Passive shim layer and magnetic resonance imaging apparatus

Abstract

This invention relates to a passive shimming layer and a magnetic resonance imaging (MRI) device. The passive shimming layer includes a support assembly, a shimming strip assembly, and a fixing assembly. The support assembly includes an elastic element and multiple support strips, which are sequentially fixed to the inner wall of a main magnet along a circumferential direction. The elastic element has an arc-shaped structure and is disposed on the inner side of the multiple support strips, so that an elastic cavity is formed between two adjacent support strips, the elastic element, and the main magnet. The shimming strip assembly is inserted into the elastic cavity. By setting the elastic element and support strips, an elastic cavity is formed between two adjacent support strips, the elastic element, and the inner wall of the main magnet. During installation, the shimming strip assembly only needs to be inserted into the elastic cavity, and the elastic element will press the shimming strip assembly tightly against the inner wall of the main magnet, thereby ensuring that the shimming strip assembly is firmly fixed within the elastic cavity, reducing vibration of the shimming strip assembly and improving imaging quality.

Description

Technical Field

[0001] This invention relates to the field of magnetic resonance imaging technology, and in particular to a passive shimming layer and a magnetic resonance imaging device. Background Technology

[0002] Magnetic Resonance Imaging (MRI) is a medical imaging technique that utilizes the magnetic resonance phenomenon. Its basic principle is that when a subject is placed in a special magnetic field, the hydrogen atoms within the body are polarized. Radio frequency pulses excite the hydrogen nuclei, causing them to resonate and absorb energy. After the radio frequency pulses cease, the hydrogen nuclei emit radio signals at a specific frequency, releasing the absorbed energy. These signals are then received and processed by an external receiver to obtain an image.

[0003] Magnetic resonance imaging (MRI) equipment typically includes a main magnet, gradient coils, and a passive shimming layer. An aperture is formed within the main magnet, and the gradient coils and passive shimming layer are both housed within this aperture. The main magnet generates a uniform magnetic field. The gradient coils generate a linearly distributed gradient magnetic field in space. The passive shimming layer improves the uniformity of the main magnetic field.

[0004] In existing technologies, a shimming hole extending along the axial direction is typically provided inside the gradient coil, and a shimming strip is installed in the shimming hole. However, since the shimming strip is generally installed in the shimming hole by insertion, the size of the shimming hole is larger than the size of the shimming strip to facilitate insertion. This results in the shimming strip not being able to be firmly secured after insertion, and under the influence of the magnetic field, it will vibrate or even deform, thus affecting the imaging quality. Summary of the Invention

[0005] Based on this, it is necessary to propose a passive shimming layer and magnetic resonance imaging device to address the problem that the shimming strip cannot be firmly fixed after insertion, thus affecting the imaging quality.

[0006] A passive shim layer, comprising:

[0007] A support assembly includes an elastic element and multiple support bars. The multiple support bars are sequentially fixed to the inner wall of the main magnet at intervals along a circumferential direction. The elastic element has an arc-shaped structure and is disposed on the inner side of the multiple support bars, so that an elastic cavity is formed between adjacent support bars, the elastic element, and the main magnet; and

[0008] A field shim assembly is inserted into the elastic cavity, and the elastic element is used to press the field shim assembly against the inner wall of the main magnet.

[0009] In one embodiment, the elastic element includes a plurality of elastic units arranged sequentially on each of the support bars along the axial direction of the main magnet, with at least one end of each elastic unit extending beyond the support bar.

[0010] In one embodiment, the two ends of the elastic unit extend out of the support bar, and the ends of the elastic units on two adjacent support bars are close to each other.

[0011] In one embodiment, along the insertion direction of the shimming strip assembly, the end of the elastic unit extending beyond the support strip is provided with a guide angle;

[0012] The shimming strip assembly has an insertion end that is first inserted into the elastic cavity, and the thickness of the insertion end gradually increases from both sides near the support strip to the center away from the support strip.

[0013] In one embodiment, a plurality of the elastic elements on the same support bar are connected to each other along the axial direction of the main magnet.

