Shimming device, design method, decoupling method for shim coils and magnetic resonance system

Abstract

The application relates to a shimming device, a design method, a decoupling method of a shim coil and a magnetic resonance system. The shimming device comprises a shim coil and a plurality of adjusting leads; the shim coil comprises a positive lead and a negative lead, one end of the positive lead is connected with a first-end coil of the shim coil, the other end of the positive lead is connected with a positive electrode of a shim power supply, one end of the negative lead is connected with a last-end coil of the shim coil, and the other end of the negative lead is connected with a negative electrode of the shim power supply; and the plurality of adjusting leads are distributed on the last-end coil or the first-end coil. The shimming device provided by the application can adjust the coupling between the shim coil and a gradient coil, so as to reduce the coupling current between the shim coil and the gradient coil.

Description

Technical Field

[0001] This application relates to the field of magnetic resonance imaging technology, and in particular to a shimming device, a design method, a decoupling method for shimming coils, and a magnetic resonance system. Background Technology

[0002] The magnet system in a magnetic resonance imaging (MRI) system includes a main magnet, shimming coils, gradient coils, and radio frequency coils. During operation, significant coupling occurs between the shimming coils and gradient coils, affecting the stability of the background magnetic field generated by the main magnet and potentially causing damage to the shimming power supply of the shimming coils.

[0003] In traditional technology, designing the shimming coil with the least energy scheme can reduce the mutual inductance between the shimming coil and the gradient coil. However, in actual coil manufacturing, due to manufacturing process issues such as coil firing and assembly errors, the shimming coil and gradient coil will still have coupling and mutual inductance problems. Summary of the Invention

[0004] Therefore, it is necessary to provide a shimming device, a design method, a decoupling method for the shimming coil, and a magnetic resonance system to address the aforementioned technical problems.

[0005] In a first aspect, one embodiment of this application provides a field shimming device, which includes: a shimming coil and a plurality of adjustment leads;

[0006] The shimming coil includes a positive lead and a negative lead. One end of the positive lead is connected to the first coil of the shimming coil, and the other end of the positive lead is connected to the positive terminal of the shimming power supply. One end of the negative lead is connected to the last coil of the shimming coil, and the other end of the negative lead is connected to the negative terminal of the shimming power supply. Multiple adjustment leads are distributed on the last coil or the first coil.

[0007] In one embodiment, multiple adjustment leads are evenly distributed on the first coil, and the multiple adjustment leads are evenly and symmetrically distributed on the two coils on both sides with the first diameter of the first coil as the dividing line; the first diameter is the diameter of the connection point between the positive lead and the first coil.

[0008] In one embodiment, multiple adjustment leads are evenly distributed on the end coil, and the multiple adjustment leads are evenly and symmetrically distributed on both sides of the coil with the second diameter of the end coil as the dividing line; the second diameter is the diameter of the connection point between the negative lead and the end coil.

[0009] In one embodiment, the shimming coil includes a plurality of grid coils, each grid coil containing the same or different number of coils.

[0010] Secondly, one embodiment of this application provides a design method for a field homogenizing device, the method comprising:

[0011] Based on the energy minimization requirement and the correspondence between the energy and current of the shimming coil, the distribution of coils in each grid coil of the shimming coil is determined, and the shimming coil in the shimming device as provided in the first aspect is designed.

[0012] The angle step size between each adjustment lead is calculated based on the mutual inductance range between the shimming coil and the gradient coil, the number of multiple adjustment leads, the arc of a unit angle on the shimming coil, and the mutual inductance between the gradient coil.

[0013] Based on the angular step size between each adjustment lead, the connection positions of multiple adjustment leads on the shimming coil are determined, resulting in multiple adjustment leads in the shimming device as provided in the first aspect.

[0014] In one embodiment, the distribution of coils in each grid coil of the shimming coil is determined based on the energy minimization requirement and the correspondence between coil energy and coil current, including:

[0015] Based on the energy minimization requirement and the corresponding relationship, the current parameters of each grid coil in the shimming coil are determined;

[0016] The current parameters of each grid coil are discretized to obtain the distribution of coils in each grid coil.

[0017] In one embodiment, the angular step size between each adjustment lead is calculated based on the mutual inductance range between the shimming coil and the gradient coil, the number of multiple adjustment leads, the arc of a unit angle on the shimming coil, and the mutual inductance between the gradient coil and the shimming coil, including:

[0018] The mutual inductance adjustment step size is calculated based on the mutual inductance range between the shimming coil and the gradient coil and the number of multiple adjustment leads.

[0019] Based on the mutual inductance between the arc of a unit angle on the shimming coil and the gradient coil, and the mutual inductance adjustment step size, the angle step size between each adjustment lead is calculated.

[0020] Thirdly, one embodiment of this application provides a decoupling method for a shimming coil, which is applied to the shimming device as provided in the first aspect. The method includes:

[0021] Obtain the actual mutual inductance between the shim coil and the gradient coil;

[0022] Obtain the mutual inductance adjustment step size among multiple adjustment leads in the shimming coil;

[0023] Based on the actual mutual inductance and mutual inductance adjustment step size, the target adjustment lead is determined from multiple adjustment leads; the target adjustment lead is used to connect to the positive or negative terminal of the shimming power supply.

[0024] In one embodiment, determining a target adjustment lead from a plurality of adjustment leads based on the actual mutual inductance and the mutual inductance adjustment step size includes:

[0025] The ratio of the actual mutual inductance to the mutual inductance adjustment step size is used as the lead number;

[0026] Based on the polarity of the ratio, the region of the target adjustment lead in the shimming coil is determined from multiple adjustment leads;

[0027] Within the region, the adjustment lead corresponding to the lead number is identified as the target adjustment lead.

[0028] Fourthly, one embodiment of this application also provides a magnetic resonance system, which includes a shielding coil, a gradient coil, and a shimming device as provided in the first aspect, the shimming device being disposed in the space between the shielding coil and the gradient coil.

