Static magnetic field adjustment device and magnetic resonance imaging system

Abstract

To improve spatial uniformity of static magnetic field distribution.SOLUTION: A static magnetic field adjustment device according to an embodiment has a plurality of holders holding a magnetic body for adjusting distribution of a static magnetic field used in magnetic resonance imaging. All or some of the plurality of holders are stacked in an axial direction and / or a radial direction of a ring-shaped magnet in a first space in an inner diameter side of the magnet generating the static magnetic field.SELECTED DRAWING: Figure 7

Description

[Technical Field]

[0001] The embodiments disclosed in this specification and the drawings relate to a static magnetic field adjusting device and a magnetic resonance imaging system. [Background technology]

[0002] In magnetic resonance imaging systems, magnetic materials such as iron pieces (iron shims) are used to adjust the distribution of the static magnetic field generated by the magnet. However, due to structural restrictions on the placement of the iron pieces, it can be difficult to adjust the static magnetic field distribution in the space outside the static magnetic field magnet. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] US Patent Application Publication No. 2010 / 0207630 [Patent Document 2] US Patent Application Publication No. 2008 / 0290871 [Patent Document 3] U.S. Patent Application No. 2006 / 0001427 Summary of the Invention [Problem to be solved by the invention]

[0004] One of the problems to be solved by the embodiments disclosed in this specification and the drawings is to improve the spatial uniformity of the static magnetic field distribution. 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]

[0005] The static magnetic field adjustment device according to this embodiment includes a plurality of holders for holding magnetic bodies for adjusting the distribution of a static magnetic field used in magnetic resonance imaging. All or some of the plurality of holders are stacked in the axial and / or radial directions of a ring-shaped magnet that generates the static magnetic field in a first space on the inner diameter side of the magnet. [Brief explanation of the drawings]

[0006] [Figure 1] FIG. 1 is a diagram showing an example of the configuration of a magnetic resonance imaging system according to this embodiment. [Figure 2] FIG. 2 is a perspective view of the gantry according to this embodiment. [Figure 3] FIG. 3 is a schematic view of the YZ cross section of the pedestal shown in FIG. [Figure 4] FIG. 4 is a perspective view of one form of the static magnetic field adjusting device according to the first embodiment. [Figure 5] FIG. 5 is a perspective view of one form of the holder according to the first embodiment. [Figure 6] FIG. 6 is a plan view of the holder shown in FIG. [Figure 7] FIG. 7 is a diagram showing an example of supporting a plurality of holders by the support according to the first embodiment. [Figure 8] FIG. 8 is a view showing a YZ cross section of the first housing shown in FIG. [Figure 9] FIG. 9 is a plan view of a holder according to Modification 1 of the first embodiment. [Figure 10] FIG. 10 is a plan view of a holder according to Modification 2 of the first embodiment. [Figure 11] FIG. 11 is a plan view of a holder according to Modification 3 of the first embodiment. [Figure 12] FIG. 12 is a plan view of a holder according to Modification 4 of the first embodiment. [Figure 13] FIG. 13 is a perspective view of a static magnetic field adjusting device according to Modification 5 of the first embodiment. [Figure 14]FIG. 14 is a view showing a YZ cross section of the first housing according to the seventh modification of the first embodiment. [Figure 15] FIG. 15 is a view showing a YZ cross section of the first housing according to Modification 8 of the first embodiment. [Figure 16] FIG. 16 is a perspective view of one form of the holder according to the second embodiment. [Figure 17] FIG. 17 is a development view of the inner peripheral surface side of the lid portion according to the second embodiment. [Figure 18] FIG. 18 is a plan view of a holder with lid according to the second embodiment. [Figure 19] FIG. 19 is a plan view of a holder with lid according to a first modification of the second embodiment. [Figure 20] FIG. 20 is a plan view of a holder with lid according to Modification 2 of the second embodiment. [Figure 21] FIG. 21 is a plan view of a holder with lid according to Modification 3 of the second embodiment. [Figure 22] FIG. 22 is a plan view of a holder with lid according to Modification 4 of the second embodiment. [Figure 23] FIG. 23 is a plan view of a holder with lid according to a fifth modification of the second embodiment. [Figure 24] FIG. 24 is a plan view of a holder with lid according to a sixth modification of the second embodiment. [Figure 25] FIG. 25 is a diagram showing a first layer of a first configuration example of a static magnetic field adjustment device according to the third embodiment. [Figure 26] FIG. 26 is a diagram showing the second layer of the first configuration example of the static magnetic field adjustment device according to the third embodiment. [Figure 27] FIG. 27 is a diagram showing a static magnetic field adjustment device in which a first layer and a second layer are stacked according to a first configuration example of the third embodiment. [Figure 28] FIG. 28 is a conceptual diagram of a case where the static magnetic field adjustment device according to the third embodiment is wound. [Figure 29] FIG. 29 is a diagram showing a first layer of a second configuration example of the static magnetic field adjustment device according to the third embodiment. [Figure 30]FIG. 30 is a diagram showing a second layer of a second configuration example of the static magnetic field adjustment device according to the third embodiment. [Figure 31] FIG. 31 is a diagram showing a static magnetic field adjustment device in which a first layer and a second layer are stacked according to a second configuration example of the third embodiment. [Figure 32] FIG. 32 is a diagram showing a third configuration example of the static magnetic field adjusting device according to the third embodiment. [Figure 33] FIG. 33 is a diagram showing a fourth configuration example of the static magnetic field adjusting device according to the third embodiment. [Figure 34] FIG. 34 is a cross-sectional view passing through the center of the cylinder of the superconducting magnet in the first configuration example when the static magnetic field adjustment device according to the third embodiment is inserted into the gantry. [Figure 35] FIG. 35 is a diagram showing the positional relationship between the superconducting coil and the static magnetic field adjusting device in a first configuration example in which the static magnetic field adjusting device according to the third embodiment is inserted into a gantry. [Figure 36] FIG. 36 is a cross-sectional view passing through the center of the cylinder of the superconducting magnet in the second configuration example when the static magnetic field adjustment device according to the third embodiment is inserted into the gantry. [Figure 37] FIG. 37 is a diagram showing the positional relationship between the superconducting coil and the static magnetic field adjusting device in a second configuration example in which the static magnetic field adjusting device according to the third embodiment is inserted into a gantry. [Figure 38] FIG. 38 is a diagram showing the positional relationship between the superconducting coil and the static magnetic field adjusting device in a third configuration example in which the static magnetic field adjusting device according to the third embodiment is inserted into a gantry. [Figure 39] FIG. 39 is a diagram illustrating an example of support for placement of magnetic bodies in the static magnetic field adjusting device according to the third embodiment. [Figure 40] FIG. 40 is a diagram showing an example of a static magnetic field adjusting device according to the fourth embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0007] (First embodiment) Hereinafter, the static magnetic field adjusting device and the magnetic resonance imaging system according to the present embodiment will be described in detail with reference to the drawings.

[0008] 1 is a diagram showing an example of the configuration of a magnetic resonance imaging system 1 according to this embodiment. As shown in Fig. 1, the magnetic resonance imaging system 1 includes a gantry 11, a bed 13, a gradient magnetic field power supply 21, a transmission circuit 23, a reception circuit 25, a bed driving device 27, a sequence control circuit 29, and a host computer 50.

[0009] FIG. 2 is a perspective view of the pedestal 11 according to this embodiment. As shown in FIG. 2, the pedestal 11 has a lower housing 121 and an upper housing 122. The lower housing 121 is placed on the floor. The lower housing 121 and the upper housing 122 are connected by a pair of connecting members 123 with a space 20 between them. The support format of the lower housing 121 and the upper housing 122 by the connecting members 123 is not limited to the double-support of the lower housing 121 and the upper housing 122 by the pair of connecting members 123 as shown in FIG. 2, but may also be cantilever support by one of the connecting members 123.

[0010] The lower housing 121 and the upper housing 122 each house a static magnetic field magnet 41, a static magnetic field adjustment device 42, and a gradient magnetic field coil 43. The static magnetic field magnet 41 is a magnet having a circular ring shape that generates a static magnetic field used in magnetic resonance imaging. As the static magnetic field magnet 41, for example, a permanent magnet, an electromagnet, a superconducting magnet, or a combination of two or more of these magnets is used. Here, the central axis of the static magnetic field magnet 41 is defined as the Z axis, an axis horizontally orthogonal to the Z axis and parallel to the body axis of the subject P is defined as the Y axis, and an axis orthogonal to the Y axis and the Z axis is defined as the X axis.

[0011] The static magnetic field adjustment device 42 is a device for adjusting the spatial distribution of a static magnetic field used in magnetic resonance imaging. Specifically, the static magnetic field adjustment device 42 has a plurality of holders for holding magnetic bodies for adjusting the distribution of the static magnetic field used in magnetic resonance imaging. All or some of the plurality of holders are stacked in the Z-axis direction of the static magnetic field magnet 41 in a first space on the inner diameter side of the static magnetic field magnet 41, which has a circular ring shape and generates a static magnetic field. When some of the plurality of holders are arranged in the first space, the remaining plurality of holders may be stacked in the Z-axis direction of the static magnetic field magnet 41 in a second space other than the first space in the radial direction of the static magnetic field magnet 41.

[0012] The gradient magnetic field coil 43 generates a gradient magnetic field upon receiving a current from the gradient magnetic field power supply 21. As an example, the gradient magnetic field coil 43 has three coils corresponding to the X-axis, Y-axis, and Z-axis which are orthogonal to each other. The three coils form a gradient magnetic field whose magnetic field strength changes along each of the X-axis, Y-axis, and Z-axis. The gradient magnetic field power supply 21 supplies a current to the gradient magnetic field coil 43 in accordance with a sequence control signal from the sequence control circuit 29. The gradient magnetic field power supply 21 supplies a current to the gradient magnetic field coil 43, causing the gradient magnetic field coil 43 to generate a gradient magnetic field along each of the X-axis, Y-axis, and Z-axis. The gradient magnetic field is superimposed on the static magnetic field formed by the static magnetic field magnet 41 and applied to the subject P.

[0013] In addition, a transmitting coil 45 and a receiving coil 47 are arranged on the gantry 11. The transmitting coil 45 is arranged, for example, between the lower housing 121 and the upper housing 122, and receives a current from the transmitting circuit 23 to generate a radio frequency pulse (hereinafter referred to as an RF pulse). The transmitting circuit 23 supplies a current to the transmitting coil 45 in order to apply an RF pulse to the subject P via the transmitting coil 45, for exciting target protons present in the subject P. The RF pulse oscillates at a resonance frequency specific to the target protons, exciting the target protons. An MR signal is generated from the excited target protons and detected by the receiving coil 47.

[0014] The receiving coil 47 is disposed, for example, between the lower housing 121 and the upper housing 122, and receives MR signals emitted from target protons present in the subject P in response to the action of RF pulses. The receiving coil 47 has multiple receiving coil elements capable of receiving MR signals. The received MR signals are supplied to the receiving circuit 25 via a wired or wireless connection. The receiving circuit 25 receives MR signals generated from excited target protons via the receiving coil 47. The receiving circuit 25 processes the received MR signals to generate digital MR signals. The digital MR signals can be expressed in k-space, which is defined by spatial frequencies. Hereinafter, the digital MR signals will be referred to as k-space data. The k-space data is digital data that represents the signal intensity values of the MR signals as a function of time. The k-space data is supplied to the host computer 50 via a wired or wireless connection.

[0015] The above-described transmitting coil 45 and receiving coil 47 are merely examples. A transmitting / receiving coil having both transmitting and receiving functions may be used instead of the transmitting coil 45 and receiving coil 47. Furthermore, the transmitting coil 45, receiving coil 47, and transmitting / receiving coil may be combined.

[0016] A bed 13 is installed adjacent to the gantry 11. The bed 13 has a top plate 131 and a base 133. A subject P is placed on the top plate 131. The base 133 supports the top plate 131 so that it can slide along the X-axis, Y-axis, and Z-axis. A bed driving device 27 is housed in the base 133. The bed driving device 27 moves the top plate 131 under the control of a sequence control circuit 29. The bed driving device 27 may include any motor, such as a servo motor or a stepping motor.

[0017] The sequence control circuit 29 has, as hardware resources, a processor such as a CPU (Central Processing Unit) or an MPU (Micro Processing Unit) and memories such as a ROM (Read Only Memory) and a RAM (Random Access Memory). The sequence control circuit 29 synchronously controls the gradient magnetic field power supply 21, the transmission circuitry 23, and the reception circuitry 25 based on data acquisition conditions set by the processing circuitry 51 to execute a predetermined pulse sequence and acquire MR signals emitted from the subject P. The reception circuitry 25 receives the MR signals via the reception coil 47, processes the received MR signals, and acquires k-space data.

[0018] 1, the host computer 50 is a computer having a processing circuit 51, a memory 52, a display 53, an input interface 54, and a communication interface 55. Data communication between the processing circuit 51, the memory 52, the display 53, the input interface 54, and the communication interface 55 is performed via a bus.

