Gradient coil correction device and method

Abstract

This application provides a gradient coil calibration device, comprising: a base, a first placement body, and a second placement body; the upper surface of the base includes a first placement groove and a second placement groove; the first placement groove is used to fix the first placement body, and the second placement groove is used to fix the second placement body. Based on this gradient coil calibration device, accurate spatial position information between the first and second placement bodies can be obtained in advance, and the gradient coil can be calibrated based on this spatial position information. Using the gradient coil calibration device provided in this application for gradient coil calibration can obtain more accurate calibration results.

Description

Technical Field

[0001] This application relates to the field of magnetic resonance technology, and more specifically, to a gradient coil correction device and method. Background Technology

[0002] Magnetic Resonance Imaging (MRI) is an imaging technique that uses the principle of nuclear magnetic resonance to determine the location and type of atomic nuclei that make up an object by detecting the electromagnetic waves emitted through an external gradient magnetic field, based on the different attenuations of the released energy in different structural environments within a substance. This allows the technique to create an image of the object's internal structure.

[0003] The generation of a gradient magnetic field relies on gradient coils. The magnitude and direction of the gradient magnetic field can be controlled by passing currents of different magnitudes and directions through the gradient coils. Accurate calibration of the gradient coils is one of the prerequisites for accurate imaging in a magnetic resonance imaging system.

[0004] Gradient coil calibration can be divided into two parts: gradient coil polarity calibration and gradient coil gain calibration. Gradient coil calibration relies on a phantom that can simulate the response of human tissue to magnetic fields and radio frequency pulses. Currently, most gradient coil polarity calibrations are performed by technicians manually placing the phantom, resulting in low accuracy of the calibration results. Summary of the Invention

[0005] In view of this, the purpose of this application is to provide a gradient coil correction device and method to solve the technical problem of low accuracy in existing gradient coil correction methods.

[0006] In a first aspect, embodiments of this application provide a gradient coil correction device, which includes: a base, a first placement body, and a second placement body;

[0007] The upper surface of the base includes a first placement groove and a second placement groove;

[0008] The first placement groove is used to fix the first placement body, and the second placement groove is used to fix the second placement body.

[0009] In the above implementation process, since the upper surface of the base has a "first placement groove for fixing the first placement body" and a "second placement groove for fixing the second placement body," accurate spatial position information between the first and second placement bodies can be obtained in advance based on this base, and the polarity of the gradient coil can be corrected based on the "accurate spatial position information between the first and second placement bodies." Compared with the method of "correction by technicians manually placing the mold body," using the gradient coil correction device provided in this application can obtain a more accurate correction result.

[0010] Optionally, in this embodiment of the application, the first placement groove and the second placement groove satisfy a preset positional relationship; the preset positional relationship includes: when the second placement body is placed in the second placement groove, the second placement body does not intersect the plane containing the sagittal plane, coronal plane and cross-section of the centroid of the first placement body placed in the first placement groove.

[0011] In the above implementation process, since the first placement groove and the second placement groove satisfy the preset positional relationship, the "second placement body placed in the second placement groove" and the "sagittal plane, coronal plane and cross-sectional plane of the centroid of the first placement body placed in the first placement groove" do not intersect. This ensures that the "imaging areas of the first placement body and the second placement body in any axial slice" in the scan data acquired by the magnetic resonance system will not overlap, thereby further improving the accuracy of the correction results.

[0012] Optionally, in this embodiment of the application, the first placement body includes a first mold shell and a first liquid mold; the first mold shell has a first internal cavity for accommodating the first liquid mold; the second placement body includes a second mold shell and a second liquid mold; the second mold shell has a second internal cavity for accommodating the second liquid mold.

[0013] In the above implementation process, the first liquid phantom is contained in the first internal cavity of the first phantom shell, and the second liquid phantom is contained in the second internal cavity of the second phantom shell. The first liquid phantom is attached to the first internal cavity, and the second liquid phantom is attached to the second internal cavity, so as to avoid the influence of the fluidity of the liquid on magnetic resonance imaging and reduce the accuracy of the correction results.

