Gradient coil assembly and magnetic resonance equipment thereof

Abstract

The invention relates to the technical field of magnetic resonance equipment, in particular to a gradient coil assembly and magnetic resonance equipment thereof. A gradient coil assembly comprises a main coil, the main coil is formed by winding a conductor, the main coil surrounds to form a scanning space for a human body to enter, the end portion of the main coil is recessed in the axis direction of the main coil to form an avoiding area, and the avoiding area can accommodate at least part of the shoulder of the human body; and a shield coil provided on the outer peripheral side of the main coil. The device has the advantages that the shoulders of the human body can be accommodated in the avoiding area, so that the human body can further move towards the direction of the main coil, the head of the human body can be completely accommodated in the main coil, the main coil is arranged in the shielding coil, the diameter of the main coil is smaller than that of the shielding coil, and the main coil can be further reduced in a targeted manner; the scanning intensity of a scanning space is enhanced, and the imaging quality is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of magnetic resonance equipment, and particularly to a gradient coil assembly and a magnetic resonance equipment thereof. Background Art

[0002] Gradient coils are arranged in magnetic resonance equipment. Existing gradient coils usually adopt a whole-body symmetric gradient, that is, along the length direction of the human body, the diameter of the gradient coil is equal everywhere. However, when it is necessary to perform targeted scanning and imaging on the head of the human body, since the volume of the head of the human body is relatively small, a higher intensity of the gradient coil for the scanned part is required, and it is difficult for the gradient coil with a whole-body symmetric gradient to meet the requirements. Moreover, due to the large width of parts such as the shoulders of the human body, if the gradient coil is reduced, it will be difficult for the human body to enter the gradient coil. Summary of the Invention

[0003] Based on this, in view of the above technical problems, the present invention provides a gradient coil assembly.

[0004] A gradient coil assembly, the gradient coil assembly includes: a main coil, the main coil is formed by winding a conductor, the main coil surrounds to form a scanning space for the human body to enter, and the end of the main coil is recessed along the axial direction of the main coil to form an avoidance area, and the avoidance area can accommodate at least part of the shoulders of the human body; a shielding coil, arranged on the outer peripheral side of the main coil.

[0005] With such a setting, since the shoulders of the human body can be accommodated in the avoidance area, the human body can further move towards the direction of the main coil, so that the head of the human body can be completely accommodated in the main coil, and the main coil is arranged in the shielding coil, its diameter is smaller than that of the shielding coil, and it can be further reduced specifically to enhance the scanning intensity of the scanning space and improve the imaging quality.

[0006] In one embodiment, the avoidance area includes a first notch and a second notch, and the first notch and the second notch are respectively located on two opposite sides in the radial direction of the main coil.

[0007] In one embodiment, the central axis of the first notch, the central axis of the second notch, and the central axis of the main coil are located in the same plane.

[0008] In one embodiment, the main coil at least includes a first coil and a second coil, and along the radial direction of the main coil, the first coil is located on the outer peripheral side of the second coil or the second coil is located on the outer peripheral side of the first coil.

[0009] In one embodiment, one of the first coil and the second coil includes a first main section and a first extension section arranged in series, and the first extension section is located at an end of the first main section; the other of the first coil and the second coil includes a second main section and two of the second extension sections arranged in series, and the two second extension sections are both located at an end of the second main section and are arranged at intervals along the circumferential direction of the main coil; wherein, an avoidance area is formed between adjacent first extension sections, and the avoidance area is formed between adjacent second extension sections.

[0010] In one embodiment, there are two sets of the first coils, and the two sets of the first coils are arranged opposite to each other along the horizontal direction; and / or, there are two sets of the second coils, and the two sets of the second coils are arranged opposite to each other along the vertical direction.

[0011] In one embodiment, the second coil is located on the outer peripheral side of the first coil. The end of the first coil has two of the second extension sections, and a first avoidance space is formed between the two second extension sections along the circumferential direction of the main coil. The middle position of the end of the second coil has the first extension section, and a second avoidance space is formed between the first extension sections on adjacent second coils. The first avoidance space and the second avoidance space are arranged to coincide along the radial direction of the main coil.

[0012] In one embodiment, the first coil and / or the second coil is formed by winding a single-layer conductor to form a single-layer structure.

[0013] In one embodiment, there are multiple first coils and multiple second coils, and the multiple first coils and the multiple second coils are connected in series. The main coil further includes a third coil, and the third coil surrounds the outer peripheral sides of the first coil and the second coil.

[0014] The present invention further provides a magnetic resonance device, including the gradient coil assembly as described above and a machine body. The gradient coil assembly is arranged in the machine body, and an avoidance groove is formed on the machine body, and at least a part of the avoidance area coincides with the avoidance groove.

