JP2023181107A - Sound-proofing tube for magnetic resonance imaging apparatus, magnetic resonance imaging apparatus, and manufacturing method of sound-proofing tube for magnetic resonance imaging apparatus - Google Patents

Abstract

To provide a sound-proofing tube for a magnetic resonance imaging apparatus which is rigid and is capable of improving vibration suppression and noise suppression.SOLUTION: The sound-proofing tube for a magnetic resonance imaging apparatus according to an embodiment is formed by using a composite material including a fiber material and a resin material. In the sound-proofing tube for a magnetic resonance imaging apparatus, the fiber material forms a woven structure by being woven therein. The woven structure is formed so as to continuously extend over at least one round of the lateral face of the sound-proofing tube.SELECTED DRAWING: Figure 2

Description

The present embodiment relates to a cylindrical soundproofing material for a magnetic resonance imaging device, a magnetic resonance imaging device, and a method for manufacturing the cylindrical soundproofing material for a magnetic resonance imaging device.

Conventionally, in a magnetic resonance imaging (MRI) device, a cylindrical soundproof material (hereinafter referred to as a bore tube) is mounted on the inner circumferential side of a gradient magnetic field coil. A cylindrical soundproofing material called a bore tube is a structure made of fiber-reinforced resin material, and has the necessary strength for an MRI apparatus, and suppresses vibration and noise generated from the gradient magnetic field coil. These functions can be achieved, for example, by continuously laminating fibers multiple times using a filament winding method (hereinafter referred to as FW (Filament Winding) method), or by stacking a sheet-shaped fiber-reinforced resin material with a woven structure in advance into a cylinder. It is demonstrated by molding it into a shape.

Due to its characteristics, the FW method allows the fibers to be arranged in a continuous form, making it possible to produce a highly rigid cylinder. However, since there is a limit to increasing the density per unit area (area density) of the structure, the sound insulation performance is insufficient. That is, in order to improve the sound insulation performance, it is necessary to laminate a plurality of layers, so there is a problem that the bore tube becomes heavy. Further, although the sound insulation performance of the woven fabric sheet is improved by increasing the areal density, the rigidity is insufficient due to seams formed when the cylinder is manufactured. For these reasons, with conventional techniques, it is difficult to produce a cylindrical soundproofing material that is lightweight, highly rigid, and can exhibit soundproofing performance.

JP2009-22640A

One of the problems to be solved by the embodiments disclosed in this specification and drawings is to realize a cylindrical soundproofing material for a magnetic resonance imaging device that has high rigidity and can improve vibration suppression and noise suppression. It is in. 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 cylindrical soundproofing material for a magnetic resonance imaging device according to the embodiment is a cylindrical soundproofing material for a magnetic resonance imaging device formed of a composite material containing a fiber material and a resin material. In a tubular soundproofing material for a magnetic resonance imaging device, the fibrous material forms a woven fabric structure. The textile structure is continuously formed over at least one circumference of the side surface of the cylindrical soundproofing material.

FIG. 1 is a diagram showing an example of an MRI apparatus according to the present embodiment. FIG. 2 is an external view showing an example of the appearance of a textile structure in one layer in a bore tube according to the embodiment. FIG. 3 is a diagram showing an example of an enlarged view of a part of the bore tube shown in FIG. 2 according to the embodiment. FIG. 4 is an external view showing an example of the appearance of one layer in a bore tube according to a comparative example. FIG. 5 is an example of an enlarged view of a part of the bore tube of the comparative example shown in FIG. 4. FIG. 6 is a diagram showing an example of the composition of glass fibers and epoxy resin in a composite material in a comparative example, and an example of a composition of glass fibers and epoxy resin in a composite material in an embodiment. FIG. 7 is an enlarged view of a part of the bore tube in which a third fiber material is woven in addition to the first fiber material and the second fiber material, according to the first application example of the present embodiment. The figure which shows an example. FIG. 8 is an enlarged view of a part of the bore tube in which a third fiber material is woven in addition to the first fiber material and the second fiber material, according to a second application example of the present embodiment. The figure which shows an example. FIG. 9 is a diagram illustrating an example of the steps of the method for manufacturing the bore tube 104 according to the present embodiment. FIG. 10 is a diagram showing an example of the upper surface (vertically upward surface) of a test piece according to an example of the embodiment. FIG. 11 is a diagram showing an example of an outline of a test system for a test piece according to an example of the embodiment. FIG. 12 relates to an example of the embodiment, and shows analysis results of tests for a test piece having a set angle of 20°, a test piece having a set angle of 45°, and a test piece having a set angle of 70°. A diagram showing an example. FIG. 13 is an example of the analysis results of Young's modulus (GPa) of a test for a test piece with a 45° assembling angle and a test piece woven with 20° and 70° assembling angles, according to an example of the embodiment. Diagram showing.

Hereinafter, a cylindrical soundproofing material for a magnetic resonance imaging (hereinafter referred to as MRI) device, an MRI device, and a method for manufacturing the cylindrical soundproofing material for an MRI device will be described with reference to the drawings. The technical idea of this embodiment is based on PET (Positron Emission Tomography) - MRI apparatus, SPECT (single photon emission computed tomography) - MRI apparatus, etc. MRI machine and may be applied to various modalities in combination.