[0019] The processing circuitry 51 has a processor such as a CPU as a hardware resource. The processing circuitry 51 functions as the core of the magnetic resonance imaging system 1. For example, the processing circuitry 51 executes various programs to set data acquisition conditions, design pulse sequences, reconstruct MR images based on k-space data, process MR images, display MR images, and perform other processing. The processing circuitry 51 may also execute static magnetic field adjustment software for adjusting the static magnetic field distribution and determine the material, shape, dimensions, and / or number of magnetic bodies to be mounted in the static magnetic field adjustment device 42.

[0020] The memory 52 is a storage device that stores various information, such as an HDD (Hard Disk Drive), an SSD (Solid State Drive), an integrated circuit storage device, etc. The memory 52 may also be a drive device 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.

[0021] The display 53 displays various information under the control of the processing circuit 51. As the display 53, for example, a CRT display, a liquid crystal display, an organic EL display, an LED display, a plasma display, or any other display known in the art can be appropriately used.

[0022] The input interface 54 includes input devices that accept various commands from the 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 input devices are not limited to those equipped with physical operating components such as a mouse and a keyboard. For example, an example of the input interface 54 also includes 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 system 1 and outputs the received electrical signal to various circuits. The input interface 54 may also be a voice recognition device that converts a voice signal collected by a microphone into a command signal.

[0023] The communication interface 55 is an interface that connects the magnetic resonance imaging system 1 to a workstation, a PACS (Picture Archiving and Communication System), an HIS (Hospital Information System), a RIS (Radiology Information System), etc. via a LAN (Local Area Network), etc. The communication interface 55 transmits and receives various types of information to and from the connected workstation, PACS, HIS, and RIS.

[0024] Fig. 3 is a schematic diagram of the YZ cross section of the pedestal 11 shown in Fig. 2. As shown in Fig. 3, a lower housing 121 and an upper housing 122 are arranged with a space 20 between them. The lower housing 121 and the upper housing 122 have internal structures that are approximately symmetrical across the Y axis. In the following, to avoid duplication of explanation, only the lower housing 121 will be described with regard to elements that are common to the lower housing 121 and the upper housing 122.

[0025] The lower housing 121 has a first container 124 and a second container 125. The first container 124 is a vacuum container having a non-penetrating hollow portion 126. A cylindrical static magnetic field magnet 41 is housed in the first container 124. The static magnetic field magnet 41 is housed in the first container 124 so that the central axis of the first container 124 coincides with the central axis (Z-axis) of the static magnetic field magnet 41. One or more annular superconducting coils are used as the static magnetic field magnet 41. In addition to the static magnetic field magnet 41, the first container 124 also houses a refrigerant for maintaining the superconducting state of the static magnetic field magnet 41. For example, liquid helium is used as the refrigerant. Note that if the superconducting state can be maintained without a refrigerant, a refrigerant need not be housed. Here, the space radially inside the static magnetic field magnet 41 is referred to as an inner diameter space IS, and the space radially outside the static magnetic field magnet 41 is referred to as an outer diameter space OS. The inner diameter space IS is an example of the first space. The outer diameter space OS is an example of the second space. In this embodiment, an imaging space (FOV: Field Of View) 210 is formed in the space 20 located at a position outside the inner diameter space IS and the outer diameter space OS. As an example, the imaging space 210 is formed in a local region of the space 20 that intersects with the Z axis.

[0026] A static magnetic field adjustment device 42 is disposed in the hollow portion 126 of the first container 124, which is the inner diameter space IS of the static magnetic field magnet 41. The static magnetic field adjustment device 42 adjusts the spatial distribution of the static magnetic field generated by the static magnetic field magnet 41, and improves the uniformity of the spatial distribution in the imaging space 210. In other words, the static magnetic field adjustment device 42 is disposed at a position where the uniformity of the static magnetic field distribution in the imaging space 210 can be improved. In this embodiment, it is assumed that the imaging space 210 is located in a local region intersecting the Z axis, and therefore the static magnetic field adjustment device 42 is disposed in the inner diameter space IS in order to improve the uniformity of the static magnetic field distribution in the imaging space 210 disposed at that position.

[0027] 3, the second container 125 is disposed between the first container 124 and the space 20. The second container 125 accommodates a gradient magnetic field coil 43. The gradient magnetic field coil 43 superimposes a gradient magnetic field on the imaging space 210. The gradient magnetic field coil 43 is disposed at a position outside the inner diameter space IS and the outer diameter space OS of the static magnetic field magnet 41. The first container 124 and the second container 125 may be formed separately or integrally.

[0028] Next, the structure of the static magnetic field adjustment device 42 will be described. Fig. 4 is a perspective view of one form of the static magnetic field adjustment device 42. As shown in Fig. 4, the static magnetic field adjustment device 42 has a plurality of holders 61 stacked along the Z axis. The holders 61 have a circular ring shape with a hollow portion 62, and are structures made of a non-metallic material such as synthetic resin that has no or only a slight effect on the static magnetic field distribution.

[0029] Fig. 5 is a perspective view of one embodiment of holder 61. Fig. 6 is a plan view of holder 61 shown in Fig. 5. As shown in Figs. 5 and 6, holder 61 has a plurality of accommodating sections 63 that can accommodate magnetic bodies 71. Accommodating sections 63 are spaces that communicate with openings 631 formed in the surface of holder 61, and are non-penetrating spaces that do not penetrate to inner circumferential surface 612 of holder 61. As an example, openings 631 are formed in outer circumferential surface 611 of holder 61.

[0030] The housing 63 houses a magnetic body 71 for adjusting the spatial distribution of the static magnetic field. The dimensions and / or shape of the housing 63 formed on the outer circumferential surface 611 can be arbitrarily designed according to the dimensions and / or shape of the magnetic body 71 to be housed. The number and / or position of the housing 63 can be arbitrarily designed according to the degree of freedom in adjusting the spatial distribution of the static magnetic field by the magnetic body 71. Note that it is not necessary to provide housing 63 in all of the multiple holders 61; only some of the multiple holders 61 may be provided with housing 63. The type of magnetic body 71 can be arbitrarily selected from ferromagnetic materials and soft magnetic materials such as silicon steel plate, electromagnetic steel plate, iron, nickel, ferrite, magnet, electromagnetic soft iron, permalloy, amorphous, permendur, nanocrystal, etc. The shape of the magnetic body 71 can be arbitrarily selected from square, rectangular, cylinder, sphere, triangle, polygonal cylinder, torus, tubular, etc. The shape of the accommodating portion 63 may be designed in accordance with the shape of the magnetic body so that the magnetic body 71 can be accommodated therein.

[0031] The accommodation section 63 can accommodate a spacer 72 in addition to the magnetic body 71. The spacer 72 is a structure used to adjust and / or fix the position of the magnetic body 71 in the accommodation section 63. The shape of the spacer 72 can be arbitrarily selected from square, rectangular, cylinder, sphere, ellipse, triangle, polygonal prism, annular, tubular, etc. Typically, the spacer 72 may be arbitrarily selected from materials that have little effect on the static magnetic field distribution, such as synthetic resin.

[0032] The material, shape, size and / or number of the magnetic bodies 71 and / or spacers 72 can be determined by a static magnetic field simulation using static magnetic field adjustment software by the processing circuitry 51. In the static magnetic field simulation, the processing circuitry 51 predicts the static magnetic field distribution based on static magnetic field information inside and outside the imaging space, superconducting coil information, magnetic body electromagnetic force information, magnetic body magnetic susceptibility information, static magnetic field correction gradient magnetic field information, magnetic field distribution method by the applied RF coil and / or pulse sequence / reconstruction information to be used, and determines the material, shape, size and / or number of the magnetic bodies 71 and / or spacers 72 such that the spatial uniformity of the static magnetic field distribution in the imaging space satisfies a predetermined standard.

[0033] 5, a lid 73 for closing an opening 631 of the storage section 63 may be attached to the holder 61. For example, the lid 73 is detachably attached to the holder 61 with fasteners such as screws or adhesive tape. Note that the mounting form of the lid 73 is not limited to the above, and the lid 73 may be attached to the holder 61 with a hinge or the like so as to be openable and closable, or may be provided so as to be movable along the outer circumferential surface 611 with a linear guide or the like.

[0034] Next, support of the multiple holders 61 in the Z-axis direction will be described with reference to Fig. 7. Fig. 7 is a diagram showing an example of support of the multiple holders 61 by supports 64, 65, 66, and 67. The left diagram in Fig. 7 is a perspective view of the static magnetic field adjustment device 42 before being fixed by the supports 64, 65, 66, and 67, and the right diagram is a perspective view of the static magnetic field adjustment device 42 after being fixed by the supports 64, 65, 66, and 67. Note that, as an example, the static magnetic field adjustment device 42 in Fig. 7 holds four holders 61, but the number of holders 61 held by the static magnetic field adjustment device 42 is not limited to this, and is not limited to two or more.

[0035] As shown in the left diagram of FIG. 7 , the static magnetic field adjustment device 42 includes supports 64, 65, 66, and 67 that support multiple holders 61 so that they can be stacked in the Z-axis direction. As described above, each of the multiple holders 61 has a circular shape with a hollow portion 62 formed therein. As an example of a support, a fixed rod 64 is used, which is inserted into the hollow portion 62 of the multiple holders 61. By inserting the multiple holders 61 through the fixed rod 64, it is possible to suppress positional fluctuations of the holders 61 in the direction perpendicular to the Z-axis. To suppress rotation of the holders 61 relative to the fixed rod 64, a portion of the outer circumferential surface of the holder 61 and a corresponding portion of the side circumferential surface of the fixed rod 64 may be keyed, i.e., a protrusion and a groove that structurally fits into the protrusion may be formed on a portion of the outer circumferential surface of the holder 61 and a corresponding portion of the side circumferential surface of the fixed rod 64. This ensures correction of the static magnetic field by the magnetic material.

[0036] As shown in Fig. 7, of the multiple holders 61 inserted into a fixed rod 64, the holders 61 at both ends in relation to the Z axis are fixed to the fixed rod 64 by a pair of fasteners 65. The pair of fasteners 65 sandwich the multiple holders 61 from both sides in the Z axis direction and are then mechanically and detachably fixed to the fixed rod 64. For example, the fasteners 65 and the fixed rod 64 can be fixed by fasteners such as screws or pins, or by keyway processing. This makes it possible to ensure correction of the static magnetic field by the magnetic material.

[0037] The fixing rod 64 may have a housing (not shown in FIG. 7) into which a magnetic sensor can be inserted. The magnetic sensor detects the distribution of the magnetic field in at least one of the X-, Y-, and Z-axis directions. An electric signal (magnetic field detection signal) indicating the strength of the magnetic field detected by the magnetic sensor is supplied to the processing circuit 51 and can be used for static magnetic field simulations, etc. The magnetic sensor may be provided in the holder 61 instead of the fixing rod 64. In this case, the magnetic sensor may be housed in the housing 63 or another space, or may be attached to the surface of the holder 61.

[0038] 7, each of the multiple holders 61 serves as a support and has a convex portion 66 on a top surface 613 perpendicular to the Z-axis direction, and a concave portion 67 that can fit into the convex portion 66 on a bottom surface 614 opposite the top surface 613. That is, each holder 61 has a convex portion 66 that contacts the top surface 613 for connecting to another holder 61, and a concave portion 67 that contacts the bottom surface 614 for connecting to another holder 61; in other words, the holders 61 are provided with a keyway. The keyway processing makes it possible to prevent each holder 61 from rotating relative to the other holders 61.

[0039] Here, we will briefly explain the assembly procedure for the static magnetic field adjustment device 42. First, a magnetic body is placed in each of the housing portions 63 of the multiple holders 61. It is not necessary for all housing portions 63 to house a magnetic body. Similarly, some of the multiple holders 61 may not house a magnetic body. Next, a fixing rod 64 is inserted through the hollow portions 62 of the multiple holders 61, and the multiple holders 61 are fixed with a pair of fasteners 65. This completes the assembly of the static magnetic field adjustment device 42.

[0040] Next, the positional relationship between static magnetic field magnet 41 and static magnetic field adjusting device 42 will be described. Fig. 8 is a diagram showing a YZ cross section of first container 124 shown in Fig. 3. As shown in Fig. 8, static magnetic field magnet 41 is housed in first container 124. Static magnetic field magnet 41 has a support base 411, a first superconducting coil 412, and a second superconducting coil 413. Support base 411 is a support structure for first superconducting coil 412 and second superconducting coil 413.

[0041] The first superconducting coil 412 and the second superconducting coil 413 are annular superconducting coils having different diameters. The first superconducting coil 412 and the second superconducting coil 413 are arranged so that their central axes coincide with the Z-axis. The radial directions of the first superconducting coil 412 and the second superconducting coil 413 are arranged so that they are parallel to the Y-axis direction. The first superconducting coil 412 is located closer to the imaging space 210 than the second superconducting coil 413, and has a smaller diameter. The arrangement of the first superconducting coil 412 and the second superconducting coil 413 may be reversed. Furthermore, the number of superconducting coils included in the static magnetic field magnet 41 is not limited to two, and may be three or more.

