Superconducting magnet and magnetic resonance imaging device

Abstract

To maintain strength while reducing weight of a housing.SOLUTION: A superconducting magnet according to an embodiment includes a superconducting coil and a cryostat. The superconducting coil forms a static magnetic field and has a loop shape. The cryostat has a top plate part and a bottom plate part and is a housing for storing the superconducting coil. In at least one of a space in an inner peripheral side and a space in an outer peripheral side of the superconducting coil, a part of at least one of the top plate part and the bottom plate part is folded back in an internal direction of the cryostat and is bonded to a part of the other.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The embodiments disclosed in this specification and the drawings relate to a superconducting magnet and a magnetic resonance imaging apparatus. [Background technology]

[0002] In imaging using a typical cylindrical magnetic resonance imaging device, the subject is forced to remain motionless for long periods of time within a narrow bore and is also exposed to noise caused by switching of gradient magnetic fields, which places stress on the subject. Therefore, to alleviate the psychological anxiety caused by a confined space, open-type magnetic resonance imaging devices, in which a pair of static magnetic field magnets are arranged vertically facing each other and the side where the subject is inserted is open, are becoming more popular.

[0003] Because open-type magnetic resonance imaging systems have independent static magnetic field magnets at the top and bottom, the gantry section tends to be large. Therefore, there is a need to make the gantry as small and lightweight as possible. On the other hand, while it is possible to increase the size of the gantry section from the perspective of expanding the imaging space, there is a problem in that the components of the housing may bend as the housing becomes larger. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent No. 5057941 Summary of the Invention [Problem to be solved by the invention]

[0005] One of the problems to be solved by the embodiments disclosed in this specification and the drawings is to maintain the strength of the housing while reducing its weight. However, the problems to be solved by the embodiments disclosed in this specification and the drawings are not limited to the above problem. Problems corresponding to the effects of each configuration shown in the embodiments described below can also be positioned as other problems. [Means for solving the problem]

[0006] The superconducting magnet according to this embodiment includes a superconducting coil and a cryostat. The superconducting coil forms a static magnetic field and has a loop shape. The cryostat is a housing that has a top plate and a bottom plate and stores the superconducting coil. In at least one of the spaces on the inner periphery and the outer periphery of the superconducting coil, a portion of at least one of the top plate and the bottom plate is folded back toward the inside of the cryostat and joined to a portion of the other. [Brief explanation of the drawings]

[0007] [Figure 1] FIG. 1 is a conceptual diagram of a gantry section of a magnetic resonance imaging apparatus according to this embodiment. [Figure 2] FIG. 2 is a block diagram showing the magnetic resonance imaging apparatus according to this embodiment. [Figure 3] FIG. 3 is a cross-sectional view of a first configuration example of a superconducting magnet. [Figure 4] FIG. 4 is a diagram showing the positional relationship between the superconducting coils and shims according to the first configuration example of the superconducting magnet. [Figure 5] FIG. 5 is a cross-sectional view of a second configuration example of a superconducting magnet. [Figure 6] FIG. 6 is a diagram showing the positional relationship between the superconducting coils and shims according to the second configuration example of the superconducting magnet. [Figure 7] FIG. 7 is a cross-sectional view of a third configuration example of a superconducting magnet. [Figure 8] FIG. 8 is a cross-sectional view of a fourth configuration example of a superconducting magnet. [Figure 9] FIG. 9 is a diagram showing the positional relationship between a superconducting coil, a shim, a cold head, and a refrigerator according to the fourth configuration example of the superconducting magnet. DETAILED DESCRIPTION OF THE INVENTION

[0008] A superconducting magnet and a magnetic resonance imaging apparatus according to this embodiment will be described below with reference to the drawings. In the following embodiments, parts with the same reference numerals perform similar operations, and redundant explanations will be omitted as appropriate. One embodiment will be described below with reference to the drawings.

[0009] Next, a conceptual diagram of a gantry section of a magnetic resonance imaging apparatus according to this embodiment will be described with reference to FIG. The magnetic resonance imaging apparatus according to this embodiment is assumed to be an open-type magnetic resonance imaging apparatus. That is, the gantry section of the magnetic resonance imaging apparatus is configured such that an upper gantry section 100-1 and a lower gantry section 100-2 are arranged opposite each other. A uniform static magnetic field is generated in the space where the upper gantry section 100-1 and the lower gantry section 100-2 face each other, and this space becomes an imaging space 20. A subject P is inserted into the imaging space 20, and imaging is performed by generating a gradient magnetic field and irradiating an RF pulse according to an imaging sequence.