[0014] In one embodiment, multiple elastic elements located on the same circumference are connected to each other.

[0015] In one embodiment, the shimming strip assembly has an insertion end that is first inserted into the elastic cavity, and the thickness of the insertion end gradually decreases along the insertion direction of the shimming strip assembly.

[0016] In one embodiment, at least one of the plurality of support bars is a first support bar, and at least one of the plurality of support bars is a second support bar, wherein the cross-sectional dimension of the first support bar is larger than the cross-sectional dimension of the second support bar.

[0017] In one embodiment, the passive shimming layer further includes a fixing component disposed at one end of the support component, and the end of the shimming strip component is connected to the fixing component.

[0018] A magnetic resonance imaging device, including

[0019] The main magnet has an axially penetrating aperture through the main magnet;

[0020] A passive shimming layer is disposed within the aperture and fixedly connected to the inner wall of the main magnet. The passive shimming layer includes a support assembly and a shimming strip assembly. The support assembly includes an elastic element and multiple support strips, which are sequentially fixed to the inner wall of the main magnet at intervals along the circumferential direction. The elastic element has an arc-shaped structure and is disposed on the inner side of the multiple support strips, so that an elastic cavity is formed between two adjacent support strips, elastic elements, and the main magnet. The shimming strip assembly is inserted into the elastic cavity, and the elastic element is used to press the shimming strip assembly tightly against the inner wall of the main magnet.

[0021] The gradient coil is disposed within the cavity enclosed by the passive shimming layer.

[0022] The aforementioned passive shimming layer and magnetic resonance imaging device, through the inclusion of elastic elements and support bars, forms an elastic cavity between adjacent support bars, elastic elements, and the inner wall of the main magnet. During installation, the shimming bar assembly only needs to be inserted into the elastic cavity, and the elastic elements will press the shimming bar assembly firmly against the inner wall of the main magnet, thereby securing the shimming bar assembly within the elastic cavity. This reduces vibration of the shimming bar assembly and improves imaging quality. Attached Figure Description

[0023] Figure 1 This is a schematic diagram of the cross-sectional structure of a magnetic resonance imaging device in one embodiment;

[0024] Figure 2 This is a schematic diagram of the structure of a magnetic resonance imaging device;

[0025] Figure 3 This is a schematic diagram of the structure of the first and second support bars;

[0026] Figure 4 This is a schematic diagram of the structure of the uniform field strip assembly;

[0027] Figure 5 A schematic diagram of the structure when the field shim assembly is inserted into the field shim assembly;

[0028] Figure 6 This is a structural diagram showing the fixed component being mounted on the support component.

[0029] Figure 7 This is a schematic diagram of the structure of the elastic element in one embodiment;

[0030] Figure 8 This is a schematic diagram of the elastic element in another embodiment;

[0031] Figure 9 This is a schematic diagram of the elastic element in other embodiments.

[0032] Figure labels: 10-Main magnet; 20-Passive homogenizing layer; 30-Gradient coil;

[0033] 100-Support assembly; 110-Elastic element; 120-Elastic unit; 121-Guide angle; 130-Support bar; 140-First support bar; 141-First support base; 1411-Threaded hole; 142-First body; 150-Second support bar; 151-Second support base; 152-Second body; 160-Elastic cavity;

[0034] 200 - Shimming bar assembly; 220 - Main shimming bar; 221 - Insertion end; 222 - Mounting hole; 230 - Secondary shimming bar;

[0035] 300 - Fixing component; 310 - Arc-shaped structure; 320 - Screw. Detailed Implementation

[0036] To make the above-mentioned objects, features, and advantages of the present invention more apparent and understandable, specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings. Many specific details are set forth in the following description to provide a thorough understanding of the present invention. However, the present invention can be practiced in many other ways different from those described herein, and those skilled in the art can make similar modifications without departing from the spirit of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below.