[0015] Compared with the prior art, the present invention sets an avoidance area on the gradient coil assembly that can avoid the human body, so that the scanner can more conveniently place the part to be scanned at the designated position. The first extension section and the second extension section are arranged on the main section of the gradient coil assembly. The first extension section and the second extension section can strengthen the intensity of the gradient magnetic field near the avoidance area of the gradient coil assembly, ensure the quality of the scanned image, and the first coil and the second coil are formed by winding a single-layer conductor, occupying a small space. Therefore, multiple layers can be arranged in a limited space, and the intensity is higher after the superposition of multiple layers of gradient magnetic fields, and the quality of the scan is better. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 Partial structural schematic diagram of one embodiment of the gradient coil assembly provided by the present invention;

[0017] Figure 2 Partial structural schematic diagram of one embodiment of the gradient coil assembly provided by the present invention;

[0018] Figure 3 Structural schematic diagram of one embodiment of the first coil provided by the present invention;

[0019] Figure 4 Structural schematic diagram of one embodiment of the second coil provided by the present invention;

[0020] Figure 5 Cross-sectional view of one embodiment of the gradient coil assembly provided by the present invention;

[0021] Figure 6 Another angle cross-sectional view of one embodiment of the gradient coil assembly provided by the present invention;

[0022] Figure 7 Schematic diagram of the magnetic resonance device provided by the present invention during use;

[0023] Figure 8 Cross-sectional view of one embodiment of the magnetic resonance device provided by the present invention;

[0024] Figure 9 Cross-sectional view of one embodiment of the magnetic resonance device provided by the present invention;

[0025] Figure 10 Conductor structural schematic diagram of the Z-axis gradient coil provided by the present invention;

[0026] Figure 11 Structural schematic diagram of the Z-axis gradient coil provided by the present invention;

[0027] Figure 12 Schematic diagram of the distribution of the magnetic field strength formed by the Z-axis gradient coil provided by the present invention in the radiofrequency imaging region;

[0028] Figure 13 Schematic diagram of the magnetic field distribution formed by the X-axis gradient coil provided by the present invention;

[0029] Figure 14 Distribution of the linearity of the X-axis gradient coil provided by the present invention in the XZ plane;

[0030] Figure 15 Schematic diagram of the magnetic field distribution formed by the Y-axis gradient coil provided by the present invention;

[0031] Figure 16 It is the distribution of the linearity of the Y-axis gradient coil provided by the present invention in the YZ plane.

[0032] The meanings of the symbols in the figure are as follows:

[0033] 100. Gradient coil assembly; 10. Main coil; 11. Avoidance area; 111. First notch; 112. Second notch; 12. First coil; 121. First main body section; 122. First extension section; 13. Second coil; 131. Second main body section; 132. Second extension section; 14. First avoidance space; 15. Second avoidance space; 16. Third coil; 20. Shielding coil; 30. Body; 31. Avoidance groove. Specific embodiments

[0034] To make the above objects, features, and advantages of the present application more obvious and understandable, the following will describe the specific embodiments of the present application in detail with reference to the accompanying drawings. Many specific details are set forth in the following description to facilitate a full understanding of the present application. However, the present application can be implemented in many other ways different from those described herein, and those skilled in the art can make similar improvements without departing from the connotation of the present application. Therefore, the present application is not limited by the specific embodiments disclosed below.

[0035] It should be noted that when a mechanism is referred to as "fixed to" or "disposed on" another mechanism, it can be directly on the other mechanism or there can also be an intermediate mechanism. When a mechanism is considered to be "connected" to another mechanism, it can be directly connected to the other mechanism or there may be an intermediate mechanism at the same time. The terms "vertical", "horizontal", "upper", "lower", "left", "right" and similar expressions used in the specification of the present application are only for the purpose of illustration and do not represent the only implementation manner.

[0036] In addition, the terms "first" and "second" are only used for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly specifying the quantity of the indicated technical features. Thus, the features defined with "first" and "second" may explicitly or implicitly include at least one of the features. In the description of the present application, "a plurality of" means at least two, such as two, three, etc., unless otherwise specifically defined.

[0037] In this application, unless otherwise clearly defined and limited, the first feature being "on" or "under" the second feature may be that the first feature is in direct contact with the second feature, or the first feature is in indirect contact with the second feature through an intermediate medium. Moreover, the first feature being "above", "over" or "on top of" the second feature may mean that the first feature is directly above or obliquely above the second feature, or simply indicates that the horizontal height of the first feature is higher than that of the second feature. The first feature being "under", "below" or "beneath" the second feature may mean that the first feature is directly below or obliquely below the second feature, or simply indicates that the horizontal height of the first feature is lower than that of the second feature.

