Miniaturized wave trap and nuclear magnetic resonance imaging device

Abstract

The utility model relates to a miniaturized wave trap and a nuclear magnetic resonance imaging device. The miniaturized wave trap comprises at least one wave trapping unit, the wave trapping unit is used for sleeving a cable, the wave trapping unit comprises a first annular solenoid coil and a second annular solenoid coil, the first annular solenoid coil and the second annular solenoid coil are arranged at an interval, the first annular solenoid coil and the second annular solenoid coil are both of an unclosed structure, and the first annular solenoid coil and the second annular solenoid coil are arranged at intervals. And the rotation directions of the first annular solenoid coil and the second annular solenoid coil are the same. According to the miniaturized wave trap, parallel resonance is formed by using the distributed capacitance between the two annular solenoid coils, when common-mode current appears on the cable, energy enters the annular solenoid coils through coupling, current with the direction opposite to that of the common-mode current is formed in the centers of the annular solenoid coils, and therefore the suppression effect on the common-mode current is achieved. The miniaturized wave trap is arranged on the cable in a sleeving manner, so that the parameters of the cable cannot be influenced, and the loss of the radio frequency cable cannot be additionally increased.

Description

Technical Field

[0001] The present application relates to the technical field of wave traps, and in particular to a miniaturized wave trap and a nuclear magnetic resonance imaging device. Background Art

[0002] During MRI scanning, the VTC (Volume transmit coil) coil transmits power, and a large common-mode current is generated on the cable of the local coil, which seriously affects the local B1 field and thus the imaging quality. In order to suppress this common-mode current, a trap needs to be installed on the cable of the local coil. However, with the continuous development of technology, the number of units in the MRI receiving coil is increasing, which directly leads to the RF cable becoming thicker and thicker, thus bringing many challenges to the design of the RF trap.

[0003] In traditional technology, the common mode current is filtered out by using a cable trap, which is formed by winding the RF cable into a spiral shape and putting a shielding cover on the outside. One end of the shielding cover is directly welded to the cable, and the other end is connected through a tuning capacitor. However, since it is formed by directly winding the RF cable, the total length of the RF cable is increased, thereby increasing the loss of the RF cable. Utility Model Content

[0004] Based on this, it is necessary to provide a miniaturized notch filter that can reduce RF line loss to address the above problems.

[0005] In a first aspect, the present application provides a miniaturized wave trap, comprising: at least one wave trap unit, the wave trap unit being used to be sleeved on a cable, the wave trap unit comprising: a first annular solenoid coil and a second annular solenoid coil, the first annular solenoid coil and the second annular solenoid coil being spaced apart, the first annular solenoid coil and the second annular solenoid coil both being non-closed structures, and the first annular solenoid coil and the second annular solenoid coil having the same rotation direction.

[0006] In one of the embodiments, two adjacent wave trap units are isolated by an insulating medium.

[0007] In one embodiment, the first annular solenoid coil includes a first notch, and the second annular solenoid coil includes a second notch, the first notch divides the first annular solenoid coil into an open structure, and the second notch divides the second annular solenoid coil into an open structure.

[0008] In one embodiment, the first notch or the second notch is provided in plurality, the plurality of the first notches are alternately provided on the first annular spiral coil, and the plurality of the second notches are alternately provided on the second annular spiral coil.

[0009] In one embodiment, the notch unit further includes: a first lumped capacitor and a second lumped capacitor, wherein the first lumped capacitor is connected to the first notch, and the second lumped capacitor is connected to the second notch.

[0010] In one embodiment, the first annular solenoid coil includes a first twisted pair structure formed by winding together, and the second annular solenoid coil includes a second twisted pair structure formed by winding together.

[0011] In one of the embodiments, the miniaturized wave trap further includes: at least one annular bracket, the wave trap unit is fixedly arranged on the annular bracket, and the annular bracket is used to be sleeved on the cable.

[0012] In one embodiment, the two first ends of the first annular solenoid coil are fixed to the annular bracket by glue dispensing, and the two second ends of the second annular solenoid coil are fixed to the annular bracket by glue dispensing.