[0042] Here, the range inside first superconducting coil 412 and second superconducting coil 413 in the Y-axis direction is referred to as inner diameter range 81. More specifically, the smallest diameter formed by first superconducting coil 412 and second superconducting coil 413, i.e., the inside of the smallest diameter of first superconducting coil 412, is inner diameter range 81. The range outside inner diameter range 81 in the Y-axis direction is referred to as outer diameter range 82. Furthermore, the range occupied by first superconducting coil 412 and second superconducting coil 413 in the Z-axis direction is referred to as coil range 83, the range closer to imaging space 210 than coil range 83 is referred to as upper range 84, and the range closer to the floor than coil range 83 is referred to as lower range 85. The region where inner diameter range 81 and coil range 83 overlap is defined as inner diameter space IS. More specifically, the range overlapping inner diameter range 81 and coil range 83 and inside support base 411 is defined as inner diameter space IS. Additionally, the area where the outer diameter range 82 and the coil range 83 overlap is defined as an outer diameter space OS.

[0043] A static magnetic field is generated from the first superconducting coil 412 and the second superconducting coil 413 by supplying current to the first superconducting coil 412 and the second superconducting coil 413. By supplying currents of mutually independent intensity and / or phase to the first superconducting coil 412 and the second superconducting coil 413, an imaging space 210 having a static magnetic field uniformity usable for magnetic resonance imaging is formed in the outer region of the inner diameter space IS, more specifically, in the overlap region of the inner diameter range 81 and the upper range 84.

[0044] 8, the first container 124 and the static magnetic field magnet 41 are arranged so that the inner diameter space IS is located in the hollow portion 126 formed in the first container 124. All or some of the multiple holders included in the static magnetic field adjustment device 42 are arranged in the inner diameter space IS, in the hollow portion 126 formed by the first container 124. All or some of the multiple holders included in the static magnetic field adjustment device 42 are arranged between the bottom surface and / or inner wall surface of the first container 124 that contacts the hollow portion 126, via an instrument for adjusting the positions of all or some of the multiple holders.

[0045] Specifically, as shown in FIG. 8 , in order to place the static magnetic field adjustment device 42 in the inner diameter space IS, the static magnetic field adjustment device 42 is raised relative to the bottom surface of the non-penetrating hollow portion 126 via a spacer 421. The spacer 421 is a support structure made of a non-metallic material such as synthetic resin that has no or only a small effect on the static magnetic field distribution. The static magnetic field adjustment device 42 may extend beyond the inner diameter space IS. As shown in FIG. 8 , a holder 422 is inserted between the inner wall surface of the hollow portion 126 and the static magnetic field adjustment device 42 to fill the gap between the hollow portion 126 and the static magnetic field adjustment device 42 in the radial direction of the hollow portion 126. Inserting the holder 422 makes it possible to suppress fluctuations in the position of the static magnetic field adjustment device 42 in the hollow portion 126. Furthermore, in order to fix the static magnetic field adjustment device 42 to the first container 124, another holder 423 may be provided in a part of the opening of the hollow portion 126 above the Z axis. The static magnetic field adjustment device 42 can be held down from above by the holder 423. The holder 423 may be provided so as to cover the entire opening of the hollow portion 126 above the Z axis.

[0046] As described above, by making it possible to stack the holders for holding the magnetic body in the Z-axis direction, it becomes possible to hold the magnetic body for shimming with a high degree of freedom even in an MRI system that is not a cylindrical type with a bore. This makes it possible to design with a high degree of freedom the position and / or shape of the imaging space with a highly uniform static magnetic field distribution, outside the inner space of the annular static magnetic field magnet. The above-described embodiment is an example, and various elements can be deleted, added, and / or modified.

[0047] (Modification 1 of the first embodiment) The housing portion in the above embodiment is provided on the outer peripheral surface of the holder. However, this embodiment is not limited to this. The housing portion may be provided on the outer peripheral surface, inner peripheral surface, top surface, and / or bottom surface of the holder.

[0048] FIG. 9 is a plan view of holder 61 according to Modification 1 of the first embodiment. As shown in FIG. 9, storage section 63a is provided on outer peripheral surface 611 of holder 61, as in the above embodiment. Alternatively, storage section 63b may be provided on inner peripheral surface 612 of holder 61. Storage section 63b has opening 631 on inner peripheral surface 612 and is a non-through space that stores a magnetic body. Furthermore, storage sections 63c and 63d may be provided on top surface 613 of holder 61. Storage sections 63c and 63d have openings on top surface 613 and are non-through spaces that store a magnetic body. Storage sections 63c and 63d have different shapes. They may have an arc shape in a plane like storage section 63c, a circular shape like storage section 63d, or any other shape that can store a magnetic body.

[0049] According to the first modification of the first embodiment, the storage portion 63 for storing the magnetic body may be formed on any surface of the holder 61. This makes it possible to form the holder 61 on any surface, taking into consideration the ease of access to the storage portion 63 by an operator, etc.

[0050] (Modification 2 of the first embodiment) The holder in the above embodiment has a circular ring shape. However, this embodiment is not limited to this. The holder may have any shape as long as it can accommodate the magnetic body.

[0051] FIG. 10 is a plan view of holders 61a, 61b, and 61c according to Modification 2 of the first embodiment. As shown in FIG. 10, holders 61a, 61b, and 61c have an arc shape. The shapes of each of holders 61a, 61b, and 61c may be designed so that they form a ring shape when combined. In order to prevent misalignment between holders 61a, 61b, and 61c, holders 61a, 61b, and 61c may be fixed to each other by keyway machining or the like. Note that the shapes of holders 61a, 61b, and 61c are not limited to ring shapes or arc shapes, and may be any shape such as a polygonal shape, a spherical shape, or a linear shape.

[0052] (Modification 3 of the first embodiment) The holder according to the above embodiment has a single-layer structure in the radial direction. However, this embodiment is not limited to this. All or some of the multiple holders according to the third modification of the first embodiment have a multi-layer structure in the radial direction. Specifically, all or some of the multiple holders according to the third modification of the first embodiment have multiple holder layers arranged in a radial direction perpendicular to the Z-axis direction, and each of the multiple holder layers is capable of holding a magnetic body. The holder according to the third modification of the first embodiment will be described below.

[0053] FIG. 11 is a plan view of a holder 61d according to Modification 3 of the first embodiment. As shown in FIG. 11, the holder 61d has multiple holder layers 671, 672 arranged in the radial direction. Each of the holder layers 671, 672 has one or more accommodation sections 63 for accommodating magnetic bodies. As in the above embodiment, the position, shape, and / or number of accommodation sections 63 can be arbitrarily designed using static magnetic field correction software, etc. The number of holder layers 671, 672 is not particularly limited as long as it is two or more, but in the following description, it is assumed that there are two: a first holder layer 671 and a second holder layer 672.

[0054] As shown in Fig. 11 , in Modification 3 of the first embodiment, the accommodation section 63 is provided on the outer peripheral surface side of each of the first holder layer 671 and the second holder layer 672. A spacer layer 68 is provided between the first holder layer 671 and the second holder layer 672. The spacer layer 68 is provided to fix the positions of the first holder layer 671 and the second holder layer 672. The first holder layer 671, the spacer layer 68, and the second holder layer 672 may be provided with a fixing means such as key groove processing so that they can be fixed to one another. Note that if the positions of the holder layers can be fixed to one another, the spacer layer 68 does not have to be provided.

[0055] The assembly procedure for holder 61d according to Modification 3 of the first embodiment will now be briefly described. First, magnetic bodies are accommodated in first holder layer 671 and second holder layer 672. Next, a fixing rod (not shown in FIG. 11) is inserted into second holder layer 672, which is the innermost layer, and second holder layer 672 and the fixing rod are fixed together. Next, spacer layer 68 is fitted into second holder layer 672, and first holder layer 671 is fitted into spacer layer 68, thereby completing the assembly of holder 61d according to Modification 3 of the first embodiment.

[0056] According to variant 3 of the first embodiment, all or part of the multiple holders have a multi-layer structure in the radial direction, which improves the freedom of arrangement of the magnetic material in the radial direction, thereby making it possible to precisely adjust the static magnetic field.

[0057] (Fourth modification of the first embodiment) In the above-described third modification of the first embodiment, the first holder layer arranged at the outermost periphery has a housing portion on its outer periphery surface. However, this embodiment is not limited to this. Of the multiple holder layers according to the fourth modification of the first embodiment, holder layers other than the innermost holder layer have a first housing portion having an opening on its outer periphery surface, a second housing portion having an opening on its inner periphery surface, a third housing portion having an opening on its top surface, and / or a fourth housing portion having an opening on its bottom surface, for holding a magnetic body. Hereinafter, a static magnetic field adjustment device according to the fourth modification of the first embodiment will be described.

[0058] FIG. 12 is a plan view of a holder 61e according to Modification 4 of the first embodiment. As shown in FIG. 12, the holder 61e has multiple holder layers 671, 672 arranged in the radial direction. Each holder layer 671, 672 has one or more accommodation portions 63e, 63h, 63g, 63h for accommodating a magnetic substance. As in the above embodiment, the position, shape, and / or number of accommodation portions 63 can be arbitrarily designed using static magnetic field correction software or the like. The number of holder layers is not particularly limited as long as it is two or more, but in the following description, it is assumed that there are two: a first holder layer 671 and a second holder layer 672.

[0059] 12, the first holder layer 671 has a housing portion 63e provided on the outer peripheral surface, a housing portion 63f provided on the inner peripheral surface, and a housing portion 63h provided on the top surface. The second holder layer 672 has a housing portion 63g provided on the outer peripheral surface. Magnetic bodies and spacers can be arbitrarily placed in each of the housing portions 63e, 63h, 63g, and 63h.

[0060] Incidentally, the storage portion 63e provided on the outer peripheral surface and the storage portion 63h provided on the top surface do not necessarily have to be provided, and storage portion 63f may be provided only on the inner peripheral surface. Providing storage portion 63f on the inner peripheral surface is expected to improve workability. In addition to the outermost first holder layer 671, storage portions may also be provided on the inner peripheral surface, top surface, and / or bottom surface of the innermost second holder layer 672 and other holder layers in addition to the outer peripheral surface.

[0061] According to the fourth modification of the first embodiment, the receiving portion can be provided on any surface of each holder layer, improving accessibility to the receiving portion.

[0062] (Fifth Modification of the First Embodiment) In the above embodiment, the static magnetic field adjustment device has a support that supports multiple holders stacked in the Z-axis direction. However, this embodiment is not limited to this. The support according to the fifth modification of the first embodiment may support spacers for adjusting the spacing between the multiple holders in a stackable manner.

[0063] FIG. 13 is a perspective view of a static magnetic field adjustment device 42 according to a fifth modification of the first embodiment. The static magnetic field adjustment device 42 shown in FIG. 13 has a four-tier configuration, similar to the static magnetic field adjustment device 42 shown in FIG. 7 and other figures. As shown in FIG. 13, annular holders 61 and spacer layers 68 are stacked in the Z-axis direction, and fixing rods 64 are inserted into the hollow portions of the holders 61 and the spacer layers 68, and the holders 61 and the spacer layers 68 are fixed by fasteners 65. The spacer layers 68 are provided to space two adjacent holders 61 apart in the Z-axis direction. As with the holders 61, the spacer layers 68 may also be formed with fixing means such as keyways to fix their positions relative to the adjacent holders 61, or may be formed with fixing means such as keyways to fix their positions relative to the fixing rods 64.

[0064] 13, the spacer layer 68 is provided between the topmost holder 61 and the second-tier holder 61, but the installation position of the spacer layer 68 is not limited to this. Also, in FIG. 13, only one spacer layer 68 is provided between the topmost holder 61 and the second-tier holder 61, but two or more spacer layers 68 may be provided as necessary. The position, number and / or thickness in the Z-axis direction of the spacer layer 68 can be designed arbitrarily using static magnetic field correction software.

[0065] According to the fifth modification of the first embodiment, it is possible to provide a spacer layer between the holders, which improves the degree of freedom in arranging the magnetic material, and in turn makes it possible to adjust the static magnetic field more precisely.

[0066] (Modification 6 of the first embodiment) The first housing according to the above embodiment has a non-through hollow portion (hereinafter referred to as the non-through hollow portion) 126 in the Z-axis direction. However, this embodiment is not limited to this. The first housing according to the sixth modification of the first embodiment may have a hollow portion (hereinafter referred to as the through hollow portion) that penetrates in the Z-axis direction. In this case, the static magnetic field adjustment device is disposed in the through hollow portion. In order to fix the position of the static magnetic field adjustment device in the through hollow portion, the static magnetic field adjustment device may be fixed to the first housing via any holder. As an example, the holder may be provided so as to support the static magnetic field adjustment device from the bottom side of the through hollow portion.

