and hardened to complete the main coil 310.

  In the embodiment of FIG. 2 and FIG. 3, the diameter of the cylindrical member 332 is very large, but for the sake of easy understanding, FIG. In the description of FIG. 4, although the diameter of the cylindrical member 332 is different from that in FIGS. 2 and 3, the basic principle and the basic action are the same. When the winding jig 420 and the winding jig 422 are removed, the main coil 310 wound around the cylindrical member 332 can be taken out. FIG. 4B shows a state where the main coil 310 is fixed to the cylindrical member 332.

  In FIG. 2, the cylindrical member 332 is fixed to the end plate 334 using the main coil 310 in the state of FIG. On the other hand, as shown in FIG. 4C, it is also possible to remove the cylindrical member 332 and use only the main coil 310. In the embodiment shown in FIG. 8, the main coil 310 shown in FIG. 4 (C) is used.

5. Description of Superconducting Magnet Device According to Other Embodiments In the embodiment described above, the structure of the main coil bobbin 350 of the main coil 310 of the coil bobbin 330 is one stage, whereas in the embodiment described in FIG. The winding structure of the main coil bobbin 350 is a two-stage structure. A second cylindrical member 333 is provided on the symmetry surface 201 side that is the imaging space 204 side of the cylindrical member 332 that is the configuration of the main coil bobbin 350 illustrated in FIG. The second tubular member 333 has the same structure as the tubular member 332 and is fixed to the end plate 334 of the coil bobbin 330 via the support member 360 and the tubular member 332.

  A second support plate 363 is provided on the symmetry surface 201 side of the second cylindrical member 333, and the second main coil 311 wound around the second cylindrical member 333 is connected to the support plate 362 and the second plate of the support member 360. Provided between the support plates 363. The support member 360 is provided between the cylindrical member 332 and the second cylindrical member 333, supports the main coil 310, and holds and fixes the second support plate 363 that supports the second main coil 311. Has the function of

  As described above, in the embodiment shown in FIG. 5, the main coil bobbin 350 has a structure in which two stages are stacked in the Z-axis direction, and the main coil includes the main coil 310 and the second main coil 311. The coil 310 and the second main coil 311 are separated from each other, and one is arranged in the first stage and the other is arranged in the second stage.

  With such a configuration, the main coil 310 can be molded using the cylindrical member 332, and similarly, the second main coil 311 can be molded using the second cylindrical member 333. Can do. After the main coil 310 and the second main coil 311 are manufactured, the main coil bobbin 350 is attached to the coil bobbin 330, so that the main coil bobbin 350 is less likely to be distorted to cope with the stress acting on the main coil 310 and the second main coil 311. It can be of structure and shape. Productivity is also improved.

  Further, as shown in FIG. 5, the main coil is divided into a plurality of stages of the main coil 310 and the second main coil 311 so as to act on the second main coil 311 arranged on the symmetry plane 201 side. The suction force toward the 201 side can be reduced.

A repulsive force generated between the main coil 310 and the second main coil 311 between the shield coil 320 provided on the coil bobbin 330 acts. On the other hand, as shown in FIG. 2, since the upper superconducting magnet 300 and the lower superconducting magnet 302 are arranged to face each other with the symmetry plane 201 in between, the main coil 310 and the second main coil 311 of the upper superconducting magnet 300 An attractive force is generated between the main coil 310 and the second main coil 311 of the lower superconducting magnet 302. However, a force that attracts each other is generated between the main coil 310 and the second main coil 311 of the upper superconducting magnet 300 arranged closer to each other. The same applies to the lower superconducting magnet 302.

A force generated between the main coil 310 of the upper superconducting magnet 300 and the second main coil 311 is applied to the main coil 310 in the direction of the symmetry plane 201 in addition to the force generated between the coil of the lower superconducting magnet 302. Accordingly, a large force acts on the main coil 310. On the other hand, the second main coil 311 of the upper superconducting magnet 300 generates an attracting force with the lower superconducting magnet 302, thereby generating a force in the direction of the symmetry plane 201. Thus, a strong attractive force is generated, and the attractive force by the main coil 310 acts in a direction to cancel the attractive force by the lower superconducting magnet 302.

  For this reason, almost no force is generated in the second main coil 311 in the direction of the symmetry plane 201. Rather, a force is generated in the second main coil 311 not in the direction of the symmetry plane 201 but in the opposite main coil 310 direction. Therefore, almost no force acts on the second support plate 363. In some cases, the second support plate 363 may not be provided.

  As shown in FIG. 5, in the structure in which a plurality of main coils are provided, a large force acts on the main coil far from the symmetry plane 201, but no large force acts on the main coil closer to the symmetry plane 201. Accordingly, distortion or the like hardly occurs in the main coil closer to the symmetry plane 201. By supporting the main coil 310, which is the main coil far from the symmetry plane 201, by the support member 360 as described above, the main coil 310 can be prevented from being deformed as a whole, and quenching can be suppressed. be able to.

