JP2020006047A - Magnetic resonance imaging apparatus - Google Patents

Abstract

To provide a magnetic resonance imaging apparatus that can efficiently cool a gradient magnetic field coil unit.SOLUTION: A magnetic resonance imaging apparatus includes a gradient magnetic field coil unit, a sealing member and a groove. The gradient magnetic field coil unit 108 includes a shim tray 106. The sealing member seals a space for supplying a non-magnetic and non-conductive refrigerant and the space including the shim tray. The groove is provided at a wall surface that forms the space.SELECTED DRAWING: Figure 4

Description

  Embodiments of the present invention relate to a magnetic resonance imaging apparatus.

  The magnetic resonance imaging apparatus includes a static magnetic field magnet for generating a static magnetic field and a gradient magnetic field coil for generating a gradient magnetic field. Further, the gradient magnetic field coil is often integrated with a gradient magnetic field coil unit including a shim tray containing a shim member for correcting nonuniformity of the static magnetic field.

  Since a large current is supplied to the gradient coil, a large amount of heat is generated, and a change in the center frequency (CF: F0) due to a change in the temperature of the shim member or a change in the temperature in the bore adversely affects the subject such as a patient. In order to prevent this, the cooling of the gradient coil unit is performed.

JP 2009-240765 A JP 2010-240398 A

  The problem to be solved by the present invention is to make the cooling of the gradient coil unit more efficient.

  A magnetic resonance imaging apparatus according to an embodiment includes a gradient coil unit, a sealing member, and a groove. The gradient magnetic field coil unit includes a shim tray. The sealing member is a space in which a non-magnetic and non-conductive refrigerant is supplied, and seals a space including the shim tray. The groove is provided on a wall surface forming the space.

FIG. 1 is a diagram illustrating a configuration example of a magnetic resonance imaging apparatus. FIG. 2 is a diagram illustrating a configuration example of the gradient coil unit. FIG. 3 is a diagram illustrating a configuration example of the shim tray. FIG. 4 is a diagram showing a configuration example of the gradient coil unit after sealing. FIG. 5 is a diagram illustrating an example of the relationship between the shim member and the F0 shift. FIG. 6A is a diagram (1) illustrating an example in which a groove is provided on a side of the main coil and the shield coil facing the shim tray. FIG. 6B is a diagram (2) illustrating an example in which a groove is provided on the side of the main coil and the shield coil facing the shim tray. FIG. 7 is a diagram illustrating an example of a pattern of the gradient coil. FIG. 8 is a diagram showing another configuration example of the gradient coil unit after sealing. FIG. 9A is a diagram (1) illustrating an example in which a groove is provided on the side of the main coil and the shield coil facing the shim tray, and a groove is also provided on the opposite side. FIG. 9B is a diagram (2) illustrating an example in which a groove is provided on the side facing the shim tray of the main coil and the shield coil, and a groove is also provided on the opposite side.

  Hereinafter, embodiments of a magnetic resonance imaging apparatus will be described with reference to the drawings. The embodiment is not limited to the following contents. In addition, the contents described in one embodiment or modification are similarly applied to other embodiments or modifications in principle.

(1st Embodiment)
FIG. 1 is a diagram illustrating a configuration example of the magnetic resonance imaging apparatus 1. In FIG. 1, the magnetic resonance imaging apparatus 1 includes a magnet gantry 101 and a bed 116. In the present embodiment, the longitudinal direction of the top plate 117 of the bed 116 is perpendicular to the Z-axis direction and the Z-axis direction, and the axial direction that is horizontal to the floor is orthogonal to the X-axis direction and the Z-axis direction. The axis direction perpendicular to the axis direction is defined as a Y-axis direction. The magnet mount 101 includes a static magnetic field magnet 102, a gradient magnetic field coil unit 108, and an RF coil 115. Note that the internal configuration of the magnet mount 101 is shown in a longitudinal sectional view.

