A magnetic resonance gradient coil system

Abstract

The invention discloses a magnetic resonance gradient coil system, which relates to the field of magnetic resonance manufacturing technology, and comprises an inner tube and a multi-layer coil film body, wherein each layer of the coil film body is made of a substrate and a coil layer buried in the substrate. When the equipment is prepared, the number of coil film body layers is first set according to a target size, and then the coil film body is initially prepared, and then the size verification is performed. When the error size exceeds the set value, the assembly parameters are adjusted; the preparation of each coil film body is performed again and assembled under new assembly parameters. When the error size is greater than the target error but less than δ, the error values ​​are averaged and used as the basis for adjusting the coil layer in the corresponding substrate. The coil film body is reprocessed, assembled under the same assembly parameters, and the size verification is performed again, and the process is repeated until the error size is less than the target size. The invention can reduce the error in the preparation process of the magnetic resonance gradient coil system and effectively improve the quality of the finished equipment.

Description

Technical Field

[0001] The invention relates to the field of magnetic resonance manufacturing technology, and in particular to a method for producing and processing a magnetic resonance gradient coil. Background Art

[0002] High-field magnetic resonance systems need to be equipped with higher-performance gradient systems. The linearity and stability of the gradient field directly determine the image restoration degree after imaging. Ideally, good gradient linearity can usually be obtained through optimization calculations. However, errors in the thickness of processed materials and wiring position errors caused by assembly processes are referred to as processing errors. The present invention solves the processing error problem by optimizing the process from design to processing, and solves the random fluctuation error through novel structural design and control strategies, so that the image restoration degree of the magnetic resonance system can be better improved. Summary of the invention

[0003] The purpose of the present invention is to overcome the deficiencies of the prior art and to provide a magnetic resonance gradient coil system to solve the technical problem in the prior art that processing errors affect the image restoration degree.

[0004] The present invention is achieved through the following technical solutions:

[0005] A magnetic resonance gradient coil system comprises an inner tube and a plurality of coil film bodies nested in sequence from the inside to the outside, wherein the innermost coil film body is sleeved on the outer wall of the inner tube, and each layer of the coil film body is made of a substrate and a coil layer buried in the substrate; a method for preparing the magnetic resonance gradient coil system comprises:

[0006] Step 1, setting the target size of the outer diameter of the outermost substrate as D, and determining the number of layers M of the required coil film body according to D;

[0007] Step 2: Prepare M layers of coil membranes respectively, and number each coil membrane in order from the inside to the outside after installation, wherein the size of the substrate and coil layer corresponding to the mth coil membrane in the radial direction of the inner tube is the same as the thickness of the substrate and coil layer corresponding to the m+1th coil membrane in the radial direction of the inner tube, m={1,2,3...M-1}; the size of each substrate in the radial direction of the inner tube is L 基 The radial dimension of each coil layer in the inner tube is L 线 , L 基 >L 线 , each of the coil layers is completely buried in the corresponding matrix, initially each of the coil layers is coaxially distributed with the corresponding matrix, and the distance between the inner and outer walls of each coil layer in the radial direction of the inner tube and the inner and outer walls of the corresponding matrix is ​​not less than α, where α is a safety factor;

[0008] Step 3: Set the assembly parameters and assemble the M layers of coil membranes in order from the inside to the outside. After the assembly is completed, the outer diameter d of the outermost layer substrate is obtained. 外 ;

[0009] Step 4: If |Dd 外 |≥δ, return to step 2 and set new assembly parameters when proceeding to step 3; if A<Dd 外 <δ, then return to step 2, and when preparing each layer of coil film, move the position of the corresponding coil layer in the radial direction of the inner tube where Dd 外 When it is positive, it moves outward, and when it is negative, it moves inward. 外 |≤A, then proceed to step 5; A is the target error;

[0010] Step 5: Use the relative position relationship between each layer of the substrate and the corresponding coil layer when performing step 2 for the last time and the assembly parameters set when performing step 3 as preparation parameters and assembly parameters respectively to batch prepare and assemble the coil film body to obtain the magnetic resonance gradient coil system.

[0011] Furthermore, each of the base bodies is evenly provided with long protrusions for cooling that extend axially along the inner tube on the side wall facing the inner tube.