[0029] This application provides a shimming device, a design method, a decoupling method for a shimming coil, and a magnetic resonance system. The shimming device includes a shimming coil and multiple adjustment leads. The shimming coil includes positive and negative leads. One end of the positive lead is connected to the first coil of the shimming coil, and the other end is connected to the positive terminal of the shimming power supply. One end of the negative lead is connected to the last coil of the shimming coil, and the other end is connected to the negative terminal of the shimming power supply. The multiple adjustment leads are distributed on the last coil and the first coil. By selecting different adjustment leads to connect to the positive or negative terminal of the shimming power supply, the shimming device provided in this embodiment can adjust the mutual inductance between the shimming coil and the gradient coil, thereby reducing the coupling current of the shimming coil, preventing damage to the shimming power supply, and ensuring the normal operation of the shimming device. Attached Figure Description

[0030] To more clearly illustrate the technical solutions in the embodiments of this application or the conventional technology, the drawings used in the description of the embodiments or the conventional technology will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0031] Figure 1 A schematic diagram of the structure of a magnetic resonance system provided in one embodiment;

[0032] Figure 2 A schematic diagram of the shimming device provided in one embodiment;

[0033] Figure 3 A schematic diagram of the mesh division of a shimming coil provided for one embodiment;

[0034] Figure 4 A flowchart illustrating the design steps of a field shimming device provided in one embodiment;

[0035] Figure 5 A flowchart illustrating the steps of a design method for a field shimming device provided in another embodiment;

[0036] Figure 6 A flowchart illustrating the steps of a design method for a field shimming device provided in another embodiment;

[0037] Figure 7 A flowchart illustrating the steps of a decoupling method for a shimming coil provided in one embodiment;

[0038] Figure 8 A flowchart illustrating the steps of a decoupling method for a shimming coil provided in another embodiment;

[0039] Figure 9 A schematic diagram showing the distribution of multiple adjustment leads provided in one embodiment;

[0040] Figure 10 A schematic diagram of the structure of a magnetic resonance system provided for another embodiment;

[0041] Figure 11 A schematic diagram of the design device for a field shimming device provided in one embodiment;

[0042] Figure 12 A schematic diagram of the structure of a decoupling device for a shimming coil provided in one embodiment;

[0043] Figure 13 This is a schematic diagram of the structure of a computer device provided in one embodiment of this application.

[0044] Explanation of reference numerals in the attached figures:

[0045] 10. Shimming device; 11. Shimming coil; 12. Gradient coil; 13. Shielding coil; 14. Shimming power supply; 15. Adjustment lead; 101. Positive lead; 102. Negative lead. Detailed Implementation

[0046] To make the above-mentioned objectives, features, and advantages of this application more apparent and understandable, the specific embodiments of this application are 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 this application. However, this application can be implemented 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 this application. Therefore, this application is not limited to the specific embodiments disclosed below.

[0047] The serial numbers assigned to components in this document, such as "first" and "second," are used solely to distinguish the described objects and have no sequential or technical meaning. The terms "connection" and "linkage" used in this application, unless otherwise specified, include both direct and indirect connections (linkages). It should be understood that the terms "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," and "counterclockwise," indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings and are used solely for the convenience of describing this application and simplifying the description. They 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, and therefore should not be construed as a limitation of this application.

[0048] In this application, unless otherwise expressly 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," "on top of," and "over" 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.

[0049] The magnet system in a magnetic resonance imaging (MRI) system includes a main magnet, shimming coils, gradient coils, and radio frequency coils. The distribution of the shimming coil 11, gradient coil 12, and shielding coil 13 is as follows: Figure 1 As shown. From Figure 1 As can be seen, the shimming coil 11 is nested between the gradient coil 12 and the shielding coil 13. During the operation of the magnetic resonance system, a significant coupling occurs between the shimming coil 11 and the gradient coil 12. When running a gradient sequence, the gradient current in the Z direction of the gradient coil 12 synchronously flows into the shimming coil 11, inducing a coupling current in the shimming coil 11. This coupling current in the shimming coil 11 generates an additional coupling magnetic field, which is superimposed on the background magnetic field generated by the main magnet, thus affecting the stability of the background magnetic field. Furthermore, the coupling current in the shimming coil 11 is input to the external shimming power supply 14. If the coupling current exceeds the allowable input current of the shimming power supply 14, it will damage the shimming power supply 14, causing the shimming coil 11 to malfunction. The shielding coil 13 is used to shield the magnetic field generated by the coil (e.g., the gradient coil) from being transmitted outwards, potentially damaging the external magnet. The coupling between the shimming coil 11 and the gradient coil 12 can be expressed by formula I. K =LKI C Calculate, where K is the mutual inductance between the shimming coil 11 and the gradient coil 12, L is the self-inductance of the shimming coil 11, and I...K I is the coupling current on the shim coil 11. C This is the coupling current on gradient coil 12. The smaller K is, the greater I is. K The larger L is, the smaller I is. K The smaller the current, the better. Therefore, to reduce the coupling current, the mutual inductance between the shimming coil 11 and the gradient coil 12 can be reduced, or the self-inductance of the shimming coil 11 can be increased. In this regard, this application proposes a shimming device that can adjust the mutual inductance between the shimming coil 11 and the gradient coil 12, thereby reducing the coupling current of the shimming coil 11.

[0050] The technical solution of this application and how it solves the technical problems will be described in detail below with specific embodiments. These specific embodiments can be combined with each other, and the same or similar concepts or processes may not be described again in some embodiments. The embodiments of this application will be described below with reference to the accompanying drawings.

[0051] Please see Figure 2 One embodiment of this application provides a field shimming device 10, which includes a field shimming coil 11 and a plurality of adjustment leads 15.

[0052] The shimming coil 11 includes a positive lead 101 and a negative lead 102. One end of the positive lead 101 is connected to the first coil of the shimming coil 11, and the other end of the positive lead 101 is connected to the positive terminal of the shimming power supply 14. One end of the negative lead 102 is connected to the last coil of the shimming coil 11, and the other end of the negative lead 102 is connected to the negative terminal of the shimming power supply 14. Multiple adjustment leads 15 are distributed on the last coil or the first coil.