[0010] Next, the magnetic resonance imaging apparatus according to this embodiment will be described with reference to the block diagram of FIG. The magnetic resonance imaging apparatus 10 includes a static magnetic field magnet, a gradient magnetic field coil 103, a gradient magnetic field power supply 105, a bed 107, a bed control circuit 109, a transmission circuit 113, a transmission coil 115, a reception coil 117, a reception circuit 119, a sequence control circuit 121, a bus 123, an interface 125, a display 127, a memory device 129, and a processing circuit 131.

[0011] The static magnetic field magnets are assumed to be a pair of superconducting magnets (upper superconducting magnet 101-1 and lower superconducting magnet 101-2) that use superconducting coils. The static magnetic field magnets generate a uniform static magnetic field in the space facing the static magnetic field magnets.

[0012] The gradient magnetic field coil 103 is disposed inside the static magnetic field magnet. The gradient magnetic field coil 103 is formed by combining three coils corresponding to the mutually orthogonal x, y, and z axes. The z-axis direction is the same as the direction of the static magnetic field. The y-axis direction is the horizontal direction, and the x-axis direction is the direction perpendicular to the z and y axes. The three coils in the gradient magnetic field coil 103 are individually supplied with current from a gradient magnetic field power supply 105, and generate gradient magnetic fields whose magnetic field strength changes along each of the x, y, and z axes.

[0013] The gradient magnetic fields of the x-, y-, and z-axes generated by the gradient coil 103 form, for example, a frequency encoding gradient magnetic field (also called a readout gradient magnetic field), a slice selection gradient magnetic field, and a phase encoding gradient magnetic field. The frequency encoding gradient magnetic field is used to change the frequency of the MR signal depending on the spatial position. The slice selection gradient magnetic field is used to determine the imaging cross section. The phase encoding gradient magnetic field is used to change the phase of the MR signal depending on the spatial position.

[0014] The gradient magnetic field power supply 105 is a power supply device that supplies current to the gradient magnetic field coil 103 under the control of the sequence control circuit 121 .

[0015] The bed 107 is a device equipped with a tabletop 1071 on which the subject P is placed. The bed 107 moves the tabletop 1071 on which the subject P is placed toward the imaging space 20 under the control of a bed control circuit 109. The bed 107 is installed in an examination room in which the magnetic resonance imaging apparatus 10 is installed, for example, so that the longitudinal direction is perpendicular to the central axis of the static magnetic field magnet.

[0016] The bed control circuit 109 is a circuit that controls the bed 107, and drives the bed 107 in response to a user's instruction via the interface 125, thereby moving the tabletop 1071 in the longitudinal direction and the up-down direction.

[0017] The transmitting coil 115 is an RF coil arranged inside the gradient magnetic field coil 103. The transmitting coil 115 receives RF (Radio Frequency) pulses from the transmitting circuit 113 and generates a transmitting RF wave corresponding to a high frequency magnetic field. The transmitting coil 115 is, for example, a whole-body coil. The whole-body coil may be used as a transmitting / receiving coil. A cylindrical RF shield is installed between the whole-body coil and the gradient magnetic field coil 103 to magnetically separate these coils.

[0018] The transmission circuit 113 supplies an RF pulse corresponding to the Larmor frequency or the like to the transmission coil 115 under the control of the sequence control circuit 121 .

[0019] The receiving coil 117 is an RF coil arranged inside the gradient magnetic field coil 103. The receiving coil 117 receives MR signals emitted from the subject P by a high frequency magnetic field. The receiving coil 117 outputs the received MR signals to a receiving circuit 119. The receiving coil 117 is, for example, a coil array having one or more, typically a plurality of coil elements. The receiving coil 117 is, for example, a phased array coil.