6. Description of Superconducting Magnet Device According to Still Another Embodiment Although the structure in which the main coil is divided into a plurality of parts and arranged with reference to FIG. 5 has been described, FIG. 6 illustrates a superconducting magnet device according to still another embodiment. The configuration is shown. The embodiment of FIG. 5 shows a structure in which the main coil 310 is wound around a cylindrical member 332 and formed, and the second main coil 311 is wound around a second tubular member 333 and formed. In order to improve the productivity of the main coil 310 and the second main coil 311, and to improve the productivity of the entire MRI apparatus 100 having the configuration using the produced main coil 310 and the second main coil 311, FIG. The embodiment described in is excellent.

  Rather than separately providing the cylindrical member 332, the second cylindrical member 333, and the support plate 362, the embodiment shown in FIG. 6 uses a support member 380 having a T-shaped cross section in which these are integrated. The support member 380 has a cylindrical member 382 having an annular shape centering on the Z axis, and a support plate 384 corresponding to a T-shaped leg on the outer peripheral side thereof. A main coil 310 and a second main coil 311 wound in separate operations are fixed to the support member 380. The cylindrical member 382 of the support member 380 is fixed to the end plate 334 of the coil bobbin 330.

  Further, the end portion of the support plate 384 of the support member 380 is fixed to the end plate 334 of the coil bobbin 330 or the annular end plate 348 via the attachment member 390. The cylindrical member 382 acts as an inner peripheral side support member, and the attachment member 390 acts as an outer peripheral side support member. In this manner, both ends of the support plate 384 are fixed to the coil bobbin 330 by the inner peripheral support member and the outer peripheral support member, so that the force acting on the main coil 310 can be sufficiently opposed. That is, the support plate 384 has a structure in which twisting hardly occurs. For this reason, the occurrence of quenching is suppressed. As described above, since no large force acts on the second main coil 311, almost no force acts on the second support plate 363. The second support plate 363 may be omitted.

  The support member 380 has a function of winding and forming two coils of the main coil 310 and the second main coil 311. As shown in FIG. 7, two coils of the main coil 310 and the second main coil 311 can be formed by attaching two winding jigs 430 and 432 to the support member 380. By attaching the support member 380 having the two formed coils to the coil bobbin 330, the twist of the main coil 310 can be suppressed. Although the productivity is also improved in FIG. 5, the productivity is further improved in the embodiment shown in FIG.

7. Description of Superconducting Magnet Device According to Still Another Embodiment As yet another embodiment, a structure in which the supporting member 380 shown in FIG. 6 is fitted on the outer peripheral side of the main coil 310 or the second main coil 311 is shown in FIG. Shown in The structure, operation and effect are very similar to the embodiment of FIG. The main coil is divided into two coils and stacked in the Z direction. In the embodiment of FIG. 6, only the coil is manufactured in a separate system. In the embodiment described in FIGS. 5 and 6, the main coil is wound around an annular member centered on the Z axis, such as the cylindrical member 382, and formed.

  On the other hand, in this embodiment, as shown in FIG. 4C, the cylindrical member provided on the center side is removed from the molded coil, and only the molded coil is removed from the Z-axis side of the support member 380 to the outer peripheral side. Fit into the. The cylindrical member 482 of the support member 380 is fixed to the annular end plate 348, and the end of the support plate 384 is fixed to the end plate 334 via the fixing member 490. In this embodiment, the number of parts constituting the main coil bobbin 350 can be reduced. The main coil 310, the second main coil 311 and the support member 380 can be integrated by bonding or shrink fitting. In the embodiment of FIG. 8, the main coil is divided into a plurality of main coils of the main coil 310 and the second main coil 311. However, the present embodiment can be applied even in the case of one coil. In the case of one coil, the structure of the main coil bobbin 350 is further simplified. This improves productivity.

The MRI apparatus 100 of the present embodiment is an open type that hardly gives a subject a feeling of obstruction, and further exhibits an effect that the superconducting magnet is hardly quenched. Therefore, there is an effect that the subject 102 can be imaged stably over a long period of time. As described above, in the present invention, an MRI apparatus with excellent productivity that can reduce the occurrence of quenching can be obtained.

100 MRI device, 102 Subject, 110 Control device, 120 Input / output device, 122 Display device, 124 Input device, 130 Processing device, 140 Imaging control device, 142 Sequencer, 144 RF current supply device, 146 Gradient magnetic field power supply, 148 signal Processing device, 170 Refrigerant supply device, 180 bed, 182 Top plate, 200 MRI main body, 201 symmetry plane, 202 aperture, 204 imaging space, 206 strut, 208 strut, 210 upper gradient magnetic field generator, 211 lower gradient magnetic field generator , Coil 214 Upper RF pulse irradiation, Lower RF pulse irradiation coil 215, 252 Connection mechanism, 254 connection mechanism, 300 Upper superconducting magnet , 302 Lower superconducting magnet , 310 Main coil, 311 Second main coil, 320 Shield coil, 330 Coil bobbin, 332 cylindrical member, cylindrical member, 334 end plate, 336 main coil bobbin part, 338 shield coil bobbin part, 340 housing part, 342 inner cylinder, 350 main coil bobbin, 360 support member, 372 bolt, 380 support member, 382 Cylindrical member, 384 support plate, 390 Mounting member, 420 Winding jig, 422 Winding jig, 430 Winding jig, 432 Winding jig, 490 Fixing member