[0053] The shimming coil 11 refers to multiple coils surrounding a three-dimensional structure, which can be cylindrical, cubic, or other irregular structures. Specifically, the three-dimensional structure is cylindrical, and the shimming coil 11 refers to multiple circular coils surrounding the cylindrical structure. The shimming coil 11 includes a starting coil, an ending coil, multiple coils between the starting and ending coils (e.g., intermediate coils), a positive lead 101, and a negative lead 102. One end of the positive lead 101 is connected to one end of the starting coil, and the other end of the positive lead 101 is connected to the positive terminal of the shimming power supply 14. The other end of the starting coil is connected to one end of the ending coil (e.g., in series) through the multiple coils (intermediate coils) between the starting and ending coils. One end of the negative lead 102 is connected to the other end of the ending coil, and the other end of the negative lead 102 is connected to the negative terminal of the shimming power supply 14. The shimming power supply 14 is used to supply current to the shimming coil 11.

[0054] Multiple adjustment leads 15 are distributed on the end coil, meaning one end of each adjustment lead 15 is connected to the end coil, and the other end is used to connect to the negative terminal of the shimming power supply 14. Alternatively, the multiple adjustment leads 15 can be distributed on the beginning coil, meaning one end of each adjustment lead 15 is connected to the beginning coil, and the other end is used to connect to the positive terminal of the shimming power supply 14. This embodiment does not limit the number of adjustment leads 15 or their distribution on the beginning or end coil, as long as the function is achieved.

[0055] The shimming device 10 provided in this embodiment includes a shimming coil 11 and multiple adjusting leads 15. The shimming coil 11 includes a positive lead 101 and a negative lead 102. One end of the positive lead 101 is connected to the first coil of the shimming coil 11, and the other end of the positive lead 101 is connected to the positive terminal of the shimming power supply 14. One end of the negative lead 102 is connected to the last coil of the shimming coil 11, and the other end of the negative lead 102 is connected to the negative terminal of the shimming power supply 14. The multiple adjusting leads 15 are distributed on the last coil and the first coil. By selecting different adjusting leads 15 to connect to the positive or negative terminal of the shimming power supply 14, the shimming device 10 provided in this embodiment can adjust the mutual inductance between the shimming coil 11 and the gradient coil 12, thereby reducing the coupling current of the shimming coil 11 and preventing damage to the shimming power supply 14, thus ensuring the normal operation of the shimming device 10.

[0056] In one embodiment, a plurality of adjustment leads 15 are evenly distributed on the first end coil, and the plurality of adjustment leads 15 are evenly and symmetrically distributed on the two side coils with the first diameter of the first end coil as the dividing line; the first diameter is the diameter of the connection point between the positive lead 101 and the first end coil.

[0057] In this embodiment, the shimming coil 11 consists of multiple coils surrounding the cylindrical structure; that is, each coil is circular. Since the first-end coil is circular, its diameter, or first diameter, can be obtained through the connection point between the positive lead 101 and the first-end coil. Multiple adjustment leads 15 are evenly and symmetrically distributed on the coils on both sides of the first diameter of the first-end coil; that is, the number of adjustment leads 15 distributed on the coils on both sides of the first diameter of the first-end coil is the same. Specifically, the multiple adjustment leads 15 can be evenly distributed on the first-end coil at a preset distance; that is, the distance between any two adjustment leads 15 is a preset distance.

[0058] In this embodiment, by evenly and symmetrically distributing multiple adjustment leads 15 on the two coils with the first diameter of the first end coil as the dividing line, the mutual inductance that each adjustment lead 15 can adjust is easily obtained. This makes it convenient to adjust the mutual inductance between the shimming coil 11 and the gradient coil 12 by selecting different adjustment leads 15, thereby improving the practicality of the shimming device 10.

[0059] In one embodiment, a plurality of adjustment leads 15 are evenly distributed on the end coil, and the plurality of adjustment leads 15 are evenly and symmetrically distributed on the two coils with the second diameter of the end coil as the dividing line; the second diameter is the diameter of the connection point between the negative lead 102 and the end coil.

[0060] In this embodiment, the shimming coil 11 consists of multiple coils surrounding the cylindrical structure; that is, each coil is circular. Since the end coil is circular, a diameter, or second diameter, of the end coil can be obtained through the connection point between the negative lead 102 and the end coil. Multiple adjustment leads 15 are evenly and symmetrically distributed on the coils on both sides of the second diameter of the end coil; that is, the number of adjustment leads 15 distributed on the coils on both sides of the second diameter of the end coil is the same. Specifically, the multiple adjustment leads 15 can be evenly distributed on the end coil at a preset distance; that is, the distance between any two adjustment leads 15 is a preset distance.

[0061] The distribution of the multiple adjustment leads 15 on the end coil is as follows Figure 2 As shown, Figure 2 The rightmost coil is the end coil of the shimming coil 11. The dotted line in the end coil is the second diameter. There are 5 adjustment leads distributed on both sides of the end coil with the second diameter as the dividing line.

[0062] In this embodiment, by evenly and symmetrically distributing multiple adjustment leads 15 on the two coils with the second diameter of the end coil as the dividing line, the mutual inductance that each adjustment lead 15 can adjust is easily obtained. This makes it convenient to adjust the mutual inductance between the shimming coil 11 and the gradient coil 12 by selecting different adjustment leads 15, thereby improving the practicality of the shimming device 10.

[0063] The above embodiments provide two ways to set the adjustment lead 15: one is to set it at the first end coil of the shimming coil 11, and the other is to set it at the end coil of the shimming coil 11. The operator can set it according to the actual application.

[0064] In another embodiment, the adjusting lead 15 can be simultaneously provided at both the beginning coil and the end coil of the shimming coil 11.

[0065] In one embodiment, the shimming coil 11 includes multiple grid coils, each grid coil containing the same or different number of coils. The starting coil, ending coil, and multiple coils between the starting and ending coils in the shimming coil 11 can be divided into multiple grid coils. Each grid coil includes multiple coils, and the number of coils included in each grid coil can be the same or different. Figure 3 As shown, the shimming coil 11 includes p grids, each grid including the same or different number of coils, where p is an integer greater than 1.

