Radio frequency transmit coil shielding structure, radio frequency transmit coil assembly and magnetic resonance apparatus

Abstract

The application discloses a kind of radio frequency transmitting coil shielding structure, radio frequency transmitting coil assembly and magnetic resonance equipment, the radio frequency transmitting coil forms cylinder, the shielding structure is arranged at the outer periphery of the radio frequency transmitting coil, it is characterized in that, the shielding structure includes first shielding layer and second shielding layer;The first shielding layer and second shielding layer are stacked along the radial direction of the cylinder direction arrangement.The shielding structure of radio frequency transmitting coil disclosed in the application is two-layer structure, i.e. First shielding layer and second shielding layer are stacked along the radial direction of the cylinder direction arrangement of radio frequency transmitting coil, different shielding materials and setting mode can be used according to actual needs, radio frequency shielding efficiency can be improved, and eddy current generated by shielding structure can also be suppressed, to improve the overall performance of system.

Description

Technical Field

[0001] This invention relates to the field of magnetic resonance imaging technology, and in particular to a radio frequency transmitting coil shielding structure, a radio frequency transmitting coil assembly, and a magnetic resonance device. Background Technology

[0002] In magnetic resonance imaging systems, the radio frequency (RF) transmitting coil is located in the middle of the main magnet cavity of the magnetic resonance imaging system, and a gradient coil is also provided between the RF transmitting coil and the outer shell of the main magnet cavity. In the prior art, in order to reduce RF leakage, a PCB (Printed Circuit Board) is directly used as a shield between the detection coil and the RF coil. This will cause strong eddy currents to be generated in the shielding plate, which will affect the establishment of the gradient magnetic field. Eddy currents generate heat and consume additional energy, which will reduce the efficiency of the magnetic resonance imaging system. Furthermore, excessively high temperatures will damage the coil material. Summary of the Invention

[0003] The technical problem to be solved by the present invention is to overcome the above-mentioned defects in the prior art and provide a radio frequency transmitting coil shielding structure, a radio frequency transmitting coil assembly and a magnetic resonance device.

[0004] The present invention solves the above-mentioned technical problems through the following technical solution:

[0005] The present invention provides a shielding structure for a radio frequency transmitting coil, wherein the radio frequency transmitting coil forms a cylindrical body, and the shielding structure is arranged on the outer periphery of the radio frequency transmitting coil, the shielding structure comprising a first shielding layer and a second shielding layer;

[0006] The first shielding layer and the second shielding layer are stacked along the radial direction of the cylinder.

[0007] Preferably, the second shielding layer covers the first shielding layer.

[0008] Preferably, the first shielding layer includes a slit printed circuit board, and the second shielding layer includes a metal mesh.

[0009] Preferably, the first shielding layer includes a slit printed circuit board, and the second shielding layer includes a plurality of sheet-like metal blocks.

[0010] Preferably, the first shielding layer comprises a metal mesh, and the second shielding layer comprises a plurality of sheet-like metal blocks.

[0011] The present invention also provides a radio frequency transmitting coil assembly, comprising:

[0012] A support cylinder has two opposing ends;

[0013] The radio frequency transmitting coil conductor is disposed on the inner side of the support cylinder;

[0014] A first shielding layer is disposed on the outer surface of the support cylinder;

[0015] A second shielding layer is disposed on the outer side of the support cylinder, and the second shielding layer is stacked on the surface of the first shielding layer.

[0016] Preferably, the first shielding layer is a slotted printed circuit board and extends from one end of the support cylinder to the other end of the support cylinder;

[0017] The second shielding layer includes a metal mesh disposed in the middle region of the support cylinder and a plurality of sheet-like metal blocks disposed at both ends of the support cylinder.

[0018] The present invention also provides a magnetic resonance device, comprising:

[0019] A support cylinder has two opposing ends;

[0020] A radio frequency transmitting coil conductor is arranged around the outer side of the support cylinder;

[0021] Along the radial direction of the support cylinder, two shielding layers are stacked on the surface of the radio frequency transmitting coil conductor;

[0022] At least one shielding layer is a perforated metal mesh.