[0014] Optionally, in this embodiment, the center of mass of the first liquid mold coincides with the center of mass of the first placement body, the center of mass of the second liquid mold coincides with the center of mass of the second placement body, and the center of the upper surface of the first placement groove coincides with the center of the upper surface of the base.

[0015] In the above implementation process, since "the centroid of the first liquid phantom coincides with the centroid of the first placement body," and "the center of the upper surface of the first placement groove coincides with the center of the upper surface of the base," by placing the base at the center of the magnetic field to be corrected, the first liquid phantom can be placed at the center of the magnetic field to be corrected, reducing the difficulty of placing the base in the magnetic field to be corrected. By placing the first placement body in the first placement groove, a gain correction device for correcting the gradient coil gain can be obtained. By placing the base at the center of the magnetic field to be corrected, the first placement body can be placed at the center of the magnetic field to be corrected. Furthermore, since "the centroid of the first liquid phantom coincides with the centroid of the first placement body," it can be ensured that the imaging area of ​​the first liquid phantom is located in the center of the field of view in magnetic resonance imaging, improving the accuracy of the gradient coil gain correction result.

[0016] Optionally, in this embodiment, the first internal cavity is a spherical cavity; the second internal cavity is a cubic cavity.

[0017] In the above implementation process, the first internal cavity is a spherical cavity, that is, the first liquid phantom is a spherical phantom, which can reduce the calculation difficulty of gradient coil gain correction.

[0018] Optionally, in this embodiment, the first mold shell and the first internal cavity have the same shape, and the second mold shell and the second internal cavity have the same shape; the depth h1 of the first placement groove and the depth h2 of the second placement groove satisfy the following condition: Where R1 is the radius of the first placement body, L2 is the side length of the second placement body, and L1 is the side length of the second internal cavity; the positions of the first placement groove and the second placement groove satisfy |x2- Where (x1, y1) are the coordinates of the center position of the upper surface of the first placement groove in a Cartesian coordinate system with the plane containing the upper surface of the base as the coordinate plane, (x2, y2) are the coordinates of the center position of the upper surface of the second placement groove in a Cartesian coordinate system with the plane containing the upper surface of the base as the coordinate plane, and || is the absolute value operator.

[0019] In the above implementation process, by specifically defining the depth and position of the first placement groove and the second placement groove, it is ensured that the "second liquid phantom placed in the second placement groove" does not intersect with the "sagittal plane, coronal plane and cross-sectional plane of the centroid of the first liquid phantom placed in the first placement groove". This ensures that the "imaging areas of the first liquid phantom and the second liquid phantom in any axial slice" in the scan data acquired by the magnetic resonance system will not overlap, thereby further improving the accuracy of the correction results.

[0020] Optionally, in this embodiment, the upper surface of the base also has a placement mark; the placement mark is used to indicate the placement direction of the gradient coil correction device in the magnetic field to be corrected.

[0021] In the above implementation process, the placement of the gradient coil correction device can be indicated by the placement of the markings in the magnetic field to be corrected, thereby improving the placement efficiency and accuracy of the gradient coil correction device. Increasing the placement accuracy of the gradient coil correction device can also improve the accuracy of the correction results.

[0022] Secondly, embodiments of this application also provide a gradient coil correction method, applied to any of the gradient coil correction devices described in the first aspect above, the gradient coil correction method comprising:

[0023] The first placement body is placed in the first placement groove of the gradient coil correction device, and the second placement body is placed in the second placement groove of the gradient coil correction device to obtain the first correction device.

[0024] Place the first calibration device into the first magnetic field to be calibrated;

[0025] Acquire a first calibrated magnetic resonance image from the first calibration device;

[0026] Based on the first corrected magnetic resonance image and the spatial position information of the first and second placement bodies in the first correction device, gradient coil polarity correction is performed on the first magnetic field to be corrected.