[0020] The receiving circuit 119 generates a digital MR signal, which is digitized complex data, based on the MR signal output from the receiving coil 117 under the control of the sequence control circuit 121. Specifically, the receiving circuit 119 performs various signal processing on the MR signal output from the receiving coil 117, and then performs analog-to-digital (A / D) conversion on the data that has been subjected to various signal processing. The receiving circuit 119 samples the A / D converted data. As a result, the receiving circuit 119 generates a digital MR signal (hereinafter referred to as MR data). The receiving circuit 119 outputs the generated MR data to the sequence control circuit 121.

[0021] The sequence control circuit 121 controls the gradient magnetic field power supply 105, the transmission circuit 113, the reception circuit 119, etc. in accordance with the examination protocol output from the processing circuit 131, and performs imaging of the subject P. The examination protocol has various pulse sequences, i.e., imaging sequences, according to the examination.

[0022] The bus 123 is a transmission path for transmitting data among the interface 125, the display 127, the storage device 129, and the processing circuit 131. Various biosignal measuring devices, external storage devices, various modalities, etc. may be appropriately connected to the bus 123 via a network, etc. For example, an electrocardiograph (not shown) is connected to the bus as a biosignal measuring device.

[0023] The interface 125 includes input devices that accept various commands from a user. Examples of input devices that can be used include a keyboard, a mouse, various switches, a touch screen, and a touch pad. Note that the input devices are not limited to those equipped with physical operating components such as a mouse and a keyboard. For example, the interface 125 may also include an electrical signal processing circuit that receives an electrical signal corresponding to an input operation from an external input device provided separately from the magnetic resonance imaging apparatus 10 and outputs the received electrical signal to various circuits. The interface 125 may also be a voice recognition device that converts a voice signal collected by a microphone into a command signal.

[0024] The display 127 displays various magnetic resonance images (MR images) such as T1-weighted images and T2-weighted images generated by the image generation function 1312, various information related to imaging and image processing, and the like, under the control of the system control function 1311 in the processing circuitry 131. The display 127 is, for example, a CRT display, a liquid crystal display, an organic EL display, an LED display, a plasma display, or any other display or monitor known in the art.

[0025] The storage device 129 stores MR data filled in the k-space via the image generation function 1312, image data generated by the image generation function 1312, etc. The storage device 129 stores various examination protocols, imaging conditions including a plurality of imaging parameters defining the examination protocols, etc. The storage device 129 stores programs corresponding to various functions executed by the processing circuitry 131. The storage device 129 is, for example, a semiconductor memory element such as a read-only memory (ROM), a random access memory (RAM), or a flash memory, a hard disk drive, a solid state drive, or an optical disk. The storage device 129 may also be a drive that reads and writes various information from and to a portable storage medium such as a CD-ROM drive, a DVD drive, or a flash memory.

[0026] The processing circuitry 131 has a processor, memories such as ROM and RAM, etc. (not shown) as hardware resources, and performs overall control of the magnetic resonance imaging apparatus 10. The processing circuitry 131 includes a system control function 1311, an image generation function 1312, and a display control function 1313.

[0027] The processing circuitry 131 applies excitation pulses and applies gradient magnetic fields in accordance with an excitation pulse sequence using a system control function 1311. After executing the excitation pulse sequence using the system control function 1311, the processing circuitry 131 collects MR signals from the subject P in accordance with a data collection sequence, which is a pulse sequence for collecting various types of data, and generates MR data.

[0028] The processing circuitry 131 fills the MR data along the readout direction of the k-space according to the strength of the readout gradient magnetic field using the image generation function 1312. The processing circuitry 131 generates an MR image by performing a Fourier transform on the MR data filled in the k-space using the image generation function 1312. For example, the processing circuitry 131 can generate a magnitude image from complex MR data. The processing circuitry 131 can also generate a phase image using real part data and imaginary part data of the complex MR data.

[0029] The processing circuitry 131 uses the display control function 1313 to display the MR image on the display 127. Note that the processing circuitry 131 may also use the display control function 1313 to transmit the MR image to a network and control the MR image to be displayed on, for example, a computer in an examination room or a workstation in a hospital.

[0030] The various functions of the processing circuitry 131 are stored in the storage device 129 in the form of programs executable by a computer. The processing circuitry 131 is a processor that realizes the functions corresponding to the various functions by reading and executing the programs corresponding to the various functions from the storage device 129. In other words, the processing circuitry 131 in a state in which the programs have been read out has the multiple functions shown in the processing circuitry 131 in FIG. 2.

