Cooling unit, cooling system and gradient coil

Abstract

The invention relates to magnetic resonance imaging, in particular to a cooling unit, a cooling system and a gradient coil. The invention relates to a cooling unit which is a cooling water pipe which is of a U-shaped water pipe structure. The cooling system comprises a cooling unit and at least two C-shaped connectors, one end of the first C-shaped connector is connected with a water inlet, and a plurality of water inlet connectors are arranged on the first C-shaped connector; one end of the second C-shaped joint is connected with the water outlet, and a plurality of water outlet joints are arranged on the second C-shaped joint; the first C-shaped connector and the second C-shaped connector are connected in parallel through a plurality of cooling units, one end of each cooling unit is connected with a water inlet connector on the first C-shaped connector, and the other end of each cooling unit is connected with a water outlet connector on the second C-shaped connector. Compared with the prior art, the cooling unit, the cooling system and the gradient coil are provided, the heat conduction capacity of the cooling system is guaranteed, the water pipe is not provided with a connector in the gradient coil, and the risk of water leakage is reduced.

Description

Technical Field

[0001] The invention relates to magnetic resonance imaging, in particular to a cooling unit, a cooling system and a gradient coil. Background Art

[0002] Modern medical MRI systems consist of a main magnet, a radio frequency part, and a gradient part. The gradient coil is one of the core components of MRI, and is mainly used to realize frequency encoding, phase encoding, and layer selection during MRI scanning.

[0003] The performance of the gradient coil is related to the working voltage and current, and the voltage and current that can be applied to the gradient coil are closely related to the cooling capacity of the gradient coil. One of the existing traditional gradient coil cooling methods is to use a hollow copper tube to wind the Z coil as a cooling channel. In order to reduce the influence of eddy currents, the diameter of the Z coil cannot be too large, which affects the heat dissipation effect. In addition, the arrangement of the Z coil is subject to electromagnetic design constraints. The position of the coil needs to be strictly controlled and cannot deviate from the position or increase or decrease the number, which increases the difficulty of manufacturing. At the same time, the biggest problem of this coil is that it cannot achieve water-electricity separation. To ensure the safety of patients, deionized water must be used, which increases the difficulty and cost of maintenance. Another method is to use composite materials to wind an independent cooling layer, often using several water pipes in parallel. The patent for this cooling method is ZL201420289868.3 "An Active Shielded Gradient Coil Structure". The patent proposes a method based on winding multiple composite water pipes, and the inner and outer cooling water pipes are connected in series. However, the design does not consider the impact of the structure on flow resistance, the impact on refrigeration efficiency, and the many process difficulties in the manufacturing process.

[0004] The patent "Cooling system for magnetic resonance system and its manufacturing method" (application number CN202310197524.3) uses multiple water pipes to bend multiple times along the axial direction and arrange them in a circumferential serpentine shape to manufacture the cooling system. This method improves the flow rate to a certain extent, but the multi-tube parallel connection of each cooling unit will form a band-shaped temperature zone on the gradient coil. At the same time, more water manifolds and refrigerators are used, which has a complex structure and increases the difficulty and cost of using the gradient coil. Summary of the invention

[0005] In order to overcome the deficiencies of the prior art, the present invention provides a cooling unit, a cooling system and a gradient coil, which improve the thermal conductivity of the cooling system and the temperature balance of the gradient coil, facilitate the gradient coil to work at a higher voltage and current, improve the performance of the gradient coil, and improve the gradient strength and switching rate.

[0006] In order to achieve the above purpose, a cooling unit is designed. The cooling unit is a cooling water pipe, and the cooling water pipe is a U-shaped water pipe structure.

[0007] The cooling unit is made of composite material or copper material.

[0008] A cooling system, the cooling system comprises a cooling unit and a C-shaped joint, at least two C-shaped joints are provided, one end of the first C-shaped joint is connected to a water inlet, and the first C-shaped joint is provided with a plurality of water inlet joints; one end of the second C-shaped joint is connected to a water outlet, and the second C-shaped joint is provided with a plurality of water outlet joints; the first C-shaped joint and the second C-shaped joint are connected in parallel through a plurality of cooling units, and one end of the cooling unit is connected to the water inlet joint on the first C-shaped joint, and the other end of the cooling unit is connected to the water outlet joint on the second C-shaped joint.

