Shim tray and magnetic resonance imaging apparatus

Abstract

To reduce the temperature rise of the iron shim. [Solution] The shim tray according to the embodiment comprises a shim pocket, a lid, and a guide section. The shim pocket stores iron shims that correct spatial non-uniformity of the static magnetic field generated by a static magnetic field magnet provided in a magnetic resonance imaging apparatus. The lid covers the opening of the shim pocket. The guide section guides a coolant supplied from outside the shim tray and used to cool the iron shims into the shim pocket when the opening of the shim pocket is covered by the lid, and guides the coolant inside the shim pocket to the outside of the shim pocket when the opening of the shim pocket is covered by the lid.

Description

Technical Field

[0001] The embodiments disclosed in this specification and the drawings relate to a shim tray and a magnetic resonance imaging apparatus.

Background Art

[0002] Conventionally, in a magnetic resonance imaging (MRI) apparatus, in order to reduce the non-uniformity of the static magnetic field generated by a static magnetic field magnet, it is known to provide an iron piece (iron shim) in a magnet gantry provided in the MRI apparatus.

[0003] In imaging by an MRI apparatus, when the magnetic field applied to the iron shim changes, eddy currents are generated in the iron shim, and as a result, the temperature of the iron shim rises. Further, during imaging, the gradient magnetic field coil generates heat, and when this heat is conducted to the iron shim, the temperature of the iron shim rises. When the temperature of the iron shim rises, the magnetic permeability of the iron shim changes, and the non-uniformity of the static magnetic field increases. When the non-uniformity of the static magnetic field in the MRI apparatus increases, the magnetic resonance frequency corresponding to the position of the subject to be imaged fluctuates, which has an adverse effect on the image quality.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] One of the problems to be solved by the embodiments disclosed in this specification and the drawings is to reduce the temperature rise of the iron shim. However, the problems to be solved by the embodiments disclosed in this specification and the drawings are not limited to the above problems. The problems corresponding to the respective effects of the respective configurations shown in the embodiments described later can also be regarded as other problems.

Means for Solving the Problems

[0006] The shim tray according to this embodiment comprises a shim pocket, a lid, and a guide section. The shim pocket stores iron shims that correct spatial non-uniformity of the static magnetic field generated by a static magnetic field magnet provided in a magnetic resonance imaging apparatus. The lid covers the opening of the shim pocket. The guide section guides a coolant supplied from outside the shim tray and used to cool the iron shims into the shim pocket when the opening of the shim pocket is covered by the lid, and guides the coolant inside the shim pocket to the outside of the shim pocket when the opening of the shim pocket is covered by the lid. [Brief explanation of the drawing]

[0007] [Figure 1] A diagram showing an example configuration of an MRI apparatus according to the first embodiment. [Figure 2] A perspective view showing an example configuration of a gradient magnetic field coil unit according to the first embodiment. [Figure 3] A front view showing an example configuration of the first piping, second piping, and third piping according to the first embodiment. [Figure 4] A cross-sectional view showing an example configuration of a gradient magnetic field coil unit according to the first embodiment. [Figure 5] A vertical cross-sectional view showing an example of the configuration of a shim tray according to the first embodiment. [Figure 6] A longitudinal cross-sectional view showing an example of the configuration of a shim tray according to a first modified example in the first embodiment. [Figure 7] A cross-sectional view showing an example configuration of the first piping, second piping, and third piping according to the second embodiment. [Figure 8] A cross-sectional view showing an example configuration of the first piping, second piping, and third piping according to the third embodiment. [Figure 9] A cross-sectional view showing an example configuration of the first piping, second piping, and third piping according to the fourth embodiment. [Modes for carrying out the invention]

[0008] The embodiments of the shim tray and magnetic resonance imaging apparatus will be described in detail below with reference to the drawings.