[0013] In one of the embodiments, the miniaturized wave trap further includes: at least one annular copper sheet, wherein the annular copper sheet covers the wave trap unit.

[0014] In a second aspect, the present application also provides a nuclear magnetic resonance imaging device, comprising the miniaturized trap filter described in the embodiment of the first aspect above.

[0015] The above-mentioned miniaturized trap and nuclear magnetic resonance imaging device are achieved by sleeve-mounting a trap unit including a first annular solenoid coil and a second annular solenoid coil on a cable, and spacing the first annular solenoid coil and the second annular solenoid coil, wherein the first annular solenoid coil and the second annular solenoid coil are both non-closed structures and have the same rotation direction. The miniaturized trap of the present application forms parallel resonance by utilizing the distributed capacitance between the two annular solenoid coils, and the size of the distributed capacitance can be adjusted by adjusting the spacing between the first annular solenoid coil and the second annular solenoid coil. When a common-mode current appears on the cable, energy enters the annular solenoid coil through coupling, and a current in the opposite direction to the common-mode current is formed at the center of the annular solenoid coil, thereby suppressing the common-mode current. Since the miniaturized trap of the present application is sleeved on the cable, it will not affect the parameters of the cable itself, and therefore, will not increase the loss of the RF cable. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the conventional technology, the drawings required for use in the embodiments or the conventional technology descriptions are briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0017] FIG1 is a schematic diagram of a notch unit in one embodiment;

[0018] FIG2 is a perspective view of the notch unit in FIG1 ;

[0019] FIG3 is an equivalent circuit diagram of the trap unit in FIG1 ;

[0020] FIG4 is a schematic diagram of a plurality of notch units in one embodiment;

[0021] FIG5 is an equivalent circuit diagram of a plurality of trap units in FIG4 ;

[0022] FIG6 is a schematic diagram of multiple notches in one embodiment;

[0023] FIG7 is a schematic diagram of a lumped capacitor in one embodiment;

[0024] FIG8 is an equivalent circuit diagram of the trap unit in FIG7 ;

[0025] FIG9 is a schematic diagram of a twisted pair structure in one embodiment;

[0026] FIG. 10 is a schematic diagram of an annular copper skin in one embodiment.

[0027] Description of reference numerals:

[0028] The trap unit 100 , the first annular solenoid coil 110 , the second annular solenoid coil 120 , the annular bracket 130 , the annular copper sheet 140 , the first notch 111 , the second notch 121 , the first lumped capacitor 112 , the second lumped capacitor 122 , the first twisted pair structure 113 , the second twisted pair structure 123 , and the cable 200 . DETAILED DESCRIPTION

[0029] In order to make the above-mentioned purposes, features and advantages of the present application more obvious and easy to understand, the specific implementation methods of the present application are described in detail below in conjunction with the accompanying drawings. In the following description, many specific details are set forth to facilitate a full understanding of the present application. However, the present application can be implemented in many other ways different from those described herein, and those skilled in the art can make similar improvements without violating the connotation of the present application, so the present application is not limited by the specific embodiments disclosed below.

[0030] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include at least one of the features. In the description of this application, the meaning of "plurality" is at least two, such as two, three, etc., unless otherwise clearly and specifically defined.

[0031] In this application, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements, unless otherwise clearly defined. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0032] In the present application, unless otherwise clearly specified and limited, a first feature being “above” or “below” a second feature may mean that the first and second features are in direct contact, or the first and second features are in indirect contact through an intermediate medium. Moreover, a first feature being “above”, “above”, and “above” a second feature may mean that the first feature is directly above or obliquely above the second feature, or simply means that the first feature is higher in level than the second feature. A first feature being “below”, “below”, and “below” a second feature may mean that the first feature is directly below or obliquely below the second feature, or simply means that the first feature is lower in level than the second feature.

[0033] It should be noted that when an element is referred to as being "fixed to" or "disposed on" another element, it may be directly on the other element or there may be a central element. When an element is considered to be "connected to" another element, it may be directly connected to the other element or there may be a central element at the same time. The terms "vertical", "horizontal", "upper", "lower", "left", "right" and similar expressions used herein are for illustrative purposes only and are not intended to be the only implementation method.

