Transmitting coil

Abstract

The invention relates to a transmitting coil. The transmitting coil comprises two end rings and a plurality of coil crosspieces, wherein the plurality of coil crosspieces are arranged between the two end rings; the structure of each coil crosspiece comprises a first dielectric layer, a plurality of first metal layers and a plurality of second metal layers, the plurality of first metal layers are distributed and attached to one side of the first dielectric layer, and the plurality of second metal layers are distributed and attached to the other side of the first dielectric layer; and each first metal layer and the second metal layer at the corresponding position of the other side of the first dielectric layer form a capacitor. By using the transmitting coil provided by the invention, the specific absorption rate (SAR) in high-field magnetic resonance scanning can be reduced.

Description

Technical Field

[0001] This application relates to the field of magnetic resonance technology, and in particular to a transmitting coil. Background Technology

[0002] In magnetic resonance imaging (MRI) systems, the signal-to-noise ratio (SNR) of the image increases with the field strength, prompting major manufacturers to develop and design high-field and ultra-high-field MRI systems. Ensuring the radio frequency (RF) safety of the scanned object in high-field and ultra-high-field MRI systems presents a greater challenge than in low-field MRI systems.

[0003] Traditional techniques, such as pulse energy analysis, Q-value analysis, and calorimetry, are used to monitor contrast absorptivity to ensure the radio frequency safety of the scanned object. However, without changing the hardware design of the volumetric emitter coil in the magnetic resonance system, using traditional contrast absorptivity monitoring methods limits the performance of high-field magnetic resonance systems. Summary of the Invention

[0004] Therefore, it is necessary to provide a transmitting coil to address the aforementioned technical problems.

[0005] In a first aspect, one embodiment of this application provides a transmitting coil, including two end rings and a plurality of coil crossbars, wherein the plurality of coil crossbars are all disposed between the two end rings;

[0006] Each coil crossbar has a structure including a first dielectric layer, multiple first metal layers and multiple second metal layers, with the multiple first metal layers distributed and attached to one side of the first dielectric layer and the multiple second metal layers distributed and attached to the other side of the first dielectric layer; each first metal layer and the second metal layer at the corresponding position on the other side of the first dielectric layer form a capacitor.

[0007] In one embodiment, the lengths of the first metal layers are all the same, and the lengths of the second metal layers are all the same.

[0008] In one embodiment, the length of each first metal layer is less than the length of each second metal layer.

[0009] In one embodiment, the spacing length between adjacent first metal layers is the same as the midpoint length of the first metal layer; the midpoint length refers to the difference between the total length of the first metal layer and the overlap length of the second metal layer at the corresponding position on the other side of the first dielectric layer.

[0010] In one embodiment, the interval between the first metal layer and the end ring is a first preset threshold value, and the overlap length between each first metal layer and the second metal layer at the corresponding position on the other side of the first dielectric layer is a second preset threshold value.

[0011] In one embodiment, each end ring structure includes a second dielectric layer, a plurality of third metal layers and a plurality of fourth metal layers, wherein the plurality of third metal layers are distributed and attached to one side of the second dielectric layer, and the plurality of fourth metal layers are distributed and attached to the other side of the second dielectric layer, and each third metal layer and the fourth metal layer at the corresponding position on the other side of the second dielectric layer form a capacitor.

[0012] In one embodiment, each coil crossbar and end ring are overlapped to form a capacitor.

[0013] In one embodiment, an adjustable capacitor is provided on the coil crossbar near the end ring.

[0014] In one embodiment, the material of the first dielectric layer comprises a high dielectric constant material.

[0015] In one embodiment, the structure of the multiple coil crossbars is formed using a printed circuit board; the printed circuit board is a flexible circuit board.

[0016] This application provides a transmitting coil, which includes two end rings and multiple coil crossbars, all disposed between the two end rings. Each coil crossbar includes a first dielectric layer, multiple first metal layers, and multiple second metal layers. The multiple first metal layers are distributed and attached to one side of the first dielectric layer, and the multiple second metal layers are distributed and attached to the other side of the first dielectric layer. Each first metal layer and the corresponding second metal layer on the other side of the first dielectric layer form a capacitor. In this embodiment, each coil crossbar in the transmitting coil includes a first dielectric layer, multiple first metal layers, and multiple second metal layers, and the first dielectric layer, multiple first metal layers, and multiple second metal layers can form multiple distributed capacitors, thereby replacing the lumped capacitors provided on the coil crossbars in the conventional technology. This reduces the electric field generated by the transmitting coil, thereby reducing the specific absorption rate. Attached Figure Description

[0017] To more clearly illustrate the technical solutions in the embodiments of this application or the conventional technology, the drawings used in the description of the embodiments or the conventional technology will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0018] Figure 1 A schematic diagram of a degraded birdcage volume transmitting coil provided for one embodiment;