[0038] Unless otherwise defined, all technical and scientific terms used in the specification of this application have the same meaning as commonly understood by those skilled in the technical field to which this application belongs. The terms used in the specification of this application are only for the purpose of describing specific embodiments and are not intended to limit this application. The term "and / or" used in the specification of this application includes any and all combinations of one or more of the related listed items.

[0039] Existing gradient coils generally have a constant diameter along their axial direction. Although they can meet the scanning requirements of various parts of the body, they still cannot effectively meet the high-precision scanning imaging requirements for the head.

[0040] In view of this, the present invention provides a gradient coil assembly 100 that can form a dedicated space for accommodating the head and meet the requirements for the uniformity of the gradient field in high-precision head imaging. The gradient coil assembly 100 has an avoidance area 11 that can avoid the shoulders of the human body. The avoidance area 11 can accommodate the shoulders of the human body, enabling the head of the human body to completely enter the scanning space.

[0041] The gradient coil assembly 100 provided by the present invention is used to generate a gradient magnetic field and is mainly applied in a magnetic resonance (MR) system. Of course, in other embodiments of the present invention, the gradient coil assembly 100 can also be applied in a multimodal system formed by a positron emission tomography (PET) device and an MR device, a magnetic resonance radiotherapy positioning system (MR-RT), etc.

[0042] Please refer to Figures 1-4, the present invention provides a gradient coil assembly 100, which includes a main coil 10 and a shielding coil (secondary coil) 20. The main coil 10 is formed by winding a conductor. The main coil 10 surrounds to form a scanning space for a human body to enter, and the scanning space can be cylindrical. The main coil 10 forms a gradient field, and the end of the main coil 10 is recessed along the axial direction of the main coil 10 to form an avoidance area 11, which can accommodate at least part of the shoulder of the human body. The shielding coil 20 is also arranged in a surrounding manner and is located on the outer peripheral side of the main coil 10, and is used to form a gradient shielding field to shield the eddy current from the main coil 10 to the superconducting magnet. Thus, since the shoulder of the human body can be accommodated in the avoidance area 11, the human body can further move towards the direction of the main coil 10 so that the head of the human body can be completely accommodated in the main coil 10, and the main coil 10 is arranged inside the shielding coil 20, and its diameter is smaller than that of the shielding coil 20.

[0043] It should be noted that in this embodiment, the scanning space inside the main coil 10 is the space for scanning the head of the human body. The shielding coil 20 is arranged on the outer peripheral side of the main coil 10, and its length in the axial direction is also greater than that of the main coil 10. The space surrounded by the shielding coil 20 includes the above-mentioned scanning space, and a gradient magnetic field with a normal intensity can be generated in the area other than the scanning space in this space.

[0044] The avoidance area 11 includes a first notch 111 and a second notch 112. The first notch 111 and the second notch 112 are respectively located on two opposite sides in the radial direction of the main coil 10, that is, at the same end of the gradient coil assembly 100. Thus, the human body can enter the scanning space along the central axis position of the main coil 10, and the shoulders on both sides of the human body can be accommodated in the first notch 111 and the second notch 112, so that the head of the human body can be placed in the center of the scanning space.

[0045] In this embodiment, for the notch-type gradient coil formed by the main coil 10 with the avoidance area 11, the current density is forced to be 0 in the notch avoidance area 11, resulting in the current density that should originally be in the notch avoidance area 11 being squeezed into the circumferential area outside the notch, so that the current density in these circumferential areas increases. When the current density increases to a large enough value, a wire distribution is formed in these circumferential areas outside the notch.

[0046] Of course, it can be understood that in other embodiments, the avoidance area 11 may also have only one of the first notch 111 and the second notch 112. Alternatively, the first notch 111 and the second notch 112 are located on the same side of the main coil 10 in the radial direction, so as to be applicable to different parts of the human body or the human body in different postures. The purpose of the avoidance area 11 is to accommodate the parts of the human body that will interfere with the main coil 10, so as to facilitate the part of the human body to be scanned to enter the scanning space. Therefore, it is not limited to the above embodiment in which the two shoulders of the human body are accommodated so that the head of the human body is centered.

[0047] In this embodiment, please refer to Figure 3 , the central axes of the first notch 111, the second notch 112, and the main coil 10 are located in the same plane, so that the first notch 111 and the second notch 112 are located on opposite sides of the main coil 10, that is, the first notch 111 and the second notch 112 are located in the middle of the main coil 10. With such a setting, the distance between the first notch 111 and the second notch 112 is the farthest, the applicable range for the human body is the widest, and the formed symmetric structure on both sides is also convenient for processing and layout.