[0023] Preferably, a first shielding layer and a second shielding layer are disposed on the surface of the radio frequency transmitting coil conductor;

[0024] The first shielding layer is a slit printed circuit board, extending from one end of the support cylinder to the other end; the second shielding layer is a metal mesh; or,

[0025] The first shielding layer is a metal mesh, and the second shielding layer is a plurality of sheet-like metal blocks.

[0026] The present invention also provides a magnetic resonance device, comprising:

[0027] A support cylinder has two opposing ends;

[0028] A radio frequency transmitting coil conductor is arranged around the outer side of the support cylinder;

[0029] Along the radial direction of the support cylinder, a first shielding layer and a second shielding layer are stacked on the surface of the radio frequency transmitting coil conductor;

[0030] The first shielding layer is a slit printed circuit board, and the second shielding layer is a number of sheet-like metal blocks.

[0031] The positive and progressive effects of this invention are as follows:

[0032] The shielding structure of the radio frequency transmitting coil disclosed in this invention consists of two layers, namely a first shielding layer and a second shielding layer, which are stacked along the radial direction of the radio frequency transmitting coil cylinder. By using different shielding materials and arrangement methods according to actual needs, the radio frequency shielding efficiency can be improved, while also suppressing the eddy currents generated by the shielding structure and improving the overall performance of the system. Attached Figure Description

[0033] To more clearly illustrate the technical solutions of the embodiments in this specification, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are merely some examples or embodiments of this specification. For those skilled in the art, these drawings can be applied to other similar scenarios without creative effort. Unless obvious from the context or otherwise specified, the same reference numerals in the drawings represent the same structures or operations.

[0034] Figure 1 This is a schematic diagram of the structure of a magnetic resonance device in the prior art according to Embodiment 1 of the present invention.

[0035] Figure 2 This is a first structural schematic diagram of the shielding structure of the radio frequency transmitting coil in Embodiment 1 of the present invention.

[0036] Figure 3 This is a second structural schematic diagram of the shielding structure of the radio frequency transmitting coil in Embodiment 1 of the present invention.

[0037] Figure 4 This is a third structural schematic diagram of the shielding structure of the radio frequency transmitting coil in Embodiment 1 of the present invention. Detailed Implementation

[0038] The present invention will be further illustrated by way of embodiments below, but the present invention is not limited to the scope of the embodiments described herein.

[0039] In this document, the term "embodiment" means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of this application. The appearance of this phrase in various places throughout the document does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment mutually exclusive with other embodiments. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.

[0040] It should be understood that the terms “device,” “system,” “unit,” and / or “module” used herein are one way to distinguish different components, elements, parts, sections, or assemblies at different levels. However, if other terms can achieve the same purpose, they may be replaced by other expressions.

[0041] As illustrated herein, unless the context clearly indicates otherwise, the words “a,” “an,” “an,” and / or “the” do not specifically refer to the singular and may also include the plural. Generally speaking, the terms “comprising” and “including” only indicate the inclusion of explicitly identified steps and elements, which do not constitute an exclusive list, and the method or apparatus may also include other steps or elements.

[0042] The definitions used herein, such as the terms “having,” “may have,” “comprising,” or “may include,” indicate the presence of the corresponding function, operation, element, etc., and do not limit the presence of one or more other functions, operations, elements, etc. Furthermore, it should be understood that the terms “comprising” or “having” as used herein indicate the presence of the features, figures, steps, operations, elements, components, or combinations thereof described in the specification, without excluding the presence or addition of one or more other features, figures, steps, operations, elements, components, or combinations thereof.

[0043] Example 1

[0044] Please refer to Figure 1 This is a schematic diagram of the structure of a magnetic resonance device in the prior art in this embodiment, as shown below. Figure 1 As shown, the radio frequency transmitting coil 1 forms a cylindrical body and is located inside the magnetic resonance main magnet cavity 2. A gradient coil 3 is also provided between the radio frequency transmitting coil 1 and the outer shell of the main magnet cavity 2. The radio frequency transmitting coil 1 and the gradient coil 3 are coaxially distributed.

[0045] In this embodiment, the shielding structure (not shown) of the RF transmitting coil is arranged on the outer periphery of the RF transmitting coil 1 and is located between the RF transmitting coil 1 and the gradient coil 3 to reduce the impact of RF leakage on the gradient coil.