[0066] In this embodiment, the entire shimming coil 11 is divided into multiple grid coils, which facilitates the setting of the shimming coil 11 and can improve the efficiency of setting the shimming coil 11.

[0067] Please see Figure 4 This application provides a design method for a field shimming device in one embodiment. This embodiment is described using a computer device as the execution subject. The computer device includes, but is not limited to, control chips, personal computers, laptops, smartphones, tablets, and portable wearable devices. The method provided in this application can be implemented using JAVA software or applied to other software. The steps of the method include:

[0068] Step 400: Based on the energy minimization requirement and the correspondence between the energy and current of the shimming coil, determine the distribution of coils in each grid coil of the shimming coil, and design the shimming coil in the shimming device provided in the above embodiment.

[0069] Calculating the energy of the shimming coil requires obtaining the current flowing through it and its inductance. In this embodiment, the shimming coil is divided into multiple grid coils. Each grid coil has its own inductance and mutual inductance with other grid coils. Based on the current flowing through each grid coil, the self-inductance of each grid coil, and the mutual inductance between the grid coils, a computer can establish a correspondence between the shimming coil's energy and its current.

[0070] Based on this correspondence and energy minimization requirements, the computer device can determine the distribution of coils in each network of the shimming coil. By designing the shimming coil according to the distribution of coils in each network of the shimming coil, the shimming coil in the shimming device provided in the above embodiment can be obtained.

[0071] This embodiment does not limit the specific methods for calculating the self-inductance of each grid coil of the shimming coil, the mutual inductance between the grid coils of the shimming coil, or the specific methods for determining the distribution of coils in each network coil of the shimming coil, as long as the function can be achieved.

[0072] In an optional embodiment, the self-inductance of each grid coil of the shimming coil and the mutual inductance between the grid coils can be calculated based on the geometric parameters of each grid coil in the shimming coil. The geometric parameters of each grid coil in the shimming coil are related to the shape of the grid coil. These geometric parameters can be pre-stored in the memory of a computer device, which directly retrieves them when calculating the self-inductance of each grid coil and the mutual inductance between the grid coils in each shimming coil; alternatively, these geometric parameters can be input by the designer. If each grid coil of the shimming coil is annular, the geometric parameters include the radius, thickness, axial position, and width of the annulus.

[0073] Step 410: Calculate the angle step size between each adjustment lead based on the mutual inductance range between the shimming coil and the gradient coil, the number of multiple adjustment leads, the arc of a unit angle on the shimming coil, and the mutual inductance between the gradient coil and the shimming coil.

[0074] The mutual inductance range between the shimming coil and the gradient coil refers to the range of mutual inductance that the shimming device can adjust, which is preset by the operator. This range can be stored directly in the memory of the computer device or input into the computer device by the operator.

[0075] The number of adjustable leads can be preset by the operator and stored in the computer's memory, or it can be entered into the computer by the operator. The mutual inductance between the arc per unit angle on the shimming coil and the gradient coil can be directly stored in the computer, or it can be entered into the computer by the operator.

[0076] In an optional embodiment, the mutual inductance between the arc on the shimming coil and the gradient coil can be expressed as: in,

[0077]

[0078] Where, r i Let r be the radius of coil i in the gradient coil. j Let h be the radius of coil j in the shim coil. ij Let be the axial distance between coil i in the gradient coil and coil j in the shim coil. Let be the arc angle on the shim coil, μ0 be the permeability of free space, and q be the total number of coils in the shim coil. The angle at point i in the uniform field coil is... The mutual inductance between the circular arc and the gradient coil. In At that time, M i (1) is the mutual inductance between the unit angle arc in the shimming coil and the gradient coil. and Proportional i is the coil number, j is the coil number, and both i and j are positive integers.

[0079] After the shimming coil is designed, the computer equipment can calculate the angular step size between each adjustment lead, that is, the distance between each adjacent adjustment lead, based on the mutual inductance range between the shimming coil and the gradient coil, the number of multiple adjustment leads, and the mutual inductance between the arc of the shimming coil and the gradient coil at a unit angle.

[0080] Step 420: Determine the connection positions of multiple adjustment leads on the shimming coil according to the angle step size between each adjustment lead, so as to obtain multiple adjustment leads in the shimming device provided in the above embodiment.

[0081] After obtaining the angular step size between each adjustment lead, the terminal determines the connection position of multiple adjustment leads on the shimming coil according to the angular step size, thereby obtaining multiple adjustment leads in the shimming device provided in the above embodiment.

[0082] Specifically, the terminal determines the connection positions of multiple adjustment leads on the first coil of the shimming coil based on the angle step size, thus obtaining the distribution of the multiple adjustment leads on the first coil. Alternatively, the terminal determines the connection positions of multiple adjustment leads on the last coil of the shimming coil based on the angle step size, thus obtaining the distribution of the multiple adjustment leads on the last coil.

[0083] This embodiment determines the coil distribution in each network coil of the shimming coil based on energy minimization requirements and the correspondence between the energy and current of the shimming coil, thus obtaining the shimming coil of the shimming device. Based on the mutual inductance range between the shimming coil and the gradient coil, the number of multiple adjustment leads, the arc per unit angle on the shimming coil, and the mutual inductance between the gradient coils, the angular step size between each adjustment lead is obtained. Based on the angular step size between each adjustment lead, the connection positions of the multiple adjustment leads on the shimming coil are determined, thus obtaining the multiple adjustment leads in the shimming device. The design method provided in this embodiment can obtain a shimming device, thus possessing all the beneficial effects of a shimming device, which will not be elaborated further here. Furthermore, the design method provided in this embodiment is logically simple and easy to implement.

[0084] In addition, the shimming coil designed in this embodiment based on the principle of minimizing energy will increase the inductance of the shimming coil, thereby reducing the coupling current generated by the shimming coil and preventing damage to the shimming power supply, thus ensuring the normal operation of the shimming device.