  The gradient magnetic field coil unit 108 includes a main coil 103 and a shield coil 104. Between the main coil 103 and the shield coil 104, a shim tray 106 and a shim member 107 are included. FIG. 1 shows a state before the gradient magnetic field coil unit 108 is sealed, and passive shimming is performed in a state where such a gradient magnetic field coil unit 108 is not sealed and the shim tray 106 can be inserted and withdrawn. . After the passive shimming is completed, the gradient coil unit 108 is sealed, and a non-magnetic and non-conductive refrigerant is supplied into the sealed space, so that efficient cooling is performed. The non-magnetic and non-conductive refrigerant is, for example, a fluorinated liquid. Details of the gradient coil unit 108 will be described later.

  In addition, the magnetic resonance imaging apparatus 1 includes a gradient magnetic field power supply 122, a transmission circuit 123, a reception circuit 124, a bed control circuit 125, a sequence control circuit 126, and a computer 131. Note that the subject P (for example, a human body) is not included in the magnetic resonance imaging apparatus 1. Further, the configuration shown in FIG. 1 is only an example. For example, each unit in the sequence control circuit 126 and the computer 131 may be configured to be integrated or separated as appropriate.

  The static magnetic field magnet 102 has a substantially cylindrical shape, and generates a static magnetic field in a bore (the space inside the cylinder of the static magnetic field magnet 102) including the imaging region of the subject P. The static magnetic field magnet 102 may be a superconducting magnet or a permanent magnet.

  The gradient magnetic field coil unit 108 also has a substantially cylindrical shape, and is held inside the static magnetic field magnet 102 by a support structure such as an anti-vibration rubber. The gradient magnetic field coil unit 108 applies a gradient magnetic field in the directions of the X axis, the Y axis, and the Z axis orthogonal to each other by a current supplied from the gradient magnetic field power supply 122, and a leakage magnetic field of the main coil 103. And a shield coil 104 for canceling. The main coil 103 may be called an inner coil. The shield coil 104 may be called an outer coil. The main coil 103 and the shield coil 104 are formed by, for example, forming a coil pattern on a substantially cylindrical non-conductive / non-magnetic member and molding the same with a resin or the like. A shim tray 106 is inserted between the main coil 103 and the shield coil 104. The shim tray 106 accommodates a shim member (also referred to as an iron shim, a metal shim, or the like) 107 for correcting a non-uniform magnetic field in the bore. The details of the gradient magnetic field coil unit 108 will be described later.

  The couch 116 is provided with a couchtop 117 on which the subject P is placed. Under the control of the couch control circuit 125, the couch 117 is moved to the cavity of the gradient coil unit 108 in a state where the subject P is placed. (Imaging port). Usually, the bed 116 is installed so that the longitudinal direction is parallel to the central axis of the static magnetic field magnet 102. The bed control circuit 125 drives the bed 116 under the control of the computer 131 to move the top board 117 in the longitudinal direction and the vertical direction.

  The RF coil 115 is arranged inside the gradient magnetic field coil unit 108, and receives an RF pulse (an RF pulse corresponding to a Larmor frequency determined by the type of the target atom and the magnetic field intensity) from the transmission circuit 123. A high-frequency magnetic field is generated, a magnetic resonance signal emitted from the subject P under the influence of the high-frequency magnetic field is received, and the received magnetic resonance signal is output to the receiving circuit 124. Note that the RF coil 115 may be configured to be divided into a transmission coil and a reception coil.

  The receiving circuit 124 detects a magnetic resonance signal output from the RF coil 115, and generates magnetic resonance data based on the detected magnetic resonance signal. Specifically, the receiving circuit 124 generates magnetic resonance data by digitally converting the magnetic resonance signal received by the RF coil 115. Further, the receiving circuit 124 transmits the generated magnetic resonance data to the sequence control circuit 126. The receiving circuit 124 may be provided on the magnet gantry 101 side.