[0034] In one embodiment, as shown in Figures 1 and 2, the present application proposes a miniaturized wave trap, including: at least one wave trap unit 100, the wave trap unit 100 is used to be sleeved on a cable 200, the wave trap unit 100 includes: a first annular solenoid coil 110 and a second annular solenoid coil 120, the first annular solenoid coil 110 and the second annular solenoid coil 120 are arranged at intervals, the first annular solenoid coil 110 and the second annular solenoid coil 120 are both non-closed structures, and the first annular solenoid coil 110 and the second annular solenoid coil 120 have the same rotation direction.

[0035] Specifically, Fig. 1 and Fig. 2 are schematic diagrams including only one trap unit 100, and the trap unit 100 is detachably mounted on the cable 200, and is sleeved on the cable 200 when in use. The trap unit 100 can be a closed or unclosed ring when not in use. When the trap unit 100 is a closed ring, one end of the cable 200 can pass through the center of the ring, so that the trap unit 100 is sleeved on the cable 200; when the trap unit 100 is an unclosed ring, the cable 200 can pass through the unclosed gap of the trap unit 100, so that the trap unit 100 is sleeved on the cable 200.

[0036] The wave trap unit 100 includes a first annular solenoid coil 110 and a second annular solenoid coil 120. Both annular solenoid coils are made of conductive metal materials. When they are manufactured, they are first wound into a solenoid coil, and then the solenoid coil is wound into a ring shape to obtain an annular solenoid coil. Since the two annular solenoid coils have the same rotation direction, the winding direction when they are wound into the solenoid coils is also the same, and the two annular solenoid coils obtained are also the same in shape and size. At the same time, as shown in FIG2, both annular solenoid coils are non-closed structures, that is, the ends of the solenoid coils are not connected, and the two non-closed gaps in the figure are symmetrically arranged. In some other embodiments, the two non-closed gaps can also be arranged close to each other, and the tuning frequency can be changed by adjusting the relative position of the gap positions. When the two annular solenoid coils are formed into the wave trap unit 100, it is only necessary to space the two annular solenoid coils a certain distance from each other. The miniaturized wave trap can be composed of one or more wave trap units 100. When in use, all of them are set on the cable 200 to complete the suppression of common mode current. As the RF cable becomes thicker, the diameter of the RF cable winding also becomes larger. Compared with the wave trap formed by directly winding the RF cable, the wave trap of this embodiment is smaller in size, which facilitates miniaturization of the equipment.

[0037] The principle of the miniaturized wave trap in the above embodiment to suppress the common mode current is described in detail below, as shown in FIG3, which is an equivalent circuit diagram of the wave trap unit 100 in the embodiment of FIG1. ​​The first annular solenoid 110 includes a first inductor L1 and a third inductor L3, and the second annular solenoid 120 includes a second inductor L2 and a fourth inductor L4. A first distributed capacitance C1 and a second distributed capacitance C2 are generated between the first annular solenoid 110 and the second annular solenoid 120. The coupling between the first annular solenoid 110 and the cable 200 is represented by M1 formed by the first inductor L1 and the cable inductor L in the cable 200, and the coupling between the second annular solenoid 120 and the cable 200 is represented by M2 formed by the second inductor L2 and the cable inductor L in the cable 200. The mutual inductance between the two annular solenoids is represented by M3 formed by the third inductor L3 and the fourth inductor L4. The first distributed capacitor C1 and the second distributed capacitor C2 are used to form parallel resonance with the first inductor L1 and the third inductor L3 in the first annular solenoid 110, and the second inductor L2 and the fourth inductor L4 in the second annular solenoid 120. When a common-mode current appears on the cable 200, the energy enters the annular solenoid through coupling, and a current in the opposite direction to the common-mode current is formed at the center of the annular solenoid, thereby suppressing the common-mode current. At the same time, since the miniaturized wave trap of the present application is mounted on the cable 200, it will not affect the parameters of the cable 200 itself, and therefore, will not increase the loss of the RF cable.