[0027] In the above implementation process, by placing a first placement body in the first placement groove of the gradient coil correction device and a second placement body in the second placement groove of the gradient coil correction device, a first correction device for correcting the polarity of the gradient coil of the magnetic field to be corrected can be obtained. Based on the gradient coil correction device, accurate spatial position information between the first and second placement bodies can be obtained in advance, and the polarity of the gradient coil can be corrected based on this accurate spatial position information. Compared to the method of "correction by manual placement of the model by technicians," the gradient coil correction method provided in this application can obtain correction results with higher accuracy.

[0028] Optionally, in this embodiment of the application, after performing gradient coil polarity correction on the first magnetic field to be corrected, the method further includes: placing a first placement body in the first placement groove of the gradient coil correction device to obtain a second correction device; placing the second correction device into the second magnetic field to be corrected; wherein, the second magnetic field to be corrected is the magnetic field to be corrected after gradient coil polarity correction on the first magnetic field to be corrected; acquiring a second corrected magnetic resonance image of the second correction device; and performing gradient coil gain correction on the second magnetic field to be corrected based on the second corrected magnetic resonance image.

[0029] In the above implementation process, according to the gradient coil correction device provided in this application, a second correction device can be obtained by "placing the first placement body in the first placement groove of the gradient coil correction device", and the gradient coil gain correction can be performed on the "second magnetic field to be corrected after gradient coil polarity correction" based on the second correction device.

[0030] Thirdly, embodiments of this application also provide another gradient coil correction method, applied to any of the gradient coil correction devices described in the first aspect above, the gradient coil correction method comprising:

[0031] The first placement body is placed in the first placement groove of the gradient coil correction device to obtain the third correction device;

[0032] Place the third correction device into the gain correction magnetic field;

[0033] Acquire the gain-corrected magnetic resonance image of the third correction device;

[0034] Based on the gain-corrected magnetic resonance image, gradient coil gain correction is performed on the gain-corrected magnetic field.

[0035] In the above implementation process, according to the gradient coil correction device provided in this application, a third correction device can be obtained by "placing the first placement body in the first placement groove of the gradient coil correction device", and the gradient coil gain correction can be performed on the gain correction magnetic field based on the third correction device.

[0036] The gradient coil correction device and method provided in this application can obtain accurate spatial position information between the first and second placement objects in advance, and perform polarity correction on the gradient coil based on the accurate spatial position information between the first and second placement objects. Compared with the method of "correction by manual placement of the model by technicians", gradient correction using the gradient coil correction device provided in this application can obtain more accurate correction results. Attached Figure Description

[0037] To more clearly illustrate the technical solutions of the embodiments of this application, the accompanying drawings used in the embodiments of this application will be briefly introduced below. It should be understood that the following drawings only show some embodiments of this application and should not be regarded as a limitation of the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0038] Figure 1 This is a schematic diagram of the structure of a gradient coil correction device provided in an embodiment of this application;

[0039] Figure 2 A cross-sectional schematic diagram of a first placement body and a second placement body provided in an embodiment of this application;

[0040] Figure 3 This is a schematic diagram of the structure of a base provided in an embodiment of this application;

[0041] Figure 4 A schematic flowchart illustrating a gradient coil correction method provided in an embodiment of this application;

[0042] Figure 5 This is a flowchart illustrating another gradient coil correction method provided in an embodiment of this application. Detailed Implementation

[0043] The embodiments of the technical solution of this application will now be described in detail with reference to the accompanying drawings. These embodiments are only used to more clearly illustrate the technical solution of this application and are therefore merely examples, and should not be used to limit the scope of protection of this application.

[0044] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs; the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit this application.

[0045] In the description of the embodiments of this application, technical terms such as "first" and "second" are used only to distinguish different objects and should not be construed as indicating or implying relative importance or implicitly specifying the number, specific order, or primary and secondary relationship of the indicated technical features. In the description of the embodiments of this application, "multiple" means two or more, unless otherwise explicitly defined.

[0046] Please refer to Figure 1 , Figure 1 This is a schematic diagram of the structure of a gradient coil correction device provided in an embodiment of this application. Figure 1In the gradient coil correction device 10 shown, the first placement body 102 is not placed in the first placement groove 1011 and the second placement body 103 is not placed in the second placement groove 1012. The gradient coil correction device 10 includes: a base 101, a first placement body 102, and a second placement body 103;

[0047] The upper surface of the base 101 is provided with a first placement groove 1011 and a second placement groove 1012;

[0048] The first placement groove 1011 is used to fix the first placement body 102, and the second placement groove 1012 is used to fix the second placement body 103.