[0009] (First embodiment) Figure 1 shows an example of the configuration of an MRI apparatus 1 according to the first embodiment. As shown in Figure 1, the MRI apparatus 1 comprises a magnet base 110 and a patient bed 121. In this embodiment, the longitudinal direction of the top plate 122 provided on the patient bed 121 is the Z-axis direction, the direction perpendicular to the Z-axis direction and parallel to the floor surface is the X-axis direction, and the vertical direction is the Y-axis direction. Also, the MRI apparatus 1 does not include a subject P (e.g., a human body).

[0010] As shown in Figure 1, the magnet stand 110 comprises a static magnetic field magnet 113, a gradient magnetic field coil unit 116, and an RF coil 117. The static magnetic field magnet 113, the gradient magnetic field coil unit 116, and the RF coil 117 are covered by a housing 111 and a housing side plate 112. The housing side plate 112 is detachable from the housing 111, and when the housing side plate 112 is removed from the housing 111, at least a portion of the gradient magnetic field coil unit 116 is exposed when the magnet stand 110 is viewed along the Z-axis from the side where the bed 121 is provided. The subject P is inserted from the bed 121 side into the roughly cylindrical space S (bore) formed by the housing 111 and the housing side plate 112. Note that in Figure 1, the internal structure of the magnet stand 110 is shown in a vertical cross-sectional view.

[0011] The static magnetic field magnet 113 has a generally cylindrical shape and generates a static magnetic field within the bore that includes the imaging area of ​​the subject P. The static magnetic field magnet 113 may be a superconducting magnet or a permanent magnet.

[0012] The gradient magnetic field coil unit 116 has a generally cylindrical shape. The gradient magnetic field coil unit 116 includes a main coil 114 that applies gradient magnetic fields in the orthogonal X, Y, and Z axis directions by current supplied from the gradient magnetic field power supply 131, and a shield coil 115 that cancels the leakage magnetic field of the main coil 114.

[0013] The RF coil 117 is positioned radially inward of the gradient magnetic field coil unit 116 and generates a high-frequency magnetic field. The RF coil 117 also receives a magnetic resonance signal emitted from the subject P due to the influence of the high-frequency magnetic field. The RF coil 117 may also be configured as a transmitting coil and a receiving coil.

[0014] As shown in Figure 1, the MRI apparatus 1 comprises a cooling device 130, a gradient magnetic field power supply 131, a transmitting circuit 132, a receiving circuit 133, a patient control circuit 134, a sequence control circuit 135, and a computer 141. Furthermore, the configuration shown in Figure 1 is merely an example. For example, the components within the sequence control circuit 135 and the computer 141 may be integrated or separated as appropriate.

[0015] The receiving circuit 133 detects the magnetic resonance signal received by the RF coil 117 and generates magnetic resonance data based on the detected magnetic resonance signal. Specifically, the receiving circuit 133 generates magnetic resonance data by digitally converting the magnetic resonance signal received by the RF coil 117. The receiving circuit 133 also transmits the generated magnetic resonance data to the sequence control circuit 135.

[0016] The bed 121 moves the top plate 122 on which the subject P is placed in the Z-axis and Y-axis directions under the control of the bed control circuit 134.

[0017] The computer 141 includes a memory circuit 142, an input device 143, a display 144, a communication circuit 145, and a processing circuit 146. The sequence control circuit 135 executes a pulse sequence and images the subject P by driving the gradient magnetic field power supply 131, the transmission circuit 132, and the reception circuit 133 based on the sequence information transmitted from the processing circuit 146. Here, the sequence information is information that defines the procedure for imaging. In the sequence information, the strength of the current supplied by the gradient magnetic field power supply 131 to the main coil 114 and the shield coil 115, the timing of supplying the current, the strength of the RF pulse supplied by the transmission circuit 132 to the RF coil 117, the timing of applying the RF pulse, the timing at which the reception circuit 133 detects the magnetic resonance signal, etc. are defined as the pulse sequence. For example, the sequence control circuit 135 is realized by at least one processor. Also, the transmission circuit 132, the reception circuit 133, the bed control circuit 134, etc. are similarly constituted by electronic circuits such as the above-mentioned at least one processor.

