JP7451327B2 - Shim unit, guide member, and magnetic resonance imaging device - Google Patents

Description

Embodiments disclosed herein and in the drawings relate to a shim unit, a guide member, and a magnetic resonance imaging apparatus.

Conventionally, in magnetic resonance imaging (MRI) equipment, magnetic field distribution is corrected by inserting shims made of magnetic material such as metal into holes provided in the gantry of the magnetic resonance imaging equipment. Shimming work is known.

In this kind of shimming work, in order to avoid the influence of the magnetic field on the worker and the shim, the shim is inserted with the magnetic resonance imaging device demagnetized, and after insertion, the shim is re-energized to measure the magnetic field distribution. This process was repeated to correct the magnetic field distribution.

Japanese Patent Application Publication No. 2014-193317

One of the problems to be solved by the embodiments disclosed in this specification and the drawings is to improve the efficiency of shimming operations performed on a magnetic resonance imaging apparatus. However, the problems to be solved by the embodiments disclosed in this specification and the drawings are not limited to the above problems. Problems corresponding to the effects of each configuration shown in the embodiments described later can also be positioned as other problems.

The shim unit according to the embodiment includes a shim tray and a guide member. The shim tray is a non-magnetic material, and is housed in a storage section provided on a pedestal that includes a static field magnet that generates a static magnetic field, and stores shims that are a magnetic material. The guide member is made of a non-magnetic material and is removably attached to the rear end of the shim tray in the first direction in which the shim tray is inserted into the storage section . A protrusion protruding in a direction intersecting the first direction is provided at the rear end of the shim tray in the first direction. The length of the shim tray including the protrusion in the second direction from which the protrusion protrudes is longer than the length in the second direction of the insertion opening of the storage section into which the shim tray is inserted. The guide member is characterized in that it is removably attached to the shim tray by engaging a hole provided in the guide member with a protrusion.

FIG. 1 is a block diagram showing an example of a magnetic resonance imaging apparatus according to the first embodiment. FIG. 2 is a perspective view showing an example of the structure of the gradient magnetic field coil according to the first embodiment. FIG. 3 is a perspective view showing an example of the configuration of a shim tray included in the first embodiment. FIG. 4 is an example of an enlarged view of the periphery of the opening of the shim tray housing in the gradient magnetic field coil according to the first embodiment. FIG. 5 is a diagram illustrating an example of the shim tray insertion work performed in an excitation environment according to the first embodiment. FIG. 6 is a perspective view showing an example of the appearance of the shim tray according to the first embodiment. FIG. 7 is an enlarged view of the rear end portion of the shim tray shown in FIG. 6. FIG. 8 is a perspective view showing an example of the appearance of the guide member according to the first embodiment. FIG. 9 is a side view showing an example of the appearance of the guide member according to the present embodiment. FIG. 10 is a diagram showing an example of the appearance of a shim unit according to the first modification. FIG. 11 is a diagram showing an example of the appearance of a shim unit according to a second modification. FIG. 12 is a diagram showing an example of the appearance of a shim unit according to a third modification. FIG. 13 is a diagram showing an example of the appearance of a shim unit according to a fourth modification. FIG. 14 is a diagram showing an example of the appearance of a shim unit according to a fifth modification. FIG. 15 is a diagram illustrating an example of a shim tray insertion operation performed in an excitation environment according to the second embodiment. FIG. 16 is a perspective view showing an example of the appearance of a guide member attached to a gradient magnetic field coil according to the third embodiment. FIG. 17 is a diagram illustrating an example of a state in which the guide member according to the third embodiment is attached to the insertion opening of the shim tray storage section. FIG. 18 is a front view showing an example of a state in which the guide member according to the third embodiment is attached to the insertion port. FIG. 19 is a side view showing an example of a gradient magnetic field coil according to the third embodiment. FIG. 20 is a diagram showing an example of the internal shape of the guide member according to the third embodiment.

Hereinafter, embodiments of a shim unit, a guide member, and a magnetic resonance imaging apparatus will be described in detail with reference to the drawings.

(First embodiment)
FIG. 1 is a block diagram showing an example of a magnetic resonance imaging (MRI) apparatus 100 according to the present embodiment. As shown in FIG. 1, the magnetic resonance imaging apparatus 100 includes a static magnetic field magnet 101, a static magnetic field power source (not shown), a gradient magnetic field coil 103, a gradient magnetic field power source 104, a bed 105, and a bed control circuit 106. , a transmitting coil 107, a transmitting circuit 108, a receiving coil 109, a pedestal 140, a receiving circuit 110, a sequence control circuit 120, and a computer system 130.

Note that the configuration shown in FIG. 1 is only an example. For example, each part within the sequence control circuit 120 and the computer system 130 may be configured to be integrated or separated as appropriate. Note that the magnetic resonance imaging apparatus 100 does not include the subject P (for example, a human body).

The X, Y, and Z axes shown in FIG. 1 constitute an apparatus coordinate system specific to the magnetic resonance imaging apparatus 100. For example, the Z-axis direction coincides with the axial direction of the cylinder of the gradient magnetic field coil 103 and is set along the magnetic flux of the static magnetic field generated by the static magnetic field magnet 101. Note that in this embodiment, the term cylindrical includes a cylinder whose cross section perpendicular to the axis of the cylinder is elliptical. Furthermore, in this embodiment, the term "circle" includes an ellipse.

Further, the Z-axis direction is the same direction as the longitudinal direction of the bed 105, and also the same direction as the cranio-caudal direction of the subject P placed on the bed 105. Moreover, the X-axis direction is set along the horizontal direction orthogonal to the Z-axis direction. The Y-axis direction is set along the vertical direction orthogonal to the Z-axis direction.

The static magnetic field magnet 101 is a hollow, substantially cylindrical magnet that generates a static magnetic field in the internal space. The static magnetic field magnet 101 is, for example, a superconducting magnet or the like, and is excited by receiving current from a static magnetic field power supply. The static magnetic field power supply supplies current to the static magnetic field magnet 101. As another example, the static magnetic field magnet 101 may be a permanent magnet, and in this case, the magnetic resonance imaging apparatus 100 does not need to include a static magnetic field power supply. Further, the static magnetic field power supply may be provided separately from the magnetic resonance imaging apparatus 100.

The gradient magnetic field coil 103 is a hollow, substantially cylindrical coil, and is arranged inside the static magnetic field magnet 101. The gradient magnetic field coil 103 is formed by combining three coils corresponding to the mutually orthogonal X, Y, and Z axes, and these three coils are individually supplied with current from the gradient magnetic field power supply 104. In response, a gradient magnetic field whose magnetic field strength changes along each of the X, Y, and Z axes is generated. Further, the gradient magnetic field power supply 104 supplies current to the gradient magnetic field coil 103 under the control of the sequence control circuit 120. Details of the configuration of the gradient magnetic field coil 103 of this embodiment will be described later.

The bed 105 includes a top plate 105a on which the subject P is placed, and under the control of the bed control circuit 106, the top plate 105a is inserted into the imaging port with the subject P such as a patient placed thereon. do. The bed control circuit 106 drives the bed 105 under the control of the computer system 130 to move the top plate 105a in the longitudinal direction and the vertical direction.

The transmitting coil 107 excites any region of the subject P by applying a high frequency magnetic field. The transmitting coil 107 is, for example, a whole body type coil that surrounds the whole body of the subject P. The transmitting coil 107 receives the RF pulse from the transmitting circuit 108, generates a high frequency magnetic field, and applies the high frequency magnetic field to the subject P. The transmitter circuit 108 supplies RF pulses to the transmitter coil 107 under the control of the sequence control circuit 120 .