[0049] The base 101 must be made of a material that is low in magnetism (ensuring that the base 101 will not introduce background noise and affect image quality), such as high-density sponge or high-strength engineering plastics. Specifically, the material of the base 101 must also meet the following requirements: high stability (i.e., able to maintain a stable shape and size, unaffected by factors such as temperature and humidity), corrosion resistance (having sufficient resistance to the liquids and cleaning agents used in the magnetic resonance system to avoid corrosion or contamination), and free from substances harmful to the human body.

[0050] The shape of the first placement groove 1011 is adapted to the shape of the first placement body 102 so as to fix the first placement body 102 through the first placement groove 1011; the shape of the second placement groove 1012 is adapted to the shape of the second placement body 103 so as to fix the second placement body 103 through the second placement groove 1012.

[0051] In some optional embodiments, the first placement groove 1011 and the second placement groove 1012 satisfy a preset positional relationship; the preset positional relationship includes: when the second placement body 103 is placed in the second placement groove 1012, the second placement body 103 does not intersect the planes containing the sagittal plane, coronal plane and cross-section of the centroid of the first placement body 102 placed in the first placement groove 1011.

[0052] Among them, the sagittal plane refers to the plane that divides the body into left and right parts along the anterior-posterior direction; the coronal plane refers to the plane that divides the body into anterior and posterior parts along the lateral direction; the transverse plane refers to the plane that divides the body into upper and lower parts and is parallel to the ground; the sagittal plane, coronal plane, and transverse plane are perpendicular to each other. The sagittal plane at the center of mass of the first placement body 102 refers to "the sagittal plane that passes through the center of mass of the first placement body 102, which is likened to a human body"; the coronal plane at the center of mass of the first placement body 102 refers to "the coronal plane that passes through the center of mass of the first placement body 102, which is likened to a human body"; and the transverse plane at the center of mass of the first placement body 102 refers to "the transverse plane that passes through the center of mass of the first placement body 102, which is likened to a human body".

[0053] Please refer to Figure 2 , Figure 2 This is a cross-sectional schematic diagram of a first placement body and a second placement body provided in an embodiment of this application.

[0054] In some optional embodiments, the first placement body 102 includes a first mold shell 1021 and a first liquid mold 1022; the first mold shell 1021 has a first internal cavity 10211 for accommodating the first liquid mold 1022; the second placement body 103 includes a second mold shell 1031 and a second liquid mold 1032; the second mold shell 1031 has a second internal cavity 10311 for accommodating the second liquid mold 1032.

[0055] The first liquid mold 1022 and the first internal cavity 10211 have the same shape, and the second liquid mold 1032 has the same shape as the second internal cavity 10311. The external shape of the outer shell 1021 of the first mold can be the same as or different from the shape of the first liquid mold 1022. The external shape of the outer shell 1031 of the second mold can be the same as or different from the shape of the second liquid mold 1032. Specifically, if the outer shape of the first mold shell 1021 is a cube, the shape of the first liquid mold 1022 can be a sphere or a cube; if the outer shape of the first mold shell 1021 is a sphere, the shape of the first liquid mold 1022 can also be a sphere or a cube; if the outer shape of the second mold shell 1031 is a cube, the shape of the second liquid mold 1032 can be a sphere or a cube; if the outer shape of the second mold shell 1031 is a sphere, the shape of the second liquid mold 1032 can also be a sphere or a cube. Both the first liquid mold 1022 and the second liquid mold 1032 can be regular shapes to reduce the computational complexity of correction using the gradient coil correction device.