[0012] Furthermore, the magnetic resonance gradient coil system also includes a cooling system, which includes a guide sleeve that is sleeved on the outside of one end of the inner tube and the inner wall of the end adjacent to the outermost substrate is sealedly connected to the outer wall of the outermost substrate, while the inner wall of the end away from the outermost substrate is sealedly connected to the outer wall of the inner tube; the outer side of the guide sleeve and the outermost substrate forming a whole is also sleeved with a circulation sleeve whose inner walls at both ends are respectively sealedly connected to the outer wall of the inner tube; the inner cavity of the guide sleeve is connected to the output end of a refrigeration device arranged outside the circulation sleeve through an inlet pipe, and the inner cavity of the circulation sleeve is connected to the input end of the refrigeration device through a circulation pipe.

[0013] Furthermore, a first temperature sensor is installed in the guide sleeve, and a second temperature sensor installed in the circulation sleeve is arranged outside the end of the outermost substrate away from the guide sleeve. The refrigeration device, the first temperature sensor and the second temperature sensor are respectively connected to the controller.

[0014] Furthermore, the inner wall of the end of the circulation sleeve adjacent to the guide sleeve is sealedly connected to the outer wall of the end of the guide sleeve adjacent to the outermost substrate.

[0015] Furthermore, the connection between the circulation sleeve and the circulation pipe and the connection between the flow guide sleeve and the introduction pipe are located on the same side of the inner pipe.

[0016] Compared with the prior art, the present invention has the following advantages:

[0017] The present invention provides a magnetic resonance gradient coil system. The assembly parameters and the relative position of the substrate and the coil layer are repeatedly adjusted during multiple pre-production processes to finally obtain a magnetic resonance gradient coil system that meets the requirements. The assembly parameters and the relative position relationship between the substrate and the coil layer corresponding to the magnetic resonance gradient coil system are used as parameters for later assembly and production of coil film bodies, thereby performing batch production. The qualified rate of the magnetic resonance gradient coil systems obtained during batch production can be effectively improved, and the influence of processing errors can be effectively reduced. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 A schematic diagram of the structure of a magnetic resonance gradient coil system provided in an embodiment;

[0019] Figure 2 for Figure 1 Sectional view at AA.

[0020] In the figure: 1. coil film body; 2. substrate; 3. coil layer; 4. guide sleeve; 5. circulation sleeve; 6. inner tube; 7. inlet tube; 8. circulation tube; 9. controller; 10. first temperature sensor; 11. second temperature sensor; 12. support plate; 13. long protrusion; 14. refrigeration device. DETAILED DESCRIPTION

[0021] The technical solution of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0022] Example

[0023] Combination Figure 1 and 2 The present embodiment provides a magnetic resonance gradient coil system, comprising an inner tube 6 and a multi-layer coil film body 1 nested from the inside to the outside, that is, the multi-layer coil film body 1 is sequentially assembled on the outside of the inner tube 6, each layer of the coil film body 1 is composed of a substrate 2 and a coil layer 3 embedded in the body, and in the preparation process of the conventional magnetic resonance gradient coil, the multi-layer coil film body 1 is installed layer by layer on the outside of the inner tube 6 by an assembly device, that is, the innermost layer of the coil film body 1 is sleeved on the outer wall of the inner tube 6, and the other layers are sequentially sleeved and installed to form a multi-layer structure;

[0024] Since there is a processing error in the actual assembly process, in order to reduce the impact of the processing error, in this embodiment, the multilayer coil film body 1 is assembled using the following method:

[0025] Step 1, set the target size D of the outer diameter of the outermost substrate 2 to be, and determine the required number of layers M of the coil film body 1 according to the target size; that is, according to the size requirements of the magnetic resonance gradient coil, set a target size D of the outer diameter of the outermost substrate 2, and then calculate the number of layers of the coil film body 1 according to the target size, such as 5 layers in this embodiment. After determining the total number of layers of the coil film body 1, prepare each layer of the coil film body 1, that is, proceed to step 2.