The receiving coil 109 is arranged inside the gradient magnetic field coil 103, and receives a magnetic resonance signal (hereinafter referred to as an MR (Magnetic Resonance) signal) emitted from the subject P under the influence of a high-frequency magnetic field. Upon receiving the MR signal, the receiving coil 109 outputs the received MR signal to the receiving circuit 110.

In FIG. 1, the receiving coil 109 is provided separately from the transmitting coil 107, but this is only an example, and the present invention is not limited to this structure. For example, a configuration may be adopted in which the receiving coil 109 is also used as the transmitting coil 107.

The pedestal 140 has a hollow bore 141 formed into a substantially cylindrical shape, and includes, for example, a static magnetic field magnet 101, a gradient magnetic field coil 103, a transmitting coil 107, and a receiving coil 109. Note that the configuration of the pedestal 140 is not limited to these. The space within the bore 141 of the gantry 140 becomes an imaging space in which the subject P is placed when the subject P is imaged. Note that the pedestal 140 is also referred to as a gantry.

The receiving circuit 110 performs analog-to-digital (AD) conversion on the analog MR signal output from the receiving coil 109 to generate MR data. Further, the receiving circuit 110 transmits the generated MR data to the sequence control circuit 120. Note that AD conversion may be performed within the receiving coil 109. Further, the receiving circuit 110 can perform arbitrary signal processing other than AD conversion.

The sequence control circuit 120 images the subject P by driving the gradient magnetic field power supply 104, the transmitting circuit 108, and the receiving circuit 110 based on sequence information transmitted from the computer system 130. Sequence information is information that defines a procedure for performing imaging. The sequence information includes, for example, the strength of the current that the gradient magnetic field power supply 104 supplies to the gradient magnetic field coil 103 and the timing of supplying the current, the strength of the RF pulse that the transmitting circuit 108 supplies to the transmitting coil 107, and the timing of applying the RF pulse. , the timing at which the receiving circuit 110 detects the MR signal, etc. are defined.

The sequence control circuit 120 may be realized by a processor, or may be realized by a mixture of software and hardware.

Furthermore, upon receiving MR data from the receiving circuit 110 as a result of driving the gradient magnetic field power supply 104, the transmitting circuit 108, and the receiving circuit 110 to image the subject P, the sequence control circuit 120 transfers the received MR data to the computer system 130. Transfer to.

The computer system 130 performs overall control of the magnetic resonance imaging apparatus 100, generates MR images, and the like. As shown in FIG. 1, the computer system 130 includes an NW (network) interface 131, a storage circuit 132, a processing circuit 133, an input interface 134, and a display 135.

NW interface 131 communicates with sequence control circuit 120 and bed control circuit 106 . For example, the NW interface 131 transmits sequence information to the sequence control circuit 120. Further, the NW interface 131 receives MR data from the sequence control circuit 120.

The storage circuit 132 stores MR data received by the NW interface 131, k-space data placed in k-space by a processing circuit 133 (described later), image data generated by the processing circuit 133, and the like. The storage circuit 132 is, for example, a RAM (Random Access Memory), a semiconductor memory element such as a flash memory, a hard disk, an optical disk, or the like.

The input interface 134 accepts various instructions and information input from the operator. The input interface 134 may be, for example, a trackball, a switch button, a mouse, a keyboard, a touchpad that performs input operations by touching the operation surface, a touchscreen that integrates a display screen and a touchpad, or a non-control device that uses an optical sensor. This is realized by a touch input circuit, a voice input circuit, etc. The input interface is connected to the processing circuit 133, converts input operations received from the operator into electrical signals, and outputs the electrical signals to the processing circuit 133. Note that in this specification, the input interface is not limited to one that includes physical operation parts such as a mouse and a keyboard. For example, an example of an input interface 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 computer system 130 and outputs this electrical signal to a control circuit. .

Under the control of the processing circuit 133, the display 135 displays a GUI (Graphical User Interface) for accepting input of imaging conditions, a magnetic resonance image generated by the processing circuit 133, and the like. The display 135 is, for example, a display device such as a liquid crystal display. Display 135 is an example of a display section.

The processing circuit 133 performs overall control of the magnetic resonance imaging apparatus 100. More specifically, the processing circuit 133 controls each part of the magnetic resonance imaging apparatus 100 to execute processing such as capturing a magnetic resonance image.

More specifically, the processing circuit 133 executes pulse sequences according to various scan protocols, and sends MR data converted from MR signals generated by executing the pulse sequences to the sequence control circuit 120 via the NW interface 131. Collect from. Types of scan protocols include, for example, scan protocols for capturing magnetic resonance images and scan protocols for measuring static magnetic field distribution.

The processing circuit 133 arranges the collected MR data according to the amount of phase encoding and the amount of frequency encoding given by the gradient magnetic field. MR data arranged in k-space is referred to as k-space data. The k-space data is stored in storage circuit 132.

Further, when executing a scan protocol for capturing a magnetic resonance image, the processing circuit 133 generates a magnetic resonance image based on the k-space data. For example, the processing circuit 133 generates a magnetic resonance image by performing reconstruction processing such as Fourier transform on the k-space data.

Furthermore, when the processing circuit 133 executes a scan protocol for measuring the static magnetic field distribution, it generates a graph, an image, or the like representing the scan result of the static magnetic field distribution. Note that the scan result of the static magnetic field distribution may be output as a numerical value. The method for measuring the static magnetic field distribution is not particularly limited, and any known method can be employed.

Further, the processing circuit 133 displays the generated magnetic resonance image or the scan result of the static magnetic field distribution on the display 135. Furthermore, the processing circuit 133 displays a GUI (Graphical User Interface) on the display 135 for accepting various instructions and input operations for various information from the operator.

Here, for example, the functions of the processing circuit 133 are stored in the storage circuit 132 in the form of a computer-executable program. Processing circuit 133 is a processor. For example, the processing circuit 133 reads programs from the storage circuit 132 and executes them to realize functions corresponding to each program. Although the above-mentioned functions are described in FIG. 1 as being realized by a single processor, the processing circuit 133 is configured by combining a plurality of independent processors, and the functions are realized by each processor executing a program. It does not matter if it is something that realizes. Furthermore, in FIG. 1, the single memory circuit 132 was described as storing programs corresponding to each processing function, but a plurality of memory circuits may be distributed and arranged, and the processing circuit 133 may be stored from individual memory circuits. A configuration may also be used in which a corresponding program is read.

Furthermore, in the above description, an example has been described in which the "processor" reads out a program corresponding to each function from the storage circuit and executes it, but the embodiment is not limited to this. The term "processor" refers to, for example, a CPU (Central Processing Unit), a GPU (Graphics Processing Unit), an Application Specific Integrated Circuit (ASIC), a programmable logic device (for example, a Simple Programmable Logic Device). Logic Device (SPLD), Complex Programmable Logic Device (CPLD), and Field Programmable Gate Array (FPGA). When the processor is, for example, a CPU, the processor realizes its functions by reading and executing a program stored in a storage circuit. On the other hand, if the processor is an ASIC, instead of storing the program in a memory circuit, the functionality is directly incorporated into the processor's circuitry as a logic circuit. Note that each processor of this embodiment is not limited to being configured as a single circuit for each processor, but may also be configured as a single processor by combining multiple independent circuits to realize its functions. good. Furthermore, a plurality of components corresponding to the above-mentioned functions described as functions of the processing circuit 133 may be integrated into one processor to realize the functions.

Next, an example of the structure of the gradient magnetic field coil 103 shown in FIG. 1 will be described. FIG. 2 is a perspective view showing an example of the structure of the gradient magnetic field coil 103 according to this embodiment. The gradient magnetic field coil 103 provided in the pedestal 140 includes a main coil 103a and a shield coil 103b, as shown in FIG.