[0037] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," and "circumferential" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0038] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this invention, "a plurality of" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0039] In this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components, unless otherwise explicitly limited. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0040] In this invention, unless otherwise explicitly specified and limited, "above" or "below" the second feature can mean that the first feature is in direct contact with the second feature, or that the first feature is in indirect contact with the second feature through an intermediate medium. Furthermore, "above," "over," and "on top" of the second feature can mean that the first feature is directly above or diagonally above the second feature, or simply that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature can mean that the first feature is directly below or diagonally below the second feature, or simply that the first feature is at a lower horizontal level than the second feature.

[0041] It should be noted that when an element is referred to as being "fixed to" or "set on" another element, it can be directly on the other element or there may be an intervening element. When an element is considered to be "connected to" another element, it can be directly connected to the other element or there may be an intervening element. The terms "vertical," "horizontal," "upper," "lower," "left," "right," and similar expressions used herein are for illustrative purposes only and do not represent the only possible implementation.

[0042] See Figure 1 and Figure 2 An embodiment of the present invention provides a passive shimming layer 20, which is disposed within the aperture of a main magnet 10. The passive shimming layer 20 includes a support assembly 100 and a shimming strip assembly 200. The support assembly 100 includes an elastic element 110 and a plurality of support strips 130. The plurality of support strips 130 are sequentially fixed at intervals along the circumferential direction on the inner wall of the main magnet 10. The elastic element 110 is disposed on the inner side of the plurality of support strips 130, so that an elastic cavity 160 is formed between two adjacent support strips 130, the elastic element 110, and the main magnet 10. The shimming strip assembly 200 is inserted into the elastic cavity 160, and the elastic element 110 is used to press the shimming strip assembly 200 against the inner wall of the main magnet 10.

[0043] In this embodiment, by setting up elastic element 110 and support bar 130, an elastic cavity 160 is formed between two adjacent support bars 130, elastic element 110 and inner wall of main magnet 10. During installation, the shimming bar assembly 200 only needs to be inserted into the elastic cavity 160. The elasticity of the elastic element 110 will press the shimming bar assembly 200 against the inner wall of main magnet 10, thereby allowing the shimming bar assembly 200 to be firmly fixed in the elastic cavity 160, which helps to reduce the vibration of the shimming bar assembly 200 and improve imaging quality.

[0044] In some embodiments, combined with Figure 3 The elastic element 110 includes a plurality of elastic units 120. Along the axial direction of the main magnet 10, a plurality of elastic units 120 are arranged sequentially on each support bar 130. At least one end of the elastic unit 120 extends out of the support bar 130 to press the shimming bar assembly 200 against the inner wall of the main magnet 10.

[0045] In this embodiment, the distance between the elastic unit 120 and the main magnet 10 in its natural state can be less than the thickness of the field stabilizing bar assembly 200 along the radial direction of the main magnet 10. That is, when the field stabilizing bar assembly 200 is inserted into the elastic cavity 160, the elastic unit 120 exerts a certain squeezing effect on the field stabilizing bar assembly 200, thereby enabling the field stabilizing bar assembly 200 to be fastened. By sequentially arranging multiple elastic units 120 along the axial direction of the main magnet 10, for example, five elastic units 120 are evenly spaced on each support bar 130 along the axial direction of the main magnet 10, the entire field stabilizing bar assembly 200 can be fastened along its length, thereby effectively reducing the vibration of the field stabilizing bar assembly 200.

[0046] In some embodiments, combined Figure 5 The two ends of the elastic unit 120 extend out of the support bar 130 respectively, and the ends of the elastic units 120 on two adjacent support bars 130 approach each other to press the shimming bar assembly 200 against the inner wall of the main magnet 10 from both sides of the shimming bar assembly 200 respectively.

[0047] In this embodiment, the elastic unit 120 can be a strip structure with an arc. The length direction of the elastic unit 120 is perpendicular to the length direction of the support strip 130, and the two ends of the elastic element 110 extend out of the support strip 130 respectively. That is, the elastic elements 110 on two adjacent support strips 130 can be used to press the shimming strip assembly 200 against the inner wall of the main magnet 10 from both sides of the shimming strip assembly 200, thereby enhancing the pressing effect on the shimming strip.

