Magnetic resonance system and gradient amplifier filter for magnetic resonance system

Abstract

The invention relates to a magnetic resonance system and a gradient amplifier filter for the magnetic resonance system. The filter comprises a plurality of non-magnetic-core inductors and a printed circuit board with a multilayer structure, a plurality of filter capacitors are respectively formed in a plurality of areas of the printed circuit board, and each non-magnetic-core inductor is arranged on the printed circuit board across two of the filter capacitors.

Description

Technical Field

[0001] The present invention relates to the field of medical imaging, and in particular to a magnetic resonance system and a gradient amplifier filter used in the magnetic resonance system. Background Art

[0002] Magnetic resonance (MR) technology is one of the main imaging methods in modern medicine. A magnetic resonance system usually includes a gradient coil, which interacts with the main magnetic field generated by the main magnet to generate a magnetic field gradient to encode the spatial position of the magnetic resonance signals received from the human body, so that the human tissue image can be reconstructed based on the encoded magnetic resonance signals.

[0003] The above-mentioned gradient coil is usually arranged close to the main magnet, for example, integrated with the main magnet in the housing of the scanning device, and the housing forms a cavity for accommodating the scanned object. The scanning device having the main magnet and the gradient coil is arranged in a scanning room, and the scanning room and the equipment room are independent building spaces with physical separation. The gradient coil usually requires a large driving current, which is provided by a gradient amplifier. In the prior art, the gradient amplifier is arranged in the equipment room. One of the reasons is that the accommodation space of the magnet housing in the scanning room is limited. Another reason is that when the gradient amplifier and its connecting parts are close to the main magnet, they may be affected by the main magnetic field and produce magnetic saturation, which will seriously affect the imaging quality. Summary of the invention

[0004] One aspect of the present invention provides a gradient amplifier filter for a magnetic resonance system, comprising a plurality of non-magnetic core inductors and a printed circuit board with a multilayer structure, wherein a plurality of filter capacitors are respectively formed in a plurality of regions of the printed circuit board, wherein each non-magnetic core inductor is arranged on the printed circuit board across two of the plurality of filter capacitors.

[0005] Another aspect of the present invention provides a magnetic resonance system, comprising a magnet housing and the above-mentioned gradient amplifier filter, wherein a main magnet, a gradient coil and a gradient amplifier are arranged in the magnet housing, and the filter comprises an input end connected to the gradient amplifier and an output end connected to the gradient coil.

[0006] It should be understood that the brief description above is provided to introduce some concepts further described in the detailed description in a simplified form. It is not meant to identify key or essential features of the claimed subject matter, the scope of which is solely defined by the claims that follow the detailed description. Furthermore, the claimed subject matter is not limited to implementations that solve any disadvantages mentioned above or in any section of this disclosure. BRIEF DESCRIPTION OF THE DRAWINGS

[0007] The present invention will be better understood by reading the following description of non-limiting embodiments with reference to the accompanying drawings, in which:

[0008] Figure 1 A schematic diagram showing the structure of an exemplary magnetic resonance system 100 of some embodiments is shown;

[0009] Figure 2 A schematic diagram of the structure of a magnetic resonance system 200 according to some embodiments of the present invention is shown;

[0010] Figure 3 A schematic diagram of the structure of a gradient amplifier filter according to some embodiments of the present invention is shown;

[0011] Figure 4 Shows Figure 3 A cross-sectional view of a printed circuit board in FIG.

[0012] Figure 5 Shows Figure 4 A schematic diagram of the structure of the signal layer of the printed circuit board;

[0013] Figure 6 Shows Figure 3 Equivalent circuit diagram of the gradient amplifier filter in;

[0014] Figure 7 , Figure 8 They are shown respectively Figure 3 Different winding methods of coils of non-core inductors;

[0015] Fig. 9 Shown in Figure 3 A plurality of vias disposed on a printed circuit board;

[0016] Fig.10 , Fig.11 Schematic diagrams of performing attenuation test on the gradient amplifier filter of the embodiment of the present invention are respectively shown, wherein Fig.10 shows the common mode attenuation test results, Fig.11 Differential mode attenuation test results are shown.

