Temperature uniformizing system of mobile magnetic resonance imaging equipment

Abstract

The invention discloses a temperature uniformizing system of mobile magnetic resonance imaging equipment, a main magnet comprises a magnet supporting structure and a permanent magnet arranged in the magnet supporting structure, and a first heat insulation structure and a heat dissipation structure are arranged between the magnet supporting structure and a gradient coil. The magnet supporting structure can provide stable supporting for the permanent magnet, meanwhile, rapid conduction and dissipation of heat generated by the permanent magnet are facilitated, and the magnet supporting structure is provided with a temperature uniformizing structure to achieve temperature consistency of the permanent magnet, so that magnetic field drift is remarkably reduced, and the stability of a magnetic field is guaranteed. Meanwhile, the first heat insulation structure can effectively prevent heat generated by the gradient coil from being transmitted to the permanent magnet, the heat dissipation structure is provided with a heat dissipation ventilation channel, the heat generated by the gradient coil is rapidly dissipated to the external environment by introducing cooling airflow, the magnetic field stability of the permanent magnet is further enhanced, and therefore drifting of the magnetic field is reduced; and the stability and accuracy of magnetic resonance imaging are improved.

Description

Technical Field

[0001] The invention relates to the technical field of magnetic resonance imaging, and in particular to a temperature uniforming system of a mobile magnetic resonance imaging device. Background Art

[0002] Magnetic resonance imaging (MRI) is a key medical imaging tool that is widely used in various clinical diagnoses because it can provide high-resolution, high-contrast soft tissue images. Traditional MRI systems perform well in large hospitals and research institutions, however, these systems are usually large, expensive, and have extremely strict requirements on the installation environment. These factors limit the application of MRI in special environments such as emergency medicine, remote rural areas, battlefield medicine, and natural disasters, and cannot meet the urgent needs for timely and accurate medical images in these scenarios.

[0003] To address this limitation, portable MRI systems have been significantly developed in recent years. The advancement of portable MRI technology has not only expanded the coverage of medical services, but also significantly improved the timeliness of diagnosis and the accuracy of treatment, especially in remote areas or special environments far away from large hospital facilities. Portable MRI systems can provide efficient and immediate medical imaging in these non-traditional environments, but the core challenge lies in how to integrate high-performance magnets that can adapt to changes in ambient temperature to maintain stable magnetic field strength and uniformity under various uncertain environmental conditions, thereby ensuring that the imaging quality is not affected by external factors.

[0004] In the design of portable MRI systems, it is crucial to choose the right magnetic material. At present, neodymium iron boron (NdFeB) and samarium cobalt (SmCo) magnets are mainly used as core components. These two magnet materials have their own characteristics, which determine their applicability in different application scenarios. NdFeB magnets are popular for their excellent magnetic properties and good cost-effectiveness. They have extremely high maximum energy product and residual magnetic flux density (Br), which makes them outstanding in low-cost and high-performance applications. However, NdFeB magnets are extremely sensitive to temperature changes, and the Br temperature coefficient usually ranges from -1000 to -1200ppm / ℃. This means that in high temperature environments, NdFeB magnets are prone to demagnetization, resulting in a decrease in magnetic field strength and imaging quality. Therefore, the use of NdFeB magnets is limited in conditions where the temperature changes drastically or the ambient temperature is high. In contrast, although the cost of samarium cobalt magnets is relatively high, they have excellent thermal stability and corrosion resistance. The Br temperature coefficient of SmCo magnets is typically -300 to -450ppm / ℃, which results in less performance degradation at high temperatures and the ability to maintain a stable magnetic field strength over a wider temperature range. Although the energy product of SmCo magnets is slightly lower than that of NdFeB magnets, their stability at extreme temperatures makes them ideal for long-term use in portable MRI systems, especially when they need to operate in environments with high temperatures or large temperature fluctuations.