[0056] The first liquid phantom 1022 and the second liquid phantom 1032 can be made of materials that exhibit special properties under the influence of a strong magnetic field, specifically materials that can "simulate the response of human tissue to magnetic fields and radio frequency pulses," such as water, copper sulfate aqueous solution, or nickel chloride aqueous solution. The first phantom shell 1021 and the second phantom shell 1031 can be made of materials with high strength, high stability, wear resistance, corrosion resistance, and good magnetic permeability, such as high-strength engineering plastics like polycarbonate (PC) or polyamide (PA). These properties ensure that the phantom shells will not deform during long-term use, and the good magnetic permeability ensures that the phantom shells will not affect magnetic resonance imaging, thus ensuring the accuracy of the calibration results.

[0057] In some optional embodiments, the center of mass of the first liquid mold 1022 coincides with the center of mass of the first placement body 102, the center of mass of the second liquid mold 1032 coincides with the center of mass of the second placement body 103, and the center of the upper surface of the first placement groove 1011 coincides with the center of the upper surface of the base 101.

[0058] The first liquid phantom 1022 and the second liquid phantom 1032 are usually of regular shape. By placing the base 101 at the center of the magnetic field to be corrected, the first liquid phantom 1022 can be placed at the center of the magnetic field to be corrected. This ensures that the imaging area of ​​the first liquid phantom 1022 is located in the center of the field of view in magnetic resonance imaging to improve the accuracy of the correction results, while reducing the difficulty of placing the base 101 in the magnetic field to be corrected.

[0059] In some optional embodiments, the first internal cavity 10211 is a spherical cavity; the second internal cavity 10311 is a cubic cavity.

[0060] In this design, the first internal cavity 10211 is a spherical cavity, and therefore the first liquid phantom 1022 is also a spherical phantom; the second internal cavity 10311 is a cubic cavity, and therefore the second liquid phantom 1032 is also a cubic phantom. The spherical and cubic phantoms reduce the computational complexity during gradient coil correction. The diameter of the first internal cavity 10211 can be 170mm or 190mm, etc., and its diameter is equal to that of the first liquid phantom. The side length of the second internal cavity 10311 can be 50mm or 60mm, and its side length is equal to that of the second liquid phantom 1032.

[0061] In some optional embodiments, the first mold shell 1021 and the first internal cavity 10211 have the same shape, and the second mold shell 1031 and the second internal cavity 10311 have the same shape; the depth h1 of the first placement groove 1011 and the depth h2 of the second placement groove 1012 satisfy the following... Where R1 is the radius of the first placement body 102, L2 is the side length of the second placement body 103, and L1 is the side length of the second internal cavity 10311; the position of the first placement groove 1011 is between the position of the second placement groove 1012 and satisfies the following condition. Where (x1, y1) are the coordinates of the center position of the upper surface of the first placement groove 1011 in a Cartesian coordinate system with the plane containing the upper surface of the base 101 as the coordinate plane, (x2, y2) are the coordinates of the center position of the upper surface of the second placement groove 1012 in a Cartesian coordinate system with the plane containing the upper surface of the base 101 as the coordinate plane, and || is the absolute value operator.

[0062] Wherein, (x1, y1) and (x2, y2) are the coordinates of the center position of the upper surface of the first placement groove 1011 and the center position of the upper surface of the second placement groove 1012, respectively, in the same coordinate system.

[0063] Please refer to Figure 3 , Figure 3 This is a schematic diagram of the structure of a base 101 provided in an embodiment of this application.

[0064] In some alternative embodiments, the upper surface of the base 101 also has a placement mark 1013; the placement mark 1013 is used to indicate the placement direction of the gradient coil correction device 10 in the magnetic field to be corrected.

[0065] The placement label 1013 can be Chinese characters, such as head and feet or left and right sides; it can also be letters, such as H (Head) and F (Foot) or L (Left) and R (Right). Of course, it can also be labeled with both Chinese characters and letters, or H, F, L and R at the same time. Figure 3 The diagram shows the placement of the label 1013 as letters, with the letters H and R as the labels.