[0018] Furthermore, when the sequence control circuit 135 drives the gradient magnetic field power supply 131, the transmission circuit 132, and the reception circuit 133 to image the subject P and receives magnetic resonance data from the reception circuit 133, the received magnetic resonance data is transferred to the computer 141.

[0019] Upon receiving the magnetic resonance data, the processing circuit 146 stores the received magnetic resonance data in the memory circuit 142 as k-space data.

[0020] The memory circuit 142 stores k-space data received by the processing circuit 146, image data generated by the processing circuit 146, and other similar data. The memory circuit 142 also stores various application programs (hereinafter referred to as "applications") and various setting information executed by the processing circuit 146. Specifically, the memory circuit 142 stores applications that assist in positioning the imaging range, applications related to signal processing of magnetic resonance data, and so on. For example, the memory circuit 142 can be implemented using semiconductor memory elements such as RAM (Random Access Memory) or flash memory, a hard disk, or an optical disk.

[0021] The input device 143 is an interface that receives various instructions and information input from the operator. The input device 143 is, for example, a pointing device such as a mouse or trackball, or an input device such as a keyboard.

[0022] The display 144, under the control of the processing circuit 146, displays a GUI (Graphical User Interface) for receiving input related to setting and adjusting imaging conditions, as well as images generated by the processing circuit 146. The display 144 may be a display device such as a liquid crystal display, and may also serve as an interface for receiving input.

[0023] The communication circuit 145 communicates with external devices, etc. The communication circuit 145 is, for example, a communication interface such as a network card, network adapter, or NIC (Network Interface Controller).

[0024] The processing circuit 146 receives input of imaging conditions (imaging parameters, etc.) via the GUI, generates sequence information according to the received imaging conditions, and transmits the generated sequence information to the sequence control circuit 135. The processing circuit 146 also reads k-space data from the storage circuit 142 and generates an image by applying reconstruction processing such as Fourier transform to the read k-space data.

[0025] The processing circuit 146 is a processor. In this embodiment, the processing circuit 146 executes each function by reading the program corresponding to that function from the storage circuit 142 and executing it. In other words, the processing circuit 146, in the state in which each program has been read, has each processing function. Furthermore, although Figure 1 describes the processing circuit 146 as realizing each processing function with a single processor, the processing circuit 146 may be configured by combining multiple independent processors, and each processor may realize the function by executing a program. Also, although Figure 1 describes the single storage circuit 142 as storing the program corresponding to each processing function, multiple storage circuits 142 may be distributed and arranged so that the processing circuit 146 reads the corresponding program from each individual storage circuit 142.

[0026] In the above description, an example was given in which the processor reads and executes programs corresponding to each function from the memory circuit 142, but the embodiments are not limited to this. The term "processor" refers to circuits such as a CPU (Central Processing Unit), GPU (Graphics Processing Unit), Application Specific Integrated Circuit (ASIC), and Programmable Logic Device (e.g., Simple Programmable Logic Device (SPLD), Complex Programmable Logic Device (CLPD), and Field Programmable Gate Array (FPGA)). For example, if the processor is a CPU, the processor realizes its functions by reading and executing programs stored in the memory circuit 142. On the other hand, if the processor is an ASIC, instead of storing programs in the memory circuit 142, the functions are directly incorporated as logic circuits within the processor's circuitry. In this embodiment, each processor is not limited to being configured as a single circuit; multiple independent circuits may be combined to form a single processor and realize its functions. Furthermore, the multiple components shown in Figure 1 may be integrated into a single processor to realize their functions.

[0027] Figure 2 is a perspective view showing an example configuration of a gradient magnetic field coil unit 116 according to the first embodiment. As shown in Figure 2, a shim tray insertion guide 150 is formed between the main coil 114 and the shield coil 115. Although not shown in Figure 2, the gradient magnetic field coil unit 116 is impregnated with resin.