[0005] In the prior art, a Chinese patent with publication number CN112435824A discloses a magnet device and a magnetic resonance imaging device, in which the shim ring is partially or entirely made of permanent magnetic material. The magnetic field uniformity of the permanent magnetic magnet is greatly affected by the ambient temperature, and the magnetic field stability is relatively poor. The magnet made of permanent magnetic material will be affected by the uneven temperature distribution during operation. The change of ambient temperature or the change of the surrounding environment may cause the magnetic field uniformity to be destroyed, thereby affecting the image quality. Similarly, a Chinese patent with publication number CN106710781A discloses a nuclear magnetic resonance permanent magnet, which uses a magnet composed of the same magnetic steel component, but the magnetic field strength of the magnet is usually not more than 0.45T, which means that the signal-to-noise ratio of the imaging is low, which may affect the clarity and detail of the image, and the magnetic field will change with the temperature, usually by about 1100ppm / ℃. The magnet needs to maintain the magnetic field strength and uniformity through a self-constant temperature system, which increases the complexity and maintenance cost of the system.

[0006] Ensuring the long-term stability of the magnetic field is crucial for portable MRI systems. For example, for a permanent magnet system with a magnetic field strength of 0.06T, when the temperature changes by 1°C, the change in magnetic field strength can reach 0.072mT, which may cause the 1H nuclear resonance frequency to change by up to 3000Hz, which will seriously affect the imaging accuracy of MRI and the reliability of experimental results. Therefore, in order to ensure the accuracy and effectiveness of MRI experiments, it is particularly important to study a temperature uniformity system that can effectively reduce the temperature difference inside the permanent magnet. The design of this temperature uniformity system aims to reduce the drift of the magnetic field by improving the temperature uniformity of the permanent magnet. Summary of the invention

[0007] The purpose of the present invention is to provide a temperature uniformity system for a mobile magnetic resonance imaging device to solve the problems existing in the above-mentioned related technologies, ensure the temperature uniformity of the permanent magnet, reduce magnetic field drift, avoid heat accumulation, and further enhance the magnetic field stability.

[0008] To achieve the above object, the present invention provides the following solutions:

[0009] The present invention provides a temperature uniforming system for a mobile magnetic resonance imaging device, comprising:

[0010] A body radio frequency coil, wherein the body radio frequency coil is a cylindrical structure, and a cavity of the body radio frequency coil can accommodate a detection object;

[0011] A gradient coil, wherein the gradient coil is sleeved outside the body radio frequency coil;

[0012] A main magnet, the main magnet comprising a magnet support structure and a permanent magnet arranged in the magnet support structure, the magnet support structure is a cylindrical structure and is sleeved on the outside of the gradient coil, and the magnet support structure has a uniform temperature structure to make the temperature of the permanent magnet consistent;

[0013] A first thermal insulation structure and a heat dissipation structure are arranged between the magnet support structure and the gradient coil. The first thermal insulation structure is arranged close to the magnet support structure and is made of a heat insulation material. The heat dissipation structure is arranged close to the gradient coil and has a heat dissipation ventilation channel, which is connected to the external environment.

[0014] Preferably, the number of the permanent magnets is multiple groups, and the permanent magnets are circumferentially embedded in the magnet support structure around the axis of the gradient coil;

[0015] The permanent magnet is a samarium cobalt magnet or a neodymium iron boron magnet.

[0016] Preferably, the magnet support structure has honeycomb holes inside;

[0017] The magnet supporting structure is made of carbon fiber material.

[0018] Preferably, the magnet support structure adopts a structure in which multiple layers of support elements are stacked, the permanent magnet is connected to the support elements, the support elements are arranged along the axial direction of the gradient coil, and there are gaps between adjacent support elements to form the uniform temperature structure, the uniform temperature structure has uniform temperature vents, and the uniform temperature vents are connected to the external environment.

[0019] Preferably, the first thermal insulation structure is made of an aerogel composite material.

[0020] Preferably, the inner ring of the body radio frequency coil is provided with a second thermal insulation structure, and the second thermal insulation structure is made of a thermal insulation material.

[0021] Preferably, the heat dissipation ventilation channel is connected to an external air pump to introduce cooling gas into the heat dissipation ventilation channel.

[0022] Preferably, the heat dissipation ventilation channel adopts a reverse ventilation method.