[0017] Together with the following description, the accompanying drawings illustrate and explain the structural principles, methods and principles described herein. In the accompanying drawings, for the sake of clarity, the thickness and size of the components may be exaggerated or otherwise modified. Well-known structures, materials or operations are not shown or described in detail to avoid obscuring the components and systems described. DETAILED DESCRIPTION

[0018] The specific embodiments of the present invention will be described below. It should be noted that in the specific description of these embodiments, in order to provide a concise description, it is impossible for this specification to provide a detailed description of all the features of the actual embodiments. It should be understood that in the actual implementation of any embodiment, just as in the process of any engineering project or design project, in order to achieve the specific goals of the developer and to meet system-related or business-related restrictions, various specific decisions are often made, and this will also change from one embodiment to another. In addition, it can also be understood that although the efforts made in this development process may be complex and lengthy, for ordinary technicians in the field related to the content disclosed by the present invention, some changes such as design, manufacturing or production based on the technical content disclosed in this disclosure are just conventional technical means, and should not be understood as insufficient content of this disclosure.

[0019] Unless otherwise defined, the technical or scientific terms used in the claims and the specification should be understood by people with ordinary skills in the technical field. The words "first", "second" and similar words used in this specification and the claims do not indicate any order, quantity or importance, but are only used to distinguish different components. "One" or "one" and similar words do not indicate a quantitative limitation, but indicate the existence of at least one. "Including" or "comprising" and similar words mean that the elements or objects appearing in front of "including" or "comprising" include the elements or objects listed after "including" or "comprising" and their equivalent elements, and do not exclude other elements or objects. "Connected" or "connected" and similar words are not limited to physical or mechanical connections, nor are they limited to direct or indirect connections. In addition, it should be understood that reference to "one embodiment" or "embodiment" of the present disclosure is not intended to be interpreted as excluding the existence of additional implementation schemes that also include the cited features.

[0020] refer to Figure 1 , showing a schematic diagram of an exemplary MR (Magnetic Resonance) system 100 according to some embodiments of the present invention.

[0021] like Figure 1As shown, the operator workstation 110 is used to control the operation of the MR system 100, and the operator workstation 110 includes an input device 114, a control panel 116 and a display 118. The input device 114 can be a joystick, a keyboard, a mouse, a trackball, a touch-activated screen, voice control, or any similar or equivalent input device. The control panel 116 can include a keyboard, a touch-activated screen, voice control, buttons, sliders, or any similar or equivalent control device. The operator workstation 110 is coupled to and communicates with a computer system 120, and provides an interface for the operator to plan magnetic resonance scanning, display images, perform image processing, and store data and images. The computer system 120 enables the operator to control the generation and viewing of images or other monitoring information on the display 118 (for example, through an input device), and can also perform human-computer interaction through a user interface displayed on the display 118. The human-computer interaction can be used to: input information required for scanning, determine scanning parameters for image processing operations, select images, view quality assessment results of selected images, etc. The above-mentioned information required for scanning can include information of the scanned object, such as one or more of gender, age, height, and weight. The above-mentioned scanning parameters may include one or more of a scanning position, a scanning sequence, a selected transmitting coil, a selected receiving coil, a scanning sequence, and the like.

[0022] The computer system 120 includes a plurality of modules that communicate with each other via electrical and / or data connection modules 122. The connection modules 122 may be wired communication links, fiber optic communication links, wireless communication links, etc. The computer system 120 may include a central processing unit (CPU) 124, a memory 126, and an image processor 128. In some embodiments, the image processor 128 may be replaced by image processing functions running in the CPU 124. The computer system 120 may be connected to an archival media device, a permanent or backup storage, or a network. The computer system 120 may be coupled to and communicate with a separate MR system controller 130.

[0023] The MR system controller 130 includes a set of modules that communicate with each other via an electrical and / or data connection module 132. The connection module 132 can be a direct wired communication link, a fiber optic communication link, a wireless communication link, etc. In an alternative embodiment, the modules of the computer system 120 and the MR system controller 130 can be implemented on the same computer system or multiple computer systems. The MR system controller 130 can include a CPU 131, a sequence pulse generator 133 that communicates with the operator workstation 110, a transceiver (or RF transceiver) 135, a gradient controller 136, a memory 137, and an array processor 139.