  The sequence control circuit 126 performs imaging of the subject P by driving the gradient magnetic field power supply 122, the transmission circuit 123, and the reception circuit 124 based on the sequence information transmitted from the computer 131. Here, the sequence information is information that defines a procedure for performing imaging. The sequence information includes the intensity of the current supplied from the gradient magnetic field power supply 122 to the main coil 103, the timing at which the current is supplied, the intensity of the RF pulse supplied from the transmission circuit 123 to the RF coil 115, the timing at which the RF pulse is applied, and the reception circuit. The timing at which 124 detects a magnetic resonance signal is defined. For example, the sequence control circuit 126 is realized by a processor.

  Further, when the sequence control circuit 126 receives the magnetic resonance data from the reception circuit 124 as a result of driving the gradient magnetic field power supply 122, the transmission circuit 123, and the reception circuit 124 and capturing the image of the subject P, the sequence control circuit 126 converts the received magnetic resonance data into a computer. Transfer to 131.

  The computer 131 performs overall control of the magnetic resonance imaging apparatus 1, generation of an image, and the like. The computer 131 includes a memory 132, an input device 133, a display 134, and a processing circuit 135. The processing circuit 135 includes an interface function 136, a control function 137, and an image generation function 138.

  Each processing function performed by the interface function 136, the control function 137, and the image generation function 138 is stored in the memory 132 in the form of a program executable by the computer 131. The processing circuit 135 is a processor that reads a program from the memory 132 and executes the program to realize a function corresponding to each program. In other words, the processing circuit 135 in a state where each program is read has each function shown in the processing circuit 135 in FIG. In FIG. 1, a single processing circuit 135 implements the processing functions performed by the interface function 136, the control function 137, and the image generation function 138. However, a plurality of independent processors are combined. To form a processing circuit 135, and each processor executes a program to realize a function. In other words, the respective functions described above may be configured as programs, and one processing circuit 135 may execute each program. As another example, a specific function may be implemented in a dedicated independent program execution circuit.

  The term “processor” used in the above description may be, for example, a CPU (Central Processing Unit), a GPU (Graphics Processing Unit), an application specific integrated circuit (ASIC), a programmable logic device (eg, , A Simple Programmable Logic Device (SPLD), a Complex Programmable Logic Device (CPLD), or a Field Programmable Gate Array (FPGA). The processor realizes the functions by reading and executing the program stored in the memory 132. Instead of storing the program in the memory 132, the program may be directly incorporated in the circuit of the processor. In this case, the processor realizes a function by reading and executing a program incorporated in the circuit. Note that each processor of the present embodiment is not limited to the case where each processor is configured as a single circuit, but may be configured as one processor by combining a plurality of independent circuits to realize its function. Good.

  Similarly, the transmission circuit 123, the reception circuit 124, the bed control circuit 125, and the like are also configured by electronic circuits such as the above-described processor.

  The processing circuit 135 uses the interface function 136 to transmit sequence information to the sequence control circuit 126 and receive magnetic resonance data from the sequence control circuit 126. When receiving the magnetic resonance data, the processing circuit 135 having the interface function 136 stores the received magnetic resonance data in the memory 132. The magnetic resonance data stored in the memory 132 is arranged in the k space by the control function 137. As a result, the memory 132 stores the k-space data.

  The memory 132 stores the magnetic resonance data received by the processing circuit 135 having the interface function 136, the k-space data arranged in the k-space by the processing circuit 135 having the control function 137, and the processing circuit 135 having the image generation function 138. The image data generated by the above is stored. For example, the memory 132 is a semiconductor memory device such as a random access memory (RAM) or a flash memory, a hard disk, an optical disk, or the like.

  The input device 133 receives various instructions and information input from the operator. The input device 133 is, for example, a pointing device such as a mouse or a trackball, a selection device such as a mode switch, or an input device such as a keyboard. The input device 133 is an interface that receives an input. The display 134 displays a GUI (Graphical User Interface) for receiving an input of an imaging condition, an image generated by the processing circuit 135 having an image generation function 138, and the like under the control of the processing circuit 135 having the control function 137. I do. The display 134 is, for example, a display device such as a liquid crystal display.