[0019] Figure 2 A schematic diagram of the magnetic field distribution corresponding to a high-field degraded birdcage volume transmitting coil provided in one embodiment;

[0020] Figure 3 A schematic diagram of the electric field distribution corresponding to a high-field degraded birdcage volume transmitting coil provided in one embodiment;

[0021] Figure 4 A schematic diagram of the electric field distribution corresponding to the high-field degraded birdcage volume transmitting coil provided for another embodiment;

[0022] Figure 5 A schematic diagram of the structure of the transmitting coil provided in one embodiment;

[0023] Figure 6 A schematic diagram of the structure of the coil crossbar provided in one embodiment;

[0024] Figure 7 A schematic diagram of the equivalent circuit provided in one embodiment;

[0025] Figure 8 A front view of a volumetric transmitting coil provided in one embodiment;

[0026] Figure 9 A schematic diagram of the structure of the coil crossbar provided in another embodiment;

[0027] Figure 10 A schematic diagram of the equivalent circuit provided for another embodiment;

[0028] Figure 11 A schematic diagram of the transmitting coil is provided for another embodiment;

[0029] Figure 12 A schematic diagram of the magnetic field distribution of a volumetric transmitting coil in a conventional art and a transmitting coil provided in this application, provided as an embodiment;

[0030] Figure 13 A schematic diagram of the electric field distribution of a volumetric transmitting coil in a conventional art and a transmitting coil provided in this application, provided as an embodiment;

[0031] Figure 14 A schematic diagram of the structure of the coil crossbar provided in another embodiment;

[0032] Figure 15 This is a schematic diagram comparing a conventional volumetric transmitting coil with the transmitting coil provided in this application in one embodiment.

[0033] Explanation of reference numerals in the attached figures:

[0034] 10. Transmitting coil; 100. End ring; 110. Coil crossbar; 101. First dielectric layer; 102. First metal layer; 103. Second metal layer. Detailed Implementation

[0035] To make the objectives, technical solutions, and advantages of this application clearer, the following detailed description is provided in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the scope of this application.

[0036] The serial numbers assigned to components in this article, such as "first" and "second", are used only to distinguish the objects being described and have no sequential or technical meaning.

[0037] Before detailing the technical solutions of the embodiments of this application, the technical background or evolution of the embodiments of this application is first introduced. In the field of magnetic resonance imaging technology, as the field strength of the magnetic resonance system increases, the image signal-to-noise ratio also increases accordingly. This has led major manufacturers to deploy and design high-field magnetic resonance systems and ultra-high-field magnetic resonance systems. However, ensuring the radio frequency safety of the scanned object in high-field and ultra-high-field magnetic resonance systems is a greater challenge than in low-field magnetic resonance systems. In traditional technologies, specific absorption rate (SAR) is monitored based on techniques such as pulse energy method, Q-value method, and calorimetry to ensure the radio frequency safety of the scanned object. However, without changing the hardware design of the volumetric transmit coil in the magnetic resonance system, using the conventional method of monitoring SAR will limit the performance of the high-field magnetic resonance system or prolong the scanning time of the magnetic resonance system.

[0038] Traditional high-field magnetic resonance systems (3.0T and 5.0T field strength) commonly use volumetric transmitting coils, primarily including high-pass birdcage volumetric transmitting coils and degenerate birdcage volumetric transmitting coils (bandpass birdcage volumetric transmitting coils). The main characteristic of high-pass birdcage volumetric transmitting coils is the use of two or four orthogonally fed ports, with all tuning and matching capacitors located on the end rings; no capacitors are placed on the coil crossbars. The main characteristic of degenerate birdcage volumetric transmitting coils is the use of eight or more orthogonally fed ports to achieve B1+ field homogenization and parallel transmission (pTx). Tuning and matching capacitors are located on the end rings, and multiple capacitors are placed on the coil crossbars to achieve decoupling between adjacent units. Degenerate birdcage volumetric transmitting coils are shown below. Figure 1 As shown, Figure 1 The small squares on the middle ring and the coil crossbar refer to the solder joints used to set the capacitor.

[0039] SAR in magnetic resonance systems primarily originates from the interaction between the conductive structure of the scanned object and the electric field of the volumetric transmitting coil. SAR can be expressed by the formula... The calculation yielded the following result. This refers to the conductivity of the conductive medium of the object being scanned, and E refers to the electric field of the volumetric transmitting coil. This refers to the density of the conductive medium of the scanned object. The conductivity and density of the conductive medium are inherent properties of the scanned object, and SAR needs to be reduced by decreasing the electric field of the volumetric transmitting coil. The electric field of the volumetric transmitting coil mainly includes conservative and non-conservative fields. The conservative field is the electrostatic field, primarily generated by the lumped capacitance on the volumetric transmitting coil, with a portion originating from the distributed electric field formed between the lumped capacitance on the volumetric transmitting coil and the scanned object. The non-conservative field is the induced field, mainly the electric field associated with the radio frequency magnetic field of the volumetric transmitting coil, determined based on the law of electromagnetic induction. For the electric field of the volumetric transmitting coil, the conservative field dominates, far exceeding the non-conservative field. Therefore, it can be concluded that SAR is largely contributed by the lumped capacitance on the volumetric transmitting coil, and thus, SAR can be reduced by improving the lumped capacitance.