[0067] (Seventh modification of the first embodiment) In the above embodiment, the static magnetic field adjusting device 42 is provided in the inner diameter space IS of the static magnetic field magnet 41, as shown in Fig. 8 etc. However, this embodiment is not limited to this. All of the multiple holders according to the sixth modification of the first embodiment are arranged in the outer diameter space OS of the static magnetic field magnet 41, outside the first and second housings that house the static magnetic field magnet. Hereinafter, a static magnetic field adjusting device according to the seventh modification of the first embodiment will be described.

[0068] 14 is a diagram showing a YZ cross section of the first container 124 according to the seventh modification of the first embodiment. As shown in FIG. 14, the static magnetic field adjustment device 44 according to the seventh modification of the first embodiment has a cylindrical shape with a hollow portion, and is provided in the outer diameter space OS so as to surround the outer periphery of the first container 124. The first container 124 is disposed in the hollow portion of the static magnetic field adjustment device 44. Like the static magnetic field adjustment device 42 described above, the static magnetic field adjustment device 44 has a plurality of annular holders stacked in the Z-axis direction. In order to prevent the holders from being misaligned with each other, keyways such as the convex portion 66 and the concave portion 67 in FIG. 7 may be machined on the top and bottom surfaces of the holders.

[0069] As shown in FIG. 14 , the static magnetic field adjustment device 44 is disposed in the coil range 83 in the Z-axis direction. In order to dispose the static magnetic field adjustment device 44 in the coil range 83, it is held in the first container 124 via holders 91 and 92. Specifically, the holder 92 holds the static magnetic field adjustment device 44 in order to raise the height of the static magnetic field adjustment device 44 from the floor surface to the coil range 83. The holder 91 fixes the static magnetic field adjustment device 44 to the first container 124. If the static magnetic field adjustment device 44 can be fixed using only the holder 92, the holder 91 does not need to be provided. Note that in order to fix the static magnetic field adjustment device 44 and the first container 124, fixing means such as key grooves may be formed on both the static magnetic field adjustment device 44 and the first container 124.

[0070] According to the seventh modification of the first embodiment, by providing the static magnetic field adjustment device 44 in the outer diameter space OS, it is possible to provide a region with a uniform static magnetic field distribution in the outer diameter range 82 in the upper range 84. The outer diameter space OS in which the static magnetic field adjustment device 44 is provided is not limited to the above example. As an example, if another housing that houses a cryostat or correction coil exists in the space on the outer periphery of the first container 124, a non-through hollow portion or a through hollow portion may be provided in the other housing, and the static magnetic field adjustment device 44 may be provided in the non-through hollow portion or the through hollow portion. As another example, a non-through hollow portion or a through hollow portion may be provided on the outer periphery of the other housing, and the static magnetic field adjustment device 44 may be provided in the non-through hollow portion or the through hollow portion. These examples of the outer diameter space OS or the second space in which the static magnetic field adjustment device 44 is provided are also examples.

[0071] (Eighth Modification of the First Embodiment) All of the multiple holders in the above embodiments are provided in either the inner diameter region or the outer diameter region of the static magnetic field magnet. However, this embodiment is not limited to this. The multiple holders in Modification 7 are provided in both the inner diameter region and the outer diameter region of the static magnetic field magnet. Below, we will explain a static magnetic field adjustment device in Modification 8 of the first embodiment.

[0072] 15 is a diagram showing a YZ cross section of the first container 124 according to Modification 8 of the first embodiment. As shown in FIG. 15, a static magnetic field adjusting device 42 is provided in the inner diameter space IS, and a static magnetic field adjusting device 44 is provided in the outer diameter space OS. That is, holders for accommodating magnetic bodies are disposed in both the inner diameter space IS and the outer diameter space OS. According to Modification 8 of the first embodiment, the space in which the magnetic bodies can be disposed can be expanded, and as a result, it is expected that the imaging space 210 will be expanded.

[0073] (Modification 9 of the First Embodiment) In the first embodiment described above, the static magnetic field adjustment device 42 is provided in the hollow portion 126 of each of the lower housing 121 and the upper housing 122 shown in FIG. 3 . However, this embodiment is not limited to this. The static magnetic field adjustment device 42 may be provided in the hollow portion 126 of only one of the lower housing 121 and the upper housing 122. Furthermore, the static magnetic field adjustment device 42 is applicable not only to a magnetic resonance imaging system 1 having both the lower housing 121 and the upper housing 122, but also to a magnetic resonance imaging system having only one of the lower housing 121 and the upper housing 122.

[0074] (Second embodiment) 16 is a perspective view of one form of holder 61 according to the second embodiment. As shown in FIG. 16, holder 61 has a plurality of accommodation sections 63 that can accommodate shimming magnetic bodies 71. The accommodation sections 63 are non-penetrating spaces that communicate with openings formed in the surface of holder 61. As an example, accommodation sections 63 have openings in an outer peripheral surface 611 of holder 61 and form non-penetrating spaces that do not penetrate to an inner peripheral surface 612 of holder 61.

[0075] The housing 63 houses a shimming magnetic body 71 for adjusting the spatial distribution of the static magnetic field. The dimensions and / or shape of the housing 63 formed on the outer circumferential surface 611 can be arbitrarily designed according to the dimensions and / or shape of the magnetic body 71 to be housed. The number and / or position of the housing 63 can be arbitrarily designed according to the degree of freedom in adjusting the spatial distribution of the static magnetic field by the magnetic body 71. Note that it is not necessary to provide housing 63 in all of the multiple holders 61; housing 63 may be provided in only some of the multiple holders 61. The type of magnetic body 71 can be arbitrarily selected from ferromagnetic materials and soft magnetic materials such as silicon steel plate, electromagnetic steel plate, iron, nickel, ferrite, magnet, electromagnetic soft iron, permalloy, amorphous, permendur, nanocrystal, etc. The shape of the magnetic body 71 can be arbitrarily selected from square, rectangular, cylinder, sphere, ellipse, triangle, polygonal cylinder, torus, tubular, etc.

[0076] The accommodation section 63 can accommodate a spacer 72 in addition to the magnetic body 71. The spacer 72 is a structure used to adjust and / or fix the position of the magnetic body 71 in the accommodation section 63. The shape of the spacer 72 can be arbitrarily selected from square, rectangular, cylinder, sphere, triangle, polygonal prism, annular, tubular, etc. Typically, the spacer 72 may be arbitrarily selected from materials that have little effect on the static magnetic field distribution, such as synthetic resin.

[0077] The material, shape, size and / or number of the magnetic bodies 71 and / or spacers 72 can be determined by a static magnetic field simulation using static magnetic field adjustment software by the processing circuitry 51. In the static magnetic field simulation, the processing circuitry 51 predicts the static magnetic field distribution based on static magnetic field information inside and outside the imaging space, superconducting coil information, magnetic body electromagnetic force information, magnetic body magnetic susceptibility information, static magnetic field correction gradient magnetic field information, magnetic field distribution method by the applied RF coil and / or pulse sequence / reconstruction information to be used, and determines the material, shape, size and / or number of the magnetic bodies 71 and / or spacers 72 such that the spatial uniformity of the static magnetic field distribution in the imaging space satisfies a predetermined standard.

[0078] As shown in FIG. 16 , the holder 61 is provided with fasteners 161 for connecting a lid (not shown in FIG. 16 ), which will be described later, to the holder 61. Typically, a fastener 161 is provided for each of the plurality of storage sections 63. As an example, the fasteners 161 are provided near the upper side and the lower side of each storage section 63. As another example, the fasteners 161 may be provided only in either the upper side or the lower side. Note that the positions of the fasteners 161 are not limited to the positions illustrated in FIG. 16 , and they may be provided so as to surround each storage section 63, or may be provided near the left side and / or the right side. Details of the fasteners 161 will be described later.

[0079] 17 is a development view of the inner peripheral surface side of lid portion 171, and Fig. 18 is a plan view of holder 61 (hereinafter referred to as holder with lid) around which lid portion 171 is wrapped. Note that the "inner peripheral surface" of lid portion 171 means the surface facing outer peripheral surface 611 of holder 61. The "short axis direction" of lid portion 171 corresponds to the Z axis direction of holder 61, and the "long axis direction" of lid portion 171 corresponds to the circumferential direction of holder 61.

[0080] As shown in FIGS. 17 and 18 , the lid 171 has a flexible film-like membrane material 710. The shape of the membrane material 710 may be selected from rectangular shapes exemplified in FIG. 17 and other figures, as well as squares, ellipses, circles, arcs, curves, square lines, cylinders, spheres, triangular prisms, polygonal prisms, annuli, tubular shapes, and any other shape (free form) depending on the shape of the magnetic material and the shape of the holder 61. The material of the membrane material 710 may be selected from materials having a hardness sufficient to allow the membrane material 710 to conform to the outer circumferential surface of the holder 61. For example, soft PVC, urethane, rubber, synthetic resin, etc. may be used for the membrane material 710. Two or more fasteners 172 for fastening the magnetic material 71 housed in two or more housing sections 63 of the holder 61 to be covered are provided on the inner circumferential surface of the lid 171 at two or more positions corresponding to the two or more housing sections 63 to be covered, respectively. 17 and 18, the accommodating portions 63 to be covered are all of the accommodating portions 63 formed in the holder 61. The pitch of the fixing devices 172 in the longitudinal direction and the pitch of the accommodating portions 63 in the circumferential direction are designed to be approximately the same value.

[0081] Each of the two or more fixtures 172 is a spacer inserted into the housing 63. By inserting the fixture 172 into the housing 63, the magnetic body 71 and the spacer 72 housed in the housing 63 are pressed down and fixed by the fixture 172. The fixture 172 has a plurality of frame members 721, 722, 723, and 724 arranged so as to be insertable into the housing 63. The frame members 721, 722, 723, and 724 are rod-shaped structures made of a non-metallic material such as synthetic resin that has no or only a slight effect on the static magnetic field distribution. The plurality of frame members 721, 722, 723, and 724 are arranged with gaps between them. Providing the gaps increases the degree of adhesion between the lid 171 and the holder 61 when the lid 171 is wrapped around the holder 61. The frame materials 721, 722, 723, and 724 are fixed to the membrane material 710 by any fixing means such as fasteners such as screws or tape, adhesives, or key groove processing.

[0082] The configuration of the frame members 721, 722, 723, and 724 may be designed according to the shape of the opening of the storage section 63. For example, if the opening of the storage section 63 is rectangular, the frame members 721, 722, 723, and 724 are configured with an upper horizontal frame 721, a lower horizontal frame 722, a left vertical frame 723, and a right vertical frame 724, and the upper horizontal frame 721, the lower horizontal frame 722, the left vertical frame 723, and the right vertical frame 724 are arranged in a rectangle so as to be inscribed in the opening of the storage section 63.

[0083] Each of the frame materials 721, 722, 723, and 724 has a rectangular column shape. Each of the frame materials 721, 722, 723, and 724 has a predetermined thickness in the depth direction of the storage section 63. The frame materials 721, 722, 723, and 724 are stacked in the depth direction of the storage section 63 according to the total thickness of the magnetic substances 71 stored in the storage section 63. Specifically, the frame materials 721, 722, 723, and 724 are stacked in the depth direction to such an extent that the frame materials 721, 722, 723, and 724 come into contact with the magnetic substances 71 and spacers 72 stored in the storage section 63 when the lid portion 171 is wrapped around the holder 61. This makes it possible to press and fix the magnetic substances 71 and spacers 72 stored in the storage section 63. The stacked frame materials 721, 722, 723, and 724 may be fixed to each other using fasteners such as screws or tape, adhesives, or keyway processing. As long as the frame members 721, 722, 723, and 724 are stackable, they are not limited to a rectangular column shape and may have any shape. Alternatively, the frame members 721, 722, 723, and 724 may be configured to be expandable and contractible in the thickness direction.

[0084] The lid portion 171 shown in FIGS. 17 and 18 is formed so as to be able to cover all of the multiple storage sections 63 formed in the holder 61. In this case, the film material 710 has a length in the longitudinal direction that allows it to wrap around the outer circumferential surface of the holder 61. A pair of lid fasteners 173-1 and 173-2 for detachably connecting the film material 710 to each other is provided at both ends of the film material 710 in the longitudinal direction. The lid fasteners 173-1 and 173-2 may have any fixing means such as screws, buttons, hook-and-loop fasteners, protrusions, or grooves. This makes it possible to fix both ends of the film material 710 in the longitudinal direction to the holder 61. Because the film material 710 has a length that allows it to wrap around the outer circumferential surface of the holder 61, the lid portion 171 can cover all of the storage sections 63 provided on the outer circumferential surface of the holder 61 with one piece of lid portion 171.