[0024] The magnetic resonance system 100 may include a resonance assembly 140 and a housing (not shown) for accommodating the resonance assembly 140. A subject 170 to be subjected to magnetic resonance scanning may be positioned within a cylindrical imaging volume 146 of the resonance assembly 140, the resonance assembly 140 including a superconducting magnet having a superconducting coil 144, a radio frequency coil assembly, and a gradient coil assembly 142. The superconducting coil 144 provides a static uniform longitudinal magnetic field B throughout the cylindrical imaging volume 146 during operation. 0 . The RF coil assembly may include a body coil 148 and a surface coil 149, which may be used to send and / or receive RF signals. The RF coil assembly may also include a local coil 143, such as a head coil. The gradient coil assembly 142 is arranged around the main magnet to form a part of the resonance assembly 140. Specifically, the gradient coil assembly 142 is arranged between the superconducting magnet and the RF coil assembly, and may include three groups of gradient coils arranged along the X-axis, Y-axis, and Z-axis of the magnetic resonance system, respectively.

[0025] The radio frequency body coil 148 and the local coil 143 may be connected to a switch (not shown in the figure), and the switch is controlled by the MR system controller 130 to switch the radio frequency body coil 148 and the local coil 143. In some embodiments, the body coil 148 or the local coil 143 may be selected for imaging based on confirmation of the scanning site. For example, when performing a whole body scan, the body coil 148 may be selected based on the operation of the switch, and when performing a local scan, the local coil 143 may be selected based on the operation of the switch. The local scan may include, for example, a head scan, an abdominal scan, or a scan of other body parts.

[0026] The MR system controller 130 may receive commands from the operator workstation 110 to indicate an MR scan sequence to be performed during an MR scan. The above-mentioned "scan sequence" refers to a combination of pulses with specific intensity, shape, timing, etc. applied when performing a magnetic resonance imaging scan, and these pulses may generally include, for example, radio frequency pulses and gradient pulses. The radio frequency pulses may include, for example, radio frequency excitation pulses, radio frequency refocusing pulses, inversion recovery pulses, etc. These radio frequency pulses may have different amplitudes, phases, flip angles, etc. based on their different effects. For different magnetic resonance systems, due to different hardware designs, the required radio frequency transmission power may be different in the same flip angle requirement. The gradient pulses may include, for example, gradient pulses for layer selection, gradient pulses for phase encoding, gradient pulses for frequency encoding, gradient pulses for phase offset (phase shift), gradient pulses for discrete phase (dephasing), etc., and these gradient pulses may also have different amplitudes and / or durations.

[0027] Generally, multiple scanning sequences can be pre-set in the magnetic resonance system so that a sequence that is compatible with clinical detection requirements can be selected, and the clinical detection requirements may include, for example, imaging site, imaging function, imaging effect, etc. For example, the scanning sequence can be determined according to the site to be imaged. For example, when the imaging site is determined to be the head, the human-computer interaction interface can provide a sequence list corresponding to the head scan, and can further determine a suitable sequence in the list based on clinically relevant settings.

[0028] The gradient pulses in the scanning sequence sent by the pulse generator 133 can be generated by the gradient controller 136 and act on the gradient driver 150, which includes a gradient amplifier and a corresponding gradient amplifier filter, such as Figure 1 G shown x , G y and G z Amplifier and corresponding filter. x , G y and G z The amplifiers are used to excite the above-mentioned X-axis gradient coil, Y-axis gradient coil and Z-axis gradient coil respectively. The pulse generator 133 can operate each gradient amplifier to achieve the desired timing and shape of the gradient pulses generated during scanning. Each gradient amplifier excites the corresponding gradient coil to generate a magnetic field gradient for spatial encoding of the acquired magnetic resonance signals. Specifically, the X-axis gradient coil is used to generate G x The frequency encoding gradient in the direction and the Y-axis gradient coil are used to generate G y The phase encoding gradient in the Z-axis is used to generate the G z The above-mentioned gradient driver 150 can be arranged in the equipment room. In the embodiment of the present invention, an improved gradient amplifier filter is provided to arrange part (e.g., each gradient amplifier) ​​or all of the gradient driver 150 in the scanning room, for example, integrated in the housing together with the resonance assembly 140.

[0029] The pulse generator 133 is coupled to and in communication with a scan room interface system 145, which can receive signals from various sensors associated with the state of the resonance assembly 140 and various processors disposed in the scan room. The scan room interface system 145 is also coupled to and in communication with a patient positioning system 147, which sends and receives signals to control the patient table to a desired position for MR scanning.