The main coil 103a applies gradient magnetic fields in the X-axis, Y-axis, and Z-axis directions using current supplied from the gradient magnetic field power supply 104. The shield coil 103b cancels the leakage magnetic field of the main coil 103a. As shown in FIG. 2, a gradient magnetic field coil 103 in which a shield coil 103b is provided around a main coil 103a is called an actively shielded gradient coil (ASGC).

Further, as shown in FIG. 2, a plurality of shim tray housing portions 103c are formed between the main coil 103a and the shield coil 103b. The shim tray 30 is inserted into the shim tray storage section 103c.

The shim tray storage portion 103c is a hole in which the shim tray 30 can be stored. More specifically, the shim tray housing portion 103c of this embodiment is a through hole provided along the longitudinal direction of the gradient magnetic field coil 103, that is, along the Z-axis direction. In the present embodiment, the shim tray 30 is inserted by the operator through the insertion opening 20 provided at the bed side end of the shim tray storage section 103c. The inserted shim tray 30 is retained in the shim tray storage section 103c. Note that the shim tray storage portion 103c does not need to be a through hole, and the end of the gradient magnetic field coil 103 on the opposite side to the bed 105 may be closed.

In this embodiment, the shim tray storage section 103c is provided within the gradient magnetic field coil 103, but this is just an example, and depending on the configuration of the magnetic resonance imaging apparatus 100, the shim tray storage section 103c may be provided within the gantry 140. provided at the location. The shim tray storage section 103c is an example of a storage section in this embodiment.

The shim tray 30 is made of a non-magnetic material and can accommodate at least one shim 31 that is a magnetic material. For example, the shim tray 30 is made of resin, which is a non-magnetic and non-conductive material, and has a generally rod-like shape.

The shim 31 is a magnetic material, and is arranged within the pedestal 140 to correct the non-uniformity of the static magnetic field within the bore 141. For example, the shim 31 is a plate-shaped metal such as iron, but the material and shape of the shim 31 are not limited thereto.

FIG. 3 is a perspective view showing an example of the configuration of the shim tray 30 included in the present embodiment. For example, as shown in FIG. 3, the shim tray 30 includes an elongated box-shaped tray body 301 and an elongated plate-shaped tray lid 302. The tray main body 301 has a plurality of shim pockets 303 arranged in succession along the longitudinal direction, and each shim pocket 303 has a shim pocket 303 in order to correct the non-uniformity of the static magnetic field in the imaging space. A required number of shims 31 are stored. Note that the configuration of the shim tray 30 shown in FIG. 3 is an example, and the configuration is not limited to this.

Next, details of the insertion opening 20 of the shim tray storage section 103c will be explained. FIG. 4 is an example of an enlarged view of the vicinity of the insertion opening 20 of the shim tray housing portion 103c in the gradient magnetic field coil 103 according to the present embodiment.

As shown in FIG. 4, the insertion port 20 of the shim tray storage section 103c of this embodiment includes a first insertion port 20a and a second insertion port 20b. The first insertion port 20a and the second insertion port 20b are openings of different shim tray storage portions 103c.

More specifically, the first insertion port 20a and the second insertion port 20b are both holes into which the shim tray 30 can be inserted, but their purposes are different. For example, the first insertion port 20a is an inlet into which the shim tray 30 used for rough correction of the static magnetic field distribution is inserted. Further, the second insertion port 20b is a shim tray used to further finely adjust the static magnetic field distribution after the static magnetic field distribution is corrected by the shim 31 in the shim tray 30 inserted from the first insertion port 20a. 30 is an inlet for insertion.

Note that even if the shim tray 30 inserted from the first insertion port 20a and the shim tray 30 inserted from the second insertion port 20b are different in size, shape, or number of shims 31 that can be stored, etc. good. In FIG. 4, the length d1 in the width direction of the first insertion port 20a is shown to be longer than the length d2 in the width direction of the second insertion port 20b, but this is just an example.

In this embodiment, the shim tray 30 is inserted into the first insertion port 20a under a demagnetized environment, and the shim tray 30 is inserted into the second insertion port 20b under an excitation environment. . In this embodiment, a shimming operation performed by inserting the shim tray 30 into the second insertion port 20b in an excitation environment will be mainly described.

The shimming operation includes a series of operations: excitation of the static magnetic field magnet 101, measurement of the static magnetic field distribution, analysis of non-uniformity of the static magnetic field distribution, and correction of the static magnetic field distribution by inserting the shim tray 30. The processing of measuring the static magnetic field distribution and analyzing the non-uniformity of the static magnetic field distribution is performed by a static magnetic field measurement tool such as a scan protocol for measuring the static magnetic field distribution by the processing circuit 133 described above. Furthermore, the shim tray 30 is inserted manually by an operator.

Furthermore, after the shim tray 30 is inserted, the process of measuring the static magnetic field distribution and analyzing the non-uniformity of the static magnetic field distribution is executed again, and the processing circuit 133 analyzes whether the static magnetic field distribution has been appropriately corrected. Ru. If the static magnetic field distribution is insufficiently corrected, the shim tray 30 is removed or inserted in order to change the number or arrangement of the shims 31.

FIG. 5 is a diagram illustrating an example of the insertion work of the shim tray 30 performed in an excitation environment according to the present embodiment. In FIG. 5, the distribution of the static magnetic field generated from the static magnetic field magnet 101 included in the mount 140 of the magnetic resonance imaging apparatus 100 is illustrated as a magnetic field distribution curve 6.

As shown in the magnetic field distribution curve 6, the closer the magnetic field is to the pedestal 140, the higher the magnetic field becomes. For example, in the example shown in FIG. 5, the magnetic field strength is about 200 mT near the end of the pedestal 140 on the bed 105 side, that is, the end on the side where the insertion opening 20 of the shim tray storage section 103c is provided. On the other hand, near the end of the bed 105 that is far from the pedestal 140, the magnetic field strength has decreased to about 1 mT. Note that the magnetic field strength shown in FIG. 5 is an example, and is not limited to this.

The worker 5 shown in FIG. 5 is performing shimming work to correct the static magnetic field distribution by inserting the shim tray 30 into the second insertion port 20b in an excitation environment. In an excitation environment, an electromagnetic force derived from a magnetic field acts on the shim 31 in the shim tray 30, and a force also acts on the shim tray 30 accordingly. Furthermore, force also acts on the worker 5 holding the shim tray 30. This force can be calculated based on the magnetic quantities of the shim 31 and the static magnetic field magnet 101 and the distance between the shim 31 and the static magnetic field magnet 101. For example, when the static magnetic field strength of the static magnetic field magnet 101 is 1.5 T and the total mass of the shims 31 in the shim tray 30 is 50 g, it is known that a maximum force of 50 N (Newton) acts on the worker 5. There is. Note that the force in this case is electromagnetic force.

Furthermore, it is known that the direction of the force acting on the worker 5 changes before the worker 5 completes installing the shim tray 30 into the shim tray storage section 103c. For example, the direction of the force may be switched from a direction away from the static magnetic field magnet 101 to a direction in which the static magnetic field magnet 101 pulls the force. The direction of this force is determined by the positional relationship between the shim 31 and the static field magnet 101. Specifically, the direction in which the force acts is proportional to the gradient of the magnetic field strength, which is the normal direction of the magnetic field distribution curve 6 in FIG. 5, and a pulling force acts in the direction of the stronger magnetic field.