[0085] The holder 61 and the lid 171 each have a pair of retaining fasteners 161, 174 for detachably connecting them to each other. For example, the retaining fastener 161 on the holder 61 side has a claw, and the retaining fastener 174 on the lid 171 side has a groove that engages with the claw. The pitch of the retaining fasteners 174 in the longitudinal direction of the lid 171 and the pitch of the retaining fasteners 161 in the circumferential direction of the holder 61 are designed to be approximately the same value. The retaining fasteners 174 are preferably provided near the fixing device 172 to improve adhesion between the holder 61 and the lid 171 around the accommodation section 63.

[0086] Here, the procedure for assembling the holder 61 around which the lid portion 171 is wrapped will be described. First, a magnetic material is accommodated in the accommodation section 63 of the holder 61. Note that it is not necessary for a magnetic material to be accommodated in all accommodation sections 63. Next, the lid portion 171 is wrapped around the holder 61. Specifically, each fixing device 172 is inserted into the corresponding accommodation section 63, the holding fasteners 161 and 174 are joined together, the lid portion 171 is wrapped around the holder 61, and finally the lid fasteners 173-1 and 173-2 are joined together. This completes the assembly of the holder 61 around which the lid portion 171 is wrapped.

[0087] As described above, the holder, which has a storage section for storing magnetic material, is covered with a lid, and the storage section is closed with the lid. This makes it easier to close the storage section with the lid than in the conventional example, where a lid is placed on each storage section one by one. The above-described embodiment is an example, and various elements can be deleted, added, and / or modified.

[0088] (Modification 1 of the second embodiment) In the above embodiment, the lid portion covers the entire circumference of the holder. However, this embodiment is not limited to this. The lid portion according to Modification 1 of the second embodiment covers only a portion of the outer circumferential surface of the holder. The static magnetic field adjustment device according to Modification 1 will be described below.

[0089] FIG. 19 is a plan view of a lidded holder 61 according to Modification 1 of the second embodiment. As shown in FIG. 19, the holder 61 according to Modification 1 of the second embodiment has multiple storage sections 63a locally provided on its outer circumferential surface. A magnetic body is stored in each of the multiple storage sections 63a. The lid 171a according to Modification 1 is provided with a fixing device 172 and a holding fastener 174 on its inner circumferential surface, similar to the lid 171 shown in FIG. 17. The length of the lid 171a in the longitudinal direction is designed to be long enough to cover all of the multiple storage sections 63a to be covered with one piece of lid. Lid fasteners 173a are provided at both ends of the lid 171a in the longitudinal direction. The lid fasteners 173a are configured to be connectable to the holder 61. The lid fasteners 173a enable the lid 171a to be attached to the holder 61.

[0090] 19, and can be designed to have any shape such as a rectangular shape, a linear shape, or a circular shape. It is assumed that the storage portion 63c will be covered by a means other than the lid portion 171a.

[0091] (Modification 2 of the second embodiment) In the above embodiment, the cover portion is a single piece that covers all of the multiple storage portions provided on the outer peripheral surface of the holder. However, this embodiment is not limited to this. The cover portion according to the second modification of the second embodiment covers only some of the multiple storage portions provided on the outer peripheral surface of the holder. Hereinafter, a static magnetic field adjustment device according to the second modification of the second embodiment will be described.

[0092] Fig. 20 is a plan view of a lidded holder 61 according to Modification 2 of the second embodiment. As shown in Fig. 20, holder 61 according to Modification 2 of the second embodiment has a plurality of storage portions 63a provided on its outer circumferential surface. A magnetic body is stored in each of the storage portions 63a. The storage portions 63a are provided around the entire outer circumferential surface of holder 61.

[0093] As shown in FIG. 20 , multiple lids are provided in Modification 2 of the second embodiment. The number of lids may be any number greater than or equal to two, but FIG. 20 illustrates two lids 171b and 171c. All of the multiple storage sections 63a provided on the outer circumferential surface of the holder 61 are covered by the two lids 171b and 171c. Similar to the lid 171 shown in FIG. 17 , the lids 171b and 171c have a fixing device 172 and a retaining fastener 174 provided on their inner circumferential surfaces. The length of each of the lids 171b and 171c according to Modification 2 is designed to be long enough to cover the storage sections 63a to be covered by the lids 171b and 171c. For example, since two storage sections 63a are to be covered by the lid 171c, the lid 171c may have a length sufficient to cover all of the two storage sections 63a. Lid fasteners 173b and 173c are provided at both ends of the lid portions 171b and 171c in the longitudinal direction. The lid fasteners 173b and 173c are configured to be connectable to the holder 61. The lid portions 171b and 171c can be attached to the holder 61 by the lid fasteners 173b and 173c.

[0094] (Modification 3 of the second embodiment) In the above embodiment, the holder has a circular ring shape. However, this embodiment is not limited to this. The holder may have a polygonal shape. The polygon may be a triangle, a pentagon, a hexagon, or the like, with no limitation on the number of sides. Hereinafter, a static magnetic field adjustment device according to a third modification of the second embodiment will be described.

[0095] FIG. 21 is a plan view of a lidded holder 61a according to Modification 3 of the second embodiment. As shown in FIG. 21, the holder 61a according to Modification 3 of the second embodiment has a hexagonal shape. A plurality of storage sections 63 are locally provided on the outer peripheral surface of the holder 61a. A lid portion 171d according to Modification 3 of the second embodiment is provided with a fixing device 172 and a holding fastener 174 on its inner peripheral surface, similar to the lid portion 171 shown in FIG. 17. The length of the lid portion 171d in the major axis direction is designed to be long enough to cover all of the multiple storage sections 63 with one piece of lid portion. Lid fasteners 173d are provided on both ends of the lid portion 171d in the major axis direction. The lid fasteners 173d are configured to be connectable to the holder 61a. The lid fasteners 173d allow the lid portion 171d to be attached to the holder 61a.

[0096] Even when the holder has a polygonal shape, the housing portions may be provided over the entire outer peripheral surface. In this case, one lid portion may cover all of the housing portions formed on the outer peripheral surface, or multiple lid portions may cover all of the housing portions.

[0097] (Fourth modification of the second embodiment) In the above-described embodiment, the accommodating portion is provided on the outer peripheral surface of the holder. However, this embodiment is not limited to this. The accommodating portion according to the fourth modification of the second embodiment is provided on the inner peripheral surface of the holder. In this case, the lid portion is wrapped around the holder so that it covers two or more accommodating portions to be covered that are provided on the inner peripheral surface of the holder. Hereinafter, a static magnetic field adjustment device according to the fourth modification of the second embodiment will be described.

[0098] FIG. 22 is a plan view of a lidded holder 61b according to Modification 4 of the second embodiment. As shown in FIG. 22, the holder 61b according to Modification 4 of the second embodiment has multiple storage sections 63b provided around the entire inner circumferential surface. Each of the multiple storage sections 63b is a space that communicates with an opening formed in the inner circumferential surface and stores a magnetic body. The length of the lid section 171 in the major axis direction is designed to be long enough to cover all of the multiple storage sections 63b with one piece of lid section, in other words, long enough to cover the inner circumferential surface of the holder 61b. As shown in FIG. 17, the lid section 171 has a fixing member 172 and a holding fastener 174 provided on its inner circumferential surface. The fixing member 172 is inserted into the storage section 63b to fix the magnetic body stored in the storage section 63b. A pair of lid fasteners 173 are provided at both ends in the longitudinal direction of lid portion 171, and by connecting lid fasteners 173 together, both ends in the longitudinal direction of lid portion 171 can be fixed to holder 61b. By covering the inner circumferential surface with lid portion 171, it becomes possible for lid portion 171 to close multiple storage sections 63b formed on the inner circumferential surface.

[0099] The storage sections are not limited to being provided around the entire circumference of the inner circumferential surface, but may be provided only locally. In this case, the lid section 171 may have a length sufficient to cover the entire circumference of the inner circumferential surface, or a length sufficient to cover the range in which the storage sections are located. The storage sections are not limited to being provided around the entire circumference of the inner circumferential surface, but may be provided with a plurality of lid sections 171 to cover all of the storage sections 63b. The storage sections may be provided on both the outer and inner circumferential surfaces of the holder.

[0100] (Fifth Modification of the Second Embodiment) In the above-described embodiments, the holder has a circular ring shape or a polygonal shape. However, this embodiment is not limited to this. The holder according to the fifth modification of the second embodiment has a plate shape. Hereinafter, a static magnetic field adjustment device according to the fifth modification of the second embodiment will be described.

[0101] FIG. 23 is a plan view of a lidded holder 61e according to Modification 5 of the second embodiment. As shown in FIG. 23, the holder 61e according to Modification 5 of the second embodiment is a plate-shaped structure. A plurality of storage sections 63e are formed on one main surface of the holder 61e and are arranged in a line in the longitudinal direction. Each of the storage sections 63e accommodates a magnetic body or a spacer. It is assumed that the storage sections 63e have the same shape and dimensions. Similar to the lid 171 shown in FIG. 17 , the lid 171e according to Modification 5 has a fixing member 172 and a retaining fastener 174 on its inner circumferential surface. The length of the lid 171e in the longitudinal direction is designed to be long enough to cover the storage sections 63 to be covered. Covering the main surface of the holder 61e with the lid 171e allows the lid 171e to close the storage sections 63e formed on the main surface.

[0102] The holders 61e can also be stacked in the thickness direction of the plate shape (the depth direction of the paper in FIG. 23). A plurality of stacked holders 61e can be placed in the hollow portion 126 of the first container 124 so that the thickness direction coincides with the Z-axis direction.

[0103] The holder 61e can also be applied to a cylindrical MRI system having a bore. In this case, the holder 61e plays the same role as a shim tray. That is, the holder 61e can be inserted into a plate-shaped or rectangular space (hereinafter referred to as a storage space) that is provided in the gap between the gradient magnetic field coils of the cylindrical gantry and extends in the axial direction of the cylindrical gantry. In this case, the holder 61e is inserted into the storage space so that the long axis direction of the holder 61e is aligned with the axial direction of the cylindrical gantry.

[0104] (Modification 6 of the second embodiment) Variation 6 of the second embodiment is an application example of Variation 5 of the second embodiment. In Variation 5 of the second embodiment, the multiple accommodating sections have the same shape and dimensions and are arranged in a row in the longitudinal direction. However, this embodiment is not limited to this. The multiple accommodating sections according to Variation 6 of the second embodiment can be arranged in any layout. Below, a static magnetic field adjustment device according to Variation 6 of the second embodiment will be described.

[0105] 24 is a plan view of a lidded holder 61f according to Modification 6 of the second embodiment. As shown in FIG. 24, holder 61f according to Modification 6 of the second embodiment is a plate-shaped structure, similar to holder 61e according to Modification 5 of the second embodiment. One main surface of holder 61f is formed with a plurality of housing portions 63e, 63f, 63g, and 63h of various sizes and shapes. Each of the housing portions 63e, 63f, 63g, and 63h houses a magnetic body or a spacer. By increasing the degree of freedom in the size, shape, and / or arrangement of housing portions 63e, 63f, 63g, and 63h, it is possible to further improve the uniformity of the static magnetic field.

[0106] The lid portion 171f according to the sixth modification of the second embodiment has a fixing member 172 and a retaining fastener 174 provided on its inner circumferential surface, similar to the lid portion 171 shown in FIG. 17 . The fixing member 172 is provided at a position corresponding to the accommodation portions 63e, 63f, 63g, and 63h. This allows the magnetic bodies and spacers accommodated in each accommodation portion 63e, 63f, 63g, and 63h to be fixed. The retaining fastener 174 is also provided at a position corresponding to the accommodation portions 63e, 63f, 63g, and 63h. This allows the lid portion 171 and the holder 61 to be tightly fixed together. The length of the lid portion 171f in the major axis direction is designed to be long enough to cover the accommodation portions 63e, 63f, 63g, and 63h to be covered. By covering the main surface of the holder 61f with the lid portion 171f, it becomes possible to close the plurality of storage portions 63e, 63f, 63g, and 63h formed on the main surface with the lid portion 171f.

[0107] (Seventh modification of the second embodiment) In the second embodiment described above, the static magnetic field adjustment device 42 is provided in the inner diameter space IS of the static magnetic field magnet 41, as shown in FIG. 3 etc. However, this embodiment is not limited to this. The static magnetic field adjustment device 42 may be arranged in the outer diameter space OS of the static magnetic field magnet 41, outside the lower housing 121 that houses the static magnetic field magnet 41. By providing the static magnetic field adjustment device 42 in the outer diameter space OS, it becomes possible to change the position of the imaging space 210. Furthermore, the static magnetic field adjustment device 42 may be provided in each of the inner diameter space IS and the outer diameter space OS. This also makes it possible to expand the imaging space 210.