[0048] Exemplarily, in this embodiment, both the first notch 111 and the second notch 112 are rectangular structures. In other embodiments, the first notch 111 and the second notch 112 may also be irregular shapes such as conical, stepped, arc-shaped, semi-circular, trapezoidal, or a combination of rectangular and semi-circular.

[0049] The main coil 10 includes an X-axis gradient coil, a Y-axis gradient coil, and a Z-axis gradient coil arranged in layers. Please refer to Figures 3-4 , the main coil 10 includes at least a first coil 12 and a second coil 13, and along the radial direction of the main coil 10, the first coil 12 is located on the outer peripheral side of the second coil 13 or the second coil 13 is located on the outer peripheral side of the first coil 12, that is, the two are located in different layers in the radial direction of the cylindrical structure formed by the main coil 10. As Figure 3 shown, the first coil 12 is an X-axis gradient coil for generating an X-direction gradient field; as Figure 4 shown, the second coil 13 is a Y-axis gradient coil for generating a Y-direction gradient field.

[0050] Furthermore, both the first coil 12 and the second coil 13 are arranged in multiple layers, and the same-type first coils 12 in different layers are connected in series, and the same-type second coils 13 in different layers are connected in series.

[0051] In this embodiment, along the radial direction of the main coil 10, the first coil 12 and the second coil 13 are arranged in sequence, that is, from the inside to the outside, they are the first coil 12, the second coil 13, the first coil 12, the second coil 13, and so on. Of course, in other embodiments, the positions of the first coil 12 and the second coil 13 can also be interchanged.

[0052] One of the first coil 12 and the second coil 13 includes a first main section 121 and a first extension section 122 arranged in series. The first extension section 122 is located at the end of the first main section 121 and is centered relative to the first main section 121. The other of the first coil 12 and the second coil 13 includes a second main section 131 and two second extension sections 132 arranged in series. The two second extension sections 132 are both located at the end of the second main section 131 and are arranged at intervals; wherein, an avoidance area 11 is formed between adjacent first extension sections 122; an avoidance area 11 is formed between adjacent second extension sections 132. In this way, both the first main section 121 (second main section 131) and the first extension section 122 (second extension section 132) can generate a gradient magnetic field. The first extension section 122 (second extension section 132) is located at the end of the first main section 121 (second main section 131), which can reinforce the intensity of the gradient magnetic field at the end of the first main section 121 (second main section 131). And since the avoidance area 11 is located between two adjacent first extension sections 122 (second main extension sections), that is to say, the wiring in the first extension section 122 (second extension section 132) is the wiring at the edge of the avoidance area 11, so as to strengthen the gradient magnetic field intensity at the edge of the avoidance area 11, thereby improving the overall strength of the main coil 10.

[0053] The first extension section 122 is located at the end of the first main section 121 and is centered, which can form a convex-shaped end structure. The two spaced second extension sections 132 are arranged at the end of the second main section 131, which can form a concave-shaped structure. The convex-shaped structure and the concave-shaped structure are arranged alternately along the radial direction, so that the avoidance areas 11 formed between adjacent first extension sections 122 (second extension sections 132) coincide in the radial direction.

[0054] Further, there are two sets of the first coils 12, and the two sets of the first coils 12 are arranged opposite to each other along the horizontal direction, and / or, there are two sets of the second coils 13, and the two sets of the second coils 13 are arranged opposite to each other along the vertical direction. In this way, the two sets of the first coils 12 are respectively formed by winding conductors and then assembled together, and the processing difficulty of the process is lower than that of the direct forming method. The two sets of the second coils 13 are arranged opposite to each other and have the same technical effect, which will not be elaborated here.

[0055] Specifically, in this embodiment, the second coil 13 is located on the outer peripheral side of the first coil 12. The end of the first coil 12 has two second extension segments 132. A first avoidance space 14 is formed between the two second extension segments 132. The middle position of the end of the second coil 13 has a first extension segment 122. A second avoidance space 15 is formed between the first extension segments 122 on adjacent second coils 13. The first avoidance space 14 and the second avoidance space 15 are arranged to coincide along the radial direction of the main coil 10.

[0056] Exemplarily, in this embodiment, the diameter of the first coil 12 is set to 480 mm, and the diameter of the second coil 13 is set to 490 mm to adapt to common body shapes of the human body to be detected.

[0057] In another embodiment, the positions of the first coil 12 and the second coil 13 can be interchanged. Or, the first coil 12 is provided with a centered first extension segment 122, and the second coil 13 is provided with two second extension segments 132 arranged at intervals, both of which can achieve the technical effect of forming the avoidance area 11.