[0030] The scanning room interface system 145 may, for example, include a through-wall plate that passes through (or is embedded in) the wall of the scanning room. The through-wall plate may be used to set a gradient amplifier filter, which is used to filter the drive current generated by the gradient amplifier placed in the equipment room, so that the drive current with reduced noise interference can be provided to the gradient coil in the resonance assembly 140 via the cable in the scanning room, so as to excite the gradient coil to generate the required magnetic field gradient.

[0031] The RF pulses in the scanning sequence sent by the pulse generator 133 can be generated by the transceiver 135, and the RF pulses are amplified by the RF power amplifier 162. When the switch is switched to the body coil 148, the amplified RF pulses are provided to the body coil 148 via the transmit / receive switch (T / R switch) 164, and the RF body coil 148 then provides a transverse magnetic field B 1 , the transverse magnetic field B 1 The cylindrical imaging volume 146 is substantially perpendicular to B. 0 , the transverse magnetic field B 1 When the switch 141 is switched to the local coil 143, the amplified RF pulse is provided to the local coil 143, so that the local coil 143 provides a transverse magnetic field B. 1 .

[0032] Specifically, the RF signal generator of the transceiver 135 can generate a corresponding RF power signal based on the description of the RF pulse in a predetermined scanning sequence (for example, including one or more of amplitude, frequency, transmission power, characterization parameters for characterizing the transmission power, etc.), and the RF power signal is amplified by the RF power amplifier 162 to generate an RF power amplified signal, and the RF power amplified signal is provided to the RF body coil 148 or the local coil 143 via the RF power transmission module (for example, including the T / R switch 164).

[0033] As described above, the RF body coil 148, the local coil 143, and the RF surface coil 149 can be used to transmit radio frequency pulses and / or receive MR signals from the scanned object. The MR signals emitted by the nuclei excited in the scanned object can be sensed and received by the RF body coil 148, the local coil 143, or the RF surface coil 149 and sent back to the preamplifier 166 through the T / R switch 164. The T / R switch 164 can be controlled by a signal from the MR system controller 130 to electrically connect the radio frequency power amplifier 162 to the RF body coil 148 during the transmit mode, and to connect the preamplifier 166 to the RF body coil 148 during the receive mode. The T / R switch 164 can also enable the RF surface coil 149 and the local coil 143 to be used in the transmit mode or the receive mode.

[0034] In some embodiments, the MR signals sensed and received by the RF body coil 148, the local coil 143, or the RF surface coil 149 and amplified by the preamplifier 166 are demodulated, filtered, and digitized in the receiving portion of the transceiver 135 and transmitted to the memory 137 in the MR system controller 130 as a raw k-space data array.

[0035] Reconstructed magnetic resonance images can be acquired by transforming / processing the stored raw k-space data. For each image to be reconstructed, the data is rearranged into a separate k-space data array, and each of these separate k-space data arrays is input to an array processor 139, which is operated to Fourier transform the data into an array of image data.

[0036] The array processor 139 uses a transform method, most commonly a Fourier transform, to create images from the received MR signals. These images are transmitted to the computer system 120 and stored in the memory 126. In response to commands received from the operator workstation 110, the image data may be stored in long-term storage or may be further processed by the image processor 128 and transmitted to the operator workstation 110 for presentation on the display 118.

[0037] In various embodiments, components of computer system 120 and MR system controller 130 may be implemented on the same computer system or multiple computer systems. Figure 1 The MR system 100 shown is for illustration purposes. Suitable MR systems may include more, fewer, and / or different components.

[0038] The MR system controller 130 and the image processor 128 may include a computer processor and a storage medium, respectively or in common, on which a program for predetermined data processing to be executed by the computer processor is recorded, for example, the storage medium may store a program for implementing scanning processing (such as scanning procedures, imaging sequences, parameter determination, etc.), image reconstruction, image processing, etc. The above-mentioned storage medium may include, for example, a ROM, a floppy disk, a hard disk, an optical disk, a magneto-optical disk, a CD-ROM, or a non-volatile memory card.