[0026] Step 2, prepare M layers of coil film bodies 1 respectively, and number each coil film body 1 in order from the inside to the outside after installation, wherein the size of the substrate 2 and the coil layer 3 corresponding to the mth coil film body 1 in the radial direction of the inner tube 6 is the same as the thickness of the substrate 2 and the coil layer 3 corresponding to the m+1th coil film body 1 in the radial direction of the inner tube 6, that is, on the cylindrical structure formed when each substrate 2 and coil film body 1 is prepared, the thickness of all substrates 2 in the inner diameter direction of the inner tube 6 is the same, and the thickness of the coil layer 3 corresponding to each substrate 2 in the inner diameter direction of the inner tube 6 is also the same, so as to facilitate the later adjustment and the preparation of each coil film body 1 in the early stage, m = {1,2,3...M-1}; the size of each substrate 2 in the radial direction of the inner tube 6 is L 基 That is, the thickness of the inner tube 6 in the radial direction. The dimension of each coil layer 3 in the radial direction of the inner tube 6 is L 线 That is, the thickness of the inner tube 6 in the radial direction, L 基 >L 线 , each coil layer 3 is completely buried in the corresponding substrate 2. Initially, each coil layer 3 is coaxially distributed with the corresponding substrate 2, that is, the coil layer 3 is in the middle position of the corresponding substrate 2. The inner and outer walls of the coil layer 3 are at the same distance from the inner and outer walls of the corresponding substrate 2, and the distance between the inner and outer walls of each coil layer 3 in the radial direction of the inner tube 6 and the inner and outer walls of the corresponding substrate 2 is not less than α, that is, there is a certain distance between the outer wall of each coil layer 3 in the radial direction of the inner tube 6 and the outer wall of the corresponding substrate 2, and the distance is not less than α, and the distance between the inner walls of the two is the same as above, so as to ensure that the coil layer 3 is always in the corresponding substrate 2 and will not be exposed to the outside, and α is a safety factor; after the preparation of each coil film body 1 is completed, the corresponding installation is carried out, that is, step 3 is carried out.

[0027] Step 3: Set the assembly parameters, assemble the M layers of coil membrane bodies 1 in order from the inside to the outside, and obtain the outer diameter d of the outermost layer substrate 2 after the assembly is completed. 外 ; That is, the installation sequence is to install the No. 1 coil film body 1 on the outer wall of the inner tube 6, then install the No. 2 coil film body 1 on the outer wall of the No. 1 coil film body 1, then the No. 3 coil film body 1, and so on until the No. M coil film body 1 is installed; after the installation is completed, the formed magnetic resonance gradient coil system is measured and verified, that is, step 4 is performed;

[0028] Step 4: If |Dd 外|≥δ, return to step 2 and set new assembly parameters when proceeding to step 3; if A<Dd 外 <δ, then return to step 2, and when preparing each layer of coil film body 1, move the corresponding coil layer 3 in the radial direction of the inner tube 6 where Dd 外 When it is positive, it moves outward, and when it is negative, it moves inward. When the value is positive, the coil layer 3 is closer to the outer wall of the corresponding substrate 1, and when it is negative, it moves away. 外 |≤A, then proceed to step 5; A is the target error; that is, when the error is too large or too small and the absolute value of the difference is not less than δ, the assembly parameters are adjusted, and after the adjustment is completed, the newly manufactured coil film bodies 1 are assembled again; when the error is greater than the target error and less than δ, it indicates that the assembly parameters are available and only the buried position of the coil layer 3 in each substrate 2 needs to be adjusted, that is, the average error value is divided by two as the adjustment amount of the position of each newly prepared coil layer 3 relative to the substrate 2, that is, the buried position of the coil layer 3 in each substrate 2 is adjusted; when the error value is less than the target error, it indicates that the error generated by the coil layer 3 in the corresponding position in the substrate 2 under this assembly parameter and preparation parameter is within an acceptable range, and no further adjustment is required, so that the above parameters can be used as production parameters for the preparation and assembly parameters of each coil film body 1, and the production of the magnetic resonance gradient coil system is carried out, that is, step 5 is performed.

[0029] Step 5: Use the relative position relationship between each layer of substrate 2 and the corresponding coil layer 3 during the last step 2 and the assembly parameters set during step 3 as preparation parameters and assembly parameters to prepare and assemble the coil film body 1 to obtain a magnetic resonance gradient coil system.

[0030] That is, after multiple rounds of pre-production, the preparation and assembly parameters required to ensure that the error range of the magnetic resonance gradient coil system after production is within the target error can be effectively obtained, thereby facilitating the quality assurance of the magnetic resonance gradient coil system produced.