[0108] (Modification 8 of the second embodiment) In the second embodiment described above, the static magnetic field adjustment device 42 is provided in the hollow portion 126 of each of the lower housing 121 and the upper housing 122 shown in FIG. 3 . However, this embodiment is not limited to this. The static magnetic field adjustment device 42 may be provided in the hollow portion 126 of only one of the lower housing 121 and the upper housing 122. Furthermore, the static magnetic field adjustment device 42 is applicable not only to a magnetic resonance imaging system 1 having both the lower housing 121 and the upper housing 122, but also to a magnetic resonance imaging system having only one of the lower housing 121 and the upper housing 122.

[0109] (Third embodiment) A first configuration example of a static magnetic field adjusting device for adjusting a static magnetic field generated by a superconducting magnet according to the third embodiment will be described with reference to FIGS. 25 to 27. FIG.

[0110] The static magnetic field adjustment device according to the first configuration example is assumed to be configured with two layers of sheets. Fig. 25 shows the first layer 30 of the static magnetic field adjustment device according to the first configuration example. The first layer 30 includes a first sheet 31, first partition members 32 and 33, and a fixing part 34.

[0111] The first sheet 31 is a planar sheet on which a magnetic material is arranged, and is assumed to be made of a flexible material. That is, the first sheet 31 has flexibility. For example, the first sheet 31 may be made of a flexible material such as soft PVC, urethane, or rubber, or a material with low rigidity, which may be formed into a sheet shape.

[0112] The first partition members 32 and 33 are formed on the surface on which the magnetic material 71 is disposed and separate the area in which the magnetic material is disposed. The first partition members 32 and 33 may be formed of, for example, a flexible material. They may also be made of a plastic or rigid material as long as they are not affected by winding. The first partition member 32 is a rectangular partition extending in the vertical direction of FIG. 25 and has a predetermined height from the first sheet 31. Similarly, the first partition member 33 is a rectangular partition extending in the horizontal direction of FIG. 25 and has a predetermined height from the first sheet 31. The first partition members 32 and 33 are arranged in a two-dimensional lattice pattern, and the magnetic material 71 is disposed in the area surrounded by the first partition members 32 and 33. The height of the first partition members 32 and 33 from the first sheet 31 may be appropriately designed depending on the maximum height (maximum thickness) of the magnetic material 71 to be disposed.

[0113] The fixing portion 34 is a member used to fix the sheets together or to fix the static magnetic field adjustment device 42 in a rolled shape. The fixing portion 34 may be any fixing member or method such as a screw, a pin, a button, a hook-and-loop fastener, a groove fitting method, or a claw engagement method.

[0114] The magnetic body 71 is a magnetic body for adjusting the magnetic field, and may be formed of a ferromagnetic or soft magnetic material such as silicon steel plate, electromagnetic steel plate, iron, nickel, ferrite, magnet, electromagnetic soft iron, permalloy, amorphous, permendur, nanocrystal, etc. The magnetic body 71 is assumed to be in the shape of a rectangular plate. The first sheet 31 may have guide lines drawn thereon to indicate the positions where the magnetic bodies 71 are to be placed.

[0115] 26 shows the second layer 35 of the static magnetic field adjustment device 42. In the second layer 35, a second sheet 36, a second partition member 37, and a fixing portion 34 are arranged.

[0116] The second sheet 36 is a sheet made of the same material as the first sheet 36. That is, the second sheet 36 is a flexible, planar sheet.

[0117] The second partition member 37 is a rectangular partition extending in the horizontal direction of Figure 26. The second partition member 37 is formed on the surface of the second layer 35 that faces the surface of the first layer 30 on which the magnetic material 71 is disposed. When the first layer 30 and the second layer 35 are laminated, the second partition member 37 is disposed in the gap between the first partition members 32 and 33, thereby surrounding the region in which the magnetic material 71 is disposed. The second partition member 37 may also be formed from the same material as the first partition members 32 and 33.

[0118] Next, a static magnetic field adjustment device 42 in which the first layer 30 and the second layer 35 according to the first configuration example are stacked will be described with reference to FIG. FIG. 27 is a conceptual diagram illustrating the interlayer component arrangement when the first layer 30 and the second layer 35 are stacked and fixed. Specifically, the first layer 30 is stacked so that the surface on which the magnetic material 71 and the first partition members 32 and 33 are arranged faces the surface on which the second layer 35 is placed, facing the surface on which the second partition member 37 is arranged. The first layer 30 and the second layer 35 are fixed to each other by the fastening members 34. For example, if the fastening members 34 are screws, the first layer 30 and the second layer 35 can be fastened to each other by screwing them together. Alternatively, if the fastening members 34 are engagement-type fastening members, the fastening members 34 of the first layer 30 can be formed as fastening members, and the second layer can be formed as fastening members such as grooves, and the fastening members 34 of the first layer 30 can be fastened by engaging the fastening members with the grooves of the second layer. Alternatively, fastening members may be fastened with buttons, hook-and-loop fasteners, adhesives, or the like. The stacked first sheet 31 and the second sheet 36 are also simply referred to as a sheet.

[0119] The first partition members 32 and 33, the second partition member 37, and the magnetic material 71 are fixed by being sandwiched between the first layer 30 and the second layer 35, that is, within the sheet, to form the static magnetic field adjustment device 42. As shown in Fig. 27, the second partition member 37 is disposed in the gap between the first partition members 32 and 33, thereby forming a lattice-like wall, which partitions the area in which the magnetic material 71 is disposed.

[0120] In addition, when the number of magnetic bodies 71 is small, spacers 72 made of rubber, resin, or the like may be stored in the area where the magnetic bodies 71 are arranged to hold down and fix the magnetic bodies 71. Furthermore, the first partition members 32 and 33 and the second partition member 37 may be formed with grooves or recesses for fixing the magnetic bodies 71.

[0121] Next, a conceptual diagram of winding the static magnetic field adjusting device 42 is shown in FIG. As shown in Fig. 28, the static magnetic field adjustment device 42 can be wound with the first layer 30 and the second layer 35 stacked on top of each other. For example, the static magnetic field adjustment device 42 can be wound around a winding core, which is a core material for winding, and the ends can be fixed together by a fixing part 34 arranged at the ends in the winding direction, thereby forming a cylindrical static magnetic field adjustment device 42. Of course, the static magnetic field adjustment device 42 can be fixed by winding another sheet or tape from the outer periphery of the static magnetic field adjustment device 42 after being wound around the winding core, without being limited to the fixing part 34. Note that the static magnetic field adjustment device 42 is not limited to being wound around one revolution, and may have a curved shape like a semicircle or other arc, in other words, a semicylindrical shape.

[0122] In this way, the first partition members 32 and 33 and the second partition member 37 only need to be formed in a shape and arrangement that allows winding without interference between adjacent members when winding the first layer 30 and the second layer 35 in a stacked state. In other words, by arranging the second partition member 37 so as to fill the gap between the first partition members 32 and 33 that are designed for winding the first layer 30 into a cylindrical shape, it is possible to form a lattice-like wall that fixes and holds the magnetic body 71 in a cylindrical state.

[0123] The first partition member 33 and the second partition member 37 may be tapered from the surface of the first layer 30 toward the coaxial center of the winding core, depending on the curvature of the winding around the winding core. In other words, the first partition member 33 and the second partition member 37 may be configured in a shape that brings them into close contact with each other when wound.

[0124] Furthermore, in areas where the magnetic material 71 is not disposed, spacers 72 made of resin, rubber, or the like may be disposed instead of the magnetic material 71. As a result, for example, when a magnetic field is applied to the static magnetic field adjustment device 42, the shape may be deformed by the magnetic force depending on the material of each partition member, and the space in the area where the magnetic material 71 is not disposed may be crushed, thereby changing the thickness of the sheet. Therefore, by disposing the spacers 72, the thickness between the layers of the static magnetic field adjustment device 42 can be kept constant.

[0125] Next, a second configuration example of the static magnetic field adjusting device 42 will be described with reference to Fig. 29 to Fig. 31. First, Fig. 29 shows the first layer 30 of the static magnetic field adjusting device 42 according to the second configuration example. The static magnetic field adjustment device 42 according to the second configuration example is different in the size and shape of the magnetic body 71. In the example of Fig. 29, based on Fig. 25, the magnetic body 71 is arranged across two regions in the horizontal direction, and the magnetic body 71 is arranged across three or more regions in the vertical direction. The arrangement of the first partition members 32 and 33 may be adjusted according to the size and shape of the magnetic body 71. For example, to arrange the magnetic body 71 across two regions in the horizontal direction, one of the first partition members 33 in the vertical direction may be removed.

[0126] The second layer 35 of the static magnetic field adjusting device 42 according to the second configuration example is shown in FIG. In the second layer 35, the arrangement of the second partition members 37 is adjusted to match the size and shape of the magnetic bodies 71 arranged in the first layer 30.

[0127] Next, a static magnetic field adjustment device 42 according to a second configuration example, in which the first layer 30 and the second layer 35 are stacked, will be described with reference to FIG. 31 is a conceptual diagram showing the arrangement of components between the first layer 30 and the second layer 35 when they are stacked and fixed together, similar to FIG. 27. By appropriately removing the first partition members 32 and 33 and the second partition member 37 and adjusting the walls formed by each partition member according to the size and shape of the magnetic material 71, magnetic materials 71 of different sizes and shapes can be arranged regardless of the size and shape of the magnetic material 71.

[0128] 25 to 31, a rectangular magnetic body 71 is assumed, but any shape that facilitates fine adjustment of the magnetic field may be used, such as a square, circle, cylinder, sphere, polygon, ring, tube, etc. In this case, the shapes of the first partition members 32 and 33 and the second partition member 37 may be changed to match the shape of the magnetic body 71.

[0129] Moreover, although an example has been shown in which the second partition member 37 is arranged on the second layer 35, the present invention is not limited to this. The first partition members 32 and 33 and the second partition member 37 may be arranged on the first layer 30 side, and the second layer 35 may be only the second sheet 36, as long as the second sheet 36 fixes the magnetic body 71 and each partition member. Furthermore, the static magnetic field adjustment device 42 is not limited to a two-layer structure, and may have a configuration in which three or more layers are stacked. Alternatively, the static magnetic field adjustment device 42 may have a two-layer structure in which a single sheet is folded over.

[0130] A third configuration example of the static magnetic field adjusting device 42 will be described with reference to FIG. The static magnetic field adjustment device 42 according to the third configuration example is formed from one sheet, and is divided into a first region R1 and a second region R2 with a folding line B as a reference.

[0131] In the first region R1, first partition members 32 and 33 and a second partition member 37 are formed, and a magnetic body 71 is disposed in the region surrounded by the first partition members 32 and 33 and the second partition member 37. On the other hand, in the second region R2, no partition members are formed. A two-layered static magnetic field adjustment device 42 can be produced by folding back the second region R2 toward the first region R1 along the folding line B and bonding them together. After bonding them together, the sheets can be fixed by a fixing part 34, for example.

[0132] Next, a fourth configuration example of the static magnetic field adjusting device 42 will be described with reference to FIG. In the static magnetic field adjustment device 42 according to the fourth configuration example, first partition members 32 and 33 are formed in the first region R1, and a second partition member 37 is formed in the second region R2. As in the case of Fig. 32, the second region R2 is folded back toward the first region R1 and attached to create a two-layered static magnetic field adjustment device 42. This is the same configuration as when the first layer 30 shown in Fig. 25 and the second layer 35 shown in Fig. 26 are stacked.

[0133] Next, a first configuration example in which the static magnetic field adjusting device 42 is inserted into the gantry 11 will be described with reference to FIGS. FIG. 34 is a cross-sectional view taken along the center of the cylinder of the first container 124-1 of the upper housing 122 and the first container 124 of the lower housing 121. As shown in FIG.

[0134] The first container 124 according to the third embodiment includes two superconducting coils (a first superconducting coil 412 and a second superconducting coil 413), a support base 411, a spacer 421, a static magnetic field adjusting device 42, and a winding core 70. The first container 124 is formed so that the central portion of the cylinder is concave. Alternatively, the first container 124 may be formed so that the central portion of the cylinder is bored. The first container 124 described below is not limited to being integrally molded, and may also be formed by appropriately joining a plurality of members.

[0135] The first superconducting coil 412 and the second superconducting coil 413 are arranged so that the openings of the loops face vertically (the z-axis direction in FIG. 34), and are designed so that currents flow in opposite directions to reduce leakage magnetic fields. Here, two superconducting coils are shown as an example, but this is not limiting and a static magnetic field may be formed by three or more superconducting coils. Hereinafter, the first superconducting coil 412 and the second superconducting coil 413 will also be collectively referred to as "superconducting coils" as necessary. The support base 411 is housed in the first container 124 and supports the superconducting coil. The static magnetic field adjustment device 42 wound around the winding core 70 is inserted into the recessed portion in the cylindrical center part of the first container 124. The winding core 70 and the static magnetic field adjustment device 42 may have a fixing mechanism, such as a key groove, that fixes the winding core 70 to the static magnetic field adjustment device 42 without rotating.