[0028] The shim tray insertion guide 150 is a hole formed at the end of the gradient coil unit 116 on the side where the bed 121 is located relative to the magnet mount 110 in the Z-axis direction, and is formed over the entire Z-axis direction of the gradient coil unit 116. The shim tray insertion guide 150 may be a through hole with openings at both ends in the Z-axis direction of the gradient coil unit 116, or it may be a hole with an opening only at the end of the gradient coil unit 116 opposite to the bed 121 in the Z-axis direction. Each of the multiple shim tray insertion guides 150 is formed along the circumferential direction parallel to each other in the region sandwiched between the main coil 114 and the shield coil 115. A shim tray 151 is inserted into each of the multiple shim tray insertion guides 150.

[0029] The shim tray 151 is made of a non-magnetic material and is roughly rectangular in shape. The shim tray 151 is provided with multiple shim pockets 154. Any number of stacked iron shims 152 are placed on the bottom surface of any shim pocket 154 in the shim tray 151. Then, each of the multiple shim trays 151 is inserted into a shim tray insertion guide 150 and fixed inside the gradient magnetic field coil unit 116.

[0030] Figure 3 is a cross-sectional view showing an example of the configuration of the first pipe 153a, the second pipe 153b, and the third pipe 153c according to the first embodiment. The first pipe 153a, the second pipe 153b, and the third pipe 153c are each made of a non-magnetic material. In the following description, the longitudinal direction of the shim tray 151 is referred to as the first direction, the direction perpendicular to the bottom surface of the shim pocket 154 on which the iron shim 152 is placed is referred to as the third direction, and the direction perpendicular to the first direction and the third direction is referred to as the second direction.

[0031] Figure 4 is a cross-sectional view showing an example of the configuration of a gradient coil unit 116 according to the first embodiment. Figure 4 shows the configuration of the gradient coil unit 116 when viewed from the bed 121 side along the first direction relative to the bore. Figure 4 shows a shim tray 151a inserted into a shim tray insertion guide 150a, and a shim tray 151b inserted into a shim tray insertion guide 151b adjacent to the shim tray insertion guide 150a in the circumferential direction. As shown in Figure 4, the gradient coil unit 116 is composed of a main coil 114, a shim tray insertion guide 150, and a shield coil 115 in the radial direction of the bore. Note that the housing side plate 112 is not shown in Figure 4.

[0032] The cooling device 130 is a device that supplies a refrigerant into each shim tray 151 via the first pipe 153a. The refrigerant is, for example, water, oil, or air. As shown in Figure 3, the first pipe 153a and the third pipe 153c branch to each shim tray 151 through at least one opening formed in the housing side plate 112. One end of the second pipe 153b provided on shim tray 151a and one end of the second pipe 153b provided on shim tray 151b are connected to the first pipe 153a. The other end of the second pipe 153b provided on shim tray 151a and the other end of the second pipe 153b provided on shim tray 151b are connected to the third pipe 153c. The first pipe 153a, the second pipe 153b, and the third pipe 153c constitute a circulation path through which the refrigerant supplied from the cooling device 130 passes through the shim tray 151 and returns to the cooling device 130. Specifically, the refrigerant supplied from the cooling device 130 via the first pipe 153a flows from the outside of the shim pocket 154 into the inside of the shim pocket 154 via the second pipe 153b, flows out from the inside of the shim pocket 154 to the outside of the shim pocket 154 via the second pipe 153b, and is then supplied to the third pipe 153c. Furthermore, the refrigerant supplied from the cooling device 130 via the first pipe 153a flows from the outside of the shim pocket 154 into the inside of the shim pocket 154 via the second pipe 153b provided on the shim tray 151b, flows out from the inside of the shim pocket 154 to the outside of the shim pocket 154 via the second pipe 153b, and is then supplied to the third pipe 153c. That is, the second pipe 153b functions as an inlet and outlet. The first pipe 153a, the second pipe 153b, the third pipe 153c, and the cooling device 130 are each connected by fittings such as couplers, flares, unions, and flanges. In Figure 3, the first pipe 153a and the third pipe 153c are shared for the shim trays 151a and 151b, but they may be shared for three or more shim trays.