[0048] Furthermore, in combination Figure 3 and Figure 5Along the insertion direction OA of the uniform strip assembly 200, the end of the elastic unit 120 extending beyond the support strip 130 is provided with a guide angle 121. Combined with... Figure 4 The field shim assembly 200 has an insertion end 221 that is first inserted into the elastic cavity 160. Along the circumference of the main magnet 10, the thickness of the insertion end 221 gradually increases from both sides near the support bar 130 to the center away from the support bar 130.

[0049] In this embodiment, when the field leveling strip assembly 200 is inserted, the insertion end 221 first contacts the guide angle 121. The thickness of the insertion end 221 gradually increases from the sides near the support strip 130 towards the center away from the support strip 130. That is, the insertion end 221 is inserted first from the bottom of the elastic unit 120 near the thinner sides of the support strip 130. Simultaneously, due to the guide angle 121, the field leveling strip assembly 200 can gradually extend to the bottom of the elastic unit 120, thereby gradually lifting the end of the elastic unit 120. Furthermore, along the extension direction of the elastic unit 120, the deformation of the end of the elastic unit 120 gradually increases; that is, the deformation at points a, b, c, and d in the figure increases sequentially.

[0050] The elastic unit 120 is made of a highly elastic material, which can provide a certain rebound force to maintain deformation when compressed, so as not to cause structural failure. The elastic unit 120 is provided with a guide angle 121. When the field uniform strip assembly 200 is inserted, it can gradually push up the elastic unit 120 along the direction of the guide angle 121 without collision interference, so as to smoothly insert the field uniform strip assembly 200.

[0051] In some other embodiments, one end of the elastic unit extends beyond the support bar, and the elastic unit extends from one side of the shimming bar assembly along the circumference of the main magnet to press the shimming bar assembly.

[0052] In other embodiments, one end of the elastic unit may extend beyond the support bar, and some of the elastic units on the same support bar may extend clockwise along the circumference of the main magnet, while other elastic units may extend counterclockwise along the circumference of the main magnet.

[0053] In some embodiments, combined with Figure 2 and Figure 4 The field leveling strip assembly 200 has an insertion end 221 that is first inserted into the elastic cavity 160. Along the insertion direction OA of the field leveling strip assembly 200, the thickness of the insertion end 221 gradually decreases. That is, when the field leveling strip assembly 200 is inserted, it first enters the bottom of the elastic unit 120 through the thinner end, and then, as the field leveling strip assembly 200 is inserted, it gradually pushes up the elastic unit 120, thereby enabling the field leveling strip assembly 200 to be inserted quickly.

[0054] In some embodiments, combined with Figure 4 and Figure 5 The shimming strip assembly 200 includes a main shimming strip 220 and at least two secondary shimming strips 230. Secondary shimming strips 230 are respectively provided on both sides of the main shimming strip 220. The cross-sectional dimensions of the main shimming strip 220 are different from those of the secondary shimming strips 230.

[0055] Among them, the primary shimming strip 220 has a greater impact on the magnetic field, while the secondary shimming strip 230 has a smaller impact. Different primary shimming strips 220 and secondary shimming strips 230 contain different amounts of magnetic material. In actual use, the uniformity of the magnetic field can be achieved to the expected standard by adjusting and replacing different primary shimming strips 220 and secondary shimming strips 230. The shimming strip assembly 200 may include one primary shimming strip 220 and at least two secondary shimming strips 230.

[0056] The specific number of secondary shimming strips 230 can be set according to the actual shimming needs, and there is no specific limitation here. For example, there can be one main shimming strip 220 and three secondary shimming strips 230, with the three secondary shimming strips 230 all located on one side of the main shimming strip 220 along the circumference of the main magnet 10.

[0057] Furthermore, the shimming strip assembly 200 includes a main shimming strip 220 and two secondary shimming strips 230, with the two secondary shimming strips 230 located on both sides of the main shimming strip 220. One end of the main shimming strip 220 and the secondary shimming strips 230 each has an insertion end 221. The insertion end 221 of the main shimming strip 220 has a T-shaped structure, while the insertion end 221 of the secondary shimming strips 230 has a strip-shaped structure, with the end of the strip-shaped structure abutting against the T-shaped structure.