[0046] Please refer to Figure 2 This is a first structural schematic diagram of the shielding structure of the radio frequency transmitting coil in this embodiment, as shown below. Figure 2 As shown, the shielding structure includes a first shielding layer 4 and a second shielding layer 5. Preferably, the first shielding layer 4 and the second shielding layer 5 can be made of different shielding materials and / or have different configurations. On the one hand, this can ensure the shielding efficiency of the shielding structure. On the other hand, the first shielding layer 4 and the second shielding layer 5 have different effects on eddy current loss. Therefore, the eddy current of the magnetic resonance system can be controlled by adjusting the eddy current factor (used to characterize the factors affecting eddy current loss) of the first shielding layer 4 and the second shielding layer 5 according to actual needs.

[0047] Shielding efficiency (SE) = incident field amplitude / transmitted field amplitude; unit: dB. The higher the SE value, the better the shielding performance.

[0048] The shielding performance of steel mesh can be determined using the following formula:

[0049] SE=20*lg(C / (2*f*g))+20*lg(1+(π*d) / g)

[0050] Where SE represents shielding performance; C represents the speed of light; f represents the center frequency; and g represents the gravitational acceleration constant.

[0051] The above calculation formula shows that the shielding performance of the RF shielding layer is determined by multiple factors. Since the magnetic resonance transmitting coil is generally a high-power component, considering both cost and performance, a flexible PCB with a thickness of 0.1mm (double-layer PCB) is commonly used, offering relatively good shielding performance, but at a high cost. Combining stencils with metal sheets or double-layer stencil shielding can achieve better shielding effects at a significantly lower cost than the double-layer PCB solution.

[0052] like Figure 2 As shown, the mesh density of the shielding mesh can be uniformly distributed or selectively set, for example, the mesh density can be higher at the antenna port than at other locations. Due to the structure of the transmitting coil, the radio frequency signal is stronger at the port and symmetrical locations than at other locations, so the number of mesh openings can be selectively distributed; the denser the mesh, the better the shielding effect.

[0053] The shielding structure in the magnetic resonance device is arranged as follows: the first shielding layer 4 and the second shielding layer 5 are stacked along the radial direction of the cylinder formed by the radio frequency transmitting coil 1.

[0054] In this embodiment, the second shielding layer 5 covers the first shielding layer 4.

[0055] In one alternative implementation, the first shielding layer includes a slit printed circuit board, and the second shielding layer includes a metal mesh.

[0056] Specifically, the eddy current loss pe can be determined according to the following formula:

[0057]

[0058] Where Ke is the eddy current coefficient, B is the magnetic flux density, f is the frequency, t is the conductor thickness, and V is the conductor volume; the conductor volume is determined by multiplying the surface area by the overall thickness of the shielding layer. Compared to slotted printed circuit boards (PCBs), the conductor thickness, conductor area, and conductor volume of a metal mesh are all significantly lower. The magnetic flux density and frequency of the metal mesh are also generally slightly lower than those of slotted PCBs. Therefore, a shielding structure made by covering a slotted PCB with a metal mesh can effectively reduce eddy currents in a magnetic resonance system. Preferably, the metal mesh can be made of steel mesh.

[0059] Please refer to Figure 3This is a second structural schematic diagram of the shielding structure of the radio frequency transmitting coil in this embodiment, as shown below. Figure 3 As shown, in another optional embodiment, the first shielding layer 4 includes a slit printed circuit board, and the second shielding layer 5 includes several sheet-like metal blocks. Similarly, a shielding structure made by covering the slit printed circuit board with several sheet-like metal blocks can also effectively reduce eddy currents in the magnetic resonance system. Preferably, the several sheet-like metal blocks can be arranged only at the corresponding positions on the radio frequency transmitting coil where the signal strength is greater than a preset threshold to enhance the shielding effect; other areas can be arranged with only one layer of slit printed circuit board, which can effectively reduce eddy currents in the magnetic resonance system. Figure 3 As shown, several sheet-like metal blocks can be evenly distributed or strategically positioned, for example, with a greater number at the port location than at other locations. Due to the structure of the transmitting coil, the radio frequency signal at the port location and symmetrical locations is stronger than at other locations, allowing for a targeted distribution of the number of sheet-like metal blocks to improve the shielding effect.