  The processing circuit 135 performs overall control of the magnetic resonance imaging apparatus 1 by the control function 137, and controls imaging, generation of an image, display of an image, and the like. For example, the processing circuit 135 having the control function 137 receives an input of an imaging condition (an imaging parameter or the like) on a GUI, and generates sequence information according to the received imaging condition. Further, the processing circuit 135 having the control function 137 transmits the generated sequence information to the sequence control circuit 126. The processing circuit 135 generates an image by reading out the k-space data from the memory 132 by the image generation function 138 and performing reconstruction processing such as Fourier transform on the read-out k-space data.

  FIG. 2 is a diagram showing a configuration example of the gradient magnetic field coil unit 108, and shows a state before sealing. In FIG. 2, between the main coil 103 and the shield coil 104 of the gradient coil unit 108, a plurality of slots 105a are provided at substantially equal intervals in the circumferential direction. The slot 105a is formed, for example, by an inner wall of a tubular shim tray guide (a shim tray guide 105 described later) having a rectangular cross section. Note that the number of slots 105a is not limited to the illustrated one.

  The slot 105a is a through hole that has an opening formed at both end surfaces of the gradient magnetic field coil unit 108 and is formed over substantially the entire length of the gradient magnetic field coil unit 108 in the longitudinal direction (long axis direction). A shim tray 106 is inserted into each slot 105a, and each shim tray 106 is fixed to a substantially central portion of the gradient coil unit 108. The shim tray 106 is formed of a resin that is a non-magnetic and non-conductive material, and has a substantially rod shape.

  FIG. 3 is a diagram illustrating a configuration example of the shim tray 106. In FIG. 3, a plurality of pockets 106a formed continuously are formed in the longitudinal direction of the shim tray 106. The number of pockets 106a is not limited to the illustrated one. In each pocket 106a, a necessary number of shim members 107 are accommodated in necessary places for the purpose of equalizing the static magnetic field in the imaging space in the bore. The shim member 107 is a thin metal plate (typically, a silicon steel plate) of about the size of a business card.

  FIG. 4 is a diagram illustrating a configuration example of the gradient coil unit 108 after sealing, and illustrates a cross-sectional view of a structural portion. 4, the ends of the main coil 103 and the shield coil 104 in the Z-axis direction (axial direction) are sealed by, for example, a substantially donut-shaped side plate 109 when viewed from the Z-axis direction. The side plate 109 is an example of a sealing member. The main coil 103 and the shield coil 104 are appropriately supported and fixed at various places so that a space is formed between them. A coil conductor 103a is embedded in the main coil 103, and a coil conductor 104a is embedded in the shield coil 104. For example, a tubular shim tray guide 105 having a rectangular cross section, in which a shim tray 106 is accommodated, is supported in a space interposed between the main coil 103 and the shield coil 104, and has a non-magnetic and non-conductive When the refrigerant is supplied and filled, the refrigerant can flow from both ends in the Z-axis direction of the shim tray guide 105, and the outer wall and the inner wall of the shim tray guide 105 are in direct contact with the refrigerant. The shim tray guide 105 may be provided with holes or slits penetrating the inner and outer walls to make it easier for the refrigerant to enter the inside, or only the frame that guides the four corners of the shim tray 106 may be used. It may be formed.