[0085] In one embodiment, such as Figure 5As shown, this relates to a possible implementation of determining the distribution of coils in each grid coil of a shimming coil based on energy minimization requirements and the correspondence between the energy and current of the shimming coil. The steps of this implementation include:

[0086] Step 500: Determine the current parameters of each grid coil in the shimming coil based on the energy minimization requirement and the corresponding relationship.

[0087] Based on the relationship between the energy and current parameters of the shimming coil, and the energy minimization requirement, the computer equipment can establish the minimum energy function of the shimming coil. The minimum energy function f2 of the shimming coil can be expressed as: Where p is the number of grid coils in the shimming coil, h and k are the grid coil numbers, and both are positive integers, I h Let I be the current in the h-th grid coil of the shim coil. k Let L be the current in the k-th grid coil of the shim coil. When h = k, hk Let L be the self-inductance of the h-th grid coil of the shim coil. When h ≠ k, hk Let be the mutual inductance between the h-th grid coil and the k-th grid coil of the shim coil.

[0088] According to the Biot-Savart law, the mutual inductance L between the h-th grid coil and the k-th grid coil of the shimming coil is... hk It can be represented as: in,

[0089]

[0090] Among them, R h R is the radius of the h-th grid coil. k Let s be the radius of the k-th grid coil. hk denoted as the axial distance between the h-th grid coil and the k-th grid coil, μ0 is the permeability of free space, and p is the total number of grid coils in the shimming coil.

[0091] The self-inductance L of the h-th grid coil of the shim coil h It can be represented as: in,

[0092]

[0093] Among them, a h Let be the radius of the transverse interface of the h-th grid coil.

[0094] After obtaining the minimum energy function of the shimming coil, the computer device obtains the constraints of this minimum energy function and solves for the minimum energy function based on these constraints to obtain the current parameters of each network coil. Specifically, the constraints may include the magnetic field deviation constraint and the maximum permissible mutual inductance constraint of the shimming device.

[0095] The formula for calculating the magnetic field deviation of the shimming device is: Where S represents the magnetic field deviation of the shimming device, m is the magnetic field region, and B mh I represents the magnetic field strength of the h-th grid coil at location m in the magnetic field region of the shimming device. h BTarget represents the current flowing through the h-th grid coil of the shim coil. m This represents the target magnetic field strength at location m in the magnetic field region of the shimming device.

[0096] In an optional embodiment, the target magnetic field strength at the magnetic field region m of the shimming device can be expressed by the formula... Calculate, where (x,y,z) represents the coordinates of the magnetic field region m. Let represent the magnetic field strength of various shimming devices. For example, for the A30 shimming device, Let represent the magnetic field strength of the A30 shimming device, while the magnetic field strength of all other shimming devices is zero. Then, the target magnetic field strength of the A30 shimming device can be expressed as:

[0097] The magnetic field deviation constraint condition refers to whether the difference between the magnetic field deviation of the shimming device and the maximum allowable magnetic field deviation of the shimming device is less than or equal to zero. Specifically, Where, ε m This represents the maximum allowable deviation of the shimming device.

[0098] The maximum allowable mutual inductance constraint can be expressed as: Where I0 is the current flowing through the shimming coil, I h The current in the h-th grid coil, M h M is the mutual inductance between the h-th grid coil and the gradient coil. max This represents the maximum permissible mutual inductance between the shimming coil and the gradient coil.

[0099] Step 510: Discretize the current parameters of each grid coil to obtain the distribution of coils in each grid coil.

[0100] After obtaining the current parameters of each grid coil in the shimming coil, the computer device discretizes the current parameters of each grid coil, thereby determining the current of each coil in each grid coil and thus determining the distribution of coils in each grid coil.

[0101] The method for determining the distribution of coils in each grid coil of the shimming coil in this embodiment is logically simple and easy to implement.

[0102] In one embodiment, such as Figure 6 As shown, a possible implementation method involves calculating the angular step size between each adjustment lead based on the mutual inductance range between the shimming coil and the gradient coil, the number of multiple adjustment leads, the arc of a unit angle on the shimming coil, and the mutual inductance between the gradient coil and the shimming coil. The steps of this implementation method include:

[0103] Step 600: Calculate the mutual inductance adjustment step size based on the mutual inductance range between the shimming coil and the gradient coil and the number of multiple adjustment leads.

[0104] After obtaining the mutual inductance range between the shimming coil and the gradient coil, as well as the number of adjustment leads, the computer equipment can calculate the mutual inductance adjustment step size based on the mutual inductance range and the number of adjustment leads.

[0105] Assuming the mutual inductance adjustment range is (-W, +W), and the number of adjustment leads is 2n+1 (in this embodiment, a positive or negative lead is also considered as an adjustment lead), the mutual inductance adjustment step size ΔM can be expressed as: Where W represents the absolute value of the maximum value in the mutual inductance range, and n is a positive integer.

[0106] Step 610: Calculate the angle step between each adjustment lead based on the mutual inductance between the arc of a unit angle on the shimming coil and the gradient coil, as well as the mutual inductance adjustment step.

[0107] After obtaining the mutual inductance adjustment step size, the computer equipment can calculate the angular step size between each adjustment lead based on the unit angle arc on the shimming coil and the mutual inductance and adjustment step size between the gradient coils. Specifically, the angular step size between each adjustment lead... It can be represented as:

[0108] This embodiment can obtain the angle step size between each adjustment lead through a simple calculation formula. The method is simple, easy to implement, and has high calculation efficiency.

[0109] Please see Figure 7 In one embodiment, this application provides a decoupling method for a shimming coil. This decoupling method is applied to the shimming device provided in the above embodiments, that is, the shimming device provided in the above embodiments is used to decouple the shimming coil. This embodiment uses a computer device as an example for specific description, and the method includes:

[0110] Step 700: Obtain the actual mutual inductance between the shimming coil and the gradient coil.