[0031] 2, it has been explained that these various functions are realized by a single processing circuit 131, but it is also possible to configure the processing circuit 131 by combining multiple independent processors, and have each processor execute a program to realize the function. In other words, it is possible that each of the above-mentioned functions is configured as a program and one processing circuit executes each program, or that a specific function is implemented in a dedicated, independent program execution circuit.

[0032] Next, a first configuration example of the superconducting magnet 101 according to this embodiment will be described with reference to FIG. 3 is a cross-sectional view passing through the center of the cylinder of the upper superconducting magnet 101-1 and the lower superconducting magnet 101-2. Here, the upper superconducting magnet 101-1 and the lower superconducting magnet 101-2 have the same configuration and are arranged symmetrically with respect to the imaging space, so they will be collectively described as the superconducting magnet 101.

[0033] Superconducting magnet 101 includes cryostat 31 , two superconducting coils 32 and 33 , a support portion 34 , a shim 35 , a reinforcing portion 36 , and a shim fixing portion 37 .

[0034] Cryostat 31 is a housing having a top plate and a bottom plate, and stores superconducting coil 32 and superconducting coil 33. Specifically, cryostat 31 is a vacuum vessel formed by joining and fixing first housing member 31-1 and second housing member 31-2 together. In the example of FIG. 3 , the surface of first housing member 31-1 facing the other superconducting magnet 101 is referred to as top plate 31-1a. The surface of second housing member 31-2 opposite top plate 31-1a of first housing member 31-1 is referred to as bottom plate 31-2a. Cryostat 31 is filled with liquid helium, and superconducting coil 32 and superconducting coil 33 are immersed in the liquid helium. The cryostat 31 described below is not limited to being formed by joining a first housing member 31-1 and a second housing member 31-2 together, but may be integrally molded or may be formed by appropriately joining three or more members together.

[0035] Superconducting coil 32 and superconducting coil 33 are loop-shaped coils that generate a static magnetic field, and are housed in cryostat 31. Superconducting coil 32 and superconducting coil 33 are arranged so that the openings of the loops face vertically (the z-axis direction in FIG. 3). Superconducting coil 32 and superconducting coil 33 are designed so that currents flow in opposite directions to each other so as to reduce leakage magnetic fields. Hereinafter, two superconducting coils are shown as an example, but the static magnetic field may be formed by three or more superconducting coils. Hereinafter, as necessary, the two superconducting coils 32 and superconducting coil 33 will also be collectively referred to simply as superconducting coils.

[0036] The support 34 is housed in the cryostat 31 and supports the superconducting coil 32 and the superconducting coil 33 .

[0037] Shim 35 is a magnetic material for shimming that can adjust the static magnetic field generated by superconducting coil 32 and superconducting coil 33. Shim 35 may be formed, for example, by a shim tray storing a plurality of magnetic plates such as iron or copper, a shim coil, or the like. Here, it is assumed that shim 35 is arranged in a cylindrical shape within the area of shim fixing portion 37.

[0038] The shim fixing portion 37 to which the shim 35 is fixed is formed in the cylindrical central portion of the cryostat 31. For example, the shim fixing portion 37 is formed in a space formed by folding back a portion of at least one of the top plate portion 31-1a or the bottom plate portion 31-2a of the cryostat 31 toward the inside of the cryostat 31 and joining it to a portion of the other, in at least one of the spaces on the inner circumferential side and the outer circumferential side of the superconducting coil, that is, in the space outside the cryostat 31. That is, in FIG. 3 , the shim fixing portion 37 is formed in a region where the first housing member 31-1 and the second housing member 31-2 forming the cryostat 31 have a recessed structure toward the inside of the housing of the cryostat 31.