[0136] Although the static magnetic field adjustment device 42 has been described above as having a two-layer structure, the static magnetic field adjustment device 42 may be formed from a single sheet. For example, the first partition members 32 and 33 and the second partition member 37 are formed on the first sheet 31, and the magnetic body 71 is fixed in a predetermined area with an adhesive. By winding the surface on which the magnetic body 71 is fixed around the winding core 70, the magnetic body 71 can be fixed by the winding core 70 in addition to being fixed with the adhesive.

[0137] The spacer 421 is arranged to raise the bottom of the winding core 70 and the static magnetic field adjustment device 42. Note that if the spacer 421 is not necessary because the depth of the recessed shape of the first container 124 is shallow, the spacer 421 does not have to be arranged.

[0138] 35 is a diagram showing the positional relationship between the superconducting coil and static magnetic field adjusting device 42 when viewing the gantry 11 side from imaging space 210. As shown in Fig. 35, the superconducting coil is arranged in a loop shape with its opening facing the z-axis direction. Static magnetic field adjusting device 42 wound around winding core 70 is arranged on the inner periphery side of the superconducting coil (here, on the inner periphery side of first superconducting coil 412).

[0139] Next, a second configuration example in which the static magnetic field adjusting device 42 is inserted into the gantry 11 will be described with reference to FIGS. Fig. 36 is a cross-sectional view passing through the center of the cylinder of the first container 124 in the second configuration example when the static magnetic field adjustment device 42 is inserted into the gantry 11. Fig. 37 is a diagram showing the positional relationship between the superconducting coil and the static magnetic field adjustment device 42 in the second configuration example when the static magnetic field adjustment device 42 is inserted into the gantry 11.

[0140] In the second configuration example, a plurality of static magnetic field adjustment devices 42 are inserted into the gantry 11. Here, a first static magnetic field adjustment device 42 is wound around a winding core 70, and a spacer 74 is wound around the first static magnetic field adjustment device 42. A second static magnetic field adjustment device 42 is wound around the spacer 74. The spacer 74 may be made of the same material as the winding core 70, or may be made of a different material. By inserting the spacer 74, the distance between the first static magnetic field adjustment device 42 and the second static magnetic field adjustment device 42 can be adjusted.

[0141] In this way, a plurality of static magnetic field adjustment devices 42 may be arranged in a plurality of layers. Note that it is only necessary that the static magnetic field adjustment devices 42 are fixed by the spacers 74 between them so that the static magnetic field adjustment devices 42 do not move. Furthermore, it is not limited to arranging a plurality of static magnetic field adjustment devices 42 in layers, and one static magnetic field adjustment device 42 may be arranged by being wound in a spiral shape together with the spacer 74.

[0142] Next, FIG. 38 shows the positional relationship between the superconducting coils and the static magnetic field adjusting device in a third configuration example in which the static magnetic field adjusting device 42 is inserted into the gantry 11. As shown in Fig. 38, a plurality of static magnetic field adjustment devices 42 may be inserted partially along the circumferential direction. That is, the static magnetic field adjustment devices 42 may not be formed by rolling them into a cylindrical shape, but may be formed in a columnar shape having a curvature along the circumferential direction of the superconducting coil, i.e., a semi-cylindrical shape, and may be inserted on the inner circumferential side of the superconducting coil.

[0143] As shown in Figures 36 to 38, by using multiple static magnetic field adjustment devices 42, for example, by inserting and removing some of the static magnetic field adjustment devices 42 while a static magnetic field is being generated, it is possible to fine-tune the static magnetic field without excitation or demagnetization.

[0144] According to the third embodiment described above, a static magnetic field adjustment device is produced that has partition members for holding multiple magnetic bodies on or within a flexible sheet. Furthermore, in the case of a two-layer structure, a static magnetic field adjustment device is produced that has a first partition member formed on the surface where the magnetic bodies of the first layer are arranged and that separates the area where the magnetic bodies are arranged, and a second partition member formed on the second layer when the first and second layers are stacked, so that it is disposed in the gaps between the first partition member and surrounds the area where the magnetic bodies are arranged. The first partition member and the second partition member are formed in positions and with sizes that do not interfere with each other when the static magnetic field adjustment device is rolled into a cylindrical shape.

[0145] This has the advantage of reducing the number of steps required, since the static magnetic field adjustment device can adjust the magnetic field to handle multiple shim trays, compared to conventional shim trays.Furthermore, compared to cylindrical magnetic resonance imaging devices that require a large space for arranging conventional shim trays, a shimming device with a high degree of freedom that allows for appropriate magnetic field adjustment can be provided even in magnetic resonance imaging devices such as opposing types that do not have a large installation space.

[0146] A method for assisting in the placement of the magnetic material 71 in the static magnetic field adjusting device 42 according to the third embodiment will be described with reference to FIG. FIG. 39 shows an example in which guide information 80 is displayed for a sheet (for example, the first layer 30) on which magnetic materials 71 are to be placed. Specifically, in an area partitioned by partition members where the magnetic materials 71 should be placed, at least one piece of information such as the type, number, and shape of the magnetic materials 71, the number of spacers 72 to be placed in place of the magnetic materials 71, whether or not the partition members surrounding the area are to be removed, and if a partition member is to be removed, the partition member to be removed is displayed on the sheet as guide information 80. The type of magnetic material 71 indicates, for example, differences in type and thickness of the magnetic material. Note that information regarding differences in shape may also be treated as the type of magnetic material 71.

[0147] 39, "A shim: 3, B shim: 1, C shim: 2" and "A shim: 1, B shim: 1, spacer: 4" are displayed in the area where the magnetic material 71 should be placed. This allows the user to understand the type and number of magnetic material 71 to be placed, the presence or absence of spacers, etc.

[0148] The guide information 80 may be determined by, for example, general software for adjusting a magnetic field. Specifically, the guide information 80 may be determined by the software for adjusting a magnetic field in consideration of at least one of the static magnetic fields inside and outside the imaging space 210, the superconducting coil, the electromagnetic force and magnetic susceptibility of a magnetic material, the gradient magnetic field, the magnetic field distribution by an RF coil, the pulse sequence to be used, and information on an image reconstruction method.

[0149] Furthermore, the guide information 80 may be printed directly on the sheet, or may be displayed on the sheet by optical projection means such as projection mapping. When the guide information 80 is projected by optical projection means, it may be projected onto the surface on which the magnetic material 71 is placed, or may be projected from the back side of the surface on which the magnetic material 71 is placed, or may be projected from both surfaces. Alternatively, if the sheet is translucent and the stand on which the sheet is placed is a display, the guide information 80 may be displayed on the display, and the worker may check the guide information 80 by looking through the sheet.

[0150] According to the above-described embodiment, guide information is printed directly on the sheet in the area where the magnetic material should be placed, or is displayed on the sheet using an optical projection device. This allows the operator to easily grasp the position, type, number, and shape of the magnetic material to be placed, as well as whether or not each partition member needs to be removed, without requiring additional man-hours. Therefore, a shimming device with a high degree of freedom that allows for appropriate magnetic field adjustment can be provided.

[0151] Although the present embodiment is based on the assumption of an open-type magnetic resonance imaging system, the static magnetic field adjustment device according to the above-described embodiment can also be applied to a general cylindrical magnetic resonance imaging device, for example, by inserting the static magnetic field adjustment device according to the above-described embodiment in place of a plurality of shim trays.

[0152] Alternatively, the static magnetic field adjustment device 42 may be applied to a magnetic resonance imaging system using a superconducting magnet on only one side, in which the gradient magnetic field coil 43 and the transmission coil 45 are stacked in the upper housing 122 or the lower housing 121 shown in this embodiment. If an imaging space can be formed in the space below the upper housing 122 or in the space above the lower housing 121, imaging can be performed in the same way as in an open-type magnetic resonance imaging system.

[0153] (Fourth embodiment) In the fourth embodiment, it is assumed that the configurations of the static magnetic field adjusting device 42 according to the above-described first to third embodiments are combined appropriately.

[0154] FIG. 40 shows a conceptual diagram of a static magnetic field adjusting device 42 according to the fourth embodiment. 40 is a plan view of a static magnetic field adjustment device formed by a lidded holder similar to that of FIG. 18, but shows an example in which the lid portion 171 according to the second embodiment is formed by the sheet-like static magnetic field adjustment device according to the third embodiment. That is, in addition to being able to store the magnetic body 71 and the spacer 72 in the storage portion 63 of the holder 61, the magnetic body 71 and the spacer 72 may also be stored between the first layer 30 and the second layer 35, which act as a lid so as to surround the outer periphery of the holder 61. The storage positions of the magnetic body 71 and the spacer 72 surrounded by the first and second partition members between the first and second layers 30 and 35 (rectangular areas in the first and second layers 30 and 35 in FIG. 40) may be positions facing the storage portion 63 or positions deviated from the storage portion 63.

[0155] According to the fourth embodiment described above, the configuration of the lid portion according to the second embodiment is formed using the first and second layers according to the third embodiment, which allows for more flexible design of the placement location of the magnetic material.

[0156] According to at least one of the embodiments described above, the spatial uniformity of the static magnetic field distribution can be improved.

[0157] The term "processor" used in the above description refers to a circuit such as a CPU, a GPU, an application specific integrated circuit (ASIC), a programmable logic device (e.g., a simple programmable logic device (SPLD), a complex programmable logic device (CPLD), and a field programmable gate array (FPGA)). A processor realizes its function by reading and executing a program stored in a memory circuit. Note that instead of storing a program in a memory circuit, the program may be directly embedded in the processor circuit. In this case, the processor realizes its function by reading and executing the program embedded in the circuit. On the other hand, if the processor is, for example, an ASIC, the function is directly embedded in the processor circuit as a logic circuit instead of storing the program in a memory circuit. Note that each processor in this embodiment is not limited to being configured as a single circuit for each processor, but may be configured as a single processor by combining multiple independent circuits to realize its function. Furthermore, multiple components in FIG. 1 may be integrated into a single processor to realize its function.

[0158] The following are additional notes. (1-1) a plurality of holders for holding magnetic bodies for adjusting the distribution of a static magnetic field used in magnetic resonance imaging; All or some of the plurality of holders are stacked in the axial direction of the magnet in a first space on the inner diameter side of the annular magnet that generates the static magnetic field. Static magnetic field adjustment device.

[0159] (2-1) The static magnetic field adjustment device according to (1-1), further comprising a support that supports the plurality of holders so that they can be stacked in the axial direction.

[0160] (3-1) Each of the plurality of holders has a circular ring shape with a hollow portion formed therein, The support includes a fixing rod inserted through the hollow portions of the plurality of holders. A static magnetic field adjusting device according to (2-1).

[0161] (4-1) The static magnetic field adjustment device according to (3-1), wherein the support has a pair of fasteners for fixing the holders at both ends of the plurality of holders inserted through the fixing bar to the fixing bar.

[0162] (5-1) The static magnetic field adjustment device according to (3-1), wherein the plurality of holders and the fixing rod each have a protrusion and a groove so that they can be fitted together.

[0163] (6-1) The static magnetic field adjustment device according to (3-1), wherein the fixing rod has a first housing portion into which a magnetic sensor for detecting the distribution of the magnetic field in the axial direction can be inserted.

[0164] (7-1) Each of the plurality of holders serves as the support. a first surface perpendicular to the axial direction having a convex portion; The static magnetic field adjustment device according to (2-1), wherein a second surface opposite to the first surface has a recess that can be fitted into a protrusion provided on the first surface of another holder.

[0165] (8-1) The static magnetic field adjustment device according to (2-1), wherein the support supports stackable spacers for adjusting the spacing between the plurality of holders.

[0166] (9-1) The static magnetic field adjustment device according to (1-1), wherein each of the plurality of holders has a plurality of second housing portions that communicate with openings formed on the surface of the holder and are capable of housing the magnetic body.

[0167] (10-1) The static magnetic field adjustment device according to (9-1), wherein a lid for closing the opening of each of the second storage sections is attached to each of the plurality of holders.

[0168] (11-1) The static magnetic field adjustment device according to (9-1), wherein each of the plurality of second accommodating sections is formed on an outer peripheral surface, an inner peripheral surface, a top surface and / or a bottom surface of the holder.

[0169] (12-1) The static magnetic field adjustment device according to (9-1), wherein each of the plurality of second accommodating portions is capable of accommodating, in addition to the magnetic body, a spacer for adjusting and / or fixing the position of the magnetic body.

[0170] (13-1) All or some of the plurality of holders have a plurality of holder layers arranged in a radial direction perpendicular to the axial direction, The static magnetic field adjustment device according to (1-1), wherein each of the plurality of holder layers is capable of holding the magnetic body.

[0171] (14-1) A static magnetic field adjustment device as described in (13-1), wherein the holder layers other than the innermost holder layer among the plurality of holder layers have a first container having an opening on the outer peripheral surface, a second container having an opening on the inner peripheral surface, a third container having an opening on the top surface, and / or a fourth container having an opening on the bottom surface for holding the magnetic body.