[0040] For high-pass birdcage volumetric transmitter coils, because the lumped capacitance is located on the end rings far from the human body, their SAR performance is significantly better than that of low-pass and band-pass birdcage volumetric transmitter coils. When using an MRI system to scan areas such as the abdomen, prostate, and liver, the dominant electric field is located in the arm and shoulder areas closest to the volumetric transmitter coil. The |B1+| field distribution corresponding to a high-field degraded birdcage volumetric transmitter coil is shown below. Figure 2 As shown, the darker the color, the lower the magnetic field strength. The non-conservative electric field originates from the electric field accompanying the |B1+| field. Figure 2 As can be seen, under constant amplitude and azimuth phase feeding, the port of the high-field degenerate birdcage volume transmitting coil generates a uniform |B1+| field distribution on the cross-section, which is used to excite the magnetic resonance signal. The |E| field distribution of the high-field degenerate birdcage volume transmitting coil at different cross-sections is shown in the figure. Figure 3 and Figure 4 As shown, the darker the color, the lower the electric field. The |E| field distribution of the central cross-section is similar to that of the central cross-section of the low-pass birdcage transmitting coil. The high electric field intensity region is mainly concentrated near the location of the coil crossbar. The electric field distribution on the end ring sides of the coronal and sagittal planes is similar to that of the high-pass birdcage volume transmitting coil. The high electric field region is the sum of that of the low-pass and high-pass birdcage volume transmitting coils. From... Figure 3 It can be seen that, from an axial perspective, the end-ring plane is a high |E| field region. From Figure 4 It can be seen that even in the end-ring region, the |E| field intensity in the end-ring plane where the feed port is located is significantly higher than that in the end-ring plane without a feed port. In other words, the high-field excitation port has a significant impact on the |E| field distribution. Figure 4The |E| field distribution on the inclined plane where the crossbars (coil crossbars) are located shows that each row of lumped capacitances on the coil crossbars corresponds to a high point in the |E| field. Therefore, compared to high-pass birdcage volumetric transmitter coils, bandpass degraded birdcage volumetric transmitter coils, due to the need for decoupling between adjacent units, use a large number of paired lumped capacitances on the coil crossbars, which greatly increases the |E| field in the central region of the volumetric transmitter coil. The intensity of the conservative |E| field caused by the charging and discharging of lumped capacitances is inversely proportional to the square of the distance. Considering the special structure of the scanned object (human body), if the arm is placed horizontally at both sides of the body in a natural posture during scanning, the scanned object presents a low-profile cuboid shape, and the arm and shoulder will face a huge conservative electric field. These locations face a greater SAR risk when scanning areas such as the abdomen, prostate, and liver. Therefore, this paper proposes a volumetric transmitter coil that can reduce SAR.

[0041] Please see Figure 5 One embodiment of this application provides a transmitting coil 10, including: two end rings 100 and a plurality of coil crossbars 110, the plurality of coil crossbars 110 being disposed between the two end rings 100; each coil crossbar 110 includes a first dielectric layer 101, a plurality of first metal layers 102 and a plurality of second metal layers 103, the plurality of first metal layers 102 being distributed and attached to one side of the first dielectric layer 101, and the plurality of second metal layers 103 being distributed and attached to the other side of the first dielectric layer 101; each first metal layer 102 and the second metal layer 103 at the corresponding position on the other side of the first dielectric layer 101 form a capacitor.

[0042] The transmitting coil 10 can be a volumetric transmitting coil used in a magnetic resonance system. The transmitting coil 10 is a birdcage-shaped coil, including two end loops 100 and a plurality of coil crossbars 110 disposed between the two end loops 100. The plurality of coil crossbars 110 can be evenly distributed between the two end loops 100 at a predetermined interval. The number of coil crossbars 110 can be determined based on the circumference of the end loops 100 and the predetermined interval; this embodiment does not impose any limitation on this.