[0058] Preferably, the first coil 12 and / or the second coil 13 are wound by a single-layer conductor to form a single-layer structure. In this way, the single-layer conductor is wound to form the first coil 12 and the second coil 13, which have a small thickness and occupy less space. Therefore, on the premise of the same space, compared with the embodiment in which the first coil 12 and the second coil 13 are formed by the cooperation of two layers of conductors up and down, the present application can set more layers of the first coil 12 and the second coil 13, the intensity of the gradient magnetic field is stronger, and the imaging quality is higher.

[0059] Please refer to Figures 8-9 , the gradient coil assembly 100 further includes a third coil 16. The third coil 16 is arranged on the outer peripheral side of the second coil 13 and is circumferentially arranged around the cylindrical structure formed by the main coil 10 to form a gradient field in the Z direction.

[0060] The third coil 16 is a Z-axis gradient coil, which is wound by a first conductor group and a second conductor group that are centrosymmetric about the center of the cylindrical structure. Among them: the first conductor group includes a first conductor and a second conductor connected in parallel; the second conductor group includes a third conductor and a fourth conductor connected in parallel, the third conductor is connected in series with the first conductor, and the fourth conductor is connected in series with the second conductor.

[0061] Among them, Figure 10Schematic diagram of the conductor structure of the Z-axis gradient coil according to this embodiment. The first conductor group includes a first conductor A and a second conductor B, and the first conductor A and the second conductor B are connected in parallel; the second conductor group includes a third conductor C and a fourth conductor D, and the third conductor C and the fourth conductor D are connected in parallel. After current is passed through the first conductor group or the second conductor group, the current will form two branches. One branch is the current branch (I1) formed by the series connection of the first conductor A and the third conductor C, and the other branch is the branch (I2) formed by the series connection of the second conductor B and the fourth conductor D. The coil radii at which the first conductor A, the second conductor B, the third conductor C, and the fourth conductor D are wound are the same, and the first conductor group and the second conductor group are centrosymmetric about the center of the gradient coil.

[0062] In this embodiment, a magnetic field is generated by a gradient coil assembly wound by a first conductor group and a second conductor group that are centrosymmetric about the center of the gradient coil. The first conductor group includes a first conductor and a second conductor connected in parallel; the second conductor group includes a third conductor and a fourth conductor connected in parallel. The third conductor is connected in series with the first conductor, and the fourth conductor is connected in series with the second conductor. While ensuring that the intensity of the gradient magnetic field in the imaging region remains unchanged, the conductors are wound in two paths. Without changing the magnetic field intensity, the distribution area of the current is increased, and at the same time, the current intensity of each path is reduced, so that the inflection point position of the gradient magnetic field is farther away, and artifacts are not easily generated during imaging, solving the problem of low accuracy in nuclear magnetic resonance imaging in the related art and improving the accuracy of nuclear magnetic resonance imaging.

[0063] In one embodiment, the first conductor and the second conductor at the end of the gradient coil are joined together.

[0064] Among them, as Figure 10 shown, at the end of the gradient coil, the first conductor A and the second conductor B are joined together, and the joining method can be welding, crimping, or other joining methods that can connect the first conductor A and the second conductor B.

[0065] In this embodiment, by joining the first conductor A and the second conductor B at the end of the gradient coil, the parallel connection relationship between the first conductor A and the second conductor B is ensured, so that when current is passed through, two branches can be formed in the first conductor A and the second conductor B respectively. Without changing the magnetic field intensity, the distribution area of the current is increased; at the same time, due to the shunting of the two branches, the current of each branch is reduced, so that the inflection point of the magnetic field of the coil is farther away in the corresponding coordinates and artifacts are not easily generated.

[0066] In one embodiment, the third conductor and the fourth conductor at the end of the gradient coil are joined together.

[0067] Among them, as Figure 10As shown, at the end of the gradient coil, the third conductor C is joined to the fourth conductor D, and the joining method can be welding, pressing, or other joining methods that can connect the third conductor C and the fourth conductor D.

[0068] In this embodiment, by joining the third conductor C and the fourth conductor D at the end of the gradient coil, the parallel connection relationship between the third conductor C and the fourth conductor D is ensured, so that the current passed through can form two branches in the third conductor C and the fourth conductor D respectively, increasing the current distribution area under the condition of constant magnetic field strength; at the same time, due to the shunt of the two branches, the current of each branch is reduced, so that the inflection point of the magnetic field of the coil is farther under the corresponding coordinates and it is not easy to appear artifacts.

[0069] In one embodiment, the first conductor near the center of the gradient coil is joined to the third conductor.