[0066] Please refer to Figure 4 , Figure 4 This is a flowchart illustrating a gradient coil calibration method provided in an embodiment of this application. This gradient coil calibration method can be applied to, for example... Figure 1 The gradient coil correction device 10 shown herein may include the following steps:

[0067] Step 201: Place the first placement body in the first placement groove of the gradient coil correction device, and place the second placement body in the second placement groove of the gradient coil correction device to obtain the first correction device;

[0068] Step 202: Place the first calibration device into the first magnetic field to be calibrated;

[0069] Step 203: Obtain the first calibrated magnetic resonance image from the first calibration device;

[0070] Step 204: Based on the first corrected magnetic resonance image and the spatial position information of the first and second placement bodies in the first correction device, perform gradient coil polarity correction on the first magnetic field to be corrected.

[0071] The first magnetic field to be corrected can be a magnetic field requiring gradient coil polarity correction, or a magnetic field requiring both gradient coil polarity correction and gradient coil gain correction. A first corrected magnetic resonance image of the first correction device can be acquired using a magnetic resonance imaging system.

[0072] Specifically, existing image recognition algorithms can be used to identify the spatial position information of the first and second placement objects in the first calibrated magnetic resonance image. This spatial position information is then compared with the accurate spatial position information between the first and second placement objects obtained in advance based on the first calibration device. Based on the comparison result, gradient coil polarity correction is performed on the first magnetic field to be calibrated. For instance, if the image of the second placement object should be located to the lower right of the first placement object's image in the cross-sectional magnetic resonance imaging obtained in advance based on the first calibration device, but the image of the second placement object is located to the lower left of the first placement object's image in the actual cross-sectional magnetic resonance imaging obtained by the first calibration device, this indicates that the horizontal polarity of the first magnetic field to be calibrated is reversed, and horizontal polarity correction is required.

[0073] This process can involve pre-acquiring multiple training magnetic resonance images of the first calibration device and a corresponding polarity correction image for each training magnetic resonance image. Based on these images, a gradient coil polarity correction model is trained to obtain a trained gradient coil polarity correction model. Then, based on the trained model and the first calibration magnetic resonance image, gradient coil gain correction is performed on the gain correction magnetic field. The polarity correction image for each training magnetic resonance image can be obtained "based on the accurate spatial position information between the first and second placement bodies pre-acquired by the first calibration device."

[0074] The spatial position information of the first placement body and the second placement body includes: the position of the center of mass of the first placement body, the position of the center of mass of the second placement body, and the positional relationship between the first placement body and the second placement body.

[0075] Therefore, the gradient coil correction method provided in this application embodiment is based on the fact that the first correction device can obtain accurate spatial position information between the first placement body and the second placement body in advance, and performs polarity correction on the gradient coil based on the "accurate spatial position information between the first placement body and the second placement body". Compared with the method of "correction by technicians manually placing the model", the gradient coil correction method provided in this application can obtain a more accurate correction result.

[0076] In some optional embodiments, after step 204, based on the first corrected magnetic resonance image and the spatial position information of the first and second placement bodies in the first correction device, performing gradient coil polarity correction on the first magnetic field to be corrected, the gradient coil correction method further includes: placing the first placement body in the first placement groove of the gradient coil correction device to obtain a second correction device; placing the second correction device in the second magnetic field to be corrected; wherein, the second magnetic field to be corrected is the magnetic field to be corrected after gradient coil polarity correction of the first magnetic field to be corrected; acquiring the second corrected magnetic resonance image of the second correction device; and performing gradient coil gain correction on the second magnetic field to be corrected based on the second corrected magnetic resonance image.

[0077] Specifically, a second calibrated magnetic resonance image of the second calibration device can be acquired using a magnetic resonance imaging system. Gradient coil gain correction can be performed on the second magnetic field to be calibrated based on the relationship between the magnification of the first placement object in various directions and the target magnification in the second calibrated magnetic resonance image. Specifically, multiple training magnetic resonance images of the second calibration device and a corresponding gain correction image for each training magnetic resonance image can be acquired in advance. The gradient coil gain correction model to be trained is then trained based on the training magnetic resonance images and the corresponding gain correction images to obtain a trained gradient coil gain correction model. Gradient coil gain correction is then performed on the second magnetic field to be calibrated based on the trained gradient coil gain correction model and the second calibrated magnetic resonance image.