(Embodiment)
FIG. 1 is a diagram showing an example of an MRI apparatus 100 according to the present embodiment. As shown in FIG. 1, the MRI apparatus 100 includes a static magnetic field magnet 101, a gradient magnetic field coil 103, a bore tube 104, a gradient magnetic field power supply 105, a bed 107, a bed control circuit 109, a transmission circuit 113, A transmitting coil 115, a receiving coil 117, a receiving circuit 119, a sequence control circuit (which may also be called an imaging control circuit, an imaging control section, etc.) 121, a system control circuit (system control section) 123, and a memory 125. , an input interface 127 , a display 129 , and a processing circuit 131 .

The static field magnet 101 is a hollow, substantially cylindrical magnet. The static magnetic field magnet 101 generates a substantially uniform static magnetic field in the internal space. As the static magnetic field magnet 101, for example, a superconducting magnet or the like is used.

The gradient magnetic field coil 103 is a hollow, substantially cylindrical coil, and is arranged on the inner surface of the cylindrical cooling container. That is, the gradient magnetic field coil 103 is provided on the inner peripheral side of the static magnetic field magnet 101. As the gradient magnetic field coil 103, for example, an actively (self-shielded) gradient magnetic field coil (ASGC) is used.

The gradient magnetic field coils 103 individually receive current supply from the gradient magnetic field power supply 105 and generate gradient magnetic fields whose magnetic field strengths vary along the X, Y, and Z axes that are orthogonal to each other. The gradient magnetic fields of the X, Y, and Z axes generated by the gradient magnetic field coil 103 form, for example, a slice selection gradient magnetic field, a phase encoding gradient magnetic field, and a frequency encoding gradient magnetic field. The slice selection gradient magnetic field is used to arbitrarily determine the imaging section. The phase encoding gradient magnetic field is used to change the phase of a magnetic resonance signal (hereinafter referred to as an MR (Magnetic Resonance) signal) depending on the spatial position. Frequency encoding gradient magnetic fields are utilized to change the frequency of the MR signal depending on spatial location.

The bore tube 104 forms a space (bore 111) in which the subject P is placed. Bore tube 104 is arranged in a space inside gradient magnetic field coil 103 . The bore tube 104 corresponds to a cylindrical soundproof material for the magnetic resonance imaging apparatus 100 formed of a composite material containing a fiber material and a resin material on the inner peripheral side of the gradient magnetic field coil 103. A transmitting coil 115 and a bed rail are installed in the bore tube 104. The bed rail is a rail for inserting the top plate 1071 on which the subject P is placed into the bore 111. Details of the bore tube 104 will be explained later.

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

The bed 107 is a device that includes a top plate 1071 on which the subject P is placed. The bed 107 inserts the top plate 1071 on which the subject P is placed into the bore 111 under the control of the bed control circuit 109 .

The bed control circuit 109 is a circuit that controls the bed 107. The bed control circuit 109 moves the top plate 1071 in the longitudinal direction and in the vertical direction by driving the bed 107 according to instructions from the operator via the input/output interface 17.

The transmitting circuit 113 supplies a high frequency pulse modulated at the Larmor frequency to the transmitting coil 115 under the control of the sequence control circuit 121 . For example, the transmission circuit 113 includes an oscillation section, a phase selection section, a frequency conversion section, an amplitude modulation section, an RF (Radio Frequency) amplifier, and the like. The oscillator generates an RF pulse at a resonance frequency specific to a target atomic nucleus in a static magnetic field. The phase selection section selects the phase of the RF pulse generated by the oscillation section. The frequency converter converts the frequency of the RF pulse output from the phase selector. The amplitude modulation section modulates the amplitude of the RF pulse output from the frequency conversion section, for example, according to a sinc function. The RF amplifier amplifies the RF pulse output from the amplitude modulation section and supplies the amplified RF pulse to the transmitting coil 115.

Transmission coil 115 is an RF coil placed inside gradient magnetic field coil 103. The transmitting coil 115 generates an RF pulse corresponding to a high frequency magnetic field in response to the output from the transmitting circuit 113. The transmitting coil 115 is also called a WB (Whole Body) coil. Transmission coil 115 is supported by bore tube 104, for example.

The receiving coil 117 is an RF coil placed inside the gradient magnetic field coil 103. The receiving coil 117 receives the MR signal emitted from the subject P using a high frequency magnetic field. Receiving coil 117 outputs the received MR signal to receiving circuit 119. The receiving coil 117 is, for example, a coil array having one or more, typically a plurality of coil elements (hereinafter referred to as a plurality of coils).

Note that although the transmitting coil 115 and the receiving coil 117 are shown as separate RF coils in FIG. 1, the transmitting coil 115 and the receiving coil 117 may be implemented as an integrated transmitting/receiving coil. The transmitting/receiving coil corresponds to the imaging region of the subject P, and is, for example, a local transmitting/receiving RF coil such as a head coil.

The receiving circuit 119 generates a digital MR signal (hereinafter referred to as MR data) based on the MR signal output from the receiving coil 117 under the control of the sequence control circuit 121 . Specifically, the receiving circuit 119 performs signal processing such as detection and filtering on the MR signal output from the receiving coil 117, and then performs analog/digital (analog/digital) processing on the data subjected to the signal processing. A/D (Analog to Digital) conversion (hereinafter referred to as A/D conversion) is performed to generate MR data. The receiving circuit 119 outputs the generated MR data to the sequence control circuit 121. For example, MR data is generated in each of the plurality of coils and output to the sequence control circuit 121 together with a tag that identifies each of the plurality of coils.