[0009] The first C-shaped joint and the second C-shaped joint are arranged adjacent to each other up and down.

[0010] The diameter of the first C-shaped connector is smaller than or equal to the diameter of the second C-shaped connector.

[0011] The C-shaped joint is made of composite material or copper material.

[0012] A gradient coil comprises a cooling unit, a cooling part composed of a cooling system, a coil part, and a shimming part. The outer side of the shimming part wraps the cooling part. The cooling part comprises a shielding cooling part and a main cooling part. The outer side of the cooling part wraps the coil part. The coil part comprises a main coil and a shielding coil.

[0013] The main cooling part and the main coil are located on the inner side of the shim part; the shielding cooling part and the shielding coil are located on the outer side of the shim part.

[0014] The shimming part is one of active shimming, passive shimming, and a combination of active shimming and passive shimming.

[0015] The gradient coil is a cylindrical structure.

[0016] Compared with the prior art, the present invention provides a cooling unit, a cooling system and a gradient coil, which ensure the heat conductivity of the cooling system, and the water pipe has no joints inside the gradient coil, thereby reducing the risk of water leakage.

[0017] The gradient coil structure of the present invention takes into account the performance of the gradient coil, and the cooling water pipes are located on both sides of the shim part, thereby ensuring the temperature stability of the shim part and thus ensuring the uniformity of the magnetic field. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figures 1 to 3 Schematic diagram of the cooling unit structure.

[0019] Figure 4 It is a traditional wound water pipe structure.

[0020] Figure 5 Schematic diagram of the C-shaped joint structure.

[0021] Figure 6 It is a schematic diagram of the cooling system structure.

[0022] Figure 7 Schematic diagram of cooling water flow direction.

[0023] Figure 8 This is a cross-sectional view of the gradient coil of the present invention.

[0024] Fig. 9 A gradient coil structure arranged in a single layer.

[0025] Fig.10 The gradient coil structure has a common cooling unit.

[0026] Fig.11 The gradient coil structure is an independent cooling unit.

[0027] Fig.12 It is a gradient coil structure with mixed cooling method.

[0028] Fig.13 for Fig.12 Side view of.

[0029] Fig.14 Schematic diagram of thermal simulation of traditional wound water tube gradient coil.

[0030] Fig.15 It is a thermal simulation schematic diagram of the present invention.

[0031] Fig.16 It is a schematic diagram of the appearance structure of the present invention.

[0032] See also Figure 5 , Figure 6 , 2 is the first C-shaped joint, 2-1 is the water inlet, 2-2 is the water inlet joint, 3 is the second C-shaped joint, 3-1 is the water outlet, and 3-2 is the water outlet joint.

[0033] See also Figures 8 to 13 , 4 is the main coil, 5 is the shielding coil, 6 is the uniform field part, 7 is the shielding cooling part, 8 is the main cooling part, and 9 is the imaging area. DETAILED DESCRIPTION

[0034] The present invention will be further described below with reference to the accompanying drawings.

[0035] like Figures 1 to 3 A cooling unit is shown, wherein the cooling unit 1 is a cooling water pipe, and the cooling water pipe is a U-shaped water pipe structure.

[0036] The cooling unit 1 is made of composite material or copper material.

[0037] Each cooling unit 1 includes only one water pipe, which is arranged along the axial direction and bends back. The pipe is short, the flow resistance is low, the cooling efficiency is high, the forming difficulty is low, and it is easy to manufacture and use; the material of the cooling unit 1 can be a composite water pipe or a copper pipe. When using a composite material, you only need to determine the length of the water pipe, and manually form it according to the actual space during assembly. When using a copper pipe, it needs to be formed in advance according to a certain geometric structure.