[0058] In actual installation, the main uniform field strip 220 is first inserted into the elastic cavity 160, and then the secondary uniform field strips 230 are installed from both sides of the main uniform field strip 220. The insertion end 221 of the main uniform field strip 220 has a T-shaped structure. Along the circumference of the main magnet 10, the support strips 130 on both sides of the main uniform field strip 220 can limit the symmetrical ends of the T-shaped structure, thereby preventing the main uniform field strip 220 from bending under the action of gravity, which would cause the main uniform field strip 220 to squeeze the installation space of the secondary uniform field strip 230 and make the installation of the secondary uniform field strip 230 difficult.

[0059] Specifically, the insertion end 221 of the main shimming bar 220 gradually decreases in thickness along the insertion direction OA of the shimming bar assembly 200; simultaneously, the thickness of the insertion end 221 of the main shimming bar 220 gradually increases from both sides near the support bar 130 to the center away from the support bar 130 along the circumferential direction of the main magnet 10. The insertion end 221 of the secondary shimming bar 230 contracts inward along both the circumferential and axial directions of the main magnet 10 to form a certain taper, facilitating rapid insertion into the support bar 130.

[0060] It should be noted that the main uniform field strip 220 includes a housing and multiple magnetic materials disposed within the housing. The magnetic materials located within the housing are used to influence the magnetic field. The changes in the shape and structure of the insertion end 221 mentioned above refer to changes in the shape and structure of the housing, and therefore will not affect the performance of the main uniform field strip 220.

[0061] In other embodiments, the shimming bar assembly 200 may include only at least one main shimming bar 220, and the uniformity of the magnetic field may be adjusted only by setting the main shimming bar 220.

[0062] In some other embodiments, the shimming bar assembly 200 may include only at least one secondary shimming bar 230, and the uniformity of the magnetic field may be adjusted only by setting the secondary shimming bar 230.

[0063] In some embodiments, combined with Figure 3 At least one of the multiple support bars 130 is a first support bar 140, and at least one of the multiple support bars 130 is a second support bar 150. The cross-sectional dimension of the first support bar 140 is larger than the cross-sectional dimension of the second support bar 150.

[0064] Specifically, the first support bar 140 includes a first support base 141 and a first support body 142 disposed on the first support base 141. The first support body 142 and the first support base 141 form a T-shape. An elastic unit 120 is disposed at the end of the first support body 142 away from the first support base 141. The first support base 141 is used for fixed connection with the inner wall of the main magnet 10. The first support body 142 is used to increase the mounting area of ​​the elastic unit 120 so that the elastic unit 120 can be stably connected. The second support bar 150 includes a second support base 151 and a second support body 152 disposed on the second support base 151. The second support body 152 and the second support base 151 form a T-shape. The elastic unit 120 is disposed at the end of the second support body 152 away from the second support base 151. The second support base 151 is used for fixing to the inner wall of the main magnet 10. The first support base 141 and the second support base 151 can be fixed to the inner wall of the main magnet 10 by welding.

[0065] Since the gradient coil 30 is disposed within the cavity enclosed by the passive shimming layer 20, the first support base 141 and the second support base 151 need to provide certain support for the gradient coil 30. The larger cross-section of the first support base 141 effectively supports the gradient coil 30, while the smaller cross-section of the second support base 151 increases the volume of the elastic cavity 160, facilitating the accommodation of more shimming strips. Furthermore, by using the first support strip 140 and the second support strip 150 with different cross-sectional dimensions, different arrangements and combinations of the first support strip 140 and the second support strip 150 can accommodate main magnets 10 with different apertures.

[0066] In some embodiments, combined with Figure 2 and Figure 6 The passive shimming layer 20 also includes a fixing component 300, which is disposed at one end of the support component 100, and the end of the shimming strip component 200 is connected to the fixing component 300.