The sequence control circuit 121 controls the gradient magnetic field power supply 105, the transmitting circuit 113, the receiving circuit 119, etc. according to the imaging protocol output from the processing circuit 131, and performs imaging of the subject P. The imaging protocol has a pulse sequence depending on the type of examination. The imaging protocol includes the magnitude of the current supplied to the gradient magnetic field coil 103 by the gradient magnetic field power supply 105, the timing at which the current is supplied to the gradient magnetic field coil 103 by the gradient magnetic field power supply 105, and the timing at which the current is supplied to the gradient magnetic field coil 115 by the transmission circuit 113. The magnitude and time width of the high frequency pulse, the timing at which the high frequency pulse is supplied to the transmitting coil 115 by the transmitting circuit 113, the timing at which the receiving coil 117 receives the MR signal, etc. are defined. When the sequence control circuit 121 receives MR data from the receiving circuit 119 as a result of driving the gradient magnetic field power supply 105, the transmitting circuit 113, the receiving circuit 119, etc. to image the subject P, the sequence control circuit 121 transmits the received MR data to the processing circuit 131. Forward.

The sequence control circuit 121 includes a processor, and memories such as ROM (Read-Only Memory) and RAM (Random Access Memory) as hardware resources. The term "processor" refers to, for example, a CPU (Central Processing Unit), an MPU (Micro Processing Unit), a GPU (Graphics Processing Unit), or an application specific integrated circuit. integrated circuit (ASIC), programmable logic device (e.g. Simple Programmable Logic Device (SPLD), Complex Programmable Logic Device (CPLD), and Field Programmable Gate Array (Field Programmable Gate A) rray: means a circuit such as FPGA). The sequence control circuit 121 corresponds to a sequence control section.

The system control circuit 123 has a processor, memories such as ROM and RAM, etc. as hardware resources, and controls the MRI apparatus 100 with a system control function. Specifically, the system control circuit 123 reads a system control program stored in the memory, expands it onto the memory, and controls each circuit of the MRI apparatus 100 according to the expanded system control program. That is, the system control circuit 123 performs overall control of the MRI apparatus 100.

For example, the system control circuit 123 reads the imaging protocol from the memory 125 based on imaging conditions input by the operator via the input interface 127. The system control circuit 123 transmits the imaging protocol to the sequence control circuit 121 and controls imaging of the subject P. The system control circuit 123 is realized by, for example, a processor. Note that the system control circuit 123 may be incorporated into the processing circuit 131. At this time, the system control function is performed by the processing circuit 131, and the processing circuit 131 functions as a substitute for the system control circuit 123. The processor that realizes the system control circuit 123 has the same contents as described above, so a description thereof will be omitted.

The memory 125 stores various programs related to system control functions executed in the system control circuit 123, various imaging protocols, imaging conditions including a plurality of imaging parameters defining the imaging protocols, and the like. Further, the memory 125 stores the image generation function 35 realized by the processing circuit 131 in the form of a computer-executable program.

The memory 125 also stores various data acquired by the sequence control circuit 121, various data used in processing performed by the image generation function 35, MR images generated by the image generation function 35, and the like. The memory 125 also stores MR data acquired by scanning the subject P and an algorithm for reconstructing an MR image based on the MR data.

Note that the memory 125 may store various data received via a communication interface (not shown). For example, the memory 125 stores information regarding an examination order for the subject P (image target region, examination purpose, etc.) received from an information processing system within a medical institution such as a radiology information system (RIS).

The memory 125 is realized by, for example, a semiconductor memory element such as a ROM, a RAM, or a flash memory, an HDD (Hard Disk Drive), an SSD (Solid State Drive), an optical disk, or the like. Further, the memory 125 may be realized by a drive device that reads and writes various information from and to a portable storage medium such as a CD (Compact Disc)-ROM drive, a DVD (Digital Versatile Disc) drive, and a flash memory. .

The input interface 127 accepts various instructions and information input from the operator. The input interface 127 includes, 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, and 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 127 is connected to the processing circuit 131 , converts an input operation received from an operator into an electrical signal, and outputs the electrical signal to the processing circuit 131 .

Note that in this specification, the input interface 127 is not limited to one that includes physical operation parts such as a mouse and a keyboard. For example, examples of the input interface 127 include an electrical signal processing circuit that receives an electrical signal corresponding to an input operation from an external input device provided separately from the MRI apparatus 100 and outputs this electrical signal to a control circuit. It will be done.

The input interface 127 inputs the FOV of the prescan image displayed on the display 129 according to a user's instruction. Specifically, the input interface 127 inputs the FOV in the locator image displayed on the display 129 based on a range setting instruction from the user. Further, the input interface 127 inputs various imaging parameters related to scanning and pulse sequence selection instructions based on user instructions based on the inspection order.

The display 129 displays various GUIs (Graphical User Interfaces), MR images generated by the processing circuit 131, etc. under the control of the processing circuit 131 or the system control circuit 123. Further, the display 129 displays imaging parameters related to scanning, various information related to image processing, and the like. Display 129 is implemented by a display device such as, for example, a CRT display, a liquid crystal display, an organic EL display, an LED display, a plasma display, or any other display or monitor known in the art.