[0033] Next, the specific configuration of the second piping 153b will be described. As shown in Figure 3, the second piping 153b is arranged to surround all four sides of the area in which the multiple shim pockets 154 are arranged. Specifically, the second piping 153b comprises two pipes that run along the first direction and pass through the area within the multiple shim pockets 154, and two pipes that run along the second direction and pass through the area within the shim pockets 154 located at both ends of the multiple shim pockets 154 in the first direction. In this way, the second piping 153b functions as a guide that directs the refrigerant flowing in from the first piping 153a, which is outside the shim tray 151, to pass through the area within the multiple shim pockets 154. Furthermore, the pipe that runs along the first direction and passes through the area within the multiple shim pockets 154 functions as the first pipe, and the pipe that runs along the second direction and passes through the area within the multiple shim pockets 154 functions as the second pipe.

[0034] In this embodiment, the first pipe 153a and the third pipe 153c are fixed to the inside of the housing side plate 112. However, for example, a flow path corresponding to the first pipe 153a and a flow path corresponding to the third pipe 153c may be formed inside the housing side plate 112, and these flow paths may be connected to the second pipe 153b.

[0035] Figure 5 is a longitudinal cross-sectional view showing an example of the arrangement of the second pipe 153b within the shim pocket 154 according to the first embodiment. As shown in Figure 5, a portion of the outer circumference of the pipe along the first direction in the second pipe 153b is exposed to the region inside the shim pocket 154. That is, the second pipe 153b passes through the region inside the shim pocket 154. The shim pocket 154 is also constructed by stacking any number of iron shims 152 inside the shim pocket 154 and closing it with a lid 155. With this configuration, even when the lid 155 is closed, the refrigerant flowing inside the second pipe 153b is thermally connected to the iron shims 152. The second pipe 153b may or may not be in contact with the iron shims 152.

[0036] In Figure 5, the second pipe 153b is shown with a portion of its outer circumference exposed within the shim pocket; however, the second pipe 153b may be positioned so that its entire circumference is exposed within the shim pocket 154. That is, the second pipe 153b should be positioned so that at least a portion of its entire circumference is exposed within the shim pocket 154.

[0037] As described above, in this embodiment, the second pipe 153b is provided on the shim tray 151 such that at least a portion of the second pipe 153b, which guides the refrigerant for cooling the iron shim, is exposed to the area inside the shim pocket 154. As a result, the heat of the iron shim 152 is efficiently absorbed by the refrigerant, and the temperature rise of the iron shim 152 can be reduced. As a result, the adverse effect on image quality in imaging by the MRI device 1 due to non-uniformity of the static magnetic field can be reduced.

[0038] In this embodiment, the temperature rise of the iron shim 152 is reduced by exposing at least a portion of the second pipe 153b that guides the refrigerant to the region inside the shim pocket 154, but this is not limited to this. For example, a through hole connecting the outside of the shim pocket 154 to the inside of the shim pocket 154 may be provided in the side wall of the shim pocket 154. As a result, the heat of the iron shim is efficiently absorbed by the refrigerant by the direct contact between the iron shim 152 and the refrigerant, thereby reducing the temperature rise of the iron shim 152 and reducing the adverse effect on image quality in imaging by the MRI device 1 due to non-uniformity of the static magnetic field. The through hole functions as a guide for the refrigerant. The through hole also functions as an inlet for the refrigerant to flow from the outside of the shim pocket 154 into the inside of the shim pocket 154, or as an outlet for the refrigerant to flow out from the inside of the shim pocket 154 to the outside of the shim pocket 154.

[0039] In this embodiment, it is assumed that there are two pipes that run along the first direction and pass through multiple shim pockets 154, but this is not limited to this. For example, there may be only one pipe that runs along the first direction and passes through multiple shim pockets 154.