Although the magnetic field distribution curve 6 is shown in FIG. 5 for explanation, the actual magnetic field distribution is not visible, so the operator 5 receives force in any direction during the insertion work of the shim tray 30. In other words, it is difficult to predict whether the force will be applied in the direction of being pulled by the static magnetic field magnet 101 or, in some cases, in the direction of moving away from the static magnetic field magnet 101.

If the operator 5 holds the tip of the shim tray 30 while inserting it, he or she may get his or her fingers caught between the pedestal 140 and the shim tray 30 due to the force in the direction of the static magnetic field magnet 101. Incidents such as getting caught may occur. Further, if the worker holds the rear end of the shim tray 30 in fear of such an incident occurring, the range on the shim tray 30 that can be held becomes narrower, making it difficult for the worker to handle the shim tray 30. Furthermore, since the length of the shim tray 30 is at most the length of the pedestal 140 in the Z-axis direction, even if the operator holds the rear end of the shim tray 30, the static magnetic field generated from the static magnetic field magnet 101 in the pedestal 140 Workers will have to enter an area that is strongly affected by the magnetic field. Therefore, when the operator 5 carries out the insertion work while holding the shim tray 30 itself, the work is generally performed in a demagnetized environment.

Note that the tip of the shim tray 30 refers to the end of both longitudinal ends of the shim tray 30 that is located on the opposite side from the bed 105 when the shim tray 30 is inserted into the mount 140 of the magnetic resonance imaging apparatus 100. means. Further, of both longitudinal ends of the shim tray 30, the end located on the bed 105 side when the shim tray 30 is inserted into the pedestal 140 of the magnetic resonance imaging apparatus 100 is referred to as the rear end of the shim tray 30.

In this embodiment, the guide member 32 is attached to the rear end of the shim tray 30 to assist the operator 5 in inserting the shim tray 30 without holding the front end of the shim tray 30.

The guide member 32 is made of a non-magnetic material, and is an auxiliary tool for assisting the operator 5 in inserting the shim tray 30.

Furthermore, as shown in FIG. 5, the operator 5 can perform the insertion work while keeping his or her body away from the pedestal 140 by holding the rear end side of the shim tray 30 and the guide member 32. It is possible to work from a place where the magnetic field strength is lower than that in the vicinity of 140 degrees. Further, the operator 5 can remove the guide member 32 from the shim tray 30 after completing the insertion of the shim tray 30 into the shim tray storage portion 103c.

Further, when the operator 5 takes out the shim tray 30 from the shim tray storage section 103c, the operator 5 attaches the guide member 32 to the shim tray 30 again. The operator 5 can take out the shim tray 30 by holding and pulling the reinstalled guide member 32.

The shim tray 30 and the guide member 32 are collectively referred to as a shim unit 300. In this embodiment, the guide member 32 is attached to the rear end of the shim tray 30, but this is just an example. The guide member 32 is removably attached to at least one of both ends of the shim tray 30.

Next, the shapes of the shim tray 30 and the guide member 32 according to this embodiment will be explained using FIGS. 6 to 9.

FIG. 6 is a perspective view showing an example of the appearance of the shim tray 30 according to the present embodiment. The left side of FIG. 6 is the tip of the shim tray 30, and the right side is the rear end of the shim tray 30.

The length d11 of the shim tray 30 in the longitudinal direction is longer than the length d12 of the shim tray 30 in the lateral direction (width direction). In order to prevent the shim tray 30 from protruding from the pedestal 140 when the shim tray 30 has been completely inserted into the shim tray housing 103c, the length d11 of the shim tray 30 in the longitudinal direction is, for example, equal to or less than the length of the pedestal 140 in the Z-axis direction. shall be. Note that the length d11 of the shim tray 30 in the longitudinal direction may exceed the length of the pedestal 140 in the Z-axis direction, as long as it does not interfere with the imaging of magnetic resonance images or the placement of the subject P.

FIG. 7 is an enlarged view of the rear end portion of the shim tray 30 shown in FIG. 6. As shown in FIG. 7, two protrusions 310a and 310b are provided at the rear end of the shim tray 30. Furthermore, such a protrusion is not provided at the front end of the shim tray 30. Hereinafter, when the projections 310a and 310b are collectively referred to, they will simply be referred to as the projection 310. Note that the number of protrusions 310 is not limited to two, and may be at least one.

The length d13 of the interval between the ends of the projections 310a and 310b is longer than the widthwise length d2 of the second insertion opening 20b. Therefore, when the insertion of the shim tray 30 into the shim tray storage portion 103c is completed, the protrusion portion 310 is caught around the second insertion opening 20b and comes out from the shim tray storage portion 103c. The protrusion 310 stops the shim tray 30 inserted by the operator 5 at an appropriate position by not entering the shim tray storage portion 103c.

FIG. 8 is a perspective view showing an example of the appearance of the guide member 32 according to this embodiment. The guide member 32 includes engaging portions 321a and 321b at the end thereof connected to the shim tray 30. The engaging portion 321a and the engaging portion 321b are provided with a hole 322a and a hole 322b, respectively. Hereinafter, when the engaging parts 321a and 321b are not particularly distinguished, they will simply be referred to as the engaging parts 321.

The engaging portion 321 engages with the protrusion 310 of the shim tray 30. More specifically, the guide member 32 can be opened and closed in the width direction, and the two holes 322a and 322b are provided at the end of the guide member 32 that can be opened and closed. The two holes 322a and 322b engage with the two protrusions 310a and 310b, respectively, when the guide member 32 is closed with the shim tray 30 sandwiched therebetween.

In the example shown in FIG. 8, the guide member 32 has a first member 32a and a second member 32b connected by a fastener 322 provided at the end opposite to the side where the engaging portion 321 is provided. are doing. The first member 32a and the second member 32b open and close in the width direction, that is, in the lateral direction of the guide member 32, centering on the fastener 322. The fastener 322 is made of non-magnetic material.

The opening angle of the guide member 32 is not particularly limited as long as it is an angle sufficient to grip the shim tray 30. As an example, it is assumed that the guide member 32 of this embodiment is opened by about 13 degrees.

With the guide member 32 opened in the width direction, the worker 5 aligns the hole 322a with the protrusion 310a and the hole 322b with the protrusion 310b, holds the shim tray 30 between the guide members 32, and then Close the guide member 32. In this case, the projection 310a is fitted into the hole 322a, and the projection 310b is fitted into the hole 322b. Moreover, the guide member 32 can be maintained in the closed state by engaging the holes 322a, 322b with the projections 310a, 310b. Further, a fixing pin provided between the protruding portion 310a and the protruding portion 310b of the shim tray 30 may be engaged between the engaging portion 321a and the engaging portion 321b of the guide member 32 for further fixation.

Furthermore, when the operator 5 removes the guide member 32 from the shim tray 30, it is assumed that the guide member 32 can be opened while removing the holes 322a, 322b from the protrusions 310a, 310b by hand.

The guide member 32 can be removed from the shim tray 30 while the shim tray 30 remains inserted into the pedestal 140. Specifically, when the insertion of the shim tray 30 into the shim tray storage part 103c is completed, the projection part 310 of the shim tray 30 is in a state of coming out from the shim tray storage part 103c. By opening the guide member 32 outside the portion 103c, the holes 322a and 322b of the guide member 32 can be removed from the projections 310a and 310b of the shim tray 30.

In addition, in FIG. 8, the engaging part 321 is plate-shaped, and the holes 322a and 322b are illustrated as through holes provided in the plate, but the shape of the engaging part 321 is not limited to this. . For example, the holes 322a and 322b provided in the engaging portion 321 may be recesses or grooves that can be engaged with the projections 310a and 310b, instead of being through holes.