  In addition, a refrigerant circulating unit 111 for circulating a non-magnetic and non-conductive refrigerant is provided, and through the pipe 111a, substantially corresponds to the center of the magnetic field of the space in the gradient magnetic field coil unit 108, and is substantially in the Z-axis direction. Refrigerant is supplied from a portion near the shim tray 106 at the center, and the refrigerant discharged from both ends in the Z-axis direction returns to the refrigerant circulating unit 111 via the pipes 111b and 111c. The pipes 111 a, 111 b, and 111 c are connected to penetrate the main coil 103 and the wall surface of the side plate 109 in a state where the airtightness of the space between the main coil 103 and the shield coil 104 is maintained. The refrigerant circulation unit 111 circulates while cooling the refrigerant so that the refrigerant maintains a predetermined temperature. In FIG. 4, the supply port and the discharge port of the refrigerant are provided at the lower part of the gradient coil unit 108, but the supply port and the discharge port may be provided at the upper part, the center part, and the like of the gradient coil unit 108. And the number can be increased. It is assumed that the space between the main coil 103 and the shield coil 104 is completely filled with the refrigerant. However, if the cooling effect is sufficient, the entire space is completely filled with the refrigerant. It does not have to be done.

  Here, the significance of setting the supply port of the refrigerant to a substantially central portion (magnetic field center portion) in the Z-axis direction of the gradient magnetic field coil unit 108 will be described. FIG. 5 is a diagram illustrating an example of the relationship between the shim member and the F0 shift. In FIG. 5, the horizontal axis of the graph is the pocket number of the shim tray 106, and the vertical axis is the F0 shift influence coefficient. The F0 shift influence coefficient is an amount obtained by normalizing the F0 shift amount per unit number of shim members arranged in each pocket by the F0 shift amount of the pocket number. The F0 shift amount is a value obtained for each pocket when the same temperature change is applied to the same unit number of shim members.

  Referring to the graph of FIG. 5, the absolute value of the F0 shift influence coefficient is large near the pocket number “8”, that is, near the center of the magnetic field, and small near the magnet end far from the center of the magnetic field. . In addition, the F0 shift influence coefficient of the shim member arranged near the end of the magnet remote from the center of the magnetic field is opposite to the F0 shift influence coefficient of the shim member near the center of the magnetic field. For example, when the shim member is heated, the shim member near the center of the magnetic field raises F0, and the shim member near the magnet end far from the center of the magnetic field lowers F0. As described above, the direction and magnitude of changing the F0 shift differ depending on the position of the shim member in the Z-axis direction from the center of the magnetic field.

  In the passive shimming, the arrangement of the shim members is determined so that the inhomogeneity of the static magnetic field falls within a predetermined allowable range at the installation stage. Generally, since many shim members are often arranged near the center of the magnetic field, the F0 shift amount tends to increase when the temperature of the shim members increases as a whole. Accordingly, by supplying the refrigerant from the refrigerant circulating unit 111 to the substantially central portion (magnetic field center portion) of the gradient magnetic field coil unit 108 near the center of the magnetic field in the Z-axis direction, it is possible to efficiently cool the F0 shift. Can be.

  Next, an example in which a groove is provided in a portion (wall surface forming a space) of the main coil 103 and the shield coil 104 facing the shim tray 106 to further increase the cooling efficiency of the gradient coil unit 108 will be described. . The groove increases the contact area with the refrigerant, and increases the cooling efficiency.

  FIG. 6A is a diagram showing an example in which grooves 103b and 104b are provided on the side of the main coil 103 and the shield coil 104 facing the shim tray 106, and the grooves 103b and 104b along the axial direction of the gradient coil unit 108 are not shown. It is an example provided. Note that only the upper cross section of the gradient magnetic field coil unit 108 is shown, and the lower side is omitted. A plurality of grooves 103b are provided on the outer peripheral wall of the main coil 103 facing the shim tray 106. The size of the groove 103b and the pitch and number provided on the outer peripheral wall can be arbitrarily determined from the relationship with the required cooling effect. A plurality of grooves 104b are provided on the inner peripheral wall facing the shim tray guide 105 and the shim tray 106 of the shield coil 104. The size of the groove 104b and the pitch and number provided on the inner peripheral wall can be arbitrarily determined from the relationship with the required cooling effect. Both grooves 103b and 104b may be provided as shown, or only one may be provided.