[0060] This embodiment does not limit the specific shape of the sheet metal block. Different shape combinations can be selected according to actual needs to improve the mechanical structure fit of the shielding structure.

[0061] Please refer to Figure 4 This is a third structural schematic diagram of the shielding structure of the radio frequency transmitting coil in this embodiment, as shown below. Figure 4 As shown, in another optional embodiment, the first shielding layer 4 includes a metal mesh, and the second shielding layer 5 includes several sheet-like metal blocks. When the requirement for reducing eddy currents in the shielding structure of the magnetic resonance system far outweighs the requirement for effective shielding, the shielding structure can be selected in the form of several sheet-like metal blocks covering the metal mesh. On the one hand, the shielding structure provides a certain shielding effect; on the other hand, it greatly reduces the eddy currents of the magnetic resonance system. Preferably, the metal mesh can be a steel mesh. Figure 4 As shown, the mesh density and sheet metal blocks of the shielding mesh can be uniformly distributed or selectively configured. For example, the mesh density and the number of sheet metal blocks can be increased at the antenna port location compared to other locations. Due to the structure of the transmitting coil, the radio frequency signal at the port location and symmetrical locations is stronger than at other locations. Therefore, the number of mesh holes and sheet metal blocks can be selectively distributed. The denser the mesh and the more sheet metal blocks, the better the shielding effect.

[0062] In addition, both the first and second shielding layers can be made of metal mesh.

[0063] When setting up the shielding structure, the sections of the first and second shielding layers are welded together, and ground wires are led out from both ends of the aperture to achieve common ground with the entire system.

[0064] The shielding structure of the radio frequency transmitting coil provided in this embodiment consists of two layers, namely a first shielding layer and a second shielding layer, which are stacked along the radial direction of the radio frequency transmitting coil cylinder. By using different shielding materials and setting methods according to actual needs, the radio frequency shielding efficiency can be improved, and the eddy currents generated by the shielding structure can be suppressed, thereby improving the overall performance of the system.

[0065] Example 2

[0066] This embodiment provides a radio frequency transmitting coil assembly, including:

[0067] A support cylinder has two opposing ends;

[0068] The radio frequency transmitting coil conductor is located on the inner side of the support cylinder;

[0069] The first shielding layer is set on the outer side of the support cylinder;

[0070] The second shielding layer is disposed on the outer side of the support cylinder, and the second shielding layer is stacked on the surface of the first shielding layer.

[0071] Preferably, the first shielding layer is a slit printed circuit board and extends from one end of the support cylinder to the other end of the support cylinder;

[0072] The second shielding layer includes a metal mesh disposed in the middle region of the support cylinder and several sheet-like metal blocks disposed at both ends of the support cylinder.

[0073] The radio frequency transmitting coil assembly provided in this embodiment, by adopting the shielding structure of the radio frequency transmitting coil in Embodiment 1, can improve the radio frequency shielding efficiency and suppress the eddy currents generated by the shielding structure, thereby improving the overall performance of the system.

[0074] Example 3

[0075] This embodiment provides a magnetic resonance imaging (MRI) device, including:

[0076] A support cylinder has two opposing ends;

[0077] The radio frequency transmitting coil conductor is arranged around the outer side of the support cylinder;

[0078] Along the radial direction of the support cylinder, two shielding layers are stacked on the surface of the radio frequency transmitting coil conductor;

[0079] At least one shielding layer is a perforated metal mesh.

[0080] Preferably, a first shielding layer and a second shielding layer are disposed on the surface of the radio frequency transmitting coil conductor;

[0081] The first shielding layer is a slotted printed circuit board, extending from one end of the support cylinder to the other; the second shielding layer is a metal mesh; or...

[0082] The first shielding layer is a metal mesh, and the second shielding layer consists of several sheet-like metal blocks.

[0083] The magnetic resonance device provided in this embodiment, by adopting the shielding structure of the radio frequency transmitting coil in Embodiment 1, can improve the radio frequency shielding efficiency and suppress the eddy currents generated by the shielding structure, thereby improving the overall performance of the system.