[0111] The actual mutual inductance between the shimming coil and the gradient coil refers to the actual mutual inductance that exists between them after the shimming device has been designed. The computer equipment acquires the actual mutual inductance between the shimming coil and the gradient coil. This actual mutual inductance can be detected by specific detection equipment and sent to the computer equipment, or it can be acquired by personnel and input into the computer equipment. This embodiment does not limit the specific method for acquiring the actual mutual inductance between the shimming coil and the gradient coil, as long as the function can be achieved.

[0112] Step 710: Obtain the mutual inductance adjustment step size between multiple adjustment leads in the shimming coil.

[0113] After the shimming device is designed, the mutual inductance step size between the multiple adjusting leads in the shimming coil of the device is also determined. The method for determining the mutual inductance adjustment step size between the multiple adjusting leads can be referred to the specific description in the above embodiments, and will not be repeated here. The computer device can directly obtain the mutual inductance adjustment step size between each adjusting lead. The mutual inductance adjustment step size can be stored in the computer device or input into the computer device by the operator. This embodiment does not limit the specific method for obtaining the mutual inductance adjustment step size between the multiple adjusting leads in the shimming coil, as long as the function can be achieved.

[0114] Step 720: Based on the actual mutual inductance and mutual inductance adjustment step size, determine the target adjustment lead from multiple adjustment leads; the target adjustment lead is used to connect the positive or negative terminal of the shimming power supply.

[0115] The computer device determines a target adjustment lead from multiple adjustment leads based on the actual mutual inductance between the shimming coil and the gradient coil, as well as the mutual inductance adjustment step size. The other end of the target adjustment lead is then connected to either the positive or negative terminal of the shimming power supply. In other words, if multiple adjustment leads are located at the beginning of the shimming coil, a target adjustment lead capable of decoupling the coupling between the shimming coil and the gradient coil is determined, and one end of the target adjustment lead is connected to the positive terminal of the shimming power supply. If multiple adjustment leads are located at the end of the shimming coil, a target adjustment lead is determined, and one end of the target adjustment lead is connected to the negative terminal of the shimming power supply.

[0116] The decoupling method for the shimming coil provided in this embodiment can determine the target adjustment lead from multiple adjustment leads based on the obtained actual mutual inductance and mutual inductance adjustment step size. Connecting the determined target adjustment lead to the positive or negative terminal of the shimming power supply can decouple the coupling between the shimming coil and the gradient coil, thereby reducing the coupling current of the shimming coil, preventing damage to the shimming power supply, and ensuring the normal operation of the shimming device.

[0117] In one embodiment, such as Figure 8 As shown, this involves determining the target adjustment lead from multiple adjustment leads based on the actual mutual inductance and the mutual inductance adjustment step size, including:

[0118] Step 800: Use the ratio of the actual mutual inductance to the mutual inductance adjustment step size as the lead number.

[0119] After obtaining the actual mutual inductance M and the mutual inductance adjustment step size, the computer equipment calculates the ratio between the actual mutual inductance and the mutual inductance adjustment step size, i.e. Based on this ratio, the lead numbers corresponding to multiple adjustment leads are determined. The lead numbers are integers. If the ratio between the actual mutual inductance and the mutual inductance adjustment step size is a decimal, it is rounded down to obtain the lead number. Specifically, the lead number 'b' of the multiple adjustment leads can be expressed as:

[0120] Step 810: Determine the region of the target adjustment lead in the shimming coil from multiple adjustment leads based on the polarity of the ratio.

[0121] The polarity of the ratio can be positive or negative. By analyzing the actual mutual inductance and the polarity of the ratio of the mutual inductance adjustment step size, the computer device can determine the region of the target adjustment lead within the shimming coil from among multiple adjustment leads. Specifically, if the multiple adjustment leads are located in the first coil of the shimming coil, the polarity of the ratio determines which coil in the first coil of the shimming coil, divided by a first diameter, contains the target adjustment lead; if the multiple adjustment leads are located in the last coil of the shimming coil, the polarity of the ratio determines which coil in the last coil of the shimming coil, divided by a second diameter, contains the target adjustment lead.

[0122] In an optional embodiment, if the ratio If the ratio is greater than zero, meaning the polarity of the ratio is positive, then the target adjustment lead is located on the innermost coil among the two coils on either side of the first diameter boundary in the beginning coil of the shimming coil, or on the innermost coil among the two coils on either side of the second diameter boundary in the end coil of the shimming coil. If the ratio... If the ratio is less than zero, meaning the polarity of the ratio is negative, then the target adjustment lead is determined to be located on the outermost coil of the two coils on either side of the shimming coil, with the first diameter as the boundary line; or the target adjustment lead is determined to be located on the outermost coil of the two coils on either side of the shimming coil, with the second diameter as the boundary line. If the ratio... If (M=0) is zero, then the target adjustment lead is either a positive lead or a negative lead.

[0123] like Figure 9 As shown, the regions where A1, A2, A3, A4, and A5 are located are ratios. When the value is greater than zero, the region where the adjusting lead is located is indicated by numbers 1, 2, 3, 4, and 5, which refer to the numbers of the adjusting leads within that region. The regions where B1, B2, B3, B4, and B5 are located are ratios. When the value is less than zero, the region where the adjusting lead is located is indicated by numbers 1, 2, 3, 4, and 5. A0 represents the ratio. Adjustment lead (negative lead) when equal to zero.

[0124] Step 820: Within the region, the adjustment lead corresponding to the lead number is identified as the target adjustment lead.

[0125] After determining the region of the target adjustment lead, the computer equipment identifies the adjustment lead within that region that corresponds to the lead number as the target adjustment lead. In other words, the computer equipment determines the target adjustment lead based on the polarity and ratio of the ratio.

[0126] like Figure 9 As shown, if M = 0, then the target adjustment lead is A0; if Greater than zero, and The target adjustment lead is A2; if Less than zero, and The target adjustment lead is B1.