[0043] Each coil crossbar 110 includes a first dielectric layer 101, a plurality of first metal layers 102, and a plurality of second metal layers 103. The first dielectric layer 101 has two surfaces (i.e., both sides). The plurality of first metal layers 102 are distributed and attached to one surface (one side) of the first dielectric layer 101, and the plurality of second metal layers 103 are distributed and attached to the other surface (the other side) of the first dielectric layer 101. Each first metal layer 102 distributed on one surface of the first dielectric layer 101 is correspondingly disposed with a second metal layer 103 distributed on the other surface of the first dielectric layer 101, and the corresponding first metal layer 102 and second metal layer 103 overlap each other to form a distributed capacitance. In other words, one first metal layer 102 corresponds to two second metal layers 103. One end of the first metal layer 102 overlaps with one end of the corresponding second metal layer 103 to form one distributed capacitance, and the other end of the first metal layer 102 overlaps with one end of the corresponding second metal layer 103 to form another distributed capacitance. Each coil crossbar 110 forms multiple distributed capacitances through a first dielectric layer 101, multiple first metal layers 102, and multiple second metal layers 103. The number of first metal layers 102 on one side of the first dielectric layer 101 and the number of second metal layers 103 on the other side of the first dielectric layer 101 can be set according to the length of the first dielectric layer 101 and the lengths of the first metal layers 102 and the second metal layers 103. This embodiment does not limit the length, material, and number of the first dielectric layer 101, the first metal layer 102, and the third metal layer 103, as long as their function can be achieved.

[0044] In an optional embodiment, based on conventional technology, the solder joints used for soldering lumped capacitance in the volumetric transmitting coil can be used as multiple second metal layers 103 on the coil crossbar 110. A first dielectric layer 101 and a first metal layer 102 are then added on top of this, so that the first metal layer 102 and the corresponding second metal layers 103 on the other side of the first dielectric layer 101 form a distributed capacitance. This design of the transmitting coil 10 is simple, and the distributed capacitance can be formed by stacking the first dielectric layer 101 and the second metal layers 103 without changing the solder joints on the coil crossbar 110.

[0045] This application provides a transmitting coil 10, including two end rings 100 and multiple coil crossbars 110, all disposed between the two end rings 100. Each coil crossbar 110 includes a first dielectric layer 101, multiple first metal layers 102, and multiple second metal layers 103. The multiple first metal layers 102 are distributed and attached to one side of the first dielectric layer 101, and the multiple second metal layers 103 are distributed and attached to the other side of the first dielectric layer 101. Each first metal layer 102 and the corresponding second metal layer 103 on the other side of the first dielectric layer 101 form a capacitor. In this embodiment, each coil crossbar 110 in the transmitting coil 10 includes a first dielectric layer 101, multiple first metal layers 102, and multiple second metal layers 103, and the first dielectric layer 101, multiple first metal layers 102, and multiple second metal layers 103 can form multiple distributed capacitors, thereby replacing the lumped capacitors provided on the coil crossbars in the conventional technology. This reduces the electric field generated by the transmitting coil 10, thereby reducing SAR. Furthermore, this embodiment reduces SAR in high-field and ultra-high-field magnetic resonance (MR) systems by improving the transmit coil used in these systems. This hardware-level SAR reduction does not impact the performance of the high-field and ultra-high-field MR systems, making it more practical. The use of distributed capacitance design provides a basis for future low-profile and filled-package transmit coils. Additionally, the distributed capacitance design reduces the material and manufacturing costs of the transmit coil, and by eliminating the soldering and inspection work of numerous lumped capacitors, production costs are reduced by approximately one-third. In summary, the proposed design offers significant advantages in reducing SAR and transmit coil costs, while also increasing the reliability and high integrability of the transmit coil.

[0046] In one embodiment, such as Figure 6 As shown, the lengths of the first metal layers 102 are all the same, and the lengths of the second metal layers 103 are all the same.

[0047] The lengths of the first metal layers 102 disposed on one side of the first dielectric layer 101 are all the same, and the lengths of the second metal layers 103 disposed on the other side of the first dielectric layer 101 are all the same. This embodiment does not limit the specific lengths of the first metal layers 102 or the second metal layers 103, as long as their function can be achieved. Capacitors are formed at the overlap positions of the first metal layers 102 and the corresponding second metal layers 103. Figure 6 As shown.

[0048] In this embodiment, the lengths of the first metal layers 102 disposed on one side of the first dielectric layer 101 are all the same, and the lengths of the second metal layers 103 disposed on the other side of the first dielectric layer 101 are all the same. This makes it easier to design the distributed capacitance of the first metal layers 102 and the second metal layers 103 at corresponding positions on the other side of the first dielectric layer 101, thereby improving the practicality of the transmitting coil 10.

[0049] Please continue reading Figure 6 In one embodiment, the length of each first metal layer 102 is less than the length of each second metal layer 103.