The processing circuit 131 is realized by, for example, the above-mentioned processor. The processing circuit 131 includes an image generation function 35 and the like. The processing circuit 131 that implements the image generation function 35 corresponds to an image generation section. Each function such as the image generation function 35 is stored in the memory 125 in the form of a computer-executable program. For example, the processing circuit 131 reads programs from the memory 125 and executes them to realize functions corresponding to each program. In other words, the processing circuit 131 in a state where each program is read has each function such as the image generation function 35. The processing circuit 131 uses the image generation function 35 to reconstruct an MR image based on the MR data transmitted from the sequence control circuit 121. The processing circuit 131 stores the reconstructed MR image in the memory 125 or displays it on the display 129.

In the above description, an example has been described in which the "processor" reads out and executes a program corresponding to each function from the memory 125, but the embodiment is not limited to this. When the processor is, for example, a CPU, the processor realizes its functions by reading and executing a program stored in the memory 125. On the other hand, if the processor is an ASIC, instead of storing the program in memory 125, the functionality is built directly 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. Further, although the description has been made assuming that a single memory circuit stores programs corresponding to each processing function, a plurality of memory circuits are distributed and arranged, and the processing circuit 131 reads the corresponding programs from the individual memory circuits. It may also be a configuration.

The outline of the MRI apparatus 100 has been described above. The bore tube 104 in this embodiment will be described below. The bore tube 104 is a cylindrical soundproofing material (hereinafter referred to as a cylindrical soundproofing material) for the MRI apparatus 100 made of a composite material containing a fiber material and a resin material. In the tubular soundproofing material 104, the fibrous materials form a woven structure woven along a plurality of directions. The textile structure is continuously formed over at least one circumference of the side surface of the cylindrical soundproofing material 104. Here, each of the plurality of directions is a direction along the angle (set angle) of the fiber material with respect to the longitudinal direction of the bore tube 104 (that is, also referred to as the Z direction).

FIG. 2 is an external view showing an example of the appearance of the fabric structure on the mandrel after one lamination in the manufacturing process of the bore tube 104. FIG. 3 is a diagram showing an example of an enlarged view EBT in which a part of the bore tube 104 shown in FIG. 2 is enlarged. In FIGS. 2 and 3, the first fiber material FM1 from the upper left to the lower right has a first set angle θ1. Further, in FIGS. 2 and 3, the second fiber material FM2 from the lower left to the upper right has a second assembly angle θ2. The first fiber material FM1 and the second fiber material FM2 may be glass fibers with different specific gravity, or may be glass fibers with the same specific gravity. Further, the first fiber material FM1 and the second fiber material FM2 may be different glass fibers or may be made of different materials (for example, glass fibers and various fibers such as carbon fibers or resin fibers). good.

In FIGS. 2 and 3, a resin material is filled between the first fiber material FM1 and the second fiber material FM2. Any resin that can be impregnated into fibers and hardened can be used as the resin material. For example, a thermosetting resin that hardens when heated or a thermoplastic resin that softens when heated can be used. As the thermosetting resin, unsaturated polyester resin is suitable, but epoxy resin, phenol resin, etc. can also be used. A composite material including a fiber material (first fiber material FM1 and second fiber material FM2) and a resin material is, for example, fiber reinforced plastics (FRP). When the fiber material is glass fiber, the composite material corresponds to glass fiber reinforced plastic (GFRP).

The angle of the fibrous material constituting the textile structure shown in FIGS. 2 and 3 is, for example, a predetermined angle that can suppress vibration and noise caused by the gradient magnetic field coil 103. The inventor has found that the vibration and noise suppression effect is higher when the fiber direction of the fibrous material and the vibration propagation direction are closer to parallel. Based on this knowledge, the designer arbitrarily sets the first assembling angle θ1 and the second assembling angle θ2 shown in FIGS. 2 and 3 so as to be suitable for suppressing vibration and noise by the gradient magnetic field coil 103. It is possible. The assembling angles (for example, the first assembling angle θ1 and the second assembling angle θ2) can be arbitrarily set in the range of 20° or more and 70° or less during the manufacturing process of the bore tube 104, for example. That is, the angle of the fibrous materials constituting the textile structure is 20° or more and 70° or less with respect to the long axis direction of the cylindrical soundproofing material 104.

Further, the density of the composite material is a predetermined density that can suppress vibration and noise caused by the gradient magnetic field coil 103. That is, the specific gravity of the composite material made of the first fiber material FM1, the second fiber material FM2, and the resin material shown in FIGS. It can be set arbitrarily by the person.

Although FIGS. 2 and 3 show a woven structure on a mandrel with one lamination, the bore tube 104 may also have a structure that laminates multiple layers formed of the composite material described above. good. That is, the cylindrical soundproofing material corresponding to the bore tube 104 has a laminated structure in which a plurality of layers of composite materials are laminated. At this time, the angle of the fibrous materials constituting the woven structure and the density of the composite material may be set for each of the plurality of layers in the laminated structure. Since the content of the filled resin changes depending on the difference in the content of the fiber material, the density of the composite material can be adjusted as a result. Further, the number of layers in the laminated structure is such that vibration and noise caused by the gradient magnetic field coil 103 can be suppressed, and can be arbitrarily set.

Furthermore, in order to reduce the weight of the cylindrical soundproof material corresponding to the bore tube 104, the specific gravity of the fiber material needs to be greater than the specific gravity of the resin material. That is, the specific gravity of the first fiber material FM1 and the specific gravity of the second fiber material FM2 are both greater than the specific gravity of the resin material.

As a method for forming (manufacturing) the bore tube 104, for example, a known string making method can be applied. That is, as a means for producing a fibrous material into a cylindrical woven structure, for example, a string-making method is used.