[0038] like Figures 5 to 7 As shown, a cooling system includes a cooling unit and a C-shaped joint, at least two C-shaped joints are provided, one end of the first C-shaped joint 2 is connected to the water inlet 2-1, and the first C-shaped joint 2 is provided with a plurality of water inlet joints 2-2; one end of the second C-shaped joint 3 is connected to the water outlet 3-1, and the second C-shaped joint 3 is provided with a plurality of water outlet joints 3-2; the first C-shaped joint 2 and the second C-shaped joint 3 are connected in parallel through a plurality of cooling units 1, and one end of the cooling unit 1 is connected to the water inlet joint 2-2 on the first C-shaped joint 2, and the other end of the cooling unit 1 is connected to the water outlet joint 3-2 on the second C-shaped joint 3.

[0039] The first C-shaped joint 2 and the second C-shaped joint 3 are arranged adjacent to each other up and down.

[0040] The diameter of the first C-shaped joint 2 is smaller than or equal to the diameter of the second C-shaped joint 3 .

[0041] The C-shaped joint is made of composite material or copper material.

[0042] The C-shaped joint is a circular opening structure and can be made of metal or non-metal. Each joint has a water inlet / outlet and is composed of multiple water pipe joints. The water inlet / outlet is used to connect to the system main pipe, and the water pipe joint is used to connect to the cooling unit.

[0043] like Figure 8 As shown, a gradient coil includes a cooling part composed of a cooling unit and a cooling system, a coil part, and a shim part. The cooling part is wrapped around the outside of the shim part 6. The cooling part includes a shielding cooling part 7 and a main cooling part 8. The coil part is wrapped around the outside of the cooling part. The coil part includes a main coil 4 and a shielding coil 5.

[0044] Located on the inner side of the shim part 6 are the main cooling part 8 and the main coil 4 ; located on the outer side of the shim part 6 are the shielding cooling part 7 and the shielding coil 5 .

[0045] The shimming section 6 is one of active shimming, passive shimming, and a combination of active shimming and passive shimming.

[0046] The gradient coil is a cylindrical structure.

[0047] like Fig. 9As shown, the gradient coil structure is arranged on a single plane composed of cooling units 1, that is, the cooling units 1 are located in the main cooling part 8 and the shield cooling part 7 and use independent water pipes. The cooling body is located on the same circumferential surface. The main cooling part 8 and the shield cooling part 7 are both composed of multiple cooling units 1 arranged along the circumference of the cooling layer. The water flow directions of adjacent units in the same layer are opposite to ensure the temperature balance of water cooling. Since the main coil on the inside generates more heat, the number of cooling units for the main coil and the shield coil needs to be comprehensively considered during design.

[0048] like Fig.10 As shown, it is a gradient coil structure with a common cooling unit, that is, the cooling units 1 are distributed radially, half of the cooling unit 1 is used for the main cooling part 8, and the other half is used for the shielding cooling part 7. This cooling system saves cooling units, but the assembly structure is complicated.

[0049] like Fig.11 As shown, it is a gradient coil structure with independent cooling units, that is, the main cooling part 8 and the shield cooling part 7 use independent cooling units 1, but the return water of the cooling unit 1 is selected in the space of the uniform field part 6 of the gradient coil. In this way, more cooling units 1 can be arranged to enhance the cooling capacity.

[0050] like Fig.12 , Fig.13 As shown, it is a gradient coil structure of mixed cooling mode. According to the heating characteristics of the gradient coil, the main cooling part 8 adopts the return water of the uniform field part 6, and the shielding cooling part 7 adopts the mixed cooling mode of circular surface circumferential arrangement. This mode balances the number of cooling units and the cooling capacity.

[0051] The traditional winding water pipe cooling process often uses multiple composite water pipes (or copper pipes) to be wound in parallel. This method will result in a high temperature at one end and a low temperature at the other end. In order to achieve better temperature balance, the water flow direction of adjacent water pipes is usually reversed through the inlet and outlet water connections. This method improves the temperature balance, but its thermal conductivity is still limited. The thermal simulation results are as follows: Fig.14 shown.