[0050] A plurality of first metal layers 102 disposed on one side of the first dielectric layer 101 have the same length, and a plurality of second metal layers 103 disposed on the other side of the first dielectric layer 101 have the same length, wherein the length of each first metal layer 102 is less than the length of each second metal layer 103. An equivalent circuit formed by such a first metal layer 102 and two second metal layers 103 is as follows: Figure 7 As shown. Figure 7 The capacitors C1 and C2 are the distributed equivalent capacitances formed by the first metal layer 102 and the two corresponding second metal layers 103. Since the spacing between the two adjacent second metal layers 103 is small, a distributed equivalent capacitance C3 can be formed between the two adjacent second metal layers 103. The equivalent inductances of the two adjacent second metal layers 103 are inductance L1 and inductance L2, respectively. The equivalent inductance of the first metal layer 102 corresponding to the two adjacent second metal layers 103 is inductance L3.

[0051] The formula for calculating the capacitance value formed by the first metal layer 102 and the corresponding second metal layer 103 is as follows: ,in, is the dielectric constant of the first dielectric layer 101, S is the area of ​​the overlapping region between the first metal layer 102 and the corresponding second metal layer 103, d is the distance between the first metal layer 102 and the second metal layer 103, and k is the electrostatic constant. By adjusting... S and d are used to obtain the required capacitance value, thereby enabling the transmitting coil 10 to be tuned to the target operating frequency. Furthermore, when using the first dielectric layer 101, first metal layer 102, and second metal layer 103 provided in this application to form a distributed capacitance to replace the lumped capacitance in the conventional volumetric transmitting coil, the distributed capacitance value formed in this application needs to be multiplied by a coefficient a. Optionally, the coefficient a is 1.50. The value of coefficient a depends on the results of the electromagnetic simulation of the entire transmitting coil. The setting of coefficient a (i.e., the compensation for the capacitance value) mainly comes from... Figure 7 The inductance formed by the distributed capacitance design shown is not reflected in the distributed capacitance calculation formula.

[0052] In an optional embodiment, when the solder joints used for soldering lumped capacitors in a conventional volumetric transmitting coil are used as multiple second metal layers 103 on the coil crossbar 110, a first dielectric layer 101 and a first metal layer 102 with a length shorter than the second metal layers 103 can be sequentially added on the multiple second metal layers 103. A front view of a conventional volumetric transmitting coil is shown below. Figure 8 As shown, Figure 8 The rectangular blocks in the diagram represent solder joints in the conventional volumetric transmitting coil, and the area indicated by the arrow, enclosed by the dashed line, is the area where the lumped capacitor is soldered.

[0053] In this embodiment, the length of each first metal layer 102 located on both sides of the first dielectric layer 101 is less than the length of each second metal layer 103. As a result, the capacitance value of the distributed capacitor formed is smaller, which is suitable for environments where the required capacitance value is relatively small.

[0054] In one embodiment, such as Figure 9 As shown, the spacing length between adjacent first metal layers 102 is the same as the middle length of the first metal layer 102; the middle length refers to the difference between the total length of the first metal layer 102 and the overlap length of the second metal layer 103 at the corresponding position on the other side of the first dielectric layer 101.

[0055] In a plurality of first metal layers 102 on one side of the first dielectric layer 101, the spacing length between two adjacent first metal layers 102 is the same as the midpoint length of the first metal layer 102. Two adjacent first metal layers 102 correspond to one second metal layer 103 on the other side of the first dielectric layer 101. One end of one of the two adjacent first metal layers 102 overlaps with one end of the corresponding second metal layer 103, including a first overlap length; one end of the other of the two adjacent first metal layers 102 overlaps with the other end of the corresponding second metal layer 103, including a second overlap length. The midpoint length is the difference between the total length of the first metal layer 102 and the overlap length, and the overlap length is the sum of the first overlap length and the second overlap length. An equivalent circuit formed by such a first metal layer 102 and two second metal layers 103 is as follows: Figure 10 As shown. Figure 10 The capacitors C1 and C2 refer to the equivalent distributed capacitance formed by the first metal layer 102 and the two corresponding second metal layers 103. The inductor L4 is the equivalent inductance of the second metal layer 103, and the inductor L5 is the equivalent inductance of the first metal layer 102.

[0056] In an optional embodiment, the spacing length between adjacent second metal layers 103 is also the same as the midpoint length of the second metal layer 103.

[0057] In this embodiment, the spacing length between adjacent first metal layers 102 is the same as the midpoint length of the first metal layer 102; the midpoint length refers to the difference between the total length of the first metal layer 102 and the overlap length of the second metal layer 103 at the corresponding position on the other side of the first dielectric layer 101. This arrangement results in a larger spacing between the multiple first metal layers 102 on one side of the first dielectric layer 101 and between the multiple second metal layers 103 on the other side of the first dielectric layer 101. This prevents the formation of distributed capacitance between adjacent second metal layers 103, thereby increasing the capacitance value and making the transmitting coil 10 more practical.