According to the MRI apparatus 100 according to the embodiment described above, the inner circumferential side of the gradient magnetic field coil 103 provided on the inner circumferential side of the static magnetic field magnet 101 that generates a static magnetic field includes a fiber material and a resin material. In the cylindrical soundproofing material 104 for the magnetic resonance imaging apparatus 100 made of a composite material, the textile structure is continuously formed over at least one circumference of the side surface of the cylindrical soundproofing material 104 . Further, according to the cylindrical soundproofing material (bore tube) 104 for the magnetic resonance imaging apparatus 100 formed of a composite material including a fiber material and a resin material according to the present embodiment, the woven structure has a plurality of fiber materials. It is woven along the direction of , and is continuously formed over at least one circumference of the side surface of the cylindrical soundproofing material 104 .

For these reasons, according to the MRI apparatus 100 and the bore tube 104 according to the embodiment, the thickness of the bore tube 104 is increased by forming a woven structure in which a plurality of fiber materials are arranged in a continuous body and at an arbitrary angle. It is possible to maintain and improve the areal density without any problems. That is, according to the MRI apparatus 100 and the bore tube 104 according to the embodiment, the content of the fibrous material per layer can be increased by using a woven structure in which the fibrous material is woven into each layer.

Further, according to the cylindrical soundproofing material 104 for the MRI apparatus 100 according to the embodiment, the assembly angle of the fibrous material constituting the textile structure is set to a predetermined angle that can suppress vibration and noise caused by the gradient magnetic field coil 103. , can be adjusted arbitrarily. As a result, the cylindrical soundproofing material 104 for the MRI apparatus 100 according to the embodiment can have the necessary strength, noise suppression function, vibration suppression function, etc. without increasing the thickness.

Moreover, according to the cylindrical soundproof material 104 for the MRI apparatus 100 according to the embodiment, the density of the composite material has a predetermined density that can suppress the vibration and the noise. Moreover, according to the cylindrical soundproofing material 104 for the MRI apparatus 100 according to the embodiment, it has a laminated structure in which composite materials are laminated over a plurality of layers, and the above-mentioned assembly angle and the above-mentioned density are different from each other in the plurality of layers. The number of layers is set in advance for each case, and the number of layers is the number of laminated layers that can suppress the vibration and the noise. Moreover, according to the cylindrical soundproof material 104 for the MRI apparatus 100 according to the embodiment, the specific gravity of the fibrous material is greater than the specific gravity of the resin material.

For these reasons, according to the cylindrical soundproofing material 104 for the MRI apparatus 100 according to the embodiment, for example, it is possible to change the content of the fiber material and the weaving angle (stack angle) for each layer to be laminated. Depending on the specifications of the MRI apparatus 100 and the cylindrical soundproof material 104 for the MRI apparatus 100, a new bore tube 104 that exhibits the required strength, noise suppression function, vibration suppression function, etc. can be formed.

From the above, according to the bore tube 104 according to the embodiment, by having the woven structure, the content of the fiber material can be increased without increasing the thickness. In addition, according to the MRI apparatus 100 and the bore tube 104 according to the embodiment, by using a continuous fiber material in the woven structure, the desired noise suppression function, vibration suppression function, etc. can be achieved with a smaller number of laminated layers than in the past. It becomes possible to reduce the thickness of the structure (bore tube 104) while maintaining the same. Thereby, according to the cylindrical soundproofing material 104 for the MRI apparatus 100 according to the embodiment, it is possible to simultaneously realize lightweight and high rigidity, as well as vibration suppression and noise suppression. However, the thickness does not necessarily have to be reduced compared to the bore tube 104 according to the prior art, and it is not excluded that the thickness can be increased compared to the conventional technology to achieve further vibration suppression and noise suppression.

Hereinafter, the effects of this embodiment will be specifically explained using FIGS. 4 to 6. First, a comparative example to be compared with this embodiment will be explained, and the effects of this embodiment will be explained in comparison with the comparative example.

FIG. 4 is an external view showing an example of the appearance of a mandrel after one lamination in a bore tube CBT according to a comparative example. The bore tube of the comparative example has a structure in which a fiber material (reinforced fiber) is wound at an arbitrary angle (wrap angle). FIG. 5 is a diagram showing an example of an enlarged view of a part of the bore tube CBT of the comparative example shown in FIG. 4, ECBT. As shown in FIGS. 4 and 5, in a bore tube CBT on a mandrel in one stacking cycle, fibrous materials of constant width are equally spaced. That is, in one lamination cycle, the fibrous materials are wound around the mandrel in the same direction at regular intervals, as shown in FIG. In other words, there is a limit to the width of the fibers to be wound around the mandrel, and it is difficult to wrap the fiber material around the mandrel without any gaps. Therefore, as shown in FIGS. 4 and 5, it is not possible to wrap the fiber material around the entire mandrel in one lamination cycle, and some parts have the fiber material and some parts do not have the fiber material. On the other hand, according to the present embodiment, as shown in FIGS. 2 and 3, in order to wind the fiber material into a woven structure on the mandrel in one lamination cycle, the fiber material is wrapped around the entire mandrel in one lamination cycle. Can be placed.