FIG. 9 is a side view showing an example of the appearance of the guide member 32 according to this embodiment. The length d22 of the guide member 32 in the width direction is shorter than the length d21 of the guide member 32 in the longitudinal direction. Further, the length d21 of the guide member 32 in the longitudinal direction is shorter than the length d11 of the shim tray 30 in the longitudinal direction. The dimensions of the guide member 32 are determined so that the shim tray 30 to be attached can be stably gripped and the operator 5 can stably hold it by hand. Note that the dimensions of the guide member 32 refer to the length d21 in the longitudinal direction, the length d22 in the width direction, and the thickness d23.

Further, for example, the material and dimensions of the guide member 32 are determined based on the magnitude of the electromagnetic force acting on one shim tray 30 in the magnetic resonance imaging apparatus 100 into which the shim tray 30 is inserted. It is specified that work can be done from a sufficiently distant position. In the magnetic resonance imaging apparatus 100, the electromagnetic force acting on one shim tray 30 is based on information such as the magnetic field distribution in the excitation environment, the total mass of the shims 31 per one shim tray 30, and the position of the shims 31 in the shim tray 30. Calculated based on The material and dimensions of the guide member 32 may be determined in advance according to the maximum electromagnetic force estimated according to the model of the magnetic resonance imaging apparatus 100. Further, a plurality of guide members 32 having different dimensions may be used depending on the amount of shims 31 stored in the shim tray 30.

As described above, the shim unit 300 according to the present embodiment includes a shim tray 30 made of a non-magnetic material that can accommodate at least one shim 31 made of a magnetic material, and a non-magnetic material shim tray 30 that is removably attached to at least one of both ends of the shim tray 30. A guide member 32 made of a magnetic material is provided. Therefore, according to the shim unit 300 of the present embodiment, the operator 5 can hold the guide member 32, so that the operator 5 can place his/her fingers between the shim tray 30 and the pedestal 140 even under an excitation environment. Incidents such as pinching or pinching are reduced. Therefore, when using the shim unit 300 according to the present embodiment, it is essential for the operator 5 to demagnetize the static magnetic field magnet 101 before inserting the shim tray 30 and to re-energize it after inserting the shim tray 30. It disappears. As a result, the working time and work load for demagnetizing and re-exciting before and after inserting the shim tray 30 in the shimming work are reduced, and the shimming work can be made more efficient.

For example, as a comparative example, when performing shimming work without using a guide member, there is a high possibility that the worker will hold the tip side of the shim tray, resulting in the worker getting his or her fingers caught between the shim tray and the pedestal. In order to prevent the shim tray from being pinched or being subject to strong force due to the influence of the magnetic field on the operator, it is common to insert the shim tray in a demagnetized environment. In this case, the flow of the shimming work is to first excite the static magnetic field magnet, measure the static magnetic field distribution, and analyze the non-uniformity of the static magnetic field distribution. Thereafter, the static magnetic field magnet is demagnetized, and the operator inserts the shim tray into the pedestal. After that, the static magnetic field magnet is excited again, and the static magnetic field distribution is measured and the non-uniformity of the static magnetic field distribution is analyzed. If the correction of the static magnetic field distribution is insufficient, the static magnetic field magnet is demagnetized again and the work is carried out. The operator is responsible for removing or inserting the shim tray. Therefore, excitation and demagnetization of the static magnetic field magnet may be repeated multiple times. Since it may take several hours to excite and demagnetize the static magnetic field magnet, in such a comparative example, there is a possibility that the working time becomes longer and the workload of the operator increases. Furthermore, during excitation and demagnetization, for example, liquid helium as a coolant may be evaporated, which may increase the waste of resources.

On the other hand, according to the shim unit 300 of the present embodiment, as described above, the shimming work can be performed in an excitation environment, so that the number of times of excitation and demagnetization of the static magnetic field magnet 101 can be reduced. This makes it possible to shorten the working time of the entire shimming work, reduce the workload of the worker 5, and reduce the amount of resources used.

Moreover, since the guide member 32 of the shim unit 300 of this embodiment is attached to the shim tray 30, the guide member 32 can be removed after the operator 5 inserts the shim tray 30 into the shim tray storage portion 103c. Therefore, according to the shim unit 300 of this embodiment, it is possible to prevent the guide member 32 from interfering with the imaging of a magnetic resonance image or the placement of the subject P.

Furthermore, the shim tray 30 of the shim unit 300 according to the present embodiment includes a protrusion 310 at one end, and the guide member 32 has an engaging portion 321 that can engage with the protrusion 310. Therefore, according to the shim unit 300 of the present embodiment, the guide member 32 is engaged with and fixed to the shim tray 30, so that the guide member 32 is prevented from separating from the shim tray 30 during the insertion work by the operator 5. can be reduced.

Further, the shim tray 30 of the shim unit 300 according to the present embodiment can be inserted into the pedestal 140 of the magnetic resonance imaging apparatus 100 including the bed 105, and the guide member 32 is arranged so that the shim tray 30 is inserted into the pedestal 140 at both ends of the shim tray 30. It is attached to the end that will be on the bed 105 side when inserted into the bed. Therefore, according to the shim unit 300 of this embodiment, the worker 5 can start work at a position away from the pedestal 140 where the magnetic field strength is low by holding the guide member 32 while working. In addition, by holding the guide member 32 while working, the worker 5 can work without holding the vicinity of the tip of the shim tray 30, and can avoid pinching fingers between the pedestal 140 and the shim tray 30. It is also possible to reduce the occurrence of incidents such as people getting caught.

Further, the guide member 32 of the shim unit 300 according to the present embodiment is removable from the shim tray 30 inserted into the pedestal 140. Therefore, according to the shim unit 300 according to the present embodiment, the guide member 32 can be easily removed after the operator 5 inserts the shim tray 30 into the shim tray storage portion 103c, and the guide member 32 can be used for magnetic resonance imaging. It is possible to avoid interference with imaging, etc.

Furthermore, the shim tray 30 of the shim unit 300 according to the present embodiment has two protrusions 310a and 310b at one end, and the guide member 32 is capable of engaging with each of the two protrusions 310a and 310b. It has two holes 322a and 322b. Therefore, according to the shim unit 300 according to the present embodiment, the connection between the guide member 32 and the shim tray 30 can be easily maintained by engaging the two projections 310a, 310b with the two holes 322a, 322b. can do.

Further, the length d21 in the longitudinal direction of the guide member 32 of the shim unit 300 according to the present embodiment is shorter than the length d11 in the longitudinal direction of the shim tray 30. Therefore, according to the shim unit 300 according to the present embodiment, it is possible to prevent the shim unit 300 from becoming excessively long due to the attachment of the guide member 32, thereby making it difficult for the operator 5 to perform the work.

Furthermore, the length d22 in the width direction of the guide member 32 of the shim unit 300 according to the present embodiment is shorter than the length d21 in the longitudinal direction. That is, the guide member 32 of this embodiment has an elongated shape along the longitudinal direction, and has a shape that is easy for the operator 5 to hold during work.

In addition, in this embodiment, the shim tray 30 and the guide member 32 are made of non-magnetic materials, but they do not have to be limited to completely non-magnetic materials. For example, shim tray 30 and guide member 32 may have some degree of magnetism. Moreover, a magnetic material may be used for a part of the guide member 32, for example, the fastener 322 and the like. The degree of magnetism is not particularly limited, but may be any degree that does not cause strong magnetic field attraction.