[0058] Please continue reading Figure 9 In one embodiment, the interval between the first metal layer 102 and the end ring 100 is a first preset threshold value, and the overlap length between each first metal layer 102 and the second metal layer 103 at the corresponding position on the other side of the first dielectric layer 101 is a second preset threshold value.

[0059] The first and second preset thresholds can be set by the user according to the required capacitance value, specifically the interval P1 between the first metal layer 102 and the end ring 100 on each coil crossbar 110, and the overlap length between the first metal layer 102 and the corresponding second metal layer 103. The interval between the first metal layer 102 and the end ring 100 is set as the first preset threshold, and the overlap length (i.e., the portion forming the distributed capacitance) between each first metal layer 102 and the corresponding second metal layer 103 at another position of the first dielectric layer 101 is set as the second preset threshold.

[0060] In an optional embodiment, the second preset threshold is 13 mm, the first preset threshold P1 is 54 mm, and the gap between adjacent first metal layers 102 and adjacent second metal layers 103 is 41 mm. Figure 9 The coil crossbar 110 shown has a first dielectric layer 101 with a length of 390mm. Therefore, for the upper side of the first dielectric layer 101, P1*2+13*6+gap*5=390mm. Similarly, for the lower side of the first dielectric layer 101, 13*6+gap*5+P1*2=390mm.

[0061] In this embodiment, the interval between the first metal layer 102 and the end ring 100 is a first preset threshold value, and the overlap length between each first metal layer 102 and the corresponding second metal layer 103 of the first dielectric layer 101 is a second preset threshold value. This facilitates the setting of the positions of the first metal layer 102 and the second metal layer 103 in the first dielectric layer 101 in the transmitting coil 10.

[0062] In one embodiment, each end ring 100 includes a second dielectric layer, a plurality of third metal layers and a plurality of fourth metal layers, wherein the plurality of third metal layers are distributed and attached to one side of the second dielectric layer and the plurality of fourth metal layers are distributed and attached to the other side of the second dielectric layer, and each third metal layer and the fourth metal layer at the corresponding position on the other side of the second dielectric layer form a capacitor.

[0063] The second dielectric layer includes two surfaces (i.e., both sides). Multiple third metal layers are respectively attached to one surface (one side) of the second dielectric layer, and multiple fourth metal layers are respectively attached to the other surface (one side) of the second dielectric layer. Each third metal layer distributed on one surface of the second dielectric layer corresponds to a fourth metal layer distributed on the other surface of the second dielectric layer, and the corresponding third and fourth metal layers overlap to form a distributed capacitance. That is, one third metal layer corresponds to two fourth metal layers. One end of the third metal layer overlaps with one end of the corresponding fourth metal layer to form one distributed capacitance, and the other end of the third metal layer overlaps with one end of the corresponding fourth metal layer to form another distributed capacitance. Multiple distributed capacitances are formed on each end ring 100 through the second dielectric layer, multiple third metal layers, and multiple fourth metal layers. The number of third metal layers distributed on one side of the second dielectric layer and the number of fourth metal layers distributed on the other side of the second dielectric layer can be set according to the length of the end ring 100. This embodiment does not limit the length, material, or number of the second dielectric layer, third metal layer, and fourth metal layer, as long as their function can be achieved.

[0064] In this embodiment, multiple distributed capacitors formed by a second dielectric layer, multiple third metal layers, and multiple fourth metal layers are used to replace the lumped capacitors provided on the end ring 100 in the conventional technology. This can reduce the |E| field generated by the transmitting coil 10, thereby reducing SAR.

[0065] In one embodiment, such as Figure 11 As shown, each coil crossbar 110 and end ring 100 are overlapped to form a capacitor.

[0066] When the coil crossbar 110 and the end ring 100 are connected, the coil crossbar 110 and the end ring 100 are connected in an overlapping manner, so that the first metal layer 102 or the second metal layer 103 on the coil crossbar 110 overlaps with the end ring 100, forming a distributed capacitance with the dielectric in the end ring 100. Figure 11 In the image on the left, it is a schematic diagram of a conventional volumetric transmitting coil, and on the right, it is a schematic diagram of a transmitting coil in which a capacitor is formed by overlapping between each coil crossbar 110 and the end ring 100. Figure 11The middle coil crossbar is equipped with a power supply port 1 and a port parallel capacitor 2. C1-C16 represent the capacitors formed by the overlapping arrangement between each coil crossbar 110 and the end ring 100.

[0067] In this embodiment, a distributed capacitance is formed between the first metal layer 102 or the second metal layer 103 on the coil crossbar 110 and the end ring 100, which can reduce the electric field generated by the transmitting coil 10, thereby reducing the specific absorption rate.