For these reasons, as shown in Figs. 4 and 5, in the bore tube CBT, there are parts with fiber material (dense) and parts without fiber material (sparse) on the mandrel in one lamination cycle. Has a structure. Therefore, in the bore tube CBT as a comparative example, a certain number of fiber materials are laminated in order to eliminate the spacing shown in FIGS. 4 and 5 and to obtain strength, vibration suppression function, and noise suppression function. That is, in order to eliminate the sparseness in FIGS. 4 and 5, it is necessary to laminate a certain number of fiber materials (wrap them around the mandrel) so that the fibers are arranged over the entire mandrel. Laminating a certain number of layers contributes to weight increase in the bore tube CBT of the comparative example.

FIG. 6 is a diagram showing an example of a composition CE of glass fibers and an epoxy resin in a composite material in a comparative example, and an example of a composition EM of glass fibers and an epoxy resin in a composite material in an embodiment. As shown in FIG. 6, the composite material will be described as glass fiber reinforced plastic (hereinafter referred to as GFRP).

As shown in FIG. 6, the density (g/cm ³ ) of GFRP in Comparative Example CE is 2.6×50/100+1.4×50/100=2.0 (g/cm ³ ). On the other hand, if the composition of glass fiber becomes 80% and the composition of epoxy resin becomes 20% by applying the textile structure in this embodiment, the density (g/cm ³ ) of GFRP in embodiment EM is: 2.6×80/100+1.4×20/100=2.36 (g/cm ³ ). This indicates that the density of GFRP increases with increasing glass fiber composition due to the woven structure.

Next, cases in which GFRP is laminated in a comparative example and this embodiment will be described. In the comparative example, the areal density when 5 cm of GFRP is laminated is 10 (g/cm ² ). The composition of glass fiber and epoxy resin in the comparative example after 5 cm lamination is 250% glass fiber and 250% epoxy resin since the thickness is 5 times. Therefore, the density of GFRP in the comparative example after 5 cm of lamination is 10.0 (g/cm ³ ).

On the other hand, in order to obtain the same areal density as the comparative example with the composition of the GFRP in this embodiment, that is, in order to obtain the same vibration suppression function and noise suppression function as the comparative example, the laminated thickness must be approximately 4.5 mm. 24cm (10/2.36≒4.24). The composition of glass fiber and epoxy resin in this embodiment after 4.24 cm of lamination is approximately 340% glass fiber and 85% epoxy resin since the thickness is 4.24 times. Therefore, the density of GFRP in this embodiment after stacking 4.24 cm is 7.2 (g/cm ³ ). For these reasons, the present embodiment provides a cylindrical soundproofing material 104 for the magnetic resonance imaging apparatus 100 that can simultaneously achieve lighter weight, higher rigidity, vibration suppression, and noise suppression compared to conventional bore tubes. It can be realized.

(First application example)
FIG. 7 shows, as a first application example of the present embodiment, a bore in which a third fiber material FM3 is woven in addition to the first fiber material FM1 and the second fiber material FM2 shown in FIGS. 2 and 3. FIG. 3 is a diagram showing an example of an enlarged view EABT1 in which a part of the tube 104 is enlarged. As shown in FIG. 7, the third assembling angle θ3 regarding the third fibrous material FM3 is a different angle from the first assembling angle θ1 and the second assembling angle θ2.

As a result, in the first application example, the bore tube 104 can be formed into which the third fiber material FM3 having a different angle in the radial direction is further woven. That is, in the first application example, the rigidity can be improved compared to the embodiment, and vibration and noise caused by the gradient magnetic field coil 103 can be further suppressed. The effects of this application example are the same as those of the embodiment, so a description thereof will be omitted.

(Second application example)
FIG. 8 shows, as a second application example of the present embodiment, a bore in which a third fiber material FM3 is woven in addition to the first fiber material FM1 and the second fiber material FM2 shown in FIGS. 2 and 3. 6 is a diagram showing an example of an enlarged view EABT2 of a part of the tube 104. FIG. As shown in FIG. 8, the third combination angle θ3 regarding the third fiber material FM3 is the same as the first combination angle θ1, but the phase of the third fiber material FM3 is different from that of the first fiber material FM1. and the phase of the second fiber material FM2.

As a result, in the second application example, the bore tube 104 can be formed into which the third fiber material FM3 having a different phase in the radial direction is further woven. That is, in the second application example, the rigidity can be improved compared to the embodiment, and vibration and noise caused by the gradient magnetic field coil 103 can be further suppressed. The effects of this application example are the same as those of the embodiment, so a description thereof will be omitted.

(Method for manufacturing cylindrical soundproofing material 104 for magnetic resonance imaging apparatus 100)
Hereinafter, a method for manufacturing the bore tube 104 in this embodiment will be described using FIG. 9. FIG. 9 is a diagram illustrating an example of the steps of the method for manufacturing the bore tube 104 according to the present embodiment. The manufacturing method of the textile structure used for the bore tube 104 consists in forming (molding (molding)) the fibrous material into a cylindrical shape while weaving the fibrous material using a string-making method or the like. Since the string making method is a known method, detailed explanation will be omitted.

Further, the flowchart from resin impregnation to heat curing and demolding described below is just an example, and it is also possible to mold by other molding methods and means. That is, 1. placing a fibrous material having a woven structure on a mandrel; 2. impregnating the fiber material with resin; 3. As long as the three steps of curing the resin, molding the shape, and demolding are performed, the bore tube 104 shown in this embodiment can be molded regardless of the processing steps shown in the flowchart.