Further, in the present embodiment, the operator 5 inserts the shim tray 30 from the bed 105 side of the gantry 140, but the insertion direction is not limited to this. For example, the insertion opening 20 into which the shim tray 30 can be inserted may be provided at the end of the pedestal 140 that is far from the bed 105, that is, on the back side of the pedestal 140. In this case, the protrusions 310a and 310b are provided at the end located on the bed 105 side when the shim tray 30 is inserted into the pedestal 140. When this configuration is adopted, the end located on the bed 105 side when the shim tray 30 is inserted into the pedestal 140 of the magnetic resonance imaging apparatus 100 is referred to as the front end of the shim tray 30. Further, when the shim tray 30 is inserted into the pedestal 140 of the magnetic resonance imaging apparatus 100, the end located on the opposite side from the bed 105 is referred to as the rear end of the shim tray 30.

In addition, in this embodiment, the gradient magnetic field coil 103 in which two types of insertion ports (the first insertion port 20a and the second insertion port 20b) were provided for one insertion port 20 was described as an example. The shim unit 300 of this embodiment may be applied to the gradient magnetic field coil 103 provided with only one type of insertion opening for the shim tray 30.

Further, in the present embodiment, the operator 5 uses the guide member 32 when inserting the shim tray 30 into the second insertion port 20b of the first insertion port 20a and the second insertion port 20b. However, the guide member 32 may also be used when inserting the shim tray 30 into the first insertion port 20a.

(Modification of the first embodiment)
In the first embodiment described above, the shim unit 300 is described in which the guide member 32 and the shim tray 30 can be connected with the guide member 32 gripping the shim tray 30. However, the configurations of the guide member 32 and the shim tray 30 differ from this. It is not limited.

Modifications of the shim unit 300 described in the first embodiment will be described using FIGS. 10 to 14.

FIG. 10 is a diagram showing an example of the appearance of a shim unit 300 according to a first modification. The shim tray 30 of the shim unit 300 includes a protrusion 310c.

The protrusion 310c has a plate shape that is thinner than the shim unit 300 main body. As shown in FIG. 10, the length of the protrusion 310c in the height direction is shorter than the length of the shim unit 300 in the height direction. Further, the protruding portion 310c is provided with a plurality of dimples 311a to 311f.

Furthermore, the guide member 32 according to the first modification is provided with protrusions 323a to 323f. The protrusions 323a to 323f are made of an elastic non-magnetic material, and have engaging portions at their tips that engage with the dimples 311a to 311f, respectively. With the tips of the protruding parts 323a to 323f of the guide member 32 fitted into the dimples 311a to 311f of the protruding part 310c of the shim tray 30, the protruding parts 323a to 323f sandwich the protruding part 310c, so that the guide member 32 is attached to the shim tray 30. will be installed on the

Note that when the operator 5 opens the protrusions 323a to 323f of the guide member 32 in the vertical direction, the tips of the protrusions 323a to 323f come off the dimples 311a to 311f, so the guide member 32 can be removed from the shim tray 30. .

In FIG. 10, three dimples 311a to 311f are provided on the upper surface of the protrusion 310c and three on the mask, but the number of dimples 311a to 311f may be the same as the number of protrusions 323a to 323f of the guide member 32. However, it is not limited to this. Furthermore, the protrusion 310c may include a plurality of through holes instead of the dimples 311a to 311f.

Moreover, FIG. 11 is a diagram showing an example of the appearance of a shim unit 300 according to a second modification. The shim tray 30 of the shim unit 300 includes protrusions 312a and 312b. Further, a recess 312c is provided between the two protrusions 312a and 312b.

Further, the guide member 32 according to the second modification includes a protrusion 324 . The protrusion 324 of the guide member 32 fits into the recess 312c of the shim tray 30. Note that the shapes of the projections 312a, 312b, the recess 312c, and the projection 324 are not limited to the example shown in FIG. 11.

Moreover, FIG. 12 is a diagram showing an example of the appearance of a shim unit 300 according to a third modification. The shim tray 30 of the shim unit 300 includes a protrusion 313 . Grooves 313a and 313b are provided on both side surfaces of the protrusion 313 along the height direction of the shim tray 30.

Further, the guide member 32 according to the third modification includes protrusions 325a and 325b. The protrusion 325a includes a protrusion 326a. Furthermore, the protrusion 325b includes a protrusion 326b. The protrusions 326a and 326b face each other across the space between the protrusions 325a and 325b.

The protrusion 313 of the shim tray 30 can be inserted into the space between the protrusion 325a and the protrusion 325b of the guide member 32. When the protrusion 313 is inserted into the space between the protrusion 325a and the protrusion 325b, the grooves 313a and 313b engage with the protrusions 326a and 326b, respectively.

Moreover, FIG. 13 is a diagram showing an example of the appearance of a shim unit 300 according to a fourth modification. The shim tray 30 of the shim unit 300 includes a protrusion 314 . A plurality of protrusions are provided on both sides of the protrusion 314.

Further, the guide member 32 according to the fourth modification includes protrusions 327a and 327b. A plurality of protrusions are provided on the side surface of the protrusion 327a that faces the protrusion 327b. Further, among the side surfaces of the protrusion 327b, a plurality of protrusions are provided on the side facing the protrusion 327a.

The protrusion 314 of the shim tray 30 can be inserted into the space between the protrusion 327a and the protrusion 327b of the guide member 32. When the protrusion 314 is inserted into the space between the protrusion 327a and the protrusion 327b, a plurality of protrusions provided on both sides of the protrusion 314 and one side of each of the protrusion 327a and the protrusion 327b The plurality of protrusions provided on the ridges interlock with each other.

Moreover, FIG. 14 is a diagram showing an example of the appearance of a shim unit 300 according to a fifth modification. The shim tray 30 of the shim unit 300 includes a connecting portion 316 provided with a female thread 315.

Further, the guide member 32 according to the fifth modification includes a male thread 328a and a knob 328b. When the operator 5 inserts the male thread 328a into the female thread 315 and turns the knob 328b, the male thread 328a engages with the female thread 315, and the guide member 32 is fixed to the shim tray 30.

Note that the protrusions 310a, 310b, protrusions 310c, protrusions 312a, 312b, recesses 312c, protrusions 313, protrusions 314, and connection parts 316 according to the first embodiment and the first to fifth modifications are collectively referred to as In this case, it is called the shim tray side connection part.

Furthermore, the engaging portions 321a and 321b, the protruding portions 323a to 323f, the protruding portion 324, the protruding portions 325a and 325b, the protruding portions 327a and 327b, and the external thread 328a according to the first embodiment and the first to fifth modifications. , the knob 328b is collectively referred to as a guide member side connection portion.

(Second embodiment)
In the first embodiment and the first to fifth modifications described above, the guide member 32 was attached to the rear end of the shim tray 30, but the guide member was attached to the tip of the shim tray 30. Also good.

FIG. 15 is a diagram illustrating an example of the insertion work of the shim tray 30 performed in an excitation environment according to the present embodiment. As shown in FIG. 15, in the shim unit 300 of this embodiment, the guide member 33 is attached to the tip of the shim tray 30, that is, the side that is first inserted into the second insertion port 20b.

The guide member 33 is made of a non-magnetic material as in the first embodiment, and is removably attached to the shim tray 30.

After the guide member 33 of this embodiment is inserted from the second insertion port 20b by the operator 5, it passes through the shim tray storage part 103c, which is a through hole, and passes through the shim tray housing part 103c, which is a through hole, to the end of the pedestal 140 on the opposite side of the bed 105. protrude from the body. After completing the insertion of the shim tray 30, the operator 5 removes the guide member 33 protruding from the end of the gantry 140 on the side opposite to the bed 105 from the shim tray 30. The end of the pedestal 140 opposite to the bed 105 is referred to as the back surface of the pedestal 140.