[0031] After the production of the above-mentioned magnetic resonance gradient coil system is completed, in actual engineering, large gradient and high frequency operation will cause the temperature of the gradient coil to rise, and then due to the thermal expansion and contraction characteristics of the material temperature, the coil structure will be deformed or deviate from the original set position, thereby introducing new uncontrollable gradient distortion. This random distortion is difficult to compensate by image post-processing, and the image restoration degree is limited to a certain extent. In order to solve this problem, in this embodiment, each substrate 2 is evenly provided with a long strip protrusion 13 for cooling that extends along the axial direction of the inner tube 6 on the side wall facing the inner tube 6, that is, a heat dissipation space will be formed between adjacent long strip protrusions 13 in the substrate 2, so as to facilitate the rapid dissipation of heat.

[0032] In particular, in order to further improve the heat dissipation efficiency, in this embodiment, the composition of the magnetic resonance gradient coil system also includes a cooling system, which includes a guide sleeve 4 which is sleeved on the outside of one end of the inner tube 6 and the inner wall of the end adjacent to the outermost substrate 2 is sealed with the outer wall of the outermost substrate 2, while the inner wall of the end away from the outermost substrate 2 is sealed with the outer wall of the inner tube 6, that is, one end of the guide sleeve 4 is sleeved on the outer wall of the outermost substrate 2 and sealed, and the other end is sleeved on the outer wall of the inner tube 6 and sealed, so that the inner cavity of the guide sleeve 4 is connected to the output end of the refrigeration device 14 through the introduction pipe 7;

[0033] Secondly, a circulation sleeve 5 is sleeved on the outside of the guide sleeve 4 and the outermost substrate 2, and the inner walls at both ends are sealedly connected to the outer wall of the inner tube 6, and the inner cavity of the circulation sleeve 5 is connected to the input end of the refrigeration device 14 through the circulation pipe 8.

[0034] That is, the refrigerant or coolant generated by the refrigeration device 14 enters the guide sleeve 4 through the inlet pipe 7, and is then introduced by the guide sleeve 4 into the gap between adjacent long protrusions 13 in the same substrate 2, and flows axially from one side of the guide sleeve 4 along the inner tube 6 to the side of each substrate 2 away from the guide sleeve 4, and finally flows into the circulation sleeve 5, and flows into the refrigeration device 14 again through the circulation pipe 8 to be cooled and cooled, and then flows into the inlet pipe 7 again for circulation cooling, thereby achieving the purpose of overall cooling of the multi-layer coil membrane body 1.

[0035] In particular, in order to cool the outer wall of the outermost substrate 2, in the present embodiment, the connection between the circulation sleeve 5 and the circulation pipe 8 and the connection between the guide sleeve 4 and the inlet pipe 7 are on the same side of the inner pipe 6, that is, after the coolant or refrigerant flows out of the substrate 2 from the end of the substrate 2 away from the guide sleeve 4, it needs to flow through the outer wall of the outermost substrate 2 in the direction of the guide sleeve 4 before it can flow into the refrigeration device 14 through the circulation pipe 8, so that the outermost substrate 2 can be cooled in this process, and the temperature difference between the outermost substrate 2 and the inner substrate 2 can also be reduced, thereby facilitating the service life of the equipment.

[0036] In particular, in order to facilitate the monitoring of the refrigeration temperature, in the present embodiment, a first temperature sensor 10 is also installed in the guide sleeve 4, and a second temperature sensor 11 installed in the circulation sleeve 5 is arranged on the outer side of the end of the outermost substrate 2 facing away from the guide sleeve 4. The refrigeration device 14, the first temperature sensor 10 and the second temperature sensor 11 are respectively connected to the controller 9, so as to facilitate the corresponding temperature control.

[0037] As shown in the figure, in order to stabilize the relative position of all coil membrane bodies 1 constituting the whole A and the inner tube 6, support plates 12 are evenly applied on the inner tube 6 at both ends of the whole A. The support plates 12 are fixedly connected to the outer wall of the inner tube 6 and can also be connected to the inner walls of the adjacent circulation sleeve 5 and the guide sleeve 4, thereby increasing the stability of the whole A.

[0038] In this embodiment, the substrates 2 used for each coil film body 1 are all made of the same material. The thickness of each substrate 2 is the same, that is, the radial size of the inner tube 6, and the length is the same, that is, the axial length of the inner tube 6. Only the width is different. Because the circumference of different layers is different, the preparation material of each coil layer 3 is also the same specification of material, and the outer diameter of the wire is unified, which facilitates the preparation and subsequent assembly of the coil film body 1; each coil film body 1 is prepared by cutting grooves on the flattened substrates 2 and then embedding and encapsulating the corresponding coil layer 3, and the buried position of each coil layer 3 in the corresponding substrate 2 is the same, which is convenient for subsequent adjustment.