[0078] Please refer to Figure 5 , Figure 5 This is a schematic flowchart illustrating another gradient coil correction method provided in an embodiment of this application. This gradient coil correction method can also be applied to, for example... Figure 1 The gradient coil correction device 10 shown may include the following steps in its gradient coil correction method:

[0079] Step 301: Place the first placement body in the first placement groove of the gradient coil correction device to obtain the third correction device;

[0080] Step 302: Place the third correction device in the gain correction magnetic field;

[0081] Step 303: Obtain the gain-corrected magnetic resonance image of the third correction device;

[0082] Step 304: Based on the gain-corrected magnetic resonance image, perform gradient coil gain correction on the gain-corrected magnetic field.

[0083] The gain correction magnetic field is the magnetic field that requires gradient coil gain correction; specifically, it can be the magnetic field after gradient coil polarity correction through steps 201-204 above, or it can be the magnetic field after polarity correction using existing gradient coil polarity correction methods. Gain-corrected magnetic resonance images of the third correction device can be obtained using a magnetic resonance imaging system.

[0084] Specifically, gradient coil gain correction can be performed on the third magnetic field to be corrected based on the relationship between the magnification of the first placement object in various directions and the target magnification in the third corrected magnetic resonance image. More specifically, multiple training magnetic resonance images of the third correction device and a corresponding gain-corrected image for each training magnetic resonance image can be pre-acquired. The gradient coil gain correction model to be trained is then trained based on the training magnetic resonance images and the corresponding gain-corrected images to obtain a trained gradient coil gain correction model. Based on the trained gradient coil gain correction model and the gain-corrected magnetic resonance image, gradient coil gain correction is performed on the gain-corrected magnetic field.

[0085] It should be understood that the disclosed apparatus and methods can also be implemented in other ways, given the several embodiments provided in this application. The apparatus embodiments described above are merely illustrative. For example, the flowcharts and block diagrams in the accompanying drawings illustrate the architecture, functionality, and operation of possible implementations of apparatus, methods, and computer program products according to various embodiments of this application. In this regard, each block in a flowchart or block diagram may represent a module, segment, or portion of code, which contains one or more executable instructions for implementing a specified logical function. It should also be noted that in some alternative implementations, the functions marked in the blocks may occur in a different order than those marked in the drawings. For example, two consecutive blocks may actually be executed substantially in parallel, or they may sometimes be executed in reverse order, depending on the functions involved. It should also be noted that each block in a block diagram and / or flowchart, and combinations of blocks in block diagrams and / or flowcharts, can be implemented using a dedicated hardware-based system that performs the specified function or action, or using a combination of dedicated hardware and computer instructions.

[0086] In addition, the functional modules in the various embodiments of this application can be integrated together to form an independent part, or each module can exist independently, or two or more modules can be integrated to form an independent part.

[0087] The above description is only an optional implementation of the embodiments of this application, but the protection scope of the embodiments of this application is not limited thereto. Any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the embodiments of this application should be covered within the protection scope of the embodiments of this application.

Claims

1. A gradient coil correction device, characterized in that, The device includes: a base, a first placement body, and a second placement body; The upper surface of the base includes a first placement groove and a second placement groove; The first placement groove is used to fix the first placement body, and the second placement groove is used to fix the second placement body. Wherein, the first placement groove and the second placement groove satisfy a preset positional relationship; the preset positional relationship includes: when the second placement body is placed in the second placement groove, the second placement body does not intersect with the plane containing the sagittal plane, coronal plane and cross-section of the centroid of the first placement body placed in the first placement groove; The first placement body includes a first mold shell and a first liquid mold; the first mold shell has a first internal cavity for accommodating the first liquid mold; The second placement body includes a second mold shell and a second liquid mold; the second mold shell has a second internal cavity for accommodating the second liquid mold; Wherein, the center of mass of the first liquid model coincides with the center of mass of the first placement body, and the center of mass of the second liquid model coincides with the center of mass of the second placement body; The center position of the upper surface of the first placement groove coincides with the center position of the upper surface of the base; Wherein, the first internal cavity is a spherical cavity; the second internal cavity is a cubic cavity; Wherein, the first mold shell and the first internal cavity have the same shape, and the second mold shell and the second internal cavity have the same shape; Depth of the first placement groove and the depth of the second placement groove Between, satisfy ;in, Let be the radius of the first placement body. Let be the side length of the second placement object. The side length of the second internal cavity; The positions of the first placement groove and the second placement groove satisfy the following conditions: ;in, Let be the coordinates of the center position of the upper surface of the first placement groove in a Cartesian coordinate system with the plane containing the upper surface of the base as the coordinate plane. Let be the coordinates of the center position of the upper surface of the second placement groove in a Cartesian coordinate system with the plane containing the upper surface of the base as the coordinate plane. This is the absolute value operator.