  FIG. 6B is a diagram showing an example in which grooves 103c and 104c are provided on the side of the main coil 103 and the shield coil 104 facing the shim tray 106, and the grooves along a direction intersecting the axial direction of the gradient magnetic field coil unit 108. This is an example in which 103c and 104c are provided. Note that only the upper cross section of the gradient magnetic field coil unit 108 is shown, and the lower side is omitted. The groove 103c is provided in a spiral shape or a plurality of annular shapes on the outer peripheral wall of the main coil 103 facing the shim tray 106. The size of the groove 103c and the pitch and number provided on the outer peripheral wall can be arbitrarily determined from the relationship with the required cooling effect. The groove 104c is provided spirally or in a plurality of annular shapes on the inner peripheral wall of the shield coil 104 facing the shim tray guide 105 and the shim tray 106. The size of the groove 104c and the pitch and number provided on the inner peripheral wall can be arbitrarily determined from the relationship with the required cooling effect. Both grooves 103c and 104c may be provided as shown, or only one may be provided. Further, a combination of the groove 103b of FIG. 6A and the groove 104c of FIG. 6B or a combination of the groove 103c of FIG. 6B and the groove 104b of FIG. 6A may be used.

  6A and 6B, it is desirable that the axial positions of the grooves 103b and 104b or the grooves 103c and 104c are provided corresponding to, for example, a portion (hot spot) having a large amount of heat generation in the gradient coil unit 108. FIG. 7 is a diagram illustrating an example of a pattern of the gradient coil, and is an example of a pattern of the gradient coil with respect to the Y axis. The pattern is conceptually shown, and the surface of the coil conductor is molded with resin or the like as described above. 7, in the gradient magnetic field coil unit 108, for example, spiral coil patterns are arranged at two places in the Z-axis direction and exist above and below the Y-axis direction. In the gradient magnetic field coil for the X-axis, similar coil patterns arranged in two places in the Z-axis direction are present before and behind in the X-axis direction. Here, since the amount of heat generated at the center of the spiral coil pattern increases and becomes a hot spot, the axial position of the groove 103b, 104b or the groove 103c, 104c in FIGS. 6A and 6B is set in accordance with the position. Have been.

  6A and 6B, the case where grooves are provided in portions of the main coil 103 and the shield coil 104 facing the shim tray 106 has been described, but similar grooves are provided on the outer surface and / or inner surface of the shim tray guide 105. It may be made to be possible.

  With the above configuration, the heat generated in the gradient coil unit 108 is efficiently cooled. As a result, it is possible to prevent a change in the center frequency due to a change in the temperature of the shim member and an adverse effect on the patient due to a change in the temperature in the bore. The image quality is improved by suppressing the change in the center frequency. Further, since the temperature change in the bore is suppressed by the effective cooling, the imaging condition can be set under a more severe condition with respect to the temperature, and the imaging that has been impossible until now can be performed.

(Second embodiment)
FIG. 8 is a diagram showing another configuration example of the gradient coil unit 108 after sealing. The configuration other than the gradient coil unit 108 is the same as that shown in FIG.

  In FIG. 8, the space including the main coil 103 and the shield coil 104 is sealed by a substantially cylindrical sealed container 110. Note that the closed container 110 can also be used as a highly airtight container for preventing noise generated in the gradient magnetic field coil unit 108 from leaking outside. The closed container 110 is an example of a closed member. A coil conductor 103a is embedded in the main coil 103, and a coil conductor 104a is embedded in the shield coil 104. A tubular shim tray guide 105 having a rectangular cross section, for example, in which a shim tray 106 is accommodated, is appropriately supported in a space sandwiched between the main coil 103 and the shield coil 104, and has a non-magnetic and non-conductive When the water-based refrigerant is filled, the refrigerant can flow from both ends of the shim tray guide 105 in the Z-axis direction, and the outer wall and the inner wall of the shim tray guide 105 are in direct contact with the refrigerant. The shim tray guide 105 may be provided with holes or slits penetrating the inner and outer walls to make it easier for the refrigerant to enter, or may be formed only of a frame that guides the four corners of the shim tray 106. It may be something.