[0039] Taking the upper superconducting magnet 101-1 as an example, the second housing member 31-2 is folded (deepened) toward the inside of the cryostat 31, and the first housing member 31-1 is folded (raised) toward the inside of the cryostat 31, and they are joined together by forming a flange structure. Taking the lower superconducting magnet 101-2 as an example, the first housing member 31-1 is dug down toward the inside of the cryostat 31 (toward the bottom plate), and the second housing member 31-2 is raised toward the inside of the cryostat 31 (toward the top plate), and they are joined together by forming a flange structure. The position (height) in the z-axis direction where a part of the first housing member 31-1 and a part of the second housing member 31-2 are joined may be of any size as long as it is large enough to accommodate the shim 35 and the shim fixing portion 37. For example, the length of the shim fixing portion 37 in the z-axis direction may be set to the minimum length that allows the shim 35 to adjust the static magnetic field, corresponding to the length of the superconducting coil in the z-axis direction.

[0040] The portion where the first housing member 31-1 and the second housing member 31-2 are folded back and joined to each other is not limited to being formed by a flange structure, but may be folded back, welded, glued, bolted, pressed, cold fitted, shrink fitted, riveted, etc. In other words, any structure may be used as long as it can join the first housing member 31-1 and the second housing member 31-2 and maintain the vacuum state inside the cryostat 31.

[0041] The reinforcing portion 36 is disposed from the rear side of the shim fixing portion 37 outside the cryostat 31, and is formed of a strong material such as stainless steel or resin. Note that the shim 35 may not be inserted into the shim fixing portion 37, and only the reinforcing portion 36 may be disposed. Furthermore, in the case of the upper superconducting magnet 101-1, the reinforcing portion 36 does not have to be disposed. While FIG. 3 shows an example in which the reinforcing portion 36 is disposed in the entire space outside the cryostat 31 where the second housing member 31-2 is folded back, the reinforcing portion 36 may be disposed partially in that space as long as the desired reinforcing strength can be ensured.

[0042] Furthermore, the thickness of the first housing member 31-1 and the second housing member 31-2 may be designed based on the size of the cryostat 31 and the expected load to be placed thereon.

[0043] Next, the positional relationship between the superconducting coil and the shim 35 according to the first configuration example of the superconducting magnet 101 is shown in FIG. Specifically, Fig. 4 is a diagram showing the positional relationship between the shim 35 and the reinforcing portion 36 of the superconducting coil, in this case the lower superconducting magnet 101-2, when looking at the superconducting magnet 101 side from the imaging space 20. As shown in Fig. 4, the superconducting coil is arranged in a loop shape with its opening facing the z-axis direction. Shim 35 is arranged in a loop shape on the inner circumferential side of the superconducting coil (here, on the inner circumferential side of superconducting coil 32). 4, the shims 35 are arranged continuously in a loop shape, but the shims 35 may be arranged discretely along the circumference. In this case, a plurality of shim trays on which iron pieces can be placed may be prepared in the shim fixing portion 37, and the shim trays may be inserted in a plurality of discrete locations along the circumference in the Z-axis direction.

[0044] Furthermore, a reinforcing portion 36 is arranged at the center of the superconducting magnet 101 from the rear side of the shim fixing portion 37. This increases the strength of the housing of the cryostat 31. Furthermore, the lower superconducting magnet 101-2 can support the load when, for example, the gradient magnetic field coil 103, the transmitting coil 115, etc. are arranged on the top plate portion 31-1a.

[0045] Next, a second configuration example of the superconducting magnet 101 according to this embodiment will be described with reference to FIGS. Fig. 5 is a cross-sectional view of an upper superconducting magnet 101-1 and a lower superconducting magnet 101-2 according to a second configuration example of the superconducting magnet 101. Fig. 6 is a diagram showing the positional relationship between the superconducting coil and the shim 35 when viewing the superconducting magnet 101 side from the imaging space 20 according to the second configuration example of the superconducting magnet 101.

[0046] 5 and 6 show an example in which the shim fixing portion 37 is formed outside the loop of the superconducting coil of the superconducting magnet 101, and the shim 35 is arranged therein, rather than the shim fixing portion 37 being arranged inside the loop of the superconducting coil of the superconducting magnet 101. In the second configuration example, similar to the first configuration example, the reinforcing portion 36 is arranged from the space outside the cryostat 31 on the opposite side of the shim fixing portion 37. In this way, the shim fixing portion 37 may be formed at a position 0° in the radial direction from the center of the Z axis of the superconducting magnet 101. In other words, the shim fixing portion 37 may be formed at any position inside or outside the loop of the superconducting coil. Furthermore, the number of shim fixing portions 37 is not limited to one, and two or more shim fixing portions 37 may be formed and shims 35 may be arranged thereon. In other words, multiple shim fixing portions 37 may be formed as long as a desired static magnetic field distribution can be obtained.