[0039] When the coil film body 1 laid flat upon preparation is wound and installed on the corresponding inner tube 6 or the cylindrical coil film body 1, a constant pressure rolling machine is used in this embodiment to install and glue it.

[0040] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A magnetic resonance gradient coil system, comprising an inner tube and a plurality of coil film bodies nested in sequence from the inside to the outside, wherein the innermost coil film body is sleeved on the outer wall of the inner tube, characterized in that: Each layer of the coil film body is made of a substrate and a coil layer buried in the substrate; the preparation method of the magnetic resonance gradient coil system includes: Step 1, setting the target size of the outer diameter of the outermost substrate as D, and determining the number of layers M of the required coil film body according to D; Step 2: Prepare M layers of coil membranes respectively, and number each coil membrane in order from the inside to the outside after installation, wherein the size of the substrate and coil layer corresponding to the mth coil membrane in the radial direction of the inner tube is the same as the thickness of the substrate and coil layer corresponding to the m+1th coil membrane in the radial direction of the inner tube, m={1,2,3...M-1}; the size of each substrate in the radial direction of the inner tube is L 基 The radial dimension of each coil layer in the inner tube is L 线 , L 基 >L 线 , each of the coil layers is completely buried in the corresponding matrix, initially each of the coil layers is coaxially distributed with the corresponding matrix, and the distance between the inner and outer walls of each coil layer in the radial direction of the inner tube and the inner and outer walls of the corresponding matrix is ​​not less than α, where α is a safety factor; Step 3: Set the assembly parameters and assemble the M layers of coil membranes in order from the inside to the outside. After the assembly is completed, the outer diameter d of the outermost layer substrate is obtained. 外 ; Step 4: If |Dd 外 |≥δ, then return to step 2 and set new assembly parameters when proceeding to step 3; if A<Dd 外 <δ, then return to step 2, and when preparing each layer of coil film, move the position of the corresponding coil layer in the radial direction of the inner tube where Dd 外 When it is positive, it moves outward, and when it is negative, it moves inward. 外 |≤A, then proceed to step 5; A is the target error; Step 5: Use the relative position relationship between each layer of the substrate and the corresponding coil layer when performing step 2 for the last time and the assembly parameters set when performing step 3 as preparation parameters and assembly parameters respectively to batch prepare and assemble the coil film body to obtain the magnetic resonance gradient coil system.

2. A magnetic resonance gradient coil system according to claim 1, characterized in that: Each of the base bodies is evenly provided with long strip protrusions for cooling that extend along the axial direction of the inner tube on the side wall facing the inner tube.

3. A magnetic resonance gradient coil system according to claim 2, characterized in that: The magnetic resonance gradient coil system also includes a cooling system, which includes a guide sleeve that is sleeved on the outside of one end of the inner tube and the inner wall of the end adjacent to the outermost substrate is sealedly connected to the outer wall of the outermost substrate, and the inner wall of the end away from the outermost substrate is sealedly connected to the outer wall of the inner tube. The guide sleeve and the outermost substrate form a whole on the outside and are also sleeved with a circulation sleeve whose inner walls at both ends are respectively sealedly connected to the outer wall of the inner tube. The inner cavity of the guide sleeve is connected to the output end of a refrigeration device arranged outside the circulation sleeve through an inlet pipe, and the inner cavity of the circulation sleeve is connected to the input end of the refrigeration device through a circulation pipe.

4. A magnetic resonance gradient coil system according to claim 3, characterized in that: A first temperature sensor is also installed in the guide sleeve, and a second temperature sensor installed in the circulation sleeve is arranged outside the end of the outermost substrate away from the guide sleeve. The refrigeration device, the first temperature sensor and the second temperature sensor are respectively connected to the controller.

5. The magnetic resonance gradient coil system according to claim 4, characterized in that: The inner wall of the end of the circulation sleeve adjacent to the guide sleeve is sealedly connected to the outer wall of the end of the guide sleeve adjacent to the outermost substrate.

6. The magnetic resonance gradient coil system according to claim 5, characterized in that: The connection between the circulation sleeve and the circulation pipe and the connection between the flow guide sleeve and the introduction pipe are located on the same side of the inner pipe.

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