[0038] In one embodiment, two adjacent trap units 100 are isolated by an insulating medium. Specifically, as shown in FIG4, the miniaturized trap filter is composed of five trap units 100, and two adjacent trap units 100 are isolated by an insulating medium. The insulating medium can be air, plastic, rubber, glass, ceramic, epoxy resin, etc. According to the material of the insulating medium, the insulation performance between two adjacent trap units 100 is also different. As shown in FIG5, it is an equivalent circuit diagram of the miniaturized trap filter in the embodiment of FIG4, wherein the equivalent circuit of each trap unit 100 is the same as that in FIG3, and the electrical relationship between all the trap units 100 is in series. In the case where a plurality of trap units 100 are provided in the miniaturized trap filter, the energy of the common mode current in the cable 200 can be dispersed in a plurality of trap units 100, reducing the heat generated by a single trap unit 100, and even in the case where individual trap units 100 are damaged, the suppression effect of the common mode current will not be affected.

[0039] In one embodiment, as shown in FIG2 , the first annular solenoid coil 110 includes: a first notch 111, and the second annular solenoid coil 120 includes: a second notch 121. The first notch 111 divides the first annular solenoid coil 110 into an open structure, and the second notch 121 divides the second annular solenoid coil 120 into an open structure. Specifically, in the embodiment of FIG2 , the first annular solenoid coil 110 is provided with a first notch 111, and the second annular solenoid coil 120 is provided with a second notch 121. One first notch 111 can divide the first annular solenoid coil 110 into an open structure, and one second notch 121 can divide the second annular solenoid coil 120 into an open structure. By setting the notch to set the annular solenoid coil to an open structure, the inductance in the annular solenoid coil and the distributed capacitance between the two annular solenoid coils can form a parallel resonance.

[0040] In one embodiment, the first notch 111 or the second notch 121 is provided in plurality, and the plurality of first notches 111 are alternately provided on the first annular solenoid coil 110, and the plurality of second notches 121 are alternately provided on the second annular solenoid coil 120. Specifically, as shown in FIG6 , two first notches 111 are alternately provided on the first annular solenoid coil 110, and two second notches 121 are alternately provided on the second annular solenoid coil 120. In some other embodiments, other numbers of notches may be provided. By providing multiple notches on the first annular solenoid coil 110 and the second annular solenoid coil 120, respectively, tuning can be performed by adjusting the number of notches and the positions of the notches, so as to facilitate debugging of the trap unit 100.

[0041] In one embodiment, as shown in FIG7 , the notch unit 100 further includes: a first lumped capacitor 112 and a second lumped capacitor 122, wherein the first lumped capacitor 112 is connected to the first notch 111, and the second lumped capacitor 122 is connected to the second notch 121. Specifically, the lumped capacitor may be composed of one or more capacitors, and by providing the first lumped capacitor 112 on the first annular solenoid 110 and the second lumped capacitor 122 on the second annular solenoid 120, tuning may be performed by changing the size of the lumped capacitor, thereby facilitating debugging of the notch unit 100. In some other embodiments, when there are multiple notches, a lumped capacitor may be provided on each notch. As shown in FIG8 , it is an equivalent circuit diagram of the trap unit 100 in the embodiment of FIG7 . The first lumped capacitor 112 (i.e., C3) on the first annular solenoid coil 110 is connected in parallel with the first inductor L1 and the third inductor L3. The second lumped capacitor 122 (i.e., C4) on the second annular solenoid coil 120 is connected in parallel with the second inductor L2 and the fourth inductor L4. A first distributed capacitor C1 and a second distributed capacitor C2 are generated between the two annular solenoid coils. By coupling the trap unit 100 with the cable 200, the common mode current on the cable 200 can be suppressed.