  Further, unlike the first embodiment, not only the outer peripheral wall of the main coil 103 and the inner peripheral wall of the shield coil 104 but also the inner peripheral wall of the main coil 103 and the outer peripheral wall of the shield coil 104 come into contact with the refrigerant. Therefore, the cooling efficiency is further improved.

  In addition, a refrigerant circulating unit 111 for circulating a non-magnetic and non-conductive refrigerant is provided, and through the pipe 111a, substantially corresponds to the center of the magnetic field of the space in the gradient magnetic field coil unit 108, and is substantially in the Z-axis direction. Refrigerant is supplied from a portion near the shim tray 106 at the center, and the refrigerant discharged from both ends in the Z-axis direction returns to the refrigerant circulating unit 111 via the pipes 111b and 111c. The pipes 111a, 111b, and 111c are connected to penetrate the wall surface of the sealed container 110 while maintaining the airtightness of the sealed container 110. Although not shown, a connection cable for supplying a drive current to the main coil 103 and the like is also connected through the wall surface of the sealed container 110 while maintaining the airtightness of the sealed container 110. . The refrigerant circulation unit 111 circulates while cooling the refrigerant so that the refrigerant maintains a predetermined temperature. In FIG. 8, the supply port and the discharge port of the refrigerant are provided in the lower part of the gradient coil unit 108, but the supply port and the discharge port may be provided in the upper part, the center part, and the like of the gradient coil unit 108. And the number can be increased.

  FIG. 9A is a diagram illustrating an example in which grooves 103b and 104b are provided on the side facing the shim tray 106 of the main coil 103 and the shield coil 104, and grooves 103d and 104d are provided on the opposite side. Note that only the upper cross section of the gradient magnetic field coil unit 108 is shown, and the lower side is omitted. First, similarly to FIG. 6A, grooves 103b and 104b are provided in portions of the main coil 103 and the shield coil 104 facing the shim tray 106.

  Further, since the inner peripheral wall of the main coil 103 and the outer peripheral wall of the shield coil 104 are also in contact with the refrigerant, the shim tray 106 of the main coil 103 and the shield coil 104 is used in order to make the cooling of the gradient coil unit 108 more efficient. A groove is also provided in a portion opposite to the side facing the. The groove increases the contact area with the refrigerant, and increases the cooling efficiency. That is, the grooves 103d and 104d are provided along the axial direction of the gradient magnetic field coil unit. A plurality of grooves 103d are provided on the inner peripheral wall of the main coil 103. The size of the groove 103d and the pitch and number provided on the inner peripheral wall can be arbitrarily determined from the relationship with the required cooling effect. A plurality of grooves 104d are provided on the outer peripheral wall of the shield coil 104. The size of the groove 104d and the pitch and number provided on the outer peripheral wall can be arbitrarily determined from the relationship with the required cooling effect. All of the grooves 103b, 104b, 103d, and 104d may be provided as shown in the figure, or some of them may be provided. Further, a groove similar to that of FIG. 6A may be provided on the outer surface and / or the inner surface of the shim tray guide 105.

  FIG. 9B is a diagram illustrating an example in which grooves 103c and 104c are provided on the side of the main coil 103 and the shield coil 104 facing the shim tray 106, and grooves 103e and 104e are provided on the opposite side. Note that only the upper cross section of the gradient magnetic field coil unit 108 is shown, and the lower side is omitted. First, similarly to FIG. 6B, grooves 103c and 104c are provided in portions of the main coil 103 and the shield coil 104 facing the shim tray 106.