[0040] (First modified example in the first embodiment) Figure 6 is a longitudinal cross-sectional view showing an example of the arrangement of the second pipe 153b within the shim pocket 154 according to the first modified example of this embodiment. In the first embodiment, the second pipe 153b was arranged on the side wall of the shim pocket 154 intersecting in the first direction, but in this modified example, the second pipe 153b is arranged on the bottom surface of the shim pocket 154.

[0041] In Figure 6, the second pipe 153b is shown with a portion of its outer circumference exposed to the shim pocket, but it may also be arranged so that its entire circumference is exposed to the shim pocket 154. That is, the second pipe 153b should be arranged so that at least a portion of its entire circumference is exposed to the shim pocket 154.

[0042] As described above, in this modified example, a coolant flow path is provided on the underside of the iron shim 152. As a result, regardless of the number of iron shims 152 placed in the shim pocket 154, the iron shim 152 and the coolant flow path are in close proximity, which can more efficiently reduce the temperature rise of the iron shim 152 and reduce the adverse effects on image quality in imaging by the MRI device 1 due to non-uniformity of the static magnetic field.

[0043] (Second embodiment) Figure 7 is a cross-sectional view showing an example configuration of the first pipe 153a, the second pipe 153b, and the third pipe 153c according to the second embodiment. Note that the same configurations as in the first embodiment will not be described. Furthermore, the same modifications as in the first embodiment can be applied to this embodiment as well.

[0044] As shown in Figure 7, the second piping 153b comprises two pipes that run along the first direction and pass through the regions within the multiple shim pockets 154, and multiple pipes that run along the second direction and pass through the internal regions of each of the multiple shim pockets 154. In this way, the refrigerant passes through the second piping 153b, which is arranged to surround all four sides of the iron shims 152 stored in each shim pocket 154. That is, the second piping 153b functions as a guide that directs the refrigerant flowing in from the first piping 153a, which is outside the shim tray 151, to pass through the regions within the multiple shim pockets 154.

[0045] As described above, in this embodiment, the second pipe 153b is provided so as to be exposed to the internal regions of each of the multiple shim pockets 154 along the first and second directions. As a result, the temperature rise of the iron shim 152 can be reduced more efficiently, and the adverse effects on image quality in imaging by the MRI device 1 due to non-uniformity of the static magnetic field can be reduced.

[0046] (Third embodiment) Figure 8 is a cross-sectional view showing an example configuration of the first pipe 153a, the second pipe 153b, and the third pipe 153c according to the third embodiment. Note that the same configurations as in the first embodiment will not be described. Furthermore, the same modifications as in the first embodiment can be applied to this embodiment as well.

[0047] As shown in Figure 8, the second pipe 153b is positioned along the first direction and in the region between the shim tray insertion guide 150 and the shim tray 151. That is, in this embodiment, the refrigerant guided by the second pipe 153b along the first direction does not pass through the region within the shim pocket 154. As shown in Figure 8, the second pipe 153b branches along the second direction so that the refrigerant guided by the second pipe 153b passes through each of the shim pockets 154. The refrigerant that has passed through each of the shim pockets 154 along the second direction merges in a pipe positioned along the first direction in the region between the shim tray insertion guide 150 and the shim tray 151, and is guided to the third pipe 153c.

[0048] In this embodiment, the second pipe 153b is positioned along the first direction and in the area between the shim tray insertion guide 150 and the shim tray 151. However, the second pipe 153b may also be positioned along the first direction and in the area between the multiple shim pockets 154 and the outer wall of the shim tray 151. That is, the second pipe 153b may be positioned along the first direction and outside the shim pockets 154.