In addition, when taking out the shim tray 30 from the shim tray storage part 103c, if there is sufficient space on the back side of the pedestal 140, the operator 5 attaches the shim tray 30 to the guide member 33 from the back of the pedestal 140, and The shim tray 30 may be pulled out to the back side of the pedestal 140 by holding and pulling the shim tray 33. Alternatively, the worker 5 attaches the shim tray 30 to the guide member 33 from the back of the pedestal 140, pushes the guide member 33 to project a part of the shim tray 30 toward the bed 105, and then moves the shim tray 30 to the bed 105. It may also be taken out from the shim tray storage section 103c by pulling it from the side.

In this embodiment, the guide member 33 passes through the shim tray storage section 103c, so the dimensions of the guide member 33 are such that it can pass through the shim tray storage section 103c.

For example, it is assumed that the length d22 of the guide member 33 in the width direction of the present embodiment is equal to or less than the length d12 of the shim tray 30 in the width direction. Furthermore, the length d23 of the guide member 33 in the height direction of the present embodiment is equal to or less than the length of the shim tray 30 in the height direction. Further, the length d22 of the guide member 33 in the width direction and the length d12 of the shim tray 30 in the width direction are both shorter than the length d2 of the second insertion opening 20b in the width direction.

Further, in the configuration in which the guide member 32 grips the shim tray 30 from the outside as in the first embodiment, it is difficult to make the length d22 of the guide member 32 in the width direction equal to or less than the length d12 of the shim tray 30 in the width direction. Therefore, the guide member 33 and shim tray 30 of this embodiment employ, for example, the configurations in the first to fifth modifications. Note that the guide member 33 and shim tray 30 of this embodiment may be connected in a configuration other than that described in the first to fifth modifications.

Further, the material and length of the guide member 33 of this embodiment are defined based on the magnitude of electromagnetic force acting on one shim tray 30 in the magnetic resonance imaging apparatus 100 into which the shim tray 30 is inserted. For example, the length of the guide member 33 may be the distance from the insertion port 20 to the outer edge of the region where the shim tray 30 is strongly influenced by the magnetic field.

For example, the length of the guide member 33 may be the distance from the insertion port 20 to a position where the magnetic field in the space is about 20 mT. Note that the strength of the magnetic field is just an example, and is not limited to this.

When the worker 5 inserts the guide member 33 into the shim tray storage part 103c from the second insertion opening 20b, the shim tray 30 moves to an area where the influence of the magnetic field is strong. Even if it is sucked, the shim tray 30 is guided by the guide member 33 that has already been inserted into the shim tray storage portion 103c, and is inserted into the second insertion opening 20b. Thereby, the operator 5 can easily insert the shim tray 30 into the shim tray storage section 103c.

The material and dimensions of the guide member 33 may be determined in advance according to the maximum electromagnetic force estimated according to the model of the magnetic resonance imaging apparatus 100. Further, a plurality of guide members 33 having different lengths may be used depending on the amount of shims 31 stored in the shim tray 30. In this embodiment, the shim tray 30 and the guide member 33 are made of non-magnetic material, but they do not have to be completely non-magnetic.

As described above, according to the shim unit 300 of the present embodiment, the guide member 33 made of a non-magnetic material is attached to the tip of the shim tray 30, so that the operator 5 can move the shim tray 30 out of the area where it is strongly influenced by the magnetic field. The guide member 33 can be inserted into the shim tray housing portion 103c in a state where the guide member 33 is located at the shim tray housing portion 103c. Therefore, even if the shim tray 30 is attracted to the static magnetic field magnet 101, the shim tray 30 is guided by the guide member 33 that has already been inserted into the shim tray storage section 103c, so that the worker 5 can easily insert the shim tray 30 into the shim tray storage section 103c. can be inserted into.

Note that, as described in the first embodiment, also in this embodiment, a configuration may be adopted in which the guide member 33 and the shim tray 30 are inserted from the back side of the pedestal 140.

Moreover, the guide member 32 attached to the rear end of the shim tray 30 described in the first embodiment and the guide member 33 of this embodiment can be used together. In this case, a guide member 32 and a guide member 33 are attached to both ends of the shim tray 30, respectively. Note that the guide member 32 attached to the rear end of the shim tray 30 may be referred to as a first guide member 32, and the guide member 33 attached to the tip of the shim tray 30 may be referred to as a second guide member 33.

(Third embodiment)
In the first and second embodiments described above, the guide members 32 and 33 attached to the shim tray 30 have been described. In this third embodiment, a guide member that can be attached to the pedestal 140 side into which the shim tray 30 is inserted will be described.

The overall configuration of the magnetic resonance imaging apparatus 100 in this embodiment is the same as that in the first embodiment.

FIG. 16 is a perspective view showing an example of the appearance of the guide member 40 attached to the gradient magnetic field coil 103 according to the present embodiment. The shape of the gradient magnetic field coil 103 in this embodiment is the same as that in the first embodiment.

As shown in FIG. 16, the guide member 40 is removably attached around the insertion opening 20 into which the shim tray 30 is inserted. The guide member 40 has a shape that becomes thicker as it gets farther away from the insertion opening 20 into which the shim tray 30 is inserted. In other words, the insertion opening 20 into which the shim tray 30 is inserted and the opening provided at the end of the guide member 40 on the mounting side (this is referred to as a first opening) are the insertion opening 20 into which the shim tray 30 is inserted. It is smaller than the opening provided at the end opposite to the mounting side (this is referred to as a second opening).

FIG. 17 is a diagram illustrating an example of a state in which the guide member 40 according to the present embodiment is attached to the insertion opening 20 of the shim tray storage section 103c. The guide member 40 is a non-magnetic elastic member, and deforms along the outer contour of the insertion port 20, as shown in FIG.

Moreover, FIG. 18 is a front view showing an example of a state in which the guide member 40 according to this embodiment is attached to the insertion port 20. In this case, the front side is the side of the gradient magnetic field coil 103 facing the bed 105 side.

As shown in FIG. 18, the first opening side of the internal space 401 passing through the first opening and the second opening of the guide member 40 is connected to the first insertion opening included in the insertion opening 20. 20a and the second insertion port 20b, only the second insertion port 20b communicates with the second insertion port 20b. Therefore, when the guide member 40 is attached to the insertion port 20, the first insertion port 20a is in a closed state. The guide member 40 of this embodiment defines the insertion path of the shim tray 30 to the second insertion opening 20b.

FIG. 19 is a side view showing an example of the gradient magnetic field coil 103 according to this embodiment. As shown in FIG. 19, in the gradient magnetic field coil 103, the outer contour of the insertion port 20 is raised like a wall surrounding the insertion port 20. The guide member 40 is attached to the gradient magnetic field coil 103 by fitting the raised portion into the first opening of the guide member 40 .

FIG. 20 is a diagram showing an example of the internal shape of the guide member 40 according to this embodiment. The opening provided at the right end of the guide member 40 shown in FIG. 20 is the first opening. Further, the opening provided at the left end of the guide member 40 shown in FIG. 20 is the second opening. As shown in FIG. 20, an internal space 401 passing through the first opening and the second opening of the guide member 40 has a tapered shape that tapers from the second opening toward the first opening. It is.

As shown in FIG. 20, the area of the internal space 401 in the CC' sectional view of the guide member 40 is the area of the internal space 401 in the BB' sectional view and the area of the internal space 401 in the AA' sectional view. larger than

Further, the size of the internal space 401 in the BB' cross-sectional view of the guide member 40 is set to a size that allows the shim tray 30 to pass through. Further, the position of the internal space 401 in the BB' cross-sectional view corresponds to the position of the second insertion port 20b in a state where the guide member 40 is attached to the insertion port 20.

