Microwave ablation antenna and control method thereof

Abstract

The invention relates to a microwave ablation antenna and a control method thereof, the microwave ablation antenna comprises a feed structure and an ablation structure, the feed structure is electrically connected with the ablation structure, the feed structure and the ablation structure are wrapped by an outer insulating layer, and the outer insulating layer is electrically connected with the feed structure. The outer insulating layer forms an insulating needle head on the side, away from the feed structure, of the ablation structure, and the feed structure, the ablation structure and the outer insulating layer wrapping the feed structure and the ablation structure form a needle rod; an external power supply is connected to the side, away from the ablation structure, of the feed structure so as to supply power to the ablation structure, and the ablation structure is used for forming an ablation area with a preset radial diameter and a preset roundness by using a superposed electromagnetic field. The device has the advantages of being large in ablation range, simple in structure and low in machining difficulty, has extremely high ablation precision and is suitable for different operation environments.

Description

Technical Field

[0001] The invention belongs to the technical field of microwave ablation, and in particular relates to a microwave ablation antenna and a control method thereof. Background Art

[0002] With the development and application of image-guided technology, tumor ablation technology based on local minimally invasive surgery has developed rapidly. Microwave ablation technology (Microwave Ablation), as one of the effective means of local tumor treatment, has the advantages of wide application range, large single-needle ablation area, fast speed, multiple energy sources without mutual interference, high cost performance and immune regulation. The microwave ablation system is generally composed of a microwave generator, a microwave ablation antenna, cables, auxiliary equipment and other accessories. In the actual operation process, the microwave ablation antenna is extended into the lesion, and the microwave energy is used to damage the nodular lesions, causing necrosis and carbonization of the lesions. After a period of carbonization, the lesions are gradually absorbed by the body and finally disappear. Microwave ablation is suitable for nodular lesions in solid organs such as the thyroid, breast, and liver.

[0003] Although the mainstream microwave ablation antenna can effectively complete the carbonization treatment of the lesion area, the ablation area produced by the microwave ablation antenna is not large enough, so the operator has to insert multiple times at multiple points to complete the treatment of the lesion area, which increases the operation time and makes it difficult to ensure the quality of the operation. Although a large number of microwave ablation antenna structures that increase the ablation area have been proposed, they are often complex in structure, have high processing requirements, and have high investment costs. Summary of the invention

[0004] In order to solve the above problems existing in the prior art, the present invention provides a microwave ablation antenna and a control method thereof. The technical problem to be solved by the present invention is achieved through the following technical solutions:

[0005] In a first aspect, the present invention provides a microwave ablation antenna, comprising: a feeding structure and an ablation structure, wherein the feeding structure and the ablation structure are electrically connected, the feeding structure and the ablation structure are wrapped by an outer insulating layer, and the outer insulating layer forms an insulating needle head on a side of the ablation structure away from the feeding structure, and the feeding structure, the ablation structure and the outer insulating layer wrapping the feeding structure and the ablation structure form a needle rod; the side of the feeding structure away from the ablation structure is connected to an external power supply to supply power to the ablation structure, and the ablation structure is used to use a superimposed electromagnetic field to form an ablation area with a preset radial diameter and a preset roundness.

[0006] In some embodiments, the ablation structure includes: a first inner conductor arranged along the axial direction of the needle rod, and a plurality of first outer conductors distributed along the axial direction of the first inner conductor; each first outer conductor is arranged around the first inner conductor and is electrically connected to the first inner conductor, and the plurality of first outer conductors can synchronously form an electromagnetic field.

[0007] In some embodiments, the feeding structure includes: a second outer conductor; wherein, in the axial direction of the first inner conductor, the spacing distance between any two adjacent first outer conductors among the multiple first outer conductors, and the spacing distance between a first outer conductor close to the second outer conductor and the second outer conductor are the same.

[0008] In some embodiments, the plurality of first outer conductors include at least a first annular conductor, a second annular conductor, and a third annular conductor.

[0009] In some embodiments, the outer diameter width of each first outer conductor is the same as the outer diameter width of the feeding structure.

[0010] In some embodiments, the plurality of first outer conductors are integrally formed with the first inner conductor; or, each first outer conductor is fixed to the first inner conductor by a conductive tape.

[0011] In some embodiments, the feeding structure includes: a second outer conductor, a dielectric layer, and a second inner conductor; the second inner conductor is an extension of the first inner conductor, the second outer conductor is sleeved on the second inner conductor, and the dielectric layer is filled between the second outer conductor and the second inner conductor; a current loop is formed between the second outer conductor and the second inner conductor.