[0070] Among them, as Figure 10 shown, at the center of the gradient coil, that is, at the end of the first conductor group and the beginning of the second conductor group, the first conductor A is joined to the third conductor C, and the joining method can be welding, pressing, or other joining methods that can connect the first conductor A and the third conductor C.

[0071] In this embodiment, by joining the first conductor A and the third conductor C at the center of the coil, the series relationship between the first conductor A and the third conductor C is ensured, so that the current passed through the first conductor A can form a branch on the first conductor A and the third conductor C, expanding the current distribution area under the condition of constant magnetic field strength.

[0072] In one embodiment, the second conductor near the center of the gradient coil is joined to the fourth conductor.

[0073] Among them, as Figure 10 shown, at the center of the gradient coil, that is, at the end of the first conductor group and the beginning of the second conductor group, the second conductor B is joined to the fourth conductor D, and the joining method can be welding, pressing, or other joining methods that can connect the second conductor B and the fourth conductor D.

[0074] In this embodiment, by joining the second conductor B and the fourth conductor D at the center of the coil, the series relationship between the second conductor B and the fourth conductor D is ensured, so that the current passed through the second conductor B can form a branch on the second conductor B and the fourth conductor D, expanding the current distribution area under the condition of constant magnetic field strength.

[0075] In one embodiment, the winding trajectories of the first conductor and the fourth conductor are symmetric about the center of the gradient coil.

[0076] Among them, the first conductor A and the fourth conductor D are symmetrically distributed on both sides of the center of the gradient field, and the winding trajectories of the first conductor A and the fourth conductor D are symmetric about the center of the gradient coil.

[0077] In this embodiment, the first conductor A and the fourth conductor D are symmetrically wound about the center of the gradient coil using the same winding trajectory, so as to ensure that the magnetic fields generated after the first conductor A and the fourth conductor D are energized are symmetric about the center of the gradient coil and do not affect the normal operation of the nuclear magnetic resonance system.

[0078] In one embodiment, the winding trajectories of the second conductor and the third conductor are symmetric about the center of the gradient coil.

[0079] As Figure 10 shown, the second conductor B and the third conductor C are symmetrically distributed on both sides of the gradient coil, and the winding trajectories of the second conductor B and the third conductor C are symmetric about the center of the gradient coil.

[0080] In this embodiment, the second conductor B and the third conductor C are symmetrically wound about the center of the gradient coil using the same winding trajectory, so as to ensure that the magnetic fields generated after the second conductor B and the third conductor C are energized are symmetric about the center of the gradient coil and do not affect the normal operation of the nuclear magnetic resonance system.

[0081] In one embodiment, the load parameters of the circuit composed of the first conductor and the third conductor are the same as those of the circuit composed of the second conductor and the fourth conductor.

[0082] Among them, the branch formed by the series connection of the first conductor A and the third conductor C and the branch formed by the series connection of the second conductor B and the fourth conductor D have winding trajectories symmetrically distributed about the center of the coil. Therefore, the load parameters of the two branches are the same, and the load parameters include the resistance and inductance of the two branches.

[0083] In this embodiment, by making the load parameters of the circuit composed of the first conductor and the third conductor the same as those of the circuit composed of the second conductor and the fourth conductor, the current of each branch is made the same in real time, and then the magnetic fields generated by the symmetrically distributed coils are made the same, ensuring the normal working state of the nuclear magnetic resonance system.

[0084] In one embodiment, Figure 11 is a schematic structural diagram of the Z-axis gradient coil (the third coil 16) of this embodiment. The third coil 16 is wound with two-branch conductors. Therefore, the current distribution area of the third coil 16 is larger, and the inflection point position of the magnetic field distribution is farther.

[0085] In this embodiment, the inflection point position of the Z-coil magnetic field distribution is at Z = 0.38 m, and in the related art, the inflection point position of the Z-coil magnetic field distribution is at Z = 0.33 m. Figure 12It is a schematic diagram of the magnetic field intensity distribution formed by the Z-axis gradient coil in this embodiment in the radiofrequency imaging region. As Figure 5 shown, the farthest radiofrequency imaging region in this embodiment is Z = 0.45 m, that is, within the region where Z < 0.45 m, radiofrequency intensity may generate image signals. During imaging, when the gradient intensity used for imaging is 30 mT / m and the magnetic field intensity corresponding to the radiofrequency receiving frequency is B0 + 7.2 mT (Bz = γf, where Bz is the magnetic field intensity, γ is the gyromagnetic ratio, which is 42.58 MHz / T for hydrogen atoms, and f is the radiofrequency receiving frequency), the image imaging position is Z = 0.24 m, and the magnetic field of the Z-gradient coil here is 7.2 mT. For the gradient coil in the related art, the magnetic field of the Z-gradient coil at Z = 0.43 m is also 7.2 mT. However, different from this embodiment, at this time, this position is within the radiofrequency imaging region (Z < 0.45 m) in the related art. Therefore, in the related art, the tissues and organs at this position will generate signals, interfering with the original image signals and thus generating artifacts. For the gradient coil in this embodiment, the magnetic field of the Z-gradient coil at Z = 0.5 m is also 7.2 mT. However, at this time, this position is no longer within the radiofrequency imaging region (Z < 0.45 m). Therefore, the tissues and organs at this position will not generate signals, and thus no artifacts will be generated, avoiding the generation of artifacts during the imaging process and improving the accuracy of nuclear magnetic resonance imaging.