[0047] Next, a third configuration example of the superconducting magnet according to this embodiment will be described with reference to FIG. FIG. 7 is a cross-sectional view of the upper superconducting magnet 101-1 and the lower superconducting magnet 101-2. 7 includes a shim 71, a high-temperature superconducting (HTS) coil 72, an HTS coil support portion 73, and a shim fixing portion 74 in addition to the configurations of FIGS.

[0048] The shim 71 is a magnetic body for shimming that can adjust the static magnetic field, similar to the shim 35 . The HTS coil 72 is a coil that has an operating temperature range different from that of the superconducting coil 32 and the superconducting coil 33. The HTS coil 72 may be used as a countermeasure against pre-polarization, may be used to increase the magnetic field strength of the static magnetic field, or may be used to change or adjust the static magnetic field distribution. The HTS coil support 73 supports the HTS coil 72 within the cryostat 31 .

[0049] Specifically, in Fig. 7, in addition to shim 35 on the inner periphery of the superconducting coil loop (at the center of cryostat 31) as shown in Fig. 3, superconducting magnet 101 also has shim 71 arranged on the outer periphery of the superconducting coil loop (on the outer periphery of cryostat 31) as shown in Fig. 5. Furthermore, HTS coil 72 is stored on the outer periphery of shim 71. HTS coil 72 is stored independently from superconducting coil 32 and superconducting coil 33 in an area within cryostat 31 separated by shim fixing portion 74, which will be described later. In other words, superconducting coils are stored independently within cryostat 31 for each operating temperature range.

[0050] In the third configuration example, the shim fixing portion 74 that stores the shim 71 is a region formed in the space outside the cryostat 31 by folding only the first housing member 31-1 toward the inside of the cryostat 31 and joining it to the second housing member 31-2. In other words, the second housing member 31-2 is not formed by folding it toward the inside of the cryostat 31, as shown in FIGS. 3 and 5. Of course, in the third configuration example, the shim fixing portion 74 may also be in the space outside the cryostat 31, formed by folding both the first housing member 31-1 and the second housing member 31-2 toward the inside and joining them, as shown in FIGS. 3 and 5.

[0051] In this way, by forming cryostat 31 in which superconducting coils having different operating temperature ranges are spatially separated, the superconducting coils are structurally separated and housing walls are provided for cryostat 31. Therefore, even if an instantaneous fluctuating magnetic field is set, the influence on other superconducting coils 32 and 33 is reduced. The folded structure and reinforcing portion 36 formed by first housing member 31-1 and second housing member 31-2 can increase the strength of cryostat 31.

[0052] Next, a fourth configuration example of the superconducting magnet 101 according to this embodiment will be described with reference to FIGS. FIG. 8 is a cross-sectional view of an upper superconducting magnet 101-1 and a lower superconducting magnet 101-2 according to a fourth configuration example of the superconducting magnet 101. As shown in FIG.

[0053] The superconducting magnet 101 according to the fourth embodiment includes a refrigerator cold head 81 and a heat transfer section 82 in addition to the first configuration example shown in FIG. The refrigerator cold head 81 is disposed to cool the interior of the cryostat 31 . The heat transfer section 82 is a liquid helium pipe connected to the tip of the refrigerator cold head 81, and is formed to cool the superconducting coil via the refrigerator cold head 81.

[0054] As shown in Fig. 8, the refrigerator cold head 81 is arranged so as to be inserted into the first housing member 31-1. The inside of the cryostat 31 is sealed off except for the area of the refrigerator cold head 81. On the other hand, the first housing member 31-1 except for the area where the refrigerator cold head 81 is arranged is folded back toward the inside of the cryostat 31 until it connects with the second housing member 31-2. As in the third configuration example in Fig. 7, a shim 35 and a reinforcing portion 36 are arranged on the inner periphery of the superconducting coil outside the cryostat 31, and a shim 71 and a reinforcing portion 36 are arranged on the outer periphery of the superconducting coil outside the cryostat 31.