Claims (6)

A pair of superconducting magnets disposed opposite to each other in the Z-axis direction with an imaging space in which a static magnetic field is to be formed therebetween, a gradient magnetic field generator, and an RF pulse irradiation coil,
Each of the pair of superconducting magnets has an annular main coil having a Z-axis at the center, a shield coil for suppressing a leakage magnetic field of the main coil, a coil bobbin, and the main coil for holding the main coil. A support plate that faces the imaging space and is arranged along the imaging space side of the main coil to support the main coil, and is made of a member different from the coil bobbin, and the Z axis of the support plate An inner peripheral side support member that fixes the side to the coil bobbin, and an outer peripheral side support member that fixes the outer peripheral side of the support plate that is opposite to the Z-axis side of the support plate to the coil bobbin,
The main coil is disposed between the support plate and the coil bobbin,
The inner peripheral side support member has an annular surface along the inner peripheral surface of the main coil,
The Z-axis side, which is the inner peripheral side of the support plate, is fixed to the coil bobbin by the inner peripheral support member made of a member different from the coil bobbin,
The support plate and the inner peripheral support member are connected ,
The inner peripheral side support member, the connection point between the inner peripheral-side supporting member and the supporting plate, a first inner peripheral side support member provided in a direction away from said imaging space, from the connection point, the imaging and a second inner peripheral side support member provided in the direction toward the space,
The inner peripheral side of the support plate is fixed to the coil bobbin by the first inner peripheral side support member,
The main coil is divided into at least two of a first main coil and a second main coil , the first main coil is disposed between the support plate and the coil bobbin, and the second main coil is the support plate. It is arrange | positioned at the said imaging space side, The magnetic resonance imaging apparatus characterized by the above-mentioned. 2. The magnetic resonance imaging apparatus according to claim 1 , wherein the first main coil is formed on the first inner peripheral support member, and the second main coil is formed on the second inner peripheral support member. The magnetic resonance imaging apparatus characterized by the above-mentioned. The magnetic resonance imaging apparatus according to claim 1 .
The support plate, the first inner peripheral side support member, and the second inner peripheral side support member are integrally formed,
Further, the first main coil is formed on the first inner peripheral support member, the second main coil is formed on the second inner peripheral support member, and the first inner peripheral support member is formed on the coil bobbin. A magnetic resonance imaging apparatus, wherein the magnetic resonance imaging apparatus is fixed to an imaging space side, and a side farther than the Z-axis side of the support plate is fixed to the imaging space side of the coil bobbin by the outer peripheral support member. The magnetic resonance imaging apparatus according to claim 1 .
The outer peripheral side support member is made integrally with the support plate, and is fixed to the coil bobbin in a shape extending in a direction away from the imaging space on the outer peripheral side of the support plate,
The outer peripheral side support member is fixed to the coil bobbin so that each of the Z-axis side and the opposite side of the Z-axis side of the support plate is supported by the coil bobbin. Resonance imaging device. The magnetic resonance imaging apparatus according to claim 1 .
A supercoiled wire is wound around the inner peripheral support member made of a member different from the coil bobbin, and a main coil fixed with resin is formed. The magnetic resonance imaging apparatus, wherein the Z-axis side is fixed to the coil bobbin. A pair of superconducting magnets disposed opposite to each other in the Z-axis direction with an imaging space in which a static magnetic field is to be formed therebetween, a gradient magnetic field generator, and an RF pulse irradiation coil,
Each of the pair of superconducting magnets has an annular main coil having a Z-axis at the center, a shield coil for suppressing a leakage magnetic field of the main coil, a coil bobbin, and the main coil for holding the main coil. A support plate that faces the imaging space and is arranged along the imaging space side of the main coil to support the main coil, and is made of a member different from the coil bobbin, and the Z axis of the support plate An inner peripheral side support member that fixes the side to the coil bobbin, and an outer peripheral side support member that fixes the outer peripheral side of the support plate that is opposite to the Z-axis side of the support plate to the coil bobbin,
The main coil is disposed between the support plate and the coil bobbin,
The outer peripheral side support member and the support plate are integrally formed, and the outer peripheral side support member is fixed to the imaging space side of the coil bobbin,
The main coil is fitted between the support plate and the imaging space side of the coil bobbin, and the Z-axis side of the support plate is fixed to the imaging space side of the coil bobbin by the inner peripheral side support member. ,
The outer peripheral side support member extends further to the imaging space side than the support plate,
Wherein the imaging space side of the support plate is further provided with a second main coil,
The main coil provided on the coil bobbin side of the support plate and the second main coil provided on the imaging space side of the support plate together serve to form the static magnetic field. Magnetic resonance imaging device.

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