[0039] As mentioned above, when the gradient amplifier and its connecting components (such as filters) are close to the main magnet, they may be affected by the main magnetic field and produce magnetic saturation. In addition, each gradient amplifier includes a topological structure of electronic switches (such as an H-bridge), and the on and off of these electronic switches are controlled by a PWM (Pulse Width Modulation) controller to generate the required gradient drive current. During the magnetic resonance scanning process, the above electronic switches are frequently switched to generate interference noise to the gradient drive current. Usually, the above interference noise is filtered out by setting a gradient filter. When considering setting the gradient amplifier in the scanning room or close to the main magnet and the gradient coil, more signal interference from the space or other functional components may be generated due to a more complex spatial arrangement, which causes problems other than magnetic saturation. For example, even if the problem of magnetic saturation is solved, the traditional filter cannot achieve the required filtering effect under such a spatial arrangement, which increases the difficulty of setting the gradient amplifier in the scanning room.

[0040] Figure 2 The schematic diagram of the structure of the magnetic resonance system of another embodiment of the present invention is shown. One or more gradient amplifiers 210 are arranged in the scanning room 201, specifically, in the space 250 defined by the housing 230 and the main magnet 240. Conventional magnetic resonance subcomponents, such as a radio frequency coil assembly 260 and a gradient coil assembly 270, may also be arranged in the space 250. The one or more gradient amplifiers 210 generate a gradient drive signal according to a received gradient control signal (the control signal is generated by a controller / control unit arranged in the equipment room or the scanning room, for example). The gradient drive signal is provided to the gradient coil assembly 260 after signal filtering by the gradient amplifier filter 300. A radio frequency control subsystem (for example, including one or more of a radio frequency signal generator, a radio frequency power amplifier, a preamplifier, a T / R switch, etc.) may also be further arranged in the space 250.

[0041] The gradient amplifier filter 300 is connected between the corresponding gradient amplifier 210 and the gradient coil of the gradient coil assembly 270 . Specifically, the gradient amplifier filter 300 includes an input terminal 301 connected to the gradient amplifier 210 and an output terminal 303 connected to the gradient coil.

[0042] In some embodiments, the gradient amplifier filter 300 is disposed in the scanning room, specifically, can be disposed near the main magnet 240, such as in the space 250. More specifically, the gradient amplifier filter 300 can be integrated with the corresponding gradient amplifier 210 (for example, disposed in an electronic device housing for accommodating the gradient amplifier 210).

[0043] The above-mentioned multiple embodiments of the gradient amplifier filter 300 will be combined with the following Figure 3-Figure 9 Provide detailed explanation.

[0044] like Figure 3 As shown, a gradient amplifier filter 300 according to an embodiment of the present invention includes a plurality of non-magnetic core inductors and a printed circuit board 330 having a multi-layer structure. A plurality of filter capacitors are formed in a plurality of regions of the printed circuit board 330, and each non-magnetic core inductor is arranged on the printed circuit board 330 across two of the plurality of filter capacitors.

[0045] Figure 3 FIG. 4 shows filter capacitors C1 to C6 formed in six regions 331 to 336 of a printed circuit board 330. Figure 3 Only the surface design of the printed circuit board 330 is shown, but it can be understood that the printed circuit board 330 has a certain thickness. Figure 3 As shown, a non-magnetic core inductor 311 is arranged between the filter capacitors C1 and C2, a non-magnetic core inductor 313 is arranged between the filter capacitors C2 and C3, a filter inductor 315 is arranged between the filter capacitors C4 and C5, and a filter inductor 317 is arranged between the filter capacitors C5 and C6. Experiments have shown that such a design can meet the size requirements of the spatial arrangement and achieve a good filtering effect. However, the overall size of the printed circuit board 330 can be changed, different numbers of filter capacitors and their arrangement methods can be set, or the area of ​​the region where each filter capacitor is located can be adjusted as needed.

[0046] The combination design of the non-magnetic core inductor and the printed circuit board avoids the magnetic saturation phenomenon caused by the traditional magnetic core inductor when it is close to the main magnetic field. As the frequency of the electric field increases, the filter capacitor can better maintain its capacitance, so that the gradient amplifier filter has a better frequency response and can be used under high-frequency conditions to meet the high-frequency filtering in magnetic resonance applications. Furthermore, when the gradient amplifier and the filter connected to the gradient amplifier are both arranged close to the main magnet, a low-noise driving signal can be provided to the gradient coil, thereby ensuring the effect and quality of magnetic resonance imaging.