[0023] Preferably, there are multiple groups of heat dissipation and ventilation channels, and the heat dissipation and ventilation channels are circumferentially arranged around the axis of the gradient coil.

[0024] Preferably, the heat dissipation structure is made of copper.

[0025] Compared with the related art, the present invention has achieved the following technical effects: the temperature uniformity system of the mobile magnetic resonance imaging device of the present invention comprises a body radio frequency coil, a gradient coil and a main magnet, the body radio frequency coil is a cylindrical structure, and the cavity of the body radio frequency coil can accommodate the detection object; the gradient coil is sleeved on the outside of the body radio frequency coil; the main magnet comprises a magnet support structure and a permanent magnet arranged in the magnet support structure, the magnet support structure is a cylindrical structure and sleeved on the outside of the gradient coil, the magnet support structure has a temperature uniformity structure to make the temperature of the permanent magnet consistent; a first thermal insulation structure and a heat dissipation structure are arranged between the magnet support structure and the gradient coil, the first thermal insulation structure is arranged close to the magnet support structure, the first thermal insulation structure is made of thermal insulation material, the heat dissipation structure is arranged close to the gradient coil, the heat dissipation structure has a heat dissipation ventilation channel, and the heat dissipation ventilation channel is connected to the external environment.

[0026] The temperature uniformity system of the mobile magnetic resonance imaging device of the present invention comprises a main magnet including a permanent magnet and a magnet support structure, wherein the magnet support structure can provide stable support for the permanent magnet, and is also conducive to the rapid conduction and dissipation of the heat generated by the permanent magnet, and the magnet support structure has a temperature uniformity structure to achieve temperature consistency of the permanent magnet, thereby significantly reducing the magnetic field drift and ensuring the stability of the magnetic field. At the same time, the present invention sets a first heat insulation structure and a heat dissipation structure between the main magnet and the gradient coil, wherein the first heat insulation structure can effectively prevent the heat generated by the gradient coil from being transferred to the permanent magnet, and the heat dissipation structure has a heat dissipation ventilation channel, and by introducing a cooling airflow, the heat generated by the gradient coil is rapidly dissipated to the external environment, further enhancing the magnetic field stability of the permanent magnet, thereby reducing the drift of the magnetic field and improving the stability and accuracy of magnetic resonance imaging. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or related technologies, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0028] Figure 1 The present invention is a schematic structural diagram of a temperature uniforming system of a mobile magnetic resonance imaging device disclosed in an embodiment of the present invention.

[0029] In the figure: 1. permanent magnet; 2. magnet support structure; 3. first thermal insulation structure; 4. heat dissipation structure; 5. uniform temperature structure; 6. gradient coil; 7. heat dissipation ventilation channel; 8. uniform temperature vent. DETAILED DESCRIPTION

[0030] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in 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.

[0031] The purpose of the present invention is to provide a temperature uniformity system for a mobile magnetic resonance imaging device to solve the problems existing in the above-mentioned related technologies, ensure the temperature uniformity of the permanent magnet, reduce magnetic field drift, avoid heat accumulation, and further enhance the magnetic field stability.

[0032] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0033] Embodiment 1

[0034] The present embodiment provides a temperature uniforming system for a mobile magnetic resonance imaging device, comprising a body radio frequency coil, a gradient coil 6 and a main magnet, wherein the body radio frequency coil is a cylindrical structure, and the cavity of the body radio frequency coil can accommodate a detection object; the gradient coil 6 is sleeved on the outside of the body radio frequency coil; the main magnet comprises a magnet support structure 2 and a permanent magnet 1 arranged in the magnet support structure 2, the magnet support structure 2 is a cylindrical structure and sleeved on the outside of the gradient coil 6, the magnet support structure 2 has a temperature uniforming structure 5 to make the temperature of the permanent magnet 1 consistent; a first thermal insulation structure 3 and a heat dissipation structure 4 are arranged between the magnet support structure 2 and the gradient coil 6, the first thermal insulation structure 3 is arranged close to the magnet support structure 2, and the first thermal insulation structure 3 is made of thermal insulation material, the heat dissipation structure 4 is arranged close to the gradient coil 6, the heat dissipation structure 4 has a heat dissipation ventilation channel 7, and the heat dissipation ventilation channel 7 is connected to the external environment.