  Further, since the inner peripheral wall of the main coil 103 and the outer peripheral wall of the shield coil 104 are also in contact with the refrigerant, the shim tray 106 of the main coil 103 and the shield coil 104 is used in order to make the cooling of the gradient coil unit 108 more efficient. A groove is also provided in a portion opposite to the side facing the. The groove increases the contact area with the refrigerant, and increases the cooling efficiency. That is, the grooves 103e and 104e are provided along a direction intersecting the axial direction of the gradient coil unit 108. A plurality of grooves 103e are provided on the inner peripheral wall of the main coil 103. The size of the groove 103e and the pitch and number provided on the inner peripheral wall can be arbitrarily determined from the relationship with the required cooling effect. A plurality of grooves 104e are provided on the outer peripheral wall of the shield coil 104. The size of the groove 104e and the pitch and number provided on the outer peripheral wall can be arbitrarily determined from the relationship with the required cooling effect. All of the grooves 103c, 104c, 103e, and 104e may be provided as illustrated, or some of them may be provided. 9A and 9B, the grooves 103b, 104b, 103d, 104d, 103c, 104c, 103e, and 104e may be appropriately combined. Further, a groove similar to that of FIG. 6B may be provided on the outer surface and / or the inner surface of the shim tray guide 105.

  According to the embodiment described above, the cooling of the gradient coil unit can be made more efficient.

  While some embodiments of the invention have been described, these embodiments have been presented by way of example only, and are not intended to limit the scope of the inventions. These embodiments can be implemented in other various forms, and various omissions, replacements, and changes can be made without departing from the spirit of the invention. These embodiments and modifications thereof are included in the scope and gist of the invention, and are also included in the invention described in the claims and the equivalents thereof.

DESCRIPTION OF SYMBOLS 1 Magnetic resonance imaging apparatus 103 Main coil 104 Shield coil 103a-e, 104a-e Groove 105 Shim tray guide 106 Shim tray 108 Gradient magnetic field coil unit 109 Side plate 110 Airtight container

Claims (10)

A gradient coil unit including a shim tray,
A space in which the supply of non-magnetic and non-conductive refrigerant is performed, and a sealing member that seals a space including the shim tray,
A groove provided on a wall surface forming the space,
A magnetic resonance imaging apparatus comprising: The gradient magnetic field coil unit includes a main coil that generates a gradient magnetic field, and a shield coil that cancels a leakage magnetic field of the main coil.
The sealing member seals a space where the shim tray is sandwiched by the main coil and the shield coil,
The magnetic resonance imaging apparatus according to claim 1. The gradient magnetic field coil unit includes a main coil that generates a gradient magnetic field, and a shield coil that cancels a leakage magnetic field of the main coil.
The sealing member seals a space including the main coil and the shield coil,
The magnetic resonance imaging apparatus according to claim 1. The supply of the refrigerant is performed to a portion of the space near the shim tray in the magnetic field center portion, and the refrigerant is discharged from both axial ends of the gradient magnetic field coil unit of the space.
The magnetic resonance imaging apparatus according to claim 1. The groove is provided at a portion of the main coil or the shield coil facing the shim tray along an axial direction of the gradient magnetic field coil unit,
The magnetic resonance imaging apparatus according to claim 2. The groove is provided on a portion of the main coil or the shield coil facing the shim tray, along a direction intersecting an axial direction of the gradient magnetic field coil unit.
The magnetic resonance imaging apparatus according to claim 2. The groove is provided along an axial direction of the gradient magnetic field coil unit on a portion of the main coil or the shield coil, which is on a side opposite to a side facing the shim tray,
The magnetic resonance imaging apparatus according to claim 3. The groove is provided along a direction intersecting the axial direction of the gradient magnetic field coil unit on a part of the main coil or the shield coil opposite to a side facing the shim tray,
The magnetic resonance imaging apparatus according to claim 3. The groove is provided in a portion having a large amount of heat generation in the gradient magnetic field coil unit,
A magnetic resonance imaging apparatus according to claim 1. A shim tray guide forming an opening through which the shim tray is inserted and withdrawn is provided.
A magnetic resonance imaging apparatus according to claim 1.