[0086] As Figure 13 shown is the schematic diagram of the magnetic field distribution formed by the X-axis gradient coil (the first coil 12) in the embodiment of the present application as Figure 3 shown. The maximum current of the X-axis gradient coil is 1000 A, the maximum voltage is 2000 V, the maximum gradient intensity is 213 mT / m, and the maximum slew rate is 680 mT / m / ms. In the figure, the abscissa is the X coordinate position, with the unit of m; the ordinate represents the magnetic field intensity generated at the corresponding coordinate position, with the unit of mT. It can be seen from the figure that from the X coordinate position of -0.1 m to 0.1 m, the magnetic field satisfies a good linear relationship.

[0087] As Figure 14 shown is the distribution of the linearity of the X-axis gradient coil in the XZ plane in the embodiment of the present application as Figure 3 shown. In the figure, the abscissa is the X coordinate position, and the ordinate represents the Z coordinate position. The circle in the figure is the ideal target imaging region, and the curve in the figure represents the deviation degree from the ideal magnetic field intensity. It can be seen that the linearity is satisfied well in most of the target imaging region, and only the edge region has a deviation degree of about 2% - 4%.

[0088] As Figure 15 shown is in the embodiment of the present application as Figure 4Schematic diagram of the magnetic field distribution formed by the Y-axis gradient coil (second coil 13) shown. The maximum current of the Y-axis gradient coil is 1000 A, the maximum voltage is 2000 V, the maximum gradient intensity is 214 mT / m, and the maximum slew rate is 663 mT / m / ms. Among them, the abscissa is the Y coordinate position, with the unit of m; the ordinate represents the magnetic field strength generated at the corresponding coordinate position, with the unit of mT. It can be seen from the figure that in the Y coordinate position from -0.1 m to 0.1 m, the magnetic field satisfies a good linear relationship.

[0089] As Figure 16 shown in the embodiment of the present application Figure 4 Distribution of the linearity of the Y-axis gradient coil in the YZ plane shown. In the figure, the abscissa is the Y coordinate position, and the ordinate represents the Z coordinate position. The circular ring in the figure is the ideal target imaging area, and the curve in the figure represents the deviation from the ideal magnetic field strength. It can be seen that good linearity is satisfied in most of the target imaging area, and only the edge area has a deviation of about 2%-4%.

[0090] The gradient coil assembly 100 further includes a cooling pipe, which is arranged along the edge of the avoidance area 11. A cooling medium flows in the cooling pipe, so as to absorb heat from the gradient coil assembly 100 to cool the gradient coil assembly 100 and improve the operation stability of the gradient coil assembly 100 and the comfort of the human body.

[0091] The present application also provides a magnetic resonance device, including the gradient coil assembly 100 and the body 30 as described above. The gradient coil assembly 100 is arranged inside the body 30, and an avoidance groove 31 is opened on the body 30. At least part of the avoidance area 11 coincides with the avoidance groove 31.

[0092] Please refer to Figures 1-2 and Figures 5-7 , there is a chamber inside the body 30. The avoidance groove 31 is opened on the opposite sides of the inner wall of the chamber and is located on the horizontal plane where the axis of the chamber is located. When the body 30 is applied to a magnetic resonance device and is placed horizontally (i.e., the axis of the body 30 is parallel to the ground) on the ground, the groove height of the avoidance groove 31 in the vertical direction is a, and the range of a satisfies 100 mm < a < 350 mm. The depth of the avoidance groove 31 in the horizontal direction is b, and the range of b satisfies 30 mm < b < 200 mm. In this way, the size of the avoidance groove 31 is reasonably set to adapt to the detected human bodies of various body types, and the applicable range is wider. Please refer to Figure 7 , due to the existence of the avoidance groove 31, the human body can be closer to the scanning center of the main coil 10 (that is, L in the figure is shorter)