[0047] In an embodiment of the present invention, the printed circuit board 330 includes stacked conductive layers, and a dielectric layer is provided between adjacent conductive layers, wherein the multiple conductive layers include multiple signal layers and multiple ground layers arranged at intervals, the multiple signal layers are connected together, each of the multiple signal layers includes multiple signal areas, and the multiple signal areas and the adjacent ground layers form the multiple filter capacitors.

[0048] Figure 4 A cross-sectional view showing an example of a printed circuit board 330 is shown. Figure 5The structure diagram of the signal layer of the printed circuit board 330 is shown. The printed circuit board includes four ground layers GND1-GND4 and four signal layers SIG1-SIG4. The four ground layers and the four signal layers are stacked in sequence, and a dielectric layer 410 is provided between each adjacent signal layer and ground layer. The design method of each signal layer is similar to that of the first signal layer. Figure 3 The surface design shown is consistent, that is, the signal area on each signal layer (such as signal areas 511-516) is consistent with Figure 3 The number, size and position of the six regions 331-336 shown are the same, that is, the signal regions on all signal layers overlap in a direction perpendicular to the printed circuit board 330, and the signal regions of all signal layers are connected by vias, which may include, for example Figure 3 The vias 338 in the six regions of the filter inductor can be connected to the filter capacitor at one end through the pad connected to the via 338. For example, an example of the via 338 is also shown in FIG. Figure 4 Shown in the cross-sectional view shown.

[0049] In this way, when all signal layers are stacked, the corresponding multiple signal areas together form an independent capacitor structure. For example, all signal areas 511 on the signal layers SIG1-SIG4 (and the adjacent ground layers and the dielectric layers therebetween) form an area 331 extending in the vertical direction to form a capacitor C1. Correspondingly, all signal areas 512 on the signal layers SIG1-SIG4 (and the adjacent ground layers and the dielectric layers therebetween) form an area 332 extending in the vertical direction to form a capacitor C2, and so on.

[0050] More specifically, each signal area on the stacked signal layer forms a plurality of stacked capacitors with the adjacent ground layer, and the plurality of stacked capacitors are connected in parallel to form a filter capacitor. For example, in area 331 of the printed circuit board 330, the signal layer SIG1 and the ground layer GND1 form a first parallel capacitor, the signal layer SIG2 and the ground layer GND1 form a second parallel capacitor, the signal layer SIG2 and the ground layer GND2 form a third parallel capacitor, the signal layer SIG3 and the ground layer GND2 form a fourth parallel capacitor, the signal layer SIG3 and the ground layer GND3 form a fifth parallel capacitor, the signal layer SIG4 and the ground layer GND3 form a sixth parallel capacitor, and the signal layer SIG4 and the ground layer GND4 form a seventh parallel capacitor. The first to seventh parallel capacitors together form capacitor C1. Similarly, other capacitors C2-C6 are formed on the printed circuit board in a similar manner.

[0051] The plurality of signal regions of each signal layer are insulated from each other. Figure 3For example, in each signal layer, in regions 511-516, insulating materials are provided between adjacent signal regions to form insulating spaces 520. In one embodiment, the insulating material may be the same as the material of the dielectric layer 410, and the material may include RF-4, whose dielectric constant is generally between 4.2 and 4.7, or other insulating materials that can be used for printed circuit boards.

[0052] like Figure 3 As shown, each signal layer is also formed with a grounding area 530, and the grounding area 530 of each signal layer is formed around the signal area on the signal layer and is insulated from each signal area. Specifically, the grounding area 530 of each signal layer is electrically connected to the adjacent grounding layer, which is convenient for realizing the equivalent design of capacitor grounding. Such electrical connection can also be realized by, for example, vias passing through the grounding area 530 and each grounding layer.