[0049] As described above, in this embodiment, the refrigerant is guided along the first direction and so as not to pass through the internal region of the shim pocket 154, and then guided along the second direction to each of the multiple shim pockets 154. As a result, compared to a configuration in which the refrigerant is guided along the first direction and so as to pass through the multiple shim pockets 154, the temperature rise of the iron shims 152 stored in each of the multiple shim pockets 154 can be reduced more uniformly, and the adverse effects on image quality in imaging by the MRI device 1 due to non-uniformity of the static magnetic field can be reduced.

[0050] (Fourth embodiment) Figure 9 is a cross-sectional view showing an example configuration of the first pipe 153a, the second pipe 153b, and the third pipe 153c according to the fourth embodiment. Note that the same configurations as in the first embodiment will not be described. Furthermore, similar modifications as in the first embodiment can be applied to this embodiment as well.

[0051] As shown in Figure 9, the refrigerant in the second pipe 153b passes through the region between the shim tray insertion guide 150 and the shim tray 151 along the first direction, and then passes through the internal regions of each of the multiple shim pockets 154 provided in the first region r1 in the first direction, along the second direction. The refrigerant that has passed through the multiple shim pockets 154 provided in the first region r1 along the second direction is guided through the region between the shim tray insertion guide 150 and the shim tray 151 to the multiple shim pockets 154 provided in the second region r2 and the third region r3 in the first direction. Subsequently, the refrigerant passes through the internal regions of each of the multiple shim pockets 154 provided in the second region r2 and the third region r3 along the second direction, and is guided through the region between the shim tray insertion guide 150 and the shim tray 151 along the first direction to the third pipe 153c. Furthermore, the pipes that guide the refrigerant to each of the multiple shim pockets 154 located along the second direction and in the first region r1, and the pipes that guide the refrigerant to the third pipe 153c along the first direction are located at different positions in the third direction. Also, the first region r1 is located between the second region r2 and the third region r3 in the first direction.

[0052] In this embodiment, the first region r1 corresponds to the region where imaging by the magnetic resonance imaging apparatus is performed (i.e., the central region of the static magnetic field). The length of the first region r1 in the first direction corresponds, for example, to half the length of the shim tray 151. The lengths of the second region r2 and the third region r3 in the first direction correspond, for example, to one-quarter the length of the shim tray 151, respectively.

[0053] As described above, in this embodiment, a second pipe 153b is provided so that the refrigerant for cooling the iron shim 152 preferentially passes through the region within the shim pocket 154 provided in the first region r1. As a result, the temperature rise of the iron shim 152 near the center region of the static magnetic field can be reduced more preferentially and efficiently. Consequently, the adverse effects on image quality in imaging by the MRI device 1 due to non-uniformity of the static magnetic field can be reduced.

[0054] According to at least one embodiment (and its variations) described above, the temperature rise of the iron shim 152 can be reduced.

[0055] Furthermore, in each embodiment, the connection between the first pipe 153a and the second pipe 153b, and the connection between the third pipe 153c and the second pipe 153b were described as being located on the bed 121 side relative to the bore in the Z-axis direction. However, either connection may be located on a side different from the bed 121 in the Z-axis direction, or both connection may be located on a side different from the bed 121 in the Z-axis direction.

[0056] While several embodiments have been described, these embodiments are presented as examples only and are not intended to limit the scope of the invention. These embodiments can be carried out in a variety of 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 variations are included in the scope and spirit of the invention, as well as in the claims and their equivalents. [Explanation of Symbols]

[0057] 1 MRI machine 110 Magnetic Stand 113 Static magnetic field magnet 130 Cooling device 150 Shim Tray Insertion Guide 151 sim tray 152 Iron Sim 153a First piping 153b Second piping 153c Third pipe 154 SIM pockets 155 Lid

Claims

1. In a shim tray inserted into and removed from a magnet mount in a magnetic resonance imaging apparatus, A shim pocket on which an iron shim is placed to correct the spatial non-uniformity of the static magnetic field generated by the static magnetic field magnet provided in the magnetic resonance imaging apparatus, A lid that covers the opening of the shim pocket, A guide portion guides a refrigerant supplied from outside the shim tray and used to cool the iron shim into the shim pocket when the opening of the shim pocket is covered by the lid, and guides the refrigerant inside the shim pocket to the outside of the shim pocket when the opening of the shim pocket is covered by the lid, A sim tray equipped with [a specific feature].