[0127] In a specific embodiment, for the ring-shaped shimming device A30, the maximum allowable coupling current of the shimming power supply is 2A, the required magnetic field strength of the shimming coil is 2000uT / m³, the maximum operating current of the gradient coil is 500A, the maximum gradient strength is 30mT / m, and the maximum ramp rate is 130T / m / s. According to the decoupling design model, the self-inductance of the A30 shimming coil is L = 1000uH, and the design value of the mutual inductance between A30 and the gradient coil is M = 0uH. The adjustable mutual inductance range is set to -20uH to 20uH, and the number of adjustments is 2*5+1 = 11, i.e., the coupling adjustment step size is 4uH. If, after the shimming device and gradient coil are manufactured, the actual coupling of A30 is assumed to be within the coupling adjustment range (-20uH to 20uH), then the maximum coupling current is: Within the maximum allowable coupling current range of the uniform power supply.

[0128] After the gradient coil and shimming coil (including gradient coils and shimming coils for the X / Y / Z axes) are completed, the actual mutual inductance between the A30 coil and the gradient coil is 11uH, and the coupling current is: The maximum allowable coupling current of 2A for the shimming power supply is not met, so the shimming power supply cannot work properly.

[0129] Using the decoupling method provided in this application, the coupling adjustment current lead numbered A2 was calculated; the adjustment lead A2 was connected to the shimming power supply. The measured mutual inductance between the A30 shimming coil and the Z gradient coil was 3uH, and the coupling current was... If the maximum allowable coupling current of the shimming power supply is 2A, the shimming power supply can work normally.

[0130] It should be understood that although the steps in the flowcharts of the embodiments described above are shown sequentially according to the arrows, these steps are not necessarily executed in the order indicated by the arrows. Unless explicitly stated herein, there is no strict order restriction on the execution of these steps, and they can be executed in other orders. Moreover, at least some steps in the flowcharts of the embodiments described above may include multiple steps or multiple stages. These steps or stages are not necessarily completed at the same time, but can be executed at different times. The execution order of these steps or stages is not necessarily sequential, but can be performed alternately or in turn with other steps or at least some of the steps or stages of other steps.

[0131] Please see Figure 10 One embodiment of this application provides a magnetic resonance system 20, which includes a shielding coil 13, a gradient coil 12, and a shimming device 10 as provided in the above embodiment. The shimming device 10 is disposed in the space between the shielding coil 13 and the gradient coil 12. The magnetic resonance system 20 provided in this embodiment includes the shimming device 10, thus possessing all the beneficial effects of the shimming device 10, which will not be elaborated further here.

[0132] Based on the same inventive concept, this application also provides a design apparatus for a shimming device to implement the design method of the shimming device described above, and a decoupling apparatus for a shimming coil to implement the decoupling method of the shimming coil. The solution provided by this apparatus is similar to the solution described in the above method. Therefore, the specific limitations of the design apparatus for one or more shimming devices and the decoupling apparatus for shimming coils provided below can be found in the limitations of the design method for the shimming device and the decoupling of the shimming coils described above, and will not be repeated here.

[0133] In one embodiment, such as Figure 11 As shown, a design device 30 for a shimming device is provided. This device includes a design module 31, a calculation module 32, and a first determination module 33. Wherein,

[0134] Design module 31 is used to determine the distribution of coils in each grid coil of the shimming coil based on the energy minimization requirement and the correspondence between the energy and current of the shimming coil, and to design the shimming coil in the shimming device provided in the above embodiment.

[0135] The calculation module 32 is used to calculate the angle step between each adjustment lead based on the mutual inductance range between the shimming coil and the gradient coil, the number of multiple adjustment leads, the arc of a unit angle on the shimming coil and the mutual inductance between the gradient coil and the shimming coil.

[0136] The first determining module 33 is used to determine the connection position of multiple adjusting leads on the shimming coil according to the angular step size between each adjusting lead, so as to obtain multiple adjusting leads in the shimming device provided in the above embodiment.

[0137] In one embodiment, such as Figure 12 As shown, a decoupling device 40 for a shimming coil is provided. This device includes a first acquisition module 41, a second acquisition module 42, and a second determination module 43. Wherein,

[0138] The first acquisition module 41 is used to acquire the actual mutual inductance between the shimming coil and the gradient coil;

[0139] The second acquisition module 42 is used to acquire the mutual inductance adjustment step size between multiple adjustment leads in the shimming coil;

[0140] The second determining module 43 is used to determine the target adjusting lead from multiple adjusting leads based on the actual mutual inductance and mutual inductance adjustment step size; the target adjusting lead is used to connect to the positive or negative terminal of the shimming power supply.

[0141] The modules in the design device 30 of the shimming device and the decoupling device 40 of the shimming coil described above can be implemented entirely or partially through software, hardware, or a combination thereof. These modules can be embedded in hardware or independently of the processor in a computer device, or stored in software in the memory of a computer device, so that the processor can call and execute the operations corresponding to each module.

[0142] In one embodiment, a computer device is provided, which may be a terminal, and its internal structure diagram may be as follows: Figure 13As shown, the computer device includes a processor, memory, communication interface, display screen, and input devices connected via a system bus. The processor provides computing and control capabilities. The memory includes non-volatile storage media and internal memory. The non-volatile storage media stores the operating system and computer programs. The internal memory provides an environment for the operation of the operating system and computer programs stored in the non-volatile storage media. The communication interface is used for wired or wireless communication with external terminals; wireless communication can be achieved through Wi-Fi, mobile cellular networks, NFC (Near Field Communication), or other technologies. When executed by the processor, the computer program implements a design method for a shimming device and a decoupling method for shimming coils. The display screen can be an LCD screen or an e-ink screen. The input devices can be a touch layer covering the display screen, buttons, a trackball, or a touchpad mounted on the computer device casing, or an external keyboard, touchpad, or mouse.

[0143] Those skilled in the art will understand that Figure 13 The structure shown is merely a block diagram of a portion of the structure related to the present application and does not constitute a limitation on the computer device to which the present application is applied. Specific computer devices may include more or fewer components than those shown in the figure, or combine certain components, or have different component arrangements.