2. The apparatus according to claim 1, characterized in that, in, The upper surface of the base also has placement markings; the placement markings are used to indicate the placement direction of the gradient coil correction device in the magnetic field to be corrected.

3. A gradient coil correction method, characterized in that, Applied to the gradient coil correction apparatus as described in any one of claims 1-2, the method comprises: The first placement body is placed in the first placement groove of the gradient coil correction device, and the second placement body is placed in the second placement groove of the gradient coil correction device to obtain the first correction device. Place the first calibration device into the first magnetic field to be calibrated; Acquire a first calibrated magnetic resonance image from the first calibration device; Based on the first corrected magnetic resonance image and the spatial position information of the first and second placement bodies in the first correction device, gradient coil polarity correction is performed on the first magnetic field to be corrected. Wherein, the first placement groove and the second placement groove satisfy a preset positional relationship; the preset positional relationship includes: when the second placement body is placed in the second placement groove, the second placement body does not intersect with the plane containing the sagittal plane, coronal plane and cross-section of the centroid of the first placement body placed in the first placement groove; The first placement body includes a first mold shell and a first liquid mold; the first mold shell has a first internal cavity for accommodating the first liquid mold; The second placement body includes a second mold shell and a second liquid mold; the second mold shell has a second internal cavity for accommodating the second liquid mold; Wherein, the center of mass of the first liquid model coincides with the center of mass of the first placement body, and the center of mass of the second liquid model coincides with the center of mass of the second placement body; The center position of the upper surface of the first placement groove coincides with the center position of the upper surface of the base; Wherein, the first internal cavity is a spherical cavity; the second internal cavity is a cubic cavity; Wherein, the first mold shell and the first internal cavity have the same shape, and the second mold shell and the second internal cavity have the same shape; Depth of the first placement groove and the depth of the second placement groove Between, satisfy ;in, Let be the radius of the first placement body. Let be the side length of the second placement object. The side length of the second internal cavity; The positions of the first placement groove and the second placement groove satisfy the following conditions: ;in, Let be the coordinates of the center position of the upper surface of the first placement groove in a Cartesian coordinate system with the plane containing the upper surface of the base as the coordinate plane. Let be the coordinates of the center position of the upper surface of the second placement groove in a Cartesian coordinate system with the plane containing the upper surface of the base as the coordinate plane. This is the absolute value operator.

4. The method according to claim 3, characterized in that, After performing gradient coil polarity correction on the first magnetic field to be corrected, the method further includes: The first placement body is placed in the first placement groove of the gradient coil correction device to obtain the second correction device; The second correction device is placed in the second magnetic field to be corrected; wherein, the second magnetic field to be corrected is the magnetic field to be corrected after gradient coil polarity correction of the first magnetic field to be corrected; Acquire the second corrected magnetic resonance image from the second correction device; Based on the second corrected magnetic resonance image, gradient coil gain correction is performed on the second magnetic field to be corrected.

5. A gradient coil correction method, characterized in that, Applied to the gradient coil correction apparatus as described in any one of claims 1-2, the method comprises: The first placement body is placed in the first placement groove of the gradient coil correction device to obtain the third correction device; Place the third correction device into the gain correction magnetic field; Acquire the gain-corrected magnetic resonance image of the third correction device; Based on the gain-corrected magnetic resonance image, gradient coil gain correction is performed on the gain-corrected magnetic field.

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