[0067] Specifically, in combination Figure 4 and Figure 6 The main uniform field strip 220 and the secondary uniform field strip 230 each have mounting holes 222 at their ends furthest from the insertion end 221, for mounting to the fixing assembly 300 using screws 320. Figure 3 and Figure 6 One end of the first support base 141 is provided with a threaded hole 1411 for fixing the fixing component 300 to the first support base 141 by screws 320.

[0068] Furthermore, the fixing component 300 includes multiple arc-shaped structures 310.

[0069] Specifically, the exact number of arc-shaped structures 310 is determined based on the actual arrangement and quantity of the field uniformity strip components 200, as well as the installation process. For example, in actual use, the fixing component 300 may include three or four arc-shaped structures 310; no specific limitation is made here. 。

[0070] In one embodiment, multiple arc-shaped structures 310 can be connected end to end with screws to form a complete ring. Compared with directly setting the fixing component 300 as a whole circle, multiple arc-shaped structures 310 can eliminate the cumulative error of welding assembly, reduce the welding assembly requirements of the support component 100, and also increase the strength and elasticity of the arc-shaped structure 310.

[0071] In another embodiment, multiple arc-shaped structures 310 may be arranged at intervals, as long as the arc-shaped structures 310 connect the support component 100 and the uniform strip component 200 to fix the uniform strip component 200.

[0072] In some embodiments, combined with Figure 7 Multiple elastic units 120 on the same support bar 130 are connected to each other along the axial direction of the main magnet 10 to form an elastic element 110. That is, the elastic element 110 is a strip-shaped structure provided on the support bar 130, and the length direction of the elastic element 110 is the same as the length direction of the support bar 130. The elastic element 110 has an arc-shaped structure, and the end of the elastic element 110 is provided with a guide angle 121 to facilitate the insertion of the field uniform bar assembly 200. At the same time, the elastic unit 120 can also realize the compression of the field uniform bar.

[0073] In other embodiments, combined with Figure 1 and Figure 8 Multiple elastic units 120 located on the same circumference of the main magnet 10 are connected to each other to form an elastic element 110. For example, each support bar 130 is provided with five elastic units 120 evenly spaced along the axial direction of the main magnet 10. The first elastic unit 120 on each support bar 130 can be connected in sequence to form a ring structure. The elastic element 110 of the ring structure can also achieve the pressing of the field uniform bar assembly 200.

[0074] In other embodiments, combined with Figure 9 Alternatively, all the elastic units 120 can be interconnected. For example, a single thin steel plate can be used instead of the elastic unit 120. After the support bar 130 is welded, the thin steel plate is welded onto the support bar 130. One end of the thin steel plate is provided with a guide angle to facilitate the insertion of the field uniform bar assembly 200.

[0075] An embodiment of the present invention also discloses a magnetic resonance imaging device, including a main magnet 10, a passive shimming layer 20, and a gradient coil 30. The main magnet 10 has an aperture penetrating the main magnet 10 along the axial direction. The passive shimming layer 20 is disposed within the aperture and is fixedly connected to the inner wall of the main magnet 10. The gradient coil 30 is disposed within the cavity enclosed by the passive shimming layer 20.

[0076] The passive shimming layer 20 includes a support assembly 100, a shimming strip assembly 200, and a fixing assembly 300. The support assembly 100 includes an elastic element 110 and multiple support strips 130. The multiple support strips 130 are fixed to the inner wall of the main magnet 10 at intervals along the circumferential direction. The elastic element 110 is arranged in an arc shape on the inner side of the multiple support strips 130, so that an elastic cavity 160 is formed between two adjacent support strips 130, the elastic element 110, and the main magnet 10. The shimming strip assembly 200 is inserted into the elastic cavity 160, and the elastic element 110 is used to press the shimming strip assembly 200 against the inner wall of the main magnet 10. The fixing assembly 300 is disposed at one end of the support assembly 100, and the end of the shimming strip assembly 200 is connected to the fixing assembly 300.

[0077] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0078] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these all fall within the protection scope of the present invention. Therefore, the protection scope of this invention patent should be determined by the appended claims.