[0042] In one embodiment, as shown in FIG9 , the first annular spiral coil 110 includes a first twisted pair structure 113 formed by being intertwined, and the second annular spiral coil 120 includes a second twisted pair structure 123 formed by being intertwined. Specifically, the first annular spiral coil 110 can extend from the end at the notch thereof to form the first twisted pair structure 113 intertwined, and the second annular spiral coil 120 can extend from the end at the notch thereof to form the second twisted pair structure 123 intertwined. The extension direction of the first twisted pair structure 113 and the second twisted pair structure 123 in FIG9 is parallel to the length direction of the cable 200. By adjusting the length, position and direction of the first twisted pair structure 113 and the second twisted pair structure 123, the size of the distributed capacitance between the first annular spiral coil 110 and the second annular spiral coil 120 can be adjusted, so as to facilitate the debugging of the trap unit 100. In some other embodiments, when a plurality of notches are provided on the annular spiral coil, a twisted pair structure can also be provided on each notch.

[0043] In one embodiment, the miniaturized wave trap further includes: at least one annular bracket 130, on which the wave trap unit 100 is fixedly arranged, and the annular bracket 130 is used to be sleeved on the cable 200. Specifically, as shown in FIG. 1 and FIG. 4 , the first annular solenoid 110 and the second annular solenoid 120 are fixedly arranged on the annular bracket 130, and the annular bracket 130 plays the role of supporting and fixing the first annular solenoid 110 and the second annular solenoid 120, and the material of the annular bracket 130 is a solid insulating material. When in use, the annular bracket 130 can be sleeved on the cable 200. It can be understood that in order to protect the first annular solenoid 110 and the second annular solenoid 120, the insulating material can be filled in the gap between the annular solenoid and the annular bracket 130, or the insulating material can be filled in the part where the first annular solenoid 110 and the second annular solenoid 120 contact the cable 200. In some other embodiments, a notch can also be provided on the annular bracket 130 for sleeved the first annular solenoid 110 and the second annular solenoid 120. In some other embodiments, the annular bracket 130 may not be provided, and the first annular solenoid coil 110 and the second annular solenoid coil 120 may be directly fixed on the cable 200 using a curable insulating material.

[0044] In one embodiment, the two first ends of the first annular solenoid coil 110 are fixed to the annular bracket 130 by glue dispensing, and the two second ends of the second annular solenoid coil 120 are fixed to the annular bracket 130 by glue dispensing. Specifically, in this embodiment, the first annular solenoid coil 110 and the second annular solenoid coil 120 are each provided with only one notch. When the annular solenoid coil is fixed to the annular bracket 130, the annular solenoid coil is firstly inserted into the annular bracket 130, and then the ends of the notch are respectively fixed to the annular bracket 130 by glue dispensing. When a plurality of notches are provided on the annular solenoid coil, the ends of each notch can be fixed to the annular bracket 130 by glue dispensing. In some other embodiments, a fixing hole can also be provided on the annular bracket 130, and the first annular solenoid coil 110 and the second annular solenoid coil 120 can be fixed by fixing the ends of the annular solenoid coil in the fixing hole.

[0045] In one embodiment, as shown in FIG10 , the miniaturized wave trap further includes: at least one annular copper sheet 140, and the annular copper sheet 140 covers the wave trap unit 100. Specifically, in this embodiment, the wave trap unit 100 is covered by setting the annular copper sheet 140, so as to reduce the influence of the magnetic field leaked from the wave trap unit 100 on the radio frequency field. The annular copper sheet 140 and the wave trap unit 100 can be filled with insulating material for insulation and fixation. In the case where there are multiple wave trap units 100, each wave trap unit 100 is covered with an annular copper sheet 140. In some other embodiments, in the case where there are multiple wave trap units 100, a longer annular copper sheet 140 can also be used to cover multiple wave trap units 100 at the same time to reduce the magnetic field leaked from the wave trap unit 100. In some other embodiments, a material with a shielding effect such as aluminum, ferrite, iron, etc. can also be used to make an annular shape to cover the wave trap unit 100, and the shielding of the magnetic field generated by the wave trap unit 100 can also be completed. Among them, ferrite material is a special type of material, whose main components are iron oxide and other additives (for example: nickel oxide, zinc oxide, manganese oxide, magnesium oxide, barium oxide, strontium oxide, etc.).