[0084] Example 4

[0085] This embodiment provides a magnetic resonance imaging (MRI) device, including:

[0086] A support cylinder has two opposing ends;

[0087] The radio frequency transmitting coil conductor is arranged around the outer side of the support cylinder;

[0088] Along the radial direction of the support cylinder, a first shielding layer and a second shielding layer are stacked on the surface of the radio frequency transmitting coil conductor;

[0089] The first shielding layer is a slit printed circuit board, and the second shielding layer is several sheet-like metal blocks.

[0090] The magnetic resonance device provided in this embodiment, by adopting the shielding structure of the radio frequency transmitting coil in Embodiment 1, can improve the radio frequency shielding efficiency and suppress the eddy currents generated by the shielding structure, thereby improving the overall performance of the system.

[0091] While specific embodiments of the present invention have been described above, those skilled in the art should understand that these are merely illustrative examples, and the scope of protection of the present invention is defined by the appended claims. Those skilled in the art can make various changes or modifications to these embodiments without departing from the principles and essence of the present invention, but all such changes and modifications fall within the scope of protection of the present invention.

Claims

1. A shielding structure for a radio frequency transmitting coil, wherein the radio frequency transmitting coil forms a cylindrical body, and the shielding structure is arranged on the outer periphery of the radio frequency transmitting coil, characterized in that, The shielding structure includes a first shielding layer and a second shielding layer; The first shielding layer and the second shielding layer are stacked along the radial direction of the cylinder.

2. The shielding structure of the radio frequency transmitting coil as described in claim 1, characterized in that, The second shielding layer covers the first shielding layer.

3. The shielding structure of the radio frequency transmitting coil as described in claim 1, characterized in that, The first shielding layer includes a slit printed circuit board, and the second shielding layer includes a metal mesh.

4. The shielding structure of the radio frequency transmitting coil as described in claim 1, characterized in that, The first shielding layer includes a slit printed circuit board, and the second shielding layer includes a plurality of sheet-like metal blocks.

5. The shielding structure of the radio frequency transmitting coil as described in claim 1, characterized in that, The first shielding layer includes a metal mesh, and the second shielding layer includes a plurality of sheet-like metal blocks.

6. A radio frequency transmitting coil assembly, characterized in that, include: A support cylinder has two opposing ends; The radio frequency transmitting coil conductor is disposed on the inner side of the support cylinder; A first shielding layer is disposed on the outer surface of the support cylinder; A second shielding layer is disposed on the outer side of the support cylinder, and the second shielding layer is stacked on the surface of the first shielding layer.

7. The radio frequency transmitting coil assembly as claimed in claim 6, characterized in that, The first shielding layer is a slotted printed circuit board, and extends from one end of the support cylinder to the other end of the support cylinder; The second shielding layer includes a metal mesh disposed in the middle region of the support cylinder and a plurality of sheet-like metal blocks disposed at both ends of the support cylinder.

8. A magnetic resonance imaging device, characterized in that, include: A support cylinder has two opposing ends; A radio frequency transmitting coil conductor is arranged around the outer side of the support cylinder; Along the radial direction of the support cylinder, two shielding layers are stacked on the surface of the radio frequency transmitting coil conductor; At least one shielding layer is a perforated metal mesh.

9. The radio frequency transmitting coil assembly as claimed in claim 8, characterized in that, The surface of the radio frequency transmitting coil conductor is provided with a first shielding layer and a second shielding layer; The first shielding layer is a slit printed circuit board and extends from one end of the support cylinder to the other end; the second shielding layer is a metal mesh; or, The first shielding layer is a metal mesh, and the second shielding layer is a plurality of sheet-like metal blocks.

10. A magnetic resonance imaging device, characterized in that, include: A support cylinder has two opposing ends; A radio frequency transmitting coil conductor is arranged around the outer side of the support cylinder; Along the radial direction of the support cylinder, a first shielding layer and a second shielding layer are stacked on the surface of the radio frequency transmitting coil conductor; The first shielding layer is a slit printed circuit board, and the second shielding layer is a number of sheet-like metal blocks.

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