[0053] like Figure 3 As shown, in the embodiment of the present invention, the plurality of filter capacitors include a plurality of first capacitors (such as Figure 3 C1-C3 in the figure) and multiple second capacitors formed in parallel (such as Figure 3 C4-C6 in the figure), the printed circuit board has a symmetrical first part and a second part, the first part includes the plurality of first capacitors, the second part includes the plurality of second capacitors, the plurality of first capacitors and the plurality of second capacitors are opposite to each other, one of the plurality of non-magnetic core inductors is arranged between two adjacent first capacitors, and one of the plurality of non-magnetic core inductors is arranged between two adjacent second capacitors. In this way, the following is achieved: Figure 6 The equivalent circuit 600 shown in the figure includes capacitors C11-C16 and inductors L1-L4, wherein the capacitors C11-C16 are equivalent to the above-mentioned capacitors C1-C6, respectively, and the inductors L1-L4 are equivalent to the non-magnetic core inductors 311, 313, 315 and 317, respectively. When the amplifier filter is connected to the gradient amplifier of the magnetic resonance system, the output end of the gradient amplifier is connected to the ungrounded end of the capacitors C1 and C4 (i.e., the corresponding signal area of ​​the signal layer, equivalent to the positive input Input+ and the negative input Input-) or one end of the non-magnetic core inductors 311 and 315 coupled thereto, and the ungrounded end of the capacitors C3 and C6 (i.e., the corresponding signal area of ​​the signal layer, equivalent to the positive output Output+ and the negative output Output-) or one end of the non-magnetic core inductors 313 and 317 coupled thereto are connected to the corresponding gradient coil.

[0054] In an embodiment of the present invention, the areas of the multiple first capacitors are different, and the areas of the multiple second capacitors are different. In this way, when the layer thickness, material, etc. of the printed circuit board are fixed, the required capacitance parameters can be achieved by designing the area of ​​the signal area, thereby achieving the parameter requirements of the amplifier filter, which include, for example, the range of the filter's operating frequency.

[0055] In an embodiment of the present invention, the distances between adjacent capacitors may be different, so that when the layer thickness, material, signal area, etc. of the printed circuit board are fixed, the parameter requirements of the amplifier filter can be achieved by designing the spacing between adjacent signal areas. For example, the distance between two adjacent first capacitors may be different, and the distance between two adjacent second capacitors may be different.

[0056] In an embodiment of the present invention, each non-magnetic core inductor may be an air-core inductor, such as a spiral tube air-core inductor without a ferromagnetic core, which includes a spiral tube conductive coil, which may be as follows: Figure 7 The air core inductor may also include a flat point coil, such as Figure 8 The winding is shown to form a mosquito coil-shaped structure. The above two inductors can help reduce the size of the amplifier filter, reduce the space occupied by the filter, and make the installation position more flexible.

[0057] In an embodiment of the present invention, the two ends of each non-magnetic core inductor are respectively fixed by screws in the area where two of the multiple filter capacitors are located. Taking the non-magnetic core inductor 311 as an example, one end thereof is fixed in the area 331 (filter capacitor C1) of the printed circuit board by a first screw, and the other end is fixed in the area 332 (filter capacitor C2) of the printed circuit board by a second screw.

[0058] Specifically, a via hole 338 for cooperating with the screw is provided in the area where each filter capacitor is located on the printed circuit board, and the via hole passes through the multiple conductive layers and the multiple dielectric layers. An insulating area surrounding the hole is provided on each ground layer, and the insulating area extends outward from the hole wall of the via hole. Fig. 9 For example, each of the six regions of the printed circuit board 330 is provided with a hole 350. In each ground layer, each hole 350 is surrounded by an insulating region 360 formed of an insulating material to isolate the hole 350 from the conductive region to avoid signal crosstalk. The hole 350 may be Figure 3 , Figure 4 Via 338 in.

[0059] In other embodiments, the non-magnetic core inductor may also be soldered to a pad on a printed circuit board to form an electrical coupling structure.

[0060] In an embodiment of the present invention, a plurality of filter capacitors are formed by setting up areas on a printed circuit board, and a filter is formed by placing each non-magnetic core inductor between two capacitors, so that magnetic saturation is avoided when the filter is set close to the main magnet, and the filter can be used under high-frequency conditions. Moreover, compared with the existing gradient amplifier filter, the volume, weight and cost are greatly reduced.

[0061] Fig.10 , Fig.11 Schematic diagrams of performing attenuation test on the gradient amplifier filter of the embodiment of the present invention are respectively shown, wherein Fig.10 shows the common mode attenuation test results, Fig.11 shows the differential mode attenuation test results, in Fig.10 and Fig.11 In FIG. 1 , the horizontal axis represents frequency, and the vertical axis shows amplitude and phase, respectively. According to the test results, the gradient amplifier filter of the present invention has a good frequency response, and the signal attenuation at the main magnetic field frequency of the magnetic resonance application (for example, around 63.8 MHz and 128 MHz) is relatively low.