[0035] Magnetic resonance imaging is based on a uniform strong magnetic field generated by a magnet. Under the action of the magnetic field, combined with the specific gradient field generated by the gradient coil 6, the hydrogen nuclei in the body of the object being tested can be polarized. Subsequently, the body radio frequency coil emits radio frequency pulses to excite the hydrogen nuclei and induce nuclear magnetic resonance, thereby causing the nuclei to absorb radio frequency energy. After the radio frequency pulse is stopped, the hydrogen nuclei emit radio signals at a specific frequency and release the energy previously absorbed. An external receiver collects these signals and generates high-resolution medical images after processing by an electronic computer. Magnetic resonance imaging is common knowledge among those skilled in the art and will not be described in detail here.

[0036] The temperature-uniform system of the mobile magnetic resonance imaging device of the present invention comprises a main magnet including a permanent magnet 1 and a magnet support structure 2. The magnet support structure 2 can provide stable support for the permanent magnet 1, and is also conducive to the rapid conduction and dissipation of the heat generated by the permanent magnet 1. The magnet support structure 2 has a temperature-uniform structure 5 to achieve temperature consistency of the permanent magnet 1, thereby significantly reducing the magnetic field drift and ensuring the stability of the magnetic field. At the same time, the present invention sets a first thermal insulation structure 3 and a heat dissipation structure 4 between the main magnet and the gradient coil 6. The first thermal insulation structure 3 can effectively prevent the heat generated by the gradient coil 6 from being transferred to the permanent magnet 1. The heat dissipation structure 4 has a heat dissipation ventilation channel 7. By introducing a cooling airflow, the heat generated by the gradient coil 6 is quickly dissipated to the external environment, further enhancing the magnetic field stability of the permanent magnet 1, thereby reducing the drift of the magnetic field and improving the stability and accuracy of magnetic resonance imaging.

[0037] Among them, the number of permanent magnets 1 is multiple groups, and the permanent magnets 1 are circumferentially embedded in the magnet support structure 2 around the axis of the gradient coil 6; the permanent magnets 1 are arranged around the axis of the gradient coil 6, and the magnet support structure 2 is coaxially arranged with the gradient coil 6, which ensures the uniform temperature of the permanent magnets 1 and reduces the magnetic field drift while improving the structural stability of the system. The permanent magnets 1 are embedded in the magnet support structure 2, which ensures the structural strength and stability of the main magnet, and thus ensures the working reliability of the system. In practical applications, the layout of the permanent magnets 1 can be combined with the magnetic field analytical model through optimization algorithms, and the magnet structure with the optimal magnetic field uniformity can be achieved through global optimization design, which further enhances the imaging quality of magnetic resonance imaging.

[0038] In this specific embodiment, the permanent magnet 1 uses samarium cobalt magnets or neodymium iron boron magnets to ensure high-performance magnetic field stability. Samarium cobalt magnets have excellent thermal stability and corrosion resistance, and are suitable for harsh environments with large temperature changes; while neodymium iron boron magnets are suitable for occasions with high magnetic field strength requirements but small temperature changes due to their high magnetic properties and cost-effectiveness, and can be selected according to specific working conditions.

[0039] Specifically, the magnet support structure 2 is made of carbon fiber material, which has excellent thermal conductivity, is conducive to heat dissipation of the permanent magnet 1, and has a small mass.

[0040] More specifically, the magnet support structure 2 adopts a structure in which multiple layers of support elements are stacked, the permanent magnet 1 is connected to the support elements, the support elements are arranged along the axial direction of the gradient coil 6, and there is a gap between adjacent support elements to form a uniform temperature structure 5, the uniform temperature structure 5 has a uniform temperature vent 8, and the uniform temperature vent 8 is connected to the external environment to achieve uniform temperature distribution by controlling the flow of airflow. In other specific embodiments that can be realized by the present invention, the uniform temperature structure 5 can also adopt other forms, such as a uniform temperature plate, etc., to ensure the temperature uniformity of the permanent magnet 1.