Claims

1. A passive shim layer (20) characterized by, For setting within the aperture of the main magnet (10), including: A support assembly (100) includes an elastic element (110) and a plurality of support bars (130). The plurality of support bars (130) are sequentially fixed at intervals along the circumferential direction to the inner wall of the main magnet (10). The elastic element (110) is disposed inside the plurality of support bars (130), such that an elastic cavity (160) is formed between two adjacent support bars (130), the elastic element (110), and the main magnet (10). The elastic element (110) includes a plurality of elastic units (120). Along the axial direction of the main magnet (10), a plurality of elastic units (120) are sequentially arranged on each support bar (130), and at least one end of each elastic unit (120) extends beyond the support bar (130). A field shim assembly (200) is inserted into the elastic cavity (160), and the elastic element (110) is used to press the field shim assembly (200) against the inner wall of the main magnet (10); Along the insertion direction of the uniform strip assembly (200), the end of the elastic unit (120) extending outside the support strip (130) is provided with a guide angle (121). The uniform strip assembly (200) has an insertion end (221) that is first inserted into the elastic cavity (160), the thickness of which gradually increases from both sides near the support strip (130) to the center away from the support strip (130).

2. The passive shim layer (20) of claim 1, characterized in that The two ends of the elastic unit (120) extend out of the support bar (130), and the ends of the elastic units (120) on two adjacent support bars (130) are close to each other.

3. The passive shimming layer (20) according to claim 1, characterized in that, Multiple elastic units (120) on the same support bar (130) are connected to each other along the axial direction of the main magnet (10).

4. The passive shimming layer (20) according to claim 1, characterized in that, Multiple elastic elements (120) located on the same circumference are connected to each other.

5. The passive shimming layer (20) according to any one of claims 1-4, characterized in that, The field shimming strip assembly (200) has an insertion end (221) that is first inserted into the elastic cavity (160), and the thickness of the insertion end (221) gradually decreases along the insertion direction of the field shimming strip assembly (200).

6. The passive shimming layer (20) according to claim 1, characterized in that, At least one of the plurality of support bars (130) is a first support bar (140), and at least one of the plurality of support bars (130) is a second support bar (150), wherein the cross-sectional dimension of the first support bar (140) is larger than the cross-sectional dimension of the second support bar (150).

7. The passive shimming layer (20) according to claim 1, characterized in that, The passive shimming layer (20) includes a fixing component (300), which is disposed at one end of the support component (100), and the end of the shimming strip component (200) is connected to the fixing component (300).

8. A magnetic resonance imaging device, characterized in that, include: The main magnet (10) has an aperture that extends through the main magnet (10) along the axial direction; A passive shimming layer (20) is disposed within the aperture and fixedly connected to the inner wall of the main magnet (10). The passive shimming layer (20) includes a support assembly (100) and a shimming strip assembly (200). The support assembly (100) includes an elastic element (110) and multiple support strips (130). The multiple support strips (130) are sequentially and spaced apart on the inner wall of the main magnet (10) along the circumferential direction. The elastic element (110) is disposed on the inner side of the multiple support strips (130) so that an elastic cavity (160) is formed between two adjacent support strips (130), the elastic element (110), and the main magnet (10). The elastic element (110) includes multiple elastic units (120) along the axial direction of the main magnet (10). A plurality of elastic units (120) are arranged sequentially on the support bar (130), at least one end of the elastic unit (120) extends out of the support bar (130); the field stabilizing bar assembly (200) is inserted into the elastic cavity (160), and the elastic element (110) is used to press the field stabilizing bar assembly (200) against the inner wall of the main magnet (10); along the insertion direction of the field stabilizing bar assembly (200), the end of the elastic unit (120) extending out of the support bar (130) is provided with a guide angle (121); the field stabilizing bar assembly (200) has an insertion end (221) that is first inserted into the elastic cavity (160), and the thickness of the insertion end (221) gradually increases from both sides near the support bar (130) to the center away from the support bar (130); The gradient coil (30) is disposed within the cavity enclosed by the passive shimming layer (20).

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