[0062] In addition to any previously indicated modifications, numerous other variations and alternative arrangements may be devised by those skilled in the art without departing from the spirit and scope of the present description, and the appended claims are intended to cover such modifications and arrangements. Therefore, although the information has been described above in detail in conjunction with what are currently considered to be the most practical and preferred aspects, it will be apparent to those of ordinary skill in the art that many modifications may be made, including but not limited to form, function, mode of operation, and use, without departing from the principles and concepts set forth herein. Likewise, as used herein, examples and embodiments are intended to be illustrative in all respects only and should not be construed as limiting in any way.

[0063] The purpose of providing the above specific embodiments is to make the understanding of the disclosure of the present invention more thorough and comprehensive, but the present invention is not limited to these specific embodiments. It should be understood by those skilled in the art that various modifications, equivalent substitutions and changes, etc., may also be made to the present invention, as long as these changes do not violate the spirit of the present invention, they should all be within the protection scope of the present invention.

Claims

1. A gradient amplifier filter for a magnetic resonance system, comprising: Multiple non-core inductors; as well as, A printed circuit board with a multi-layer structure has a plurality of filter capacitors formed in a plurality of regions of the printed circuit board, wherein each non-magnetic core inductor is arranged on the printed circuit board across two of the plurality of filter capacitors.

2. The gradient amplifier filter according to claim 1, characterized in that The printed circuit board includes multiple stacked conductive layers, with a dielectric layer provided between adjacent conductive layers, wherein the multiple conductive layers include multiple signal layers and multiple ground layers arranged at intervals, the multiple signal layers are connected together, each of the multiple signal layers includes multiple signal areas to form the multiple filter capacitors with the adjacent ground layers, and the multiple signal areas of each signal layer are insulated from each other.

3. The gradient amplifier filter according to claim 2, characterized in that Each signal layer is further formed with a grounding region, and the grounding region of each signal layer is formed around the signal region on the signal layer and is insulated from the signal region.

4. The gradient amplifier filter according to claim 3, characterized in that The ground region of each signal layer is electrically connected to an adjacent ground layer.

5. The gradient amplifier filter according to claim 1, characterized in that: The multiple filter capacitors include multiple first capacitors formed side by side and multiple second capacitors formed side by side. The printed circuit board has a symmetrical first part and a second part. The first part includes the multiple first capacitors, and the second part includes the multiple second capacitors. The multiple first capacitors and the multiple second capacitors are opposite to each other one by one. One of the multiple non-magnetic core inductors is arranged between two adjacent first capacitors, and one of the multiple non-magnetic core inductors is arranged between two adjacent second capacitors.

6. The gradient amplifier filter according to claim 2, characterized in that: The areas of the plurality of first capacitors are different, and the areas of the plurality of second capacitors are different.

7. The gradient amplifier filter according to claim 2, characterized in that: The distance between each two adjacent first capacitors is different, and the distance between each two adjacent second capacitors is different.

8. The gradient amplifier filter according to claim 2, characterized in that Two ends of each non-magnetic core inductor are fixed to the region where two of the plurality of filter capacitors are located by screws.

9. The gradient amplifier filter according to claim 8, characterized in that A via hole for cooperating with the screw is provided in the area where each filter capacitor is located on the printed circuit board, and the via hole passes through the multiple conductive layers and the multiple dielectric layers. An insulating area surrounding the via hole is provided on each grounding layer, and the insulating area extends outward from the hole wall of the via hole.

10. The gradient amplifier filter according to claim 1, characterized in that: Each non-core inductor is an air-core inductor.

11. The gradient amplifier filter according to claim 1, characterized in that: Each non-core inductor includes a flat conductive coil or a toroidal conductive coil.

12. The gradient amplifier filter according to claim 1, characterized in that The filter is electrically connected to a gradient amplifier of the magnetic resonance system and is disposed together with the gradient amplifier in a magnet housing of the magnetic resonance system.

13. A magnetic resonance system, comprising: a magnet housing in which a main magnet, gradient coils and a gradient amplifier are arranged; as well as, The gradient amplifier filter according to any one of claims 1 to 12, wherein the filter comprises an input end connected to the gradient amplifier and an output end connected to the gradient coil.

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