[0055] FIG. 9 shows the positional relationship between shim 35, shim 71, and refrigerator cold head 81 when viewing the superconducting magnet 101 side from imaging space 20 according to the fourth configuration example of superconducting magnet 101.

[0056] As shown in FIG. 9 , in the space around the outer periphery of the superconducting coil loop, a portion of at least one of the top plate and the bottom plate is folded back toward the inside of the cryostat 31 along the circumferential direction of the loop, except for the refrigerator cold head 81, and joined to a portion of the other. In other words, a C-shaped notch is formed along the circumferential direction in the space around the outer periphery of the superconducting coil loop. A shim 71 and a reinforcing member 36 are arranged along the C-shaped notch. The width 91 of the notch in the circumferential direction of the C-shape may be as small as possible to accommodate the refrigerator cold head 81 and the heat transfer member 82. The refrigerator cold head 81 may be positioned anywhere in the radial direction 81 as long as it is positioned within the width 91 of the notch in the circumferential direction and does not physically interfere with the superconducting coil. 8 and 9, a support structure using reinforcing members 36 can be provided on the outside of the coil, thereby improving the strength of the housing of superconducting magnet 101. Furthermore, heat transfer member 82 ensures a heat transfer path between refrigerator cold head 81 and the liquid helium in which the superconducting coil is immersed, and a circulation path for the liquid helium can be provided, thereby cooling the superconducting coil.

[0057] According to the present embodiment described above, in the cryostat storing the superconducting coil, in at least one of the space on the inner periphery side and the space on the outer periphery side of the loop of the superconducting coil, a portion of at least one of the top plate portion of the cryostat and the bottom plate portion of the cryostat is folded back toward the inside of the cryostat and joined to a portion of the other.

[0058] This ensures the strength of the cryostat even when the thickness of the housing member of the cryostat is made thinner than before, and the thinner housing allows for a lighter and more compact cryostat.Furthermore, by locating the reinforcing part in the space outside the folded cryostat, further strength can be ensured. Furthermore, even when the cryostat is enlarged, the strength of the cryostat can be ensured because the structure folded back toward the inside of the cryostat is recessed, which reduces deflection compared to simply enlarging the housing. In other words, the housing can be made lighter while maintaining its strength.

[0059] Although the present embodiment has been described assuming an open-type magnetic resonance imaging apparatus, the static magnetic field adjustment device 50 may also be applied to a magnetic resonance imaging apparatus using a superconducting magnet on only one side, in which the gradient magnetic field coil 103 and the transmission coil 115 are stacked on the upper superconducting magnet 101-1 or the lower superconducting magnet 101-2 shown in the present embodiment. If an imaging space can be formed in the space below the upper superconducting magnet 101-1 or in the space above the lower superconducting magnet 101-2, imaging can be performed in the same way as with an open-type magnetic resonance imaging apparatus.

[0060] The term "processor" used in the above description refers to a circuit such as a central processing unit (CPU), a graphics processing unit (GPU), an application specific integrated circuit (ASIC), or a programmable logic device (e.g., a simple programmable logic device (SPLD), a complex programmable logic device (CPLD), or a field programmable gate array (FPGA)). If the processor is a CPU, for example, the processor realizes its function by reading and executing a program stored in a memory circuit. On the other hand, if the processor is an ASIC, for example, instead of storing the program in a memory circuit, the function is directly incorporated into the processor circuit as a logic circuit. Note that each processor in this embodiment is not limited to being configured as a single circuit per processor, but may be configured as a single processor by combining multiple independent circuits to realize its function. Furthermore, multiple components in the diagram may be integrated into a single processor to realize its function.

[0061] In addition, each function according to the embodiment can be realized by installing a program that executes the above-described processes in a computer such as a workstation and expanding the program in memory. In this case, the program that causes the computer to execute the above-described methods can be stored and distributed on a storage medium such as a magnetic disk (e.g., a hard disk), an optical disk (e.g., a CD-ROM or a DVD), or a semiconductor memory.