[0068] In an optional embodiment, both the transmitting coil (including distributed capacitance) provided in this embodiment and the volumetric transmitting coil (including lumped capacitance) of conventional technology are normalized to the case of an excitation power of 1W, and the |B1+| field distribution is as follows: Figure 12 As shown, the |E| field distribution is as follows Figure 13 As shown. Figure 12 The four images above show the |B1+| field distribution on the end ring 100 and the coil crossbar 110, based on the transmitting coil (including distributed capacitance) provided in this application. Figure 12 The four reference images below show the |B1+| field distribution on the end ring 100 and coil crossbar 110 of a volumetric emitter coil (including the lumped capacitor) based on conventional lumped capacitance. Figure 12 The images in the image represent the |B1+| field distribution in the central sagittal plane (Sag.-center), the central cross-section (Tra.-center), the top cross-section (Tra.-Top), and the bottom cross-section (Tra.-Bottom), respectively. Figure 13 The four images above show the |E| field distribution on the distributed capacitance transmitting coil end ring 100 and coil crossbar 110 based on the proposed application. Figure 13 The four reference images below show the |E| field distribution on the end ring 100 and coil crossbar 110 in the case of a volumetric transmitting coil (including lumped capacitance) provided in conventional technology. Figure 13 The images in the image represent the |E| field distribution in the central sagittal plane (Sag.-center), central transverse plane (Tra.-center), top transverse plane (Tra.-Top), and bottom transverse plane (Tra.-Bottom), respectively. Figure 12 and Figure 13As can be seen, using the transmitting coil 10 provided in this application, with uniformly distributed capacitance on the coil crossbar 110, the |B1+| and |E| fields near the coil crossbar 110 are uniformly distributed and relatively gentle, and the |B1+| and |E| field intensities are also relatively weak. Comparisons are made at some locations of interest within the FOV, where the superscript represents the coordinate position of the center cross-section on the center horizontal line; for example, -100 represents 100mm to the left of the center. A detailed comparison of the |B1+| and |E| field intensities is shown in the table below:

[0069]

[0070] As can be seen from the table, compared with the traditional volumetric transmitting coil based on lumped capacitance, the transmitting coil provided in this application is about 10% lower at several reference points in the |B1+| field, and about 20% lower at the maximum point in the |E| field. Under the premise of normalized |B1+| field, the SAR of the area near the transmitting coil 10 of the scanned object, that is, the local peak area, is reduced by about 20%. It is worth noting that the SAR in the local peak area is often the easiest to reach the limit value when scanning in high field, which is a weak link in SAR monitoring.

[0071] In one embodiment, an adjustable capacitor is provided on the coil crossbar 110 near the end ring 100.

[0072] An adjustable capacitor is provided at the connection point between the coil crossbar 110 and the end ring 100. This embodiment does not limit the number or value of the adjustable capacitors, as long as the function can be achieved. Optionally, the adjustable capacitor is a lumped capacitor, and the value of the lumped capacitor ranges from 1pF to 24pF.

[0073] In this embodiment, by providing an adjustable capacitor on the coil crossbar 110 near the end ring 100, the capacitance value of the transmitting coil 10 formed by the first dielectric layer 101, the first metal layer 102, and the second metal layer 103 can be adjusted, thereby making the capacitance value of the transmitting coil 10 meet the user's needs and making the transmitting coil 10 more practical.

[0074] In one embodiment, the material of the first dielectric layer 101 comprises a high dielectric constant material.

[0075] In this embodiment, the first dielectric layer 101 is made of a high dielectric constant material. High dielectric constant materials have good insulation properties, which can reduce the electric field strength generated by the transmitting coil 10, thereby reducing the specific absorption rate. Optionally, the first dielectric layer 101 is made of a high dielectric constant and low-loss material.

[0076] The material of the second dielectric layer 103 in the end ring 100 can be the same as the material of the first dielectric layer 101, and also includes high dielectric constant materials.

[0077] In one embodiment, the structure of the multiple coil crossbars 110 is formed using a printed circuit board.

[0078] In other words, the first dielectric layer 101, the plurality of first metal layers 102, and the plurality of first metal layers 103 in each coil crossbar 110 can be formed using a printed circuit board. Specifically, the printed circuit board is a double-layer metal-covered circuit board, with the substrate of the printed circuit board serving as the first dielectric layer 101, the metal layer on the first surface of the printed circuit board serving as the plurality of first metal layers 102, and the metal layer on the second surface of the printed circuit board serving as the plurality of second metal layers 103. The distributed capacitance is formed by overlapping the metal layers on the two surfaces of the substrate.

[0079] In an optional embodiment, the printed circuit board is a double-layer copper-clad circuit board.

[0080] In this embodiment, a low-cost printed circuit board is used to form the structure of each coil crossbar 110. Compared with the conventional technology of soldering non-magnetic, high-power lumped capacitors, this not only reduces material costs but also reduces the manufacturing cost of the transmitting coil 10, significantly reduces soldering time, and increases the reliability of the transmitting coil 10.