[0046] In one embodiment, the present application also proposes a nuclear magnetic resonance imaging device, including the miniaturized trap in the above embodiment. The nuclear magnetic resonance imaging device of this embodiment is provided by sleeve-mounting the trap unit 100 including the first annular solenoid 110 and the second annular solenoid 120 on the cable 200, and the first annular solenoid 110 and the second annular solenoid 120 are arranged at intervals, wherein the first annular solenoid 110 and the second annular solenoid 120 are both non-closed structures and have the same rotation direction. The miniaturized trap of the present application forms parallel resonance by utilizing the distributed capacitance between the two annular solenoids, and the size of the distributed capacitance can be adjusted by adjusting the spacing between the first annular solenoid 110 and the second annular solenoid 120. When a common mode current appears on the cable 200, the energy enters the annular solenoid through coupling, and a current in the opposite direction to the common mode current is formed at the center of the annular solenoid, thereby suppressing the common mode current. Since the miniaturized trap of the present application is sleeved on the cable 200, it will not affect the parameters of the cable 200 itself, and therefore, the loss of the RF cable will not be increased.

[0047] The technical features of the above-described embodiments may be arbitrarily combined. To make the description concise, not all possible combinations of the technical features in the above-described 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.

[0048] The above-described embodiments only express several implementation methods of the present application, and the descriptions thereof are relatively specific and detailed, but they cannot be construed as limiting the scope of the patent application. It should be pointed out that, for a person of ordinary skill in the art, several variations and improvements can be made without departing from the concept of the present application, and these all belong to the protection scope of the present application. Therefore, the protection scope of the patent application shall be subject to the attached claims.

Claims

1. A miniaturized notch filter, characterized in that: include: At least one wave trap unit (100), the wave trap unit (100) being used for being sleeved on a cable (200), the wave trap unit (100) comprising: a first annular solenoid coil (110) and a second annular solenoid coil (120), the first annular solenoid coil (110) and the second annular solenoid coil (120) being arranged at an interval, the first annular solenoid coil (110) and the second annular solenoid coil (120) both being non-closed structures, and the first annular solenoid coil (110) and the second annular solenoid coil (120) having the same rotation direction.

2. The miniaturized notch filter according to claim 1, characterized in that: Two adjacent wave trap units (100) are isolated by an insulating medium.

3. The miniaturized notch filter according to claim 1, characterized in that: The first annular solenoid coil (110) comprises a first notch (111), and the second annular solenoid coil (120) comprises a second notch (121), the first notch (111) dividing the first annular solenoid coil (110) into an open structure, and the second notch (121) dividing the second annular solenoid coil (120) into an open structure.

4. The miniaturized notch filter according to claim 3, characterized in that: The first notch (111) or the second notch (121) is arranged in plurality, the plurality of first notches (111) are arranged alternately on the first annular solenoid coil (110), and the plurality of second notches (121) are arranged alternately on the second annular solenoid coil (120).

5. The miniaturized notch filter according to claim 3, characterized in that: The notch unit (100) further comprises: a first lumped capacitor (112) and a second lumped capacitor (122), wherein the first lumped capacitor (112) is connected to the first notch (111), and the second lumped capacitor (122) is connected to the second notch (121).

6. The miniaturized notch filter according to claim 1, characterized in that: The first annular spiral coil (110) includes a first twisted pair structure (113) formed by twisting each other, and the second annular spiral coil (120) includes a second twisted pair structure (123) formed by twisting each other.

7. The miniaturized notch filter according to any one of claims 1 to 6, characterized in that: Also includes: At least one annular support (130), the wave trap unit (100) being fixedly arranged on the annular support (130), and the annular support (130) being used for being sleeved on the cable (200).

8. The miniaturized notch filter according to claim 7, characterized in that: The two first ends of the first annular solenoid coil (110) are fixed to the annular bracket (130) by glue dispensing, and the two second ends of the second annular solenoid coil (120) are fixed to the annular bracket (130) by glue dispensing.

9. The miniaturized notch filter according to claim 7, characterized in that: Also includes: At least one annular copper skin (140), wherein the annular copper skin (140) covers the wave trap unit (100).

10. A nuclear magnetic resonance imaging device, characterized in that: A miniaturized wave trap comprising any one of claims 1 to 9.

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