[0093] Compared with the prior art, in the present invention, an avoidance area 11 capable of avoiding the human body is provided on the gradient coil assembly 100, so that the scanner can more conveniently place the part to be scanned at a specified position. A first extension section 122 and a second extension section 132 are provided on the main body section of the gradient coil assembly 100. The first extension section 122 and the second extension section 132 can strengthen the intensity of the gradient magnetic field near the avoidance area 11 of the gradient coil assembly 100, ensuring the quality of the scanned image. Moreover, the first coil 12 and the second coil 13 are formed by single-layer conductor winding, occupying a relatively small space. Therefore, multiple layers can be arranged in a limited space. After the superposition of multiple layers of gradient magnetic fields, the intensity is higher and the scanning quality is better.

[0094] The technical features of the above-described embodiments can be combined arbitrarily. For the sake of brevity of description, not all possible combinations of the technical features in the above-described embodiments are described. However, as long as there is no contradiction in the combination of these technical features, it should be considered as the scope described in this specification.

[0095] The above-described embodiments merely represent several implementation manners of the present invention. The description thereof is relatively specific and detailed, but it should not be construed as a limitation on the scope of the invention patent. It should be noted that for those of ordinary skill in the art, without departing from the concept of the present invention, several modifications and improvements can be made, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the present invention patent shall be subject to the appended claims.

Claims

1. A gradient coil assembly, characterized in that, The gradient coil assembly includes: A main coil (10) formed by winding a conductor. The main coil (10) surrounds to form a scanning space for a human body to enter. An end portion of the main coil (10) is recessed along the axial direction of the main coil (10) to form an avoidance area (11), and the avoidance area (11) can accommodate at least part of a human shoulder; A shielding coil (20) disposed on the outer peripheral side of the main coil (10).

2. The gradient coil assembly according to claim 1, wherein The avoidance area (11) includes a first notch (111) and a second notch (112), and the first notch (111) and the second notch (112) are respectively located on two opposite sides in the radial direction of the main coil (10).

3. The gradient coil assembly according to claim 2, wherein, The central axis of the first notch (111), the central axis of the second notch (112), and the central axis of the main coil (10) are located in the same plane.

4. The gradient coil assembly according to claim 1, wherein The main coil (10) at least includes a first coil (12) and a second coil (13), and along the radial direction of the main coil (10), the first coil (12) is located on the outer peripheral side of the second coil (13) or the second coil (13) is located on the outer peripheral side of the first coil (12).

5. The gradient coil assembly according to claim 4, wherein One of the first coil (12) and the second coil (13) includes a first main section (121) and a first extension section (122) connected in series, and the first extension section (122) is located at an end of the first main section (121); the other of the first coil (12) and the second coil (13) includes a second main section (131) and two second extension sections (132) connected in series, and the two second extension sections (132) are both located at an end of the second main section (131) and are spaced along the circumferential direction of the main coil (10); Wherein, the avoidance area (11) is formed between adjacent first extension sections (122), and the avoidance area (11) is formed between adjacent second extension sections (132).

6. The gradient coil assembly according to claim 5, wherein The first coil (12) is in two groups, and the two groups of the first coil (12) are arranged oppositely along the horizontal direction; and / or, the second coil (13) is in two groups, and the two groups of the second coil (13) are arranged oppositely along the vertical direction.

7. The gradient coil assembly according to claim 6, wherein The second coil (13) is located on the outer peripheral side of the first coil (12). The end portion of the first coil (12) has two second extension sections (132), and along the circumferential direction of the main coil (10), a first avoidance space (14) is formed between the two second extension sections (132). The middle position of the end portion of the second coil (13) has the first extension section (122), and a second avoidance space (15) is formed between the first extension sections (122) on adjacent second coils (13). The first avoidance space (14) and the second avoidance space (15) are arranged to coincide along the radial direction of the main coil (10).

8. The gradient coil assembly according to claim 4, wherein The first coil (12) and / or the second coil (13) is formed by winding a single-layer conductor to form a single-layer structure.

9. The gradient coil assembly according to claim 4, wherein, The first coils (12) and the second coils (13) are both multiple. The multiple first coils (12) and the multiple second coils (13) are connected in series. The main coil (10) further includes a third coil (16), and the third coil (16) surrounds the outer peripheral sides of the first coils (12) and the second coils (13).

10. A magnetic resonance device, comprising a gradient coil assembly as described in any one of claims 1-9 and a body (30), characterized in that, The gradient coil assembly is disposed in the body (30), and an avoidance groove (31) is formed in the body (30). At least part of the avoidance area (11) coincides with the avoidance groove (31).

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