2. The shim tray comprises a plurality of shim pockets arranged in a first direction which is the longitudinal direction of the shim tray, The guide portion comprises a first tube that is aligned with the first direction and at least a portion of it is exposed to the region within the plurality of shim pockets. The shim tray according to claim 1.

3. The guide portion includes a second tube that is aligned along a second direction perpendicular to the direction perpendicular to the bottom surface of the shim pocket on which the iron shim is placed and perpendicular to the first direction, and is at least partially exposed to the region within the plurality of shim pockets. The shim tray according to claim 2.

4. The guide section comprises a plurality of the aforementioned second tubes, Each of the plurality of second tubes is exposed in part to a region within one of the plurality of shim pockets. The shim tray according to claim 3.

5. At least one of the plurality of second tubes is exposed in part to a region within the shim pocket provided at one end of the plurality of shim pockets in the first direction. The shim tray according to claim 4.

6. The shim tray comprises a plurality of shim pockets arranged in a first direction which is the longitudinal direction of the shim tray, The guide portion comprises a tube positioned along a first direction which is the longitudinal direction of the shim tray and in the external region of the shim pocket, and a plurality of tubes positioned along a second direction which is perpendicular to the direction perpendicular to the bottom surface of the shim pocket on which the iron shim is placed and perpendicular to the first direction, and at least a portion of which is exposed in the internal region of each of the plurality of shim pockets. The shim tray according to claim 1.

7. The shim tray comprises a plurality of shim pockets arranged in a first direction which is the longitudinal direction of the shim tray, The guide portion comprises a tube positioned along a first direction which is the longitudinal direction of the shim tray and in the area outside the shim pocket, The guide section guides the refrigerant so that it passes through the region within the shim pocket provided in the first region in the first direction along a second direction perpendicular to the direction perpendicular to the bottom surface of the shim pocket on which the iron shim is placed and perpendicular to the first direction, and then passes through the region within the shim pocket provided in the second region in the first direction and the region within the shim pocket provided in the third region in the first direction along the second direction. The first region is located between the second region and the third region in the first direction. The shim tray according to claim 1.

8. In a shim tray inserted into and removed from a magnet mount in a magnetic resonance imaging apparatus, A shim pocket in which an iron shim is stored is provided to correct the spatial non-uniformity of the static magnetic field generated by the static magnetic field magnet provided in the magnetic resonance imaging apparatus, A lid that covers the opening of the SIM pocket, A coolant supplied from outside the shim tray and used to cool the iron shims flows into the shim pocket from outside the shim pocket when the opening of the shim pocket is covered by the lid, The refrigerant flows out from the inside of the shim pocket to the outside of the shim pocket when the opening of the shim pocket is covered by the lid, A sim tray equipped with [a specific feature].

9. The inlet and outlet are formed in the side wall of the shim pocket. The shim tray according to claim 7.

10. A static magnetic field magnet that generates a static magnetic field, A gradient magnetic field coil unit including gradient magnetic field coils that generate gradient magnetic fields, A housing that covers the gradient magnetic field coil unit, A shim tray that can be inserted into and removed from the aforementioned housing, Equipped with, The shim tray is A shim pocket is provided in which an iron shim is stored and placed to correct the spatial non-uniformity of the static magnetic field generated by the aforementioned static magnetic field magnet, A lid that covers the opening of the shim pocket, With the opening of the shim pocket covered by the lid, a guide portion guides the refrigerant supplied from outside the shim tray and used to cool the iron shim into the shim pocket with the opening of the shim pocket covered by the lid, and guides the refrigerant inside the shim pocket to the outside of the shim pocket with the opening of the shim pocket covered by the lid, A magnetic resonance imaging system equipped with the following features.

Images