[0172] (15-1) The static magnetic field adjustment device according to (1-1), wherein all or some of the plurality of holders are arranged in the first space, in a hollow portion formed by a housing that houses the magnet.

[0173] (16-1) A static magnetic field adjustment device as described in (15-1), wherein all or some of the multiple holders are arranged between the bottom surface and / or inner wall surface of the housing that contacts the hollow portion and via spacers for adjusting the position of all or some of the multiple holders.

[0174] (17-1) some of the plurality of holders are disposed in the inner diameter space, The static magnetic field adjustment device according to (1-1), wherein the remaining parts of the plurality of holders are stacked in the axial direction of the magnet in a second space other than the first space with respect to the radial direction of the magnet.

[0175] (18-1) The static magnetic field adjustment device according to (17-1), wherein the second space is a space outside a housing that houses the magnet, among spaces outside the first space in the radial direction of the magnet.

[0176] (19-1) A static magnetic field adjustment device as described in (18-1), wherein the remaining portion is arranged as the second space inside or outside another housing located outside the housing that houses the magnet, in a non-penetrating hollow portion or a penetrating hollow portion in the axial direction of the magnet.

[0177] (20-1) a ring-shaped magnet that generates a static magnetic field; a plurality of holders capable of holding magnetic bodies for adjusting the distribution of the static magnetic field; The plurality of holders are stacked in the axial direction of the magnet at least on the inner diameter side of the annular magnet that generates the static magnetic field. Magnetic resonance imaging system.

[0178] (1-2) a holder having a plurality of storage portions into which magnetic bodies for correcting the distribution of a static magnetic field used in magnetic resonance imaging are inserted and removed; a lid attached to the holder so as to cover two or more of the plurality of storage sections; A static magnetic field adjustment device comprising:

[0179] (2-2) the lid portion has a flexible film-like material, A static magnetic field adjustment device as described in (1-2), wherein two or more fixing devices for fixing the magnetic bodies contained in the two or more containing sections are provided on one surface of the film material at two or more positions corresponding to the two or more containing sections, respectively.

[0180] (3-2) The static magnetic field adjustment device according to (2-2), wherein each of the two or more fixing devices is a spacer inserted into the inside of the housing portion.

[0181] (4-2) each of the two or more fixing devices has a plurality of frame members arranged so as to be insertable into the receiving portion; The static magnetic field adjustment device according to (3-2), wherein the plurality of frame members are arranged with gaps between them.

[0182] (5-2) The static magnetic field adjustment device described in (4-2), wherein the plurality of frame materials have a predetermined thickness in the depth direction of the accommodating section and are stacked in the depth direction according to the total thickness of the magnetic bodies accommodated in the accommodating section.

[0183] (6-2) The static magnetic field adjustment device according to (1-2), wherein the holder and the lid each have a pair of fasteners for detachably connecting to each other.

[0184] (7-2) the retainer has a circular ring shape; The static magnetic field adjustment device according to (1-2), wherein the plurality of accommodating sections are formed on an inner or outer peripheral surface of the holder.

[0185] (8-2) The static magnetic field adjustment device according to (7-2), wherein the lid portion has a flexible film-shaped material and covers the two or more storage portions provided on the inner or outer peripheral surface of the holder with one piece.

[0186] (9-2) the membrane material has a length in the long axis direction that allows it to wrap around the inner or outer circumferential surface of the holder; The static magnetic field adjustment device according to (8-2), wherein the film material has a pair of fasteners at both ends in the longitudinal direction thereof for detachably connecting to each other.

[0187] (10-2) There are a plurality of the holders, The static magnetic field adjusting device according to (1-2), wherein the plurality of holders are stacked in the axial direction of the annular superconducting coil that generates the static magnetic field.

[0188] (11-2) a cylindrical superconducting coil that generates a static magnetic field; a holder having a plurality of storage portions into which magnetic bodies for correcting the distribution of the static magnetic field are inserted and removed; a lid attached to the holder so as to cover two or more of the plurality of storage sections; A magnetic resonance imaging system comprising:

[0189] (1-3) a flexible sheet; A partition member for holding a plurality of magnetic bodies for adjusting a magnetic field on or within the sheet; A static magnetic field adjustment device comprising:

[0190] (2-3) The sheet is a first layer on which the partition member is formed; The static magnetic field adjustment device according to (1-3), further comprising: a second layer laminated on a surface on which the magnetic material of the first layer is disposed, and fixing the magnetic material.

[0191] (3-3) the partition member includes a first partition member and a second partition member, the first partition member is formed on a surface of the first layer on which the magnetic body is disposed, and partitions an area in which the magnetic body is disposed; A static magnetic field adjustment device as described in (2-3), wherein the second partition member is formed on the surface of the second layer facing the first layer so as to surround the area in which the magnetic body is arranged by being placed in the gap of the first partition member when the first layer and the second layer are stacked.

[0192] (4-3) The sheet is flexible, The static magnetic field adjustment device according to (3-3), further comprising a fixing part for winding and fixing the sheet.

[0193] (5-3) A static magnetic field adjustment device as described in (4-3), wherein the first partition member and the second partition member are formed in a shape and arrangement that allows them to be wound so as not to interfere with adjacent members when the first layer and the second layer are wound in a stacked state.

[0194] (6-3) The static magnetic field adjustment device according to (3-3), wherein when the second layer is stacked on the first layer, the first partition member and the second partition member form a lattice-like region where the magnetic body is fixed.

[0195] (7-3) The static magnetic field adjustment device according to (3-3), wherein the first partition member and the second partition member have a groove or a recess for fixing the magnetic body.

[0196] (8-3) The sheet is divided into a first region and a second region, The first region is formed with a first partition member that partitions the region in which the magnetic body is disposed into a rectangular shape, A static magnetic field adjustment device according to (1-3), wherein when the second region is folded back toward the first region and stacked on the first region, a second partition member is formed that is placed in the gap of the first partition member.

[0197] (9-3) The static magnetic field adjusting device according to (1-3), wherein the magnetic body is fixed by winding a surface on which the magnetic body is to be placed around a core material for winding.

[0198] (10-3) a loop-shaped superconducting coil that forms a static magnetic field; a cryostat that is a housing for storing the superconducting coil, the space on the inner circumferential side of the loop of the superconducting coil being recessed or open; The static magnetic field adjusting device according to (1-3) is inserted into the recessed space of the cryostat in a state where it is wound around a core material for winding; A superconducting magnet comprising:

[0199] (11-3) A magnetic body arrangement support method for a static magnetic field adjustment device including a flexible sheet and a partition member for holding a plurality of magnetic bodies for magnetic field adjustment on or within the sheet, comprising: and displaying at least one guide information item regarding the position, number, and type of the magnetic bodies to be arranged on the sheet by printing on the sheet or by optical projection means onto the sheet. Placement support method.

[0200] 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]

[0201] 1. Magnetic resonance imaging system 11 Mounting stand 13 berths 20 space 21 Gradient magnetic field power supply 23 Transmitting circuit 25 Receiving circuit 27 Bed drive unit 29 Sequence control circuit 30 1st layer 31 Sheet 1 32, 33 First partition member 34 Fixed part 35 2nd layer 36 2nd Sheet 37 Second partition member 41 Static magnetic field magnet 42,44 Static magnetic field adjustment device 43 Gradient magnetic field coil 45 Transmitting coil 47 receiving coil 50 Host Computer 51 Processing circuit 52 memory 53 Display 54 Input Interface 55 Communication Interface 61,61a,61b,61c,61d,61e,61f Holder 62 Hollow part 63, 63a, 63b, 63c, 63d, 63e, 63f, 63g, 63h Storage section 64 Fixed rod 65 Fasteners 66 Convex part 67 Recess 68 Spacer Layer 70 Winding core 71 Magnetic material 72 Spacer 73 Lid 74 Spacer 80 Guide Information 81 Inner diameter range 82 outer diameter range 83 Coil Range 84 Upper Range 85 lower range 91 Holder 92 Holder 121 Lower housing 122 Upper housing 123 Connecting material 124 First container 125 Second container 126 Hollow part 131 Top plate 133 Foundation 161 Retaining fasteners 171,171a,171b,171c,171d,171e,171f Lid 172 Fixtures 173,173-1,173-2,173a,173b,173c,173d Lid fastener 174 Retaining fasteners 210 Imaging Space 411 Support stand 412 First Superconducting Coil 413 Second Superconducting Coil 421 Spacer 422 Holder 611 Outer surface 612 Inner surface 613 Top 614 bottom 631 Aperture 671 First retainer layer 672 Second retainer layer 710 Membrane material 721 Upper horizontal frame (frame material) 722 Lower horizontal frame (frame material) 723 Left side vertical frame (frame material) 724 Right side vertical frame (frame material) IS inner diameter space OS outer diameter space P Subject B. Folding line R1 1st area R2 2nd area

Claims

1. a plurality of holders for holding magnetic bodies for adjusting the distribution of a static magnetic field used in magnetic resonance imaging; All or some of the plurality of holders are stacked in the axial and / or radial direction of the magnet in a first space on the inner diameter side of the annular magnet that generates the static magnetic field. Static magnetic field adjustment device.

2. 2. The static magnetic field adjusting device according to claim 1, further comprising a first receiving portion into which a magnetic sensor for detecting the distribution of the magnetic field in the axial direction and / or the radial direction can be inserted.

3. When the plurality of holders are stacked in the axial direction, Each of the plurality of holders is a first surface perpendicular to the axial direction having a convex portion; a second surface opposite to the first surface having a recess that can be fitted into a protrusion provided on the first surface of another holder; 3. The static magnetic field adjusting device according to claim 2.

4. When the plurality of holders are stacked in the radial direction, Each of the plurality of holders is a first surface perpendicular to the radial direction having a convex portion; a second surface opposite to the first surface having a recess that can be fitted into a protrusion provided on the first surface of another holder; 2. The static magnetic field adjusting device according to claim 1.

5. When the plurality of holders are stacked in the radial direction, 2. The static magnetic field adjustment device according to claim 1, wherein the plurality of holders are supported by a support that penetrates the device in the radial direction.

6. 2. The static magnetic field adjustment device according to claim 1, further comprising a support for stackably supporting spacers for adjusting the intervals between said plurality of holders.

7. 2. The static magnetic field adjustment device according to claim 1, wherein each of the plurality of holders has a plurality of second housing portions that communicate with openings formed in the surface of the holder and that can house the magnetic body.

8. 8. The static magnetic field adjusting device according to claim 7, wherein a lid for closing an opening of each of the second storage sections is attached to each of the plurality of holders.

9. 8. The static magnetic field adjustment device according to claim 7, wherein each of the plurality of second accommodating sections is formed on an outer peripheral surface, an inner peripheral surface, a top surface and / or a bottom surface of the holder.

10. 8. The static magnetic field adjustment device according to claim 7, wherein each of the plurality of second housing portions is capable of housing, in addition to the magnetic body, a spacer for adjusting and / or fixing the position of the magnetic body.

11. 2. The static magnetic field adjustment device of claim 1, wherein when the plurality of holders are stacked in the radial direction, the holders other than the innermost holder among the plurality of holders have a first container having an opening on the outer peripheral surface, a second container having an opening on the inner peripheral surface, a third container having an opening on the top surface, and / or a fourth container having an opening on the bottom surface for holding the magnetic body.

12. 2. The static magnetic field adjustment device according to claim 1, wherein all or some of the plurality of holders are arranged in a hollow portion of the first space formed by a housing that houses the magnets.

13. A static magnetic field adjustment device as described in claim 12, wherein all or some of the plurality of holders are arranged between the bottom surface and / or inner wall surface of the housing that contacts the hollow portion and via spacers for adjusting the position of all or some of the plurality of holders.

14. 2. The static magnetic field adjustment device of claim 1, wherein some of the plurality of holders are arranged in the first space, and the remaining portion of the plurality of holders are stacked in the axial direction of the magnet in a second space other than the first space with respect to the radial direction of the magnet.

15. The static magnetic field adjustment device according to claim 14 , wherein the second space is a space outside a housing that houses the magnet, among spaces outside the first space in the radial direction of the magnet.

16. The static magnetic field adjustment device of claim 15, wherein the remaining portion is arranged as the second space in a non-through hollow portion or a through hollow portion in the axial direction of the magnet, inside or outside another housing located outside the housing that houses the magnet.

17. 2. The static magnetic field adjustment device according to claim 1, wherein said holder is formed by a flexible sheet and a partition member for holding a plurality of magnetic bodies for magnetic field adjustment on or within said sheet.

18. a ring-shaped magnet that generates a static magnetic field; a plurality of holders capable of holding magnetic bodies for adjusting the distribution of the static magnetic field; A magnetic resonance imaging system in which all or some of the multiple holders are stacked in the axial and / or radial directions of a ring-shaped magnet that generates at least the static magnetic field, in a first space on the inner diameter side of the magnet.

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