(Step S901)
The fiber material is impregnated with a resin material. The resin material corresponds to an adhesive, and for example, a thermosetting resin is used. The fibrous material impregnated with the resin material is supplied to a carrier called a mandrel that supplies the core metal.

(Step S902)
The fibrous material impregnated with the resin material is continuously wound around at least one side of the mandrel at a predetermined tension while being woven by the carrier at a plurality of angles relative to the rotational axis direction of the mandrel. For example, relative circumferential movement of the carrier around the mandrel to the mandrel and relative movement of the carrier to the mandrel in the axial direction of the mandrel can cause the fibrous material to move at multiple angles of rotation relative to the axis of rotation of the mandrel. Incorporated. At this time, the assembly angle depends on the ratio of the speed of circumferential movement (rotation of the mandrel or carrier) and the speed of movement of the mandrel in the axial direction by the mandrel or carrier, as well as the number of carriers and the width of the fiber material to be supplied. is determined.

(Step S903)
If winding of the fiber material is completed over a predetermined distance along the direction of the rotation axis of the mandrel (Yes in step S903), the process in step S904 is executed. If the winding of the fiber material is not completed over a predetermined distance along the direction of the rotation axis of the mandrel (No in step S903), the steps from step S901 onwards are repeated.

(Step S904)
If the thickness of the fibrous layer reaches a predetermined thickness (Yes in step S904), the process in step S905 is executed. If the thickness of the fibrous layer has not reached the predetermined thickness (No in step S904), the steps from step S901 onwards are repeated.

(Step S905)
The resin material impregnated into the fibrous material wrapped around the mandrel is heated and cured. This completes the molding of the bore tube 104. Note that the curing of the resin material is not limited to heating, and other curing methods such as curing over time can be used as appropriate.

(Step S906)
The heat-cured composite material of resin material and fiber material is pulled out from the mandrel. The bore tube 104 is manufactured through the above steps.

As described above, according to the method for manufacturing the cylindrical soundproof material 104 for the magnetic resonance imaging apparatus 100 in the embodiment, for example, a fiber material is impregnated with a resin material, and the fiber material impregnated with the resin material is attached to the rotating shaft of the mandrel. The fiber material is continuously wound around at least one circumference of the side surface of the mandrel with a predetermined tension while weaving at multiple angles in the direction, and the resin material impregnated into the fiber material wound around the mandrel is heated and cured. A cylindrical soundproofing material for the magnetic resonance imaging apparatus 100 is manufactured by drawing a composite material of wood and fiber material from a mandrel. In addition, in the manufacturing method of the cylindrical soundproof material 104 for the magnetic resonance imaging apparatus 100, the order and method regarding resin impregnation and heat curing can be arbitrarily selected depending on each manufacturing method.

According to the method for manufacturing the bore tube 104 according to the present embodiment, the bore tube 104 is manufactured while weaving the fiber material, so that the manufacturing time of the bore tube 104 can be shortened by reducing the thickness. The effects of the manufactured bore tube 104 are the same as those in the embodiment, so a description thereof will be omitted.

(Example)
This example describes the material of a test piece regarding a cylindrical soundproofing material for an MRI apparatus having the technical features in the above embodiment, the manufacturing procedure of the test piece, the test contents for the test piece, and the results of the test for the test piece. I will explain about it.

As materials for the test piece, fiber material and resin are used. The fibrous material is, for example, glass fiber (eg E-glass fiber). Further, the resin is, for example, an epoxy resin.

The manufacturing procedure for the test piece is as follows. Glass fibers are formed into a woven structure. That is, a flat woven fabric structure is formed by weaving the glass fibers into a flat plate. Epoxy resin is then poured into the textile structure using, for example, a VaRTM (Vacuum assisted Resin Transfer Molding) method. Specifically, the flat woven fabric structure is impregnated with epoxy resin under a vacuum of about 85 kPa using RTM (Resin Transfer Molding), which is a type of molding method. The epoxy resin impregnated fabric structure is then heat cured and molded.

The impregnation temperature (heating temperature) is, for example, 130°C. Further, the heating time (curing time) is, for example, 2 hours. Note that the atmospheric pressure (85 kPa), impregnation temperature (130°C), and heating time (2 hours) regarding the vacuum impregnation of the epoxy resin are merely examples, and are not limited to these, and may be changed as appropriate depending on the material of the test piece. Can be changed. A test piece is manufactured by cutting out the molded product formed in the above manner over a length of, for example, 80 mm.

The details of the test on the test piece will be explained below. FIG. 10 is a diagram showing an example of the upper surface (vertically upward surface) of the test piece TP. As shown in FIG. 10, the length of the test piece TP in the major axis direction is 80 mm. As shown in FIG. 10, one end of the test piece TP in the longitudinal direction is supported by a supporter as a fixed end away from the floor surface. The position where the test piece TP is supported by the supporter corresponds to the support point SP in FIG. The other end of the test piece TP in the longitudinal direction is a free end. In the test piece TP, a load is applied by, for example, a force gauge at a position 5 mm away from the other end (free end) (in other words, a position 75 mm away from the fixed end). The position where the test piece TP is loaded corresponds to the vibration point (loading point) LP. A pick PPP used for measuring the acceleration of the test piece TP is pasted at a position 30 mm from the fixed end of the test piece TP. The position of the pick PPP on the test specimen TP corresponds to the acceleration pickup. Note that the dimensions in FIG. 10 are just an example, and the dimensions are not limited thereto.