[0041] In this specific embodiment, the magnet support structure 2 has honeycomb holes inside to increase the air flow path, which can further enhance the air convection effect, ensure the uniform distribution of temperature of various parts of the permanent magnet 1, and reduce the influence of temperature gradient on magnetic field stability.

[0042] It should also be noted that the first thermal insulation structure 3 can be made of a material with excellent thermal insulation performance to enhance the thermal insulation effect and effectively prevent the heat of the gradient coil 6 from being transferred to the permanent magnet 1. In this specific embodiment, the first thermal insulation structure 3 is made of an aerogel composite material. The aerogel composite material has the characteristics of low density, high porosity and high specific surface area, which makes it have excellent thermal insulation performance and ensures the thermal insulation reliability of the first thermal insulation structure 3. In practical applications, the first thermal insulation structure 3 can also be made of other thermal insulation materials to meet different working conditions and improve the flexible adaptability of the system. In addition, in other specific embodiments that can be realized by the present invention, the first thermal insulation structure 3 can be made of a multilayer composite material, which can significantly reduce heat conduction, thereby maintaining the temperature balance of the system.

[0043] Accordingly, a second thermal insulation structure may be provided in the inner circle of the body RF coil, that is, a second thermal insulation structure may be provided between the gradient coil 6 and the detection object (specifically the patient's head), which effectively isolates the heat generated by the gradient coil 6 and reduces the heat conduction to which the patient is exposed, thereby improving the comfort and safety during the imaging process and enhancing the user experience. The second thermal insulation structure is made of thermal insulation material, and may also be made of materials with excellent thermal insulation performance and light weight to improve thermal insulation efficiency. The second thermal insulation structure may adopt the same structure as the first thermal insulation structure 3.

[0044] Furthermore, the heat dissipation ventilation channel 7 is connected to an external air pump to introduce cooling gas into the heat dissipation ventilation channel 7. The air flow is guided by the air pump to form forced convection in the heat dissipation ventilation channel 7, thereby quickly taking away the heat generated by the gradient coil 6, preventing heat from accumulating inside the system, and ensuring that the gradient coil 6 works stably within the optimal temperature range.

[0045] It should also be emphasized that the heat dissipation ventilation channel 7 adopts a reverse ventilation method, which prevents the occurrence of temperature unevenness between the air inlet and the air outlet by controlling the air flow direction of the air inlet and the air outlet, thereby optimizing the overall heat dissipation effect of the system and further improving the temperature stability of the gradient coil 6.

[0046] In addition, there are multiple groups of heat dissipation and ventilation channels 7, which are arranged circumferentially around the axis of the gradient coil 6. In this specific embodiment, there are nine groups of heat dissipation and ventilation channels 7, all of which adopt reverse ventilation. In practical applications, the number and distribution of heat dissipation and ventilation channels 7 can also be adjusted according to the specifications of the system and specific working conditions to meet different usage requirements.

[0047] Among them, the heat dissipation structure 4 is made of copper material, which has excellent thermal conductivity and can effectively improve the heat dissipation efficiency.

[0048] Embodiment 2

[0049] This embodiment provides a mobile magnetic resonance imaging device, including the temperature uniforming system of the mobile magnetic resonance imaging device of the first embodiment.

[0050] The temperature uniformity system of the mobile magnetic resonance imaging device of the present invention realizes the efficient dissipation of the heat generated by the gradient coil 6 through the heat dissipation structure 4, thereby preventing the accumulation of excessive heat. At the same time, the first thermal insulation structure 3 effectively isolates the influence of the heat generated by the gradient coil 6 on the permanent magnet 1, thereby significantly reducing the overall temperature of the permanent magnet 1. The temperature uniformity structure 5 ensures that the temperature of all permanent magnets 1 is uniform by enhancing air convection, thereby effectively reducing the drift phenomenon of the magnetic field. Through the above measures, the present invention greatly improves the system stability and imaging quality of the mobile magnetic resonance imaging device, and provides a solid guarantee for efficient and reliable operation in various environments. Compared with the nuclear magnetic resonance permanent magnet in the prior art, the temperature uniformity system of the mobile magnetic resonance imaging device of the present invention has a compact structure and not only has excellent mechanical strength, but also has good thermal conductivity, which enhances the temperature uniformity effect of the permanent magnet and effectively avoids the deterioration of the magnetic field stability caused by the uneven temperature of the magnet.