[0144] Those skilled in the art will understand that all or part of the processes in the methods of the above embodiments can be implemented by a computer program instructing related hardware. The computer program can be stored in a non-volatile computer-readable storage medium, and when executed, it can include the processes of the embodiments of the above methods. Any references to memory, databases, or other media used in the embodiments provided in this application can include at least one of non-volatile and volatile memory. Non-volatile memory can include read-only memory (ROM), magnetic tape, floppy disk, flash memory, optical memory, high-density embedded non-volatile memory, resistive random access memory (ReRAM), magnetic random access memory (MRAM), ferroelectric random access memory (FRAM), phase change memory (PCM), graphene memory, etc. Volatile memory can include random access memory (RAM) or external cache memory, etc. By way of illustration and not limitation, RAM can take many forms, such as Static Random Access Memory (SRAM) or Dynamic Random Access Memory (DRAM). The databases involved in the embodiments provided in this application may include at least one type of relational database and non-relational database. Non-relational databases may include, but are not limited to, blockchain-based distributed databases. The processors involved in the embodiments provided in this application may be general-purpose processors, central processing units, graphics processing units, digital signal processors, programmable logic devices, quantum computing-based data processing logic devices, etc., and are not limited to these.

[0145] 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.

[0146] The embodiments described above are merely illustrative of several implementation methods of this application, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of this patent application. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these all fall within the protection scope of this application. Therefore, the protection scope of this application should be determined by the appended claims.

Claims

1. A field homogenizing device, characterized in that, The field shimming device includes: a shimming coil and multiple adjustment leads; The shimming coil includes a positive lead and a negative lead. One end of the positive lead is connected to the first coil of the shimming coil, and the other end of the positive lead is connected to the positive terminal of the shimming power supply. One end of the negative lead is connected to the last coil of the shimming coil, and the other end of the negative lead is connected to the negative terminal of the shimming power supply. The plurality of adjustment leads are distributed on the last coil or the first coil. In this configuration, one end of each of the plurality of adjustment leads is connected to the end coil, and the other end of each of the plurality of adjustment leads is used to connect to the negative terminal of the shimming power supply; or, one end of each of the plurality of adjustment leads is connected to the beginning coil, and the other end of each of the plurality of adjustment leads is used to connect to the positive terminal of the shimming power supply; the shimming device selects different adjustment leads to connect to the negative or positive terminal of the shimming power supply based on the mutual inductance between the shimming coil and the gradient coil.

2. The field homogenizing device according to claim 1, characterized in that, The plurality of adjustment leads are evenly distributed on the first end coil, and the plurality of adjustment leads are evenly and symmetrically distributed on the two side coils with the first diameter of the first end coil as the dividing line; the first diameter is the diameter of the connection point between the positive lead and the first end coil.

3. The field homogenizing device according to claim 1, characterized in that, The plurality of adjustment leads are evenly distributed on the end coil, and the plurality of adjustment leads are evenly and symmetrically distributed on the two coils with the second diameter of the end coil as the dividing line; the second diameter is the diameter of the connection point between the negative lead and the end coil.

4. The field homogenizing device according to claim 1, characterized in that, The shimming coil includes multiple grid coils, each of which contains the same or different number of coils.

5. A design method for a field homogenizing device, characterized in that, The method includes: Based on the energy minimization requirement and the correspondence between the energy and current of the shimming coil, the distribution of the coils in each grid coil of the shimming coil is determined, and the shimming coil in the shimming device as described in any one of claims 1-4 is designed. The angle step size between each adjustment lead is calculated based on the mutual inductance range between the shimming coil and the gradient coil, the number of multiple adjustment leads, the arc of a unit angle on the shimming coil, and the mutual inductance between the gradient coils. Based on the angular step size between each of the adjustment leads, the connection positions of the plurality of adjustment leads on the shimming coil are determined, thereby obtaining the plurality of adjustment leads in the shimming device as described in any one of claims 1-4.

6. The method according to claim 5, characterized in that, The step of determining the distribution of coils in each grid coil of the shimming coil based on the energy minimization requirement and the correspondence between the energy and current of the shimming coil includes: Based on the energy minimization requirement and the corresponding relationship, determine the current parameters of each grid coil in the shimming coil; The current parameters of each grid coil are discretized to obtain the distribution of coils in each grid coil.

7. The method according to claim 5, characterized in that, The step of calculating the angular step size between each adjustment lead based on the mutual inductance range between the shimming coil and the gradient coil, the number of multiple adjustment leads, the arc of a unit angle on the shimming coil, and the mutual inductance between the gradient coil includes: The mutual inductance adjustment step size is calculated based on the mutual inductance range between the shimming coil and the gradient coil and the number of the plurality of adjustment leads; The angle step size between each adjustment lead is calculated based on the arc of a unit angle on the shimming coil and the mutual inductance between the gradient coils, as well as the mutual inductance adjustment step size.

8. A decoupling method for a uniform field coil, characterized in that, The method is applied to the field homogenizing device as described in any one of claims 1-4, and the method includes: Obtain the actual mutual inductance between the shim coil and the gradient coil; Obtain the mutual inductance adjustment step size among multiple adjustment leads in the shimming coil; Based on the actual mutual inductance and the mutual inductance adjustment step size, a target adjustment lead is determined from a plurality of adjustment leads; the target adjustment lead is used to connect to the positive or negative terminal of the shimming power supply.

9. The method according to claim 8, characterized in that, The step of determining the target adjustment lead from a plurality of adjustment leads based on the actual mutual inductance and the mutual inductance adjustment step size includes: The ratio of the actual mutual inductance to the mutual inductance adjustment step size is used as the lead number; Based on the polarity of the ratio, the region of the target adjustment lead in the shimming coil is determined from among the plurality of adjustment leads; Within the specified area, the adjustment lead corresponding to the lead number is identified as the target adjustment lead.

10. A magnetic resonance system, characterized in that, The magnetic resonance system includes a shielding coil, a gradient coil, and a shimming device as described in any one of claims 1-4, wherein the shimming device is disposed in the space between the shielding coil and the gradient coil.

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