[0062] Although several embodiments have been described, these embodiments are presented as examples and are not intended to limit the scope of the invention. These embodiments can be implemented in various other forms, and various omissions, substitutions, modifications, and combinations of embodiments can be made without departing from the spirit of the invention. These embodiments and their modifications are included within the scope and spirit of the invention, as well as within the scope of the invention and its equivalents as defined in the claims. [Explanation of symbols]

[0063] 10. Magnetic resonance imaging equipment 20 Imaging Space 31 Cryostat 31-1 First housing member 31-1a Top plate 31-2 Second housing member 31-2a Bottom plate part 32,33 Superconducting coil 34 Support part 35,71 Sim 36 Reinforcement 37,74 Shim fixing part 72 HTS coil 73 HTS coil support 81 Refrigerator cold head 82 Heat transfer section 100-1 Upper gantry section 100-2 Lower gantry section 101-1 Upper superconducting magnet 101-2 Lower superconducting magnet 103 Gradient magnetic field coil 105 Gradient magnetic field power supply 107 Sleeper 109 Bed control circuit 113 Transmitting circuit 115 Transmitting Coil 117 Receiving Coil 119 Receiving circuit 121 Sequence control circuit 123 Bus 125 Interface 127 Display 129 Storage device 131 Processing circuit 53 input images 54 Training data 55 Machine Learning Models 1071 Top plate 1311 System Control Functions 1312 Image generation function 1313 Display Control Function

Claims

1. a loop-shaped superconducting coil that forms a static magnetic field; a cryostat that has a top plate portion and a bottom plate portion and is a housing that stores the superconducting coil; a portion of at least one of the top plate portion and the bottom plate portion is folded back toward the inside of the cryostat and joined to a portion of the other in at least one of the spaces on the inner circumferential side and the outer circumferential side of the superconducting coil; Superconducting magnet.

2. 2. The superconducting magnet according to claim 1, further comprising a reinforcing portion that is arranged in a space outside the cryostat where the bottom plate portion is folded back and that supports a load applied to the cryostat when a portion of the bottom plate portion is folded back toward the inside of the cryostat and joined to a portion of the top plate portion.

3. 2. The superconducting magnet according to claim 1, further comprising a fixing portion that is arranged in a space outside the cryostat where the top plate portion is folded back, and that fixes a shim that can adjust the static magnetic field, when a portion of the top plate portion is folded back toward the inside of the cryostat and joined to a portion of the bottom plate portion.

4. 2. The superconducting magnet according to claim 1, wherein, when both the portion of the top plate portion and the portion of the bottom plate portion are folded back toward the inside of the cryostat and joined to each other, a position of a joint between the portion of the top plate portion and the portion of the bottom plate portion is adjusted so that a shim that can adjust the static magnetic field and a fixing portion that fixes the shim can be arranged.

5. 2. The superconducting magnet according to claim 1, wherein the thickness of the top plate is designed based on the size of the cryostat and an expected load to be placed on the top plate.

6. the superconducting coil is formed of a plurality of coils having different operating temperature zones, 2. The superconducting magnet according to claim 1, wherein the plurality of coils are independently arranged for each operating temperature zone in regions within the cryostat that are separated by folding back a portion of at least one of the top plate portion and the bottom plate portion toward the inside of the cryostat and joining it to a portion of the other of the top plate portion and the bottom plate portion.

7. further comprising a cold head for cooling the inside of the cryostat by a refrigerator; 2. The superconducting magnet according to claim 1, wherein in the space on the outer periphery of the superconducting coil, a portion of at least one of the top plate portion and the bottom plate portion is folded along a circumferential direction of the superconducting coil, and a portion other than the cold head is folded back toward the interior of the cryostat and joined to a portion of the other plate portion.

8. 2. The superconducting magnet according to claim 1, wherein the joined portions are connected by at least one of welding, adhesive bonding, bolting, press fitting, cold fitting, shrink fitting, and riveting.

9. a superconducting magnet that generates a static magnetic field; a gradient coil for generating a gradient magnetic field; an RF coil for irradiating an RF pulse onto a subject in an imaging space; The superconducting magnet is a loop-shaped superconducting coil that forms a static magnetic field; a cryostat that has a top plate portion and a bottom plate portion and is a housing that stores the superconducting coil; a portion of at least one of the top plate portion and the bottom plate portion is folded back toward the inside of the cryostat and joined to a portion of the other in at least one of the spaces on the inner circumferential side and the outer circumferential side of the superconducting coil; Magnetic resonance imaging device.

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