[0081] In one embodiment, the printed circuit board is a flexible circuit board.

[0082] In this embodiment, a flexible printed circuit board (PCB) is used. Flexible PCBs are lightweight and thin, making the transmitting coil 10 made with a PCB more practical. Furthermore, even using a high-quality PCB, the transmitting coil 10 with a distributed capacitance design can reduce material costs by approximately one-third.

[0083] In an optional embodiment, the structure of the coil crossbar 110 is as follows: Figure 14 As shown. Figure 14 The black area in the middle is the first dielectric layer 101, and the rectangular blocks set on the black area are the first metal layer 102 and the second metal layer 103. The scratches (lines) on the first metal layer 102 and the second metal layer 103 are set to avoid generating eddy currents.

[0084] In an optional embodiment, a comparative schematic diagram of a conventional volumetric transmitting coil and the transmitting coil provided in this application is shown below. Figure 15 As shown. Figure 15 The coil on the left is a conventional volumetric transmitting coil, with lumped capacitors on the end rings and coil crossbars. The coil on the right is the transmitting coil provided in this application. Figure 15As can be seen from this, the transmitting coil in this application uses a coil crossbar formed by a printed circuit board to replace the coil crossbar of the conventional volume transmitting coil.

[0085] One embodiment of this application provides a magnetic resonance coil, which includes a transmitting coil 10 and a receiving coil as provided in the above embodiment.

[0086] The transmitting coil 10 is used to transmit signals, and the receiving coil is used to receive signals.

[0087] The magnetic resonance coil provided in this application includes the transmitting coil 10 as described in the above embodiments. The magnetic resonance coil has all the beneficial effects of the transmitting coil 10, which will not be repeated here.

[0088] One embodiment of this application provides a magnetic resonance device that includes a magnetic resonance coil as provided in the above embodiment.

[0089] Magnetic resonance imaging (MRI) devices are used to scan objects to obtain magnetic resonance images.

[0090] The magnetic resonance device provided in this application includes the magnetic resonance coil as described in the above embodiments. The magnetic resonance device has all the beneficial effects of the magnetic resonance coil, which will not be repeated here.

[0091] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0092] The embodiments described above are merely illustrative of several implementation methods of this application, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of this patent application. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these all fall within the protection scope of this application. Therefore, the protection scope of this patent application should be determined by the appended claims.

Claims

1. A transmitting coil, characterized by, The application relates to a capacitor structure, which comprises: two end rings and a plurality of coil crosspieces, wherein the plurality of coil crosspieces are arranged between the two end rings; the structure of each coil crosspiece comprises a first dielectric layer, a plurality of first metal layers and a plurality of second metal layers, the plurality of first metal layers are attached to one side of the first dielectric layer, and the plurality of second metal layers are attached to the other side of the first dielectric layer; each first metal layer and the second metal layer at the corresponding position on the other side of the first dielectric layer form a capacitor.

2. The transmit coil of claim 1, wherein, The length of each first metal layer is the same, and the length of each second metal layer is the same.

3. The transmit coil of claim 2, wherein, The length of each first metal layer is smaller than the length of each second metal layer.

4. The transmit coil of claim 2, wherein, The interval length between adjacent first metal layers is the same as the middle length of the first metal layer; the middle length refers to the difference between the total length of the first metal layer and the overlapping length of the second metal layer at the corresponding position on the other side of the first dielectric layer.

5. The transmit coil of claim 4, wherein, The interval between the first metal layer and the end ring is a first preset threshold, and the overlapping length between each first metal layer and the second metal layer at the corresponding position on the other side of the first dielectric layer is a second preset threshold.

6. The transmit coil according to any one of claims 1-5, characterized in that, The structure of each end ring comprises a second dielectric layer, a plurality of third metal layers and a plurality of fourth metal layers, the plurality of third metal layers are attached to one side of the second dielectric layer, and the plurality of fourth metal layers are attached to the other side of the second dielectric layer; each third metal layer and the fourth metal layer at the corresponding position on the other side of the second dielectric layer form a capacitor.

7. The transmit coil according to any one of claims 1-5, characterized in that, Each coil crosspiece and the end ring are arranged in an overlapping manner to form a capacitor.

8. The transmit coil according to any one of claims 1-5, characterized in that, An adjustable capacitor is arranged on the coil crosspiece close to the end ring.

9. The transmit coil according to any one of claims 1-5, wherein, The material of the first dielectric layer comprises a high dielectric constant material.

10. The transmit coil according to any one of claims 1-5, characterized in that, The structure of the plurality of coil crosspieces is formed by using a printed circuit board; and the printed circuit board is a flexible circuit board.

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