FIG. 11 is a diagram showing an example of an outline of a test system for the test piece TP. As shown in FIG. 11, the test piece TP is pushed vertically downward by 5 mm at the load point LP by the force gauge FG. The vertical downward depression of 5 mm by the force gauge FG corresponds to the initial displacement of the test piece TP. Thereby, as shown in FIG. 11, the test piece TP is bent downward from the horizontal direction to the vertical direction.

When the deflection of the test piece TP is released from the state where the test piece TP is bent due to the initial displacement of 5 mm at the excitation point LP, the acceleration of the test piece TP is measured via the acceleration pickup PPP. Based on the measured acceleration and the load at the time of depression measured by the force gauge FG, the Young's modulus (GPa), damping ratio ζ, etc. of the test piece TP are calculated by known analysis processing. Young's modulus is an index representing the rigidity of the test piece TP. The larger the Young's modulus, the higher the rigidity. Further, the damping ratio is an index representing the difficulty of causing vibrations. The larger the damping ratio, the less likely it is to vibrate. That is, the larger the damping ratio, the more sound caused by transmitted vibrations can be canceled. In other words, the larger the damping ratio, the quieter the material.

FIG. 12 is a diagram showing an example of the analysis results of tests for a test piece having a set angle of 20°, a test piece having a set angle of 45°, and a test piece having a set angle of 70°. As shown in FIG. 12, the Young's modulus increases as the set angle increases. Therefore, as shown in FIG. 12, the larger the assembly angle, the higher the rigidity of the cylindrical soundproofing material. Moreover, as shown in FIG. 12, the damping ratio also increases as the angle of the assembly angle increases. Therefore, as shown in FIG. 12, the larger the assembly angle, the higher the quietness of the cylindrical soundproofing material.

FIG. 13 is a diagram illustrating an example of Young's modulus (GPa) as an analysis result of a test for a test piece having a woven angle of 45° and a test piece woven with woven angles of 20° and 70°. The average braid angle in the specimens woven with braid angles of 20° and 70° is 45°. As shown in Figure 13, the Young's modulus is 10.2 GPa for the 45° single woven angle specimen, while it is 18. GPa for the 20° and 70° woven specimen. It is 4GPa. Therefore, as shown in FIG. 13, specimens woven with 20° and 70° braid angles are more rigid than specimens with a single 45° braid angle.

According to at least one embodiment described above, it is possible to realize the cylindrical soundproofing material 104 for the magnetic resonance imaging apparatus 100 that has high rigidity and can improve vibration suppression and noise suppression.

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.

35 Image generation function 100 Magnetic resonance imaging apparatus 101 Static magnetic field magnet 103 Gradient magnetic field coil 104 Bore tube 105 Gradient magnetic field power supply 107 Bed 109 Bed control circuit 111 Bore 113 Transmission circuit 115 Transmission coil 117 Receiving coil 119 Receiving circuit 121 Sequence control circuit 123 System Control circuit 125 Memory 127 Input interface 129 Display 131 Processing circuit

Claims (8)

A cylindrical soundproofing material for a magnetic resonance imaging device formed of a composite material containing a fiber material and a resin material,
the fibrous material forms a woven fabric structure;
The textile structure is formed continuously over at least one circumference of the side surface of the cylindrical soundproofing material.
Cylindrical soundproofing material for magnetic resonance imaging equipment. The fibrous material forms the woven structure woven by a plurality of corner angles.
The cylindrical soundproofing material for a magnetic resonance imaging apparatus according to claim 1. The assembly angle of the fibrous material constituting the woven structure is 20° or more and 70° or less with respect to the longitudinal direction of the cylindrical soundproofing material.
The cylindrical soundproofing material for a magnetic resonance imaging apparatus according to claim 2. The cylindrical soundproofing material has a laminated structure in which the composite material is laminated over a plurality of layers,
The assembly angle and the density of the composite material are set for each of the plurality of layers,
The cylindrical soundproofing material for a magnetic resonance imaging apparatus according to claim 3. The cylindrical soundproofing material has a laminated structure in which the composite material is laminated over a plurality of layers,
The number of the plurality of layers is the number of laminated layers that can suppress vibration and noise caused by the gradient magnetic field coil,
The cylindrical soundproofing material for a magnetic resonance imaging apparatus according to claim 1. The specific gravity of the fibrous material is greater than the specific gravity of the resin material,
A cylindrical soundproofing material for a magnetic resonance imaging apparatus according to any one of claims 1 to 5. a gradient magnetic field coil provided on the inner circumferential side of a static magnetic field magnet that generates a static magnetic field;
A cylindrical soundproofing material for a magnetic resonance imaging device formed of a composite material containing a fiber material and a resin material on the inner peripheral side of the gradient magnetic field coil;
Equipped with
the fibrous material forms a woven fabric structure;
The textile structure is formed continuously over at least one circumference of the side surface of the cylindrical soundproofing material.
Magnetic resonance imaging device. Impregnating fiber material with resin material,
Continuously winding the fiber material impregnated with the resin material over the side surface of the mandrel while weaving it at a plurality of angles relative to the rotational axis direction of the mandrel,
curing the resin material impregnated into the fiber material wound around the mandrel;
pulling out the cured composite material of the resin material and the fibrous material from the mandrel;
A method for manufacturing a cylindrical soundproofing material for a magnetic resonance imaging device, comprising: manufacturing a cylindrical soundproofing material for a magnetic resonance imaging device.

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