[0051] The present invention uses specific examples to illustrate the principles and implementation methods of the present invention. The above examples are only used to help understand the method and core ideas of the present invention. At the same time, for those skilled in the art, according to the ideas of the present invention, there will be changes in the specific implementation methods and application scope. In summary, the content of this specification should not be understood as limiting the present invention.

Claims

1. A temperature uniforming system for a mobile magnetic resonance imaging device, characterized in that: include: A body radio frequency coil, wherein the body radio frequency coil is a cylindrical structure, and a cavity of the body radio frequency coil can accommodate a detection object; A gradient coil (6), wherein the gradient coil (6) is sleeved outside the body radio frequency coil; A main magnet, the main magnet comprising a magnet support structure (2) and a permanent magnet (1) arranged in the magnet support structure (2), the magnet support structure (2) being a cylindrical structure and being sleeved on the outside of the gradient coil (6), the magnet support structure (2) having a uniform temperature structure (5) so as to make the temperature of the permanent magnet (1) uniform; A first thermal insulation structure (3) and a heat dissipation structure (4) are arranged between the magnet support structure (2) and the gradient coil (6); the first thermal insulation structure (3) is arranged close to the magnet support structure (2); the first thermal insulation structure (3) is made of a thermal insulation material; the heat dissipation structure (4) is arranged close to the gradient coil (6); the heat dissipation structure (4) has a heat dissipation ventilation channel (7); and the heat dissipation ventilation channel (7) is connected to the external environment.

2. The temperature uniforming system of the mobile magnetic resonance imaging device according to claim 1, characterized in that: The number of the permanent magnets (1) is a plurality of groups, and the permanent magnets (1) are circumferentially embedded in the magnet support structure (2) around the axis of the gradient coil (6); The permanent magnet (1) is a samarium cobalt magnet or a neodymium iron boron magnet.

3. The temperature uniforming system of the mobile magnetic resonance imaging device according to claim 1, characterized in that: The magnet support structure (2) has honeycomb holes inside; The magnet support structure (2) is made of carbon fiber material.

4. The temperature uniforming system of the mobile magnetic resonance imaging device according to claim 1, characterized in that: The magnet support structure (2) adopts a structure in which multiple layers of support elements are stacked, the permanent magnet (1) is connected to the support element, the support element is arranged along the axial direction of the gradient coil (6), and there is a gap between adjacent support elements to form the uniform temperature structure (5), the uniform temperature structure (5) has a uniform temperature vent (8), and the uniform temperature vent (8) is connected to the external environment.

5. The temperature uniforming system of the mobile magnetic resonance imaging device according to claim 1, characterized in that: The first thermal insulation structure (3) is made of an aerogel composite material.

6. The temperature uniforming system of the mobile magnetic resonance imaging device according to claim 1, characterized in that: The inner ring of the body radio frequency coil is provided with a second thermal insulation structure, and the second thermal insulation structure is made of a thermal insulation material.

7. The temperature uniforming system of the mobile magnetic resonance imaging device according to claim 1, characterized in that: The heat dissipation ventilation channel (7) is connected to an external air pump so as to introduce cooling gas into the heat dissipation ventilation channel (7).

8. The temperature uniforming system of the mobile magnetic resonance imaging device according to claim 7, characterized in that: The heat dissipation and ventilation channel (7) adopts a reverse ventilation method.

9. The temperature uniforming system of the mobile magnetic resonance imaging device according to claim 7, characterized in that: The heat dissipation and ventilation channels (7) are provided in a plurality of groups, and the heat dissipation and ventilation channels (7) are arranged circumferentially around the axis of the gradient coil (6).

10. The temperature uniforming system of a mobile magnetic resonance imaging device according to claim 1, characterized in that: The heat dissipation structure (4) is made of copper.

Images