[0052] like Fig.15 From the results shown, it can be seen that the gradient coil based on the present invention has significantly better temperature balance than the gradient coil wound with a water pipe, and has a higher heat dissipation efficiency.

[0053] In actual production, the gradient coil is a layer-by-layer process. Each coil is independently made into a module, or multiple coils are assembled into modules in advance. On a central mold, according to the design results of the gradient coil, each module is accurately assembled according to the relevant spatial positions. The gradient coil of the present invention has one module for each coil. After the assembly of the main coil is completed, the main cooling part, the shim part, the shielding cooling part, and the shielding coil are assembled. After all parts are assembled, the entire gradient coil is impregnated with epoxy resin, and the coil and the cooling system are cast into a tightly integrated whole, and the molding of the shim part is completed. The final product is as follows Fig.16 shown.

[0054] Specifically, in practical applications, the entire gradient coil ultimately has only one water inlet and one water outlet, which is convenient for users to use. The gradient coil of the present invention uses a U-shaped cooling unit to improve the thermal conductivity and temperature stability of the cooling system, wherein the shimming part is located in the middle of the cooling system, ensuring the temperature stability of the shimming material, thereby ensuring the uniformity of the magnetic field in the spatial imaging area DSV (diameter of spherical volume).

[0055] The independent cooling system not only meets the thermal conductivity requirements of the gradient coil, but also completely realizes the water-electricity separation of the gradient coil. Ordinary pure water or distilled water can be used as a refrigerant instead of deionized water, which reduces the end user's dependence on special materials and reduces maintenance costs. The shimming space is located between the shield cooling part and the main cooling part, ensuring the stability of the iron sheet temperature in the shimming part, thereby ensuring the uniformity of the magnetic field in the imaging area DSV.

Claims

1. A cooling unit, characterized in that: The cooling unit (1) is a cooling water pipe, and the cooling water pipe is a U-shaped water pipe structure.

2. A cooling unit according to claim 1, characterized in that: The cooling unit (1) is made of a composite material or a copper material.

3. A cooling system, characterized in that: The cooling system comprises a cooling unit as claimed in claim 1, and a C-shaped joint, wherein at least two C-shaped joints are provided, one end of a first C-shaped joint (2) is connected to a water inlet (2-1), and the first C-shaped joint (2) is provided with a plurality of water inlet joints (2-2); one end of a second C-shaped joint (3) is connected to a water outlet (3-1), and the second C-shaped joint (3) is provided with a plurality of water outlet joints (3-2); the first C-shaped joint (2) and the second C-shaped joint (3) are connected in parallel via a plurality of cooling units (1), and one end of the cooling unit (1) is connected to the water inlet joint (2-2) on the first C-shaped joint (2), and the other end of the cooling unit (1) is connected to the water outlet joint (3-2) on the second C-shaped joint (3).

4. A cooling system according to claim 3, characterized in that: The first C-shaped joint (2) and the second C-shaped joint (3) are arranged adjacent to each other up and down.

5. A cooling system according to claim 3, characterized in that: The diameter of the first C-shaped joint (2) is smaller than or equal to the diameter of the second C-shaped joint (3).

6. A cooling system according to claim 3, characterized in that: The C-shaped joint is made of composite material or copper material.

7. A gradient coil, characterized in that: The gradient coil comprises a cooling part composed of a cooling unit and a cooling system as described in claims 1 to 6, a coil part, a shim part, a cooling part wrapped around the outside of the shim part (6), the cooling part comprises a shielding cooling part (7) and a main cooling part (8), the cooling part wraps around the outside of the coil part, and the coil part comprises a main coil (4) and a shielding coil (5).

8. A gradient coil according to claim 7, characterized in that: Located on the inner side of the shim section (6) are a main cooling section (8) and a main coil (4); located on the outer side of the shim section (6) are a shielding cooling section (7) and a shielding coil (5).

9. The gradient coil according to claim 7, characterized in that: The shimming part (6) is one of active shimming, passive shimming, and a combination of active shimming and passive shimming.

10. The gradient coil according to claim 7, characterized in that: The gradient coil is a cylindrical structure.

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