Further, the portion from position A to position B of the guide member 40 shown in FIG. 20 is a portion that fits around the outer circumference of the insertion port 20. Since the internal space 401 in the AA′ cross-sectional view wraps around the outer shell of the insertion port 20, the area of the internal space 401 in the AA′ cross-sectional view is larger than the area of the internal space 401 in the BB′ cross-sectional view. .

Further, the material and length of the guide member 40 of this embodiment are defined based on the magnitude of electromagnetic force acting on one shim tray 30 in the magnetic resonance imaging apparatus 100 into which the shim tray 30 is inserted. For example, the length of the guide member 40 may be the distance from the insertion port 20 to the outer edge of the region where the shim tray 30 is strongly influenced by the magnetic field. For example, the length of the guide member 40 may be the distance from the insertion port 20 to a position where the magnetic field in the space is approximately 20 mT. Note that the strength of the magnetic field is just an example, and is not limited to this.

When the shim tray 30 enters the internal space 401 of the guide member 40, even if the shim tray 30 is strongly influenced by the magnetic field, it is guided by the guide member 40 to the second insertion port 20b.

In this way, in the guide member 40 of this embodiment, when the shim tray 30 is inserted into the guide member 40, the shim tray 30 enters the internal space 401 from the relatively wide second opening, and enters the tapered internal space 401. is guided toward the second insertion port 20b. Therefore, according to the guide member 40 of this embodiment, if the operator 5 inserts the shim tray 30 into the second opening of the guide member 40 which is wider than the second insertion opening 20b, the operator 5 can reach The shim tray 30 can be easily inserted into the insertion opening 20b. Therefore, the load of the work of inserting the shim tray 30 is reduced compared to when the operator 5 directly inserts the shim tray 30 into the second insertion opening 20b.

Further, the tapered shape is not necessarily required as long as the guide does not receive unexpected suction force when guiding the shim tray 30 to the second insertion port 20b. Further, the guide member 40 may guide the shim tray 30 to the final target second insertion opening 20b even if there is a slight difference in the insertion path, or may guide the shim tray 30 to the second insertion opening 20b as the final target. The insertion path to the opening 20b may be uniquely determined. When the guide member 40 uniquely defines the insertion path to the second insertion opening 20b of the shim tray 30, the internal space 401 of the guide member 40 does not need to be tapered. Further, in this case, the outer shape of the guide member 40 does not have to be a shape that becomes thinner toward the second insertion port 20b, and may be, for example, a shape such as a cylinder or a square prism with a constant thickness.

In addition, in this embodiment, although the insertion opening 20 and the shim tray storage part 103c were demonstrated as being provided in the gradient magnetic field coil 103 similarly to 1st Embodiment, this is an example. The insertion port 20 and the shim tray storage section 103c may be provided at any position within the pedestal 140 depending on the configuration of the magnetic resonance imaging apparatus 100.

Further, in this embodiment, similarly to the first embodiment, each insertion port 20 has a gradient magnetic field provided with two types of insertion ports (a first insertion port 20a and a second insertion port 20b). Although the coil 103 has been described as an example, the guide member 40 of this embodiment may be applied to the gradient magnetic field coil 103 provided with only one type of insertion port for the shim tray 30.

Further, in the present embodiment, the internal space 401 of the guide member 40 communicates only with the second insertion port 20b, but it is not limited to this configuration. For example, the internal space 401 of the guide member 40 may communicate only with the first insertion port 20a. Alternatively, the guide member 40 may include two internal spaces: an internal space communicating with the first insertion port 20a and an internal space communicating with the second insertion port 20b. In this case, the two internal spaces each have a different second opening and a different first opening.

Further, in the present embodiment, the guide member 40 has been described as one that corresponds to one insertion port 20, but it may be able to be attached to a plurality of insertion ports 20 at the same time. For example, a plurality of guide members 40 may be combined to function as one guide member. Further, for example, an annular guide member 40 that can be attached along the opening of the gradient magnetic field coil 103 and has an opening that communicates with each of the plurality of insertion ports 20 may be used.

Although the guide member 40 is made of a non-magnetic material in this embodiment, it is not limited to a material that is completely non-magnetic.

Further, the guide member 40 of this embodiment can be used in combination with the guide member 32 attached to the rear end of the shim tray 30 described in the first embodiment, and the guide member 33 of this embodiment. For example, the guide member 40 of this embodiment may be used in combination with either one of the guide member 32 or the guide member 33, or with both.

Note that the guide member 40 mounted on the pedestal 140 side as in the present embodiment may be distinguished from the first guide member 32 and the second guide member 33 as the third guide member 40.

According to at least one embodiment described above, shimming work performed on a magnetic resonance imaging apparatus can be made more efficient.

Although several embodiments have been described, these embodiments are presented by way of example and are not intended to limit the scope of the invention. These embodiments can be implemented in various other forms, and various omissions, substitutions, changes, and combinations of embodiments can be made without departing from the gist of the invention. These embodiments and their modifications are included within the scope and gist of the invention as well as within the scope of the invention described in the claims and its equivalents.

5 Operator 20 Insertion port 20a First insertion port 20b Second insertion port 30 Shim tray 31 Shim 32, 33, 40 Guide member 32a First member 32b Second member 100 Magnetic resonance imaging device 101 Static magnetic field magnet 103 Incline Magnetic field coil 104 Gradient magnetic field power supply 105 Bed 140 Frame 300 Shim unit 310, 310a, 310b Projection portion 321, 321a, 321b Engagement portion 322 Fastener 322a, 322b Hole portion 401 Internal space

Claims (7)

A shim tray of a non-magnetic material that stores a shim of a magnetic material, the shim tray being stored in a storage section provided on a pedestal having a static magnetic field magnet that generates a static magnetic field;
a non-magnetic guide member removably attached to a rear end of the shim tray in a first direction in which the shim tray is inserted into the storage section ;
has
The rear end of the shim tray in the first direction is provided with a protrusion protruding in a direction intersecting the first direction,
The length of the shim tray including the protrusion in the second direction in which the protrusion protrudes is longer than the length in the second direction of an insertion opening of the storage portion into which the shim tray is inserted;
The guide member is removably attached to the shim tray by engaging the protrusion with a hole provided in the guide member.
sim unit. The guide member can be opened and closed in the second direction,
When the guide member is closed with the shim tray sandwiched therebetween , the protrusion and the hole engage ,
When the guide member is opened, the engagement between the protrusion and the hole is released.
The shim unit according to claim 1 . The rear end of the shim tray in the first direction is provided with two protrusions that protrude in a direction intersecting the first direction,
The length of the shim tray including the two protrusions in the second direction is longer than the length of the insertion opening in the second direction,
The guide member includes two holes in the second direction and can be opened and closed in the second direction,
When the guide member is closed with the shim tray sandwiched therebetween, the two protrusions and the two holes engage with each other, so that the guide member grips the shim tray,
When the guide member is opened, the engagement between the two protrusions and the two holes is released.
The shim unit according to claim 1. The two holes are through holes, recesses, or grooves provided in two plate-like engagement portions provided at the ends of the guide member.
The shim unit according to claim 3. A fixing pin is provided between the two engaging portions of the shim tray,
the fixing pin engages between the two engaging portions of the guide member;
The shim unit according to claim 4. A non-magnetic shim tray that stores magnetic shims can be attached and removed around the insertion slot.
a first opening provided at the end connected to the insertion port is smaller than a second opening provided at the other end;
An internal space passing through the first opening and the second opening has a tapered shape that tapers from the second opening toward the first opening.
Guide member. The pedestal ;
the storage section provided in the pedestal and capable of storing the shim tray provided in the shim unit according to any one of claims 1 to 5 ;
A magnetic resonance imaging device comprising:

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