[0012] In some embodiments, the insulating needle tip is a cone, the bottom diameter of the cone is the same as the diameter of the needle rod, and the bottom diameter of the cone or the diameter of the needle rod is less than or equal to 1 mm.

[0013] In some embodiments, the preset radial diameter ranges from 33 mm to 40 mm, and the preset roundness ranges from 0.999 to 1.005.

[0014] In a second aspect, the present invention provides a control method for a microwave ablation antenna, which is applied to the microwave ablation antenna described in the first aspect, and the method includes: feeding power to the microwave ablation antenna; controlling the size and roundness of the ablation area generated by the microwave ablation antenna by controlling the input power of the microwave ablation antenna; wherein the input power is positively correlated with the size and roundness of the ablation area.

[0015] Compared with the prior art, the present invention has the following beneficial effects: In view of the problem that the ablation area generated by the existing microwave ablation antenna cannot meet the preset requirements, the present invention proposes a microwave ablation antenna and a control method thereof, wherein the microwave ablation antenna electrically connects the feeding structure and the ablation structure so that the ablation structure generates a superimposed electromagnetic field, and uses the superimposed electromagnetic field to form an ablation area with a preset radial diameter and a preset roundness, which has the advantages of a large ablation range, a simple structure, and low processing difficulty. In addition, since the present invention forms the ablation area by superimposing the electromagnetic field, the size and shape of the ablation area of ​​the microwave ablation antenna can be adjusted by changing the intensity of the electromagnetic field, and the lesions at the key organ parts can be accurately removed, and the ablation area has extremely high ablation accuracy and is suitable for different operating environments. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 is a cross-sectional view of a microwave ablation antenna provided by an embodiment of the present invention;

[0017] Figure 2 is a schematic diagram of an ablation structure provided by an embodiment of the present invention;

[0018] Figure 3 is a schematic diagram of an equivalent circuit of an ablation structure provided by an embodiment of the present invention;

[0019] Figure 4 is a schematic diagram of a feeding structure provided by an embodiment of the present invention;

[0020] Figure 5 is a simulation schematic diagram of the influence of input power on the ablation area provided by an embodiment of the present invention;

[0021] Figure 6 is a simulation schematic diagram of the effect of heating time on the ablation area provided by an embodiment of the present invention;

[0022] Figure 7 It is a schematic diagram of the effect of the ablation area produced when the input power is 60W and the heating time is 10 minutes provided in an embodiment of the present invention.

[0023] Reference numerals:

[0024] 1: feeding structure; 2: ablation structure; 3: outer insulating layer; 10: insulating needle; 11: second outer conductor; 12: dielectric layer; 13: second inner conductor; 20: needle rod; 21: first inner conductor; 22: first outer conductor; 221: first annular conductor; 222: second annular conductor; 223: third annular conductor. DETAILED DESCRIPTION

[0025] The present invention is further described in detail below with reference to specific embodiments, but the embodiments of the present invention are not limited thereto.

[0026] In the description of the present invention, 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. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of the features. In the description of the present invention, the meaning of "plurality" is two or more, unless otherwise clearly and specifically defined.

[0027] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine different embodiments or examples described in this specification.

[0028] Although the present invention is described herein in conjunction with various embodiments, in the process of implementing the claimed invention, those skilled in the art may understand and implement other variations of the disclosed embodiments by viewing the drawings, the disclosure, and the appended claims. In the claims, the word "comprising" does not exclude other components or steps, and "one" or "an" does not exclude multiple situations. A single processor or other unit may implement several functions listed in a claim. Certain measures are recorded in different dependent claims, but this does not mean that these measures cannot be combined to produce good results.

[0029] The microwave ablation antenna and the control method thereof proposed by the present invention are now introduced in conjunction with the accompanying drawings. Before introducing the specific control principle, the structure of the microwave ablation antenna is first described in detail. Figure 1 FIG. 1 is a cross-sectional view of a microwave ablation antenna provided by an embodiment of the present invention. Figure 1 As shown, the microwave ablation antenna includes: a feeding structure 1 and an ablation structure 2, the feeding structure 1 and the ablation structure 2 are electrically connected, the feeding structure 1 and the ablation structure 2 are wrapped by an outer insulating layer 3, and the outer insulating layer 3 forms an insulating needle head 10 on the side of the ablation structure 2 away from the feeding structure 1, the feeding structure 1, the ablation structure 2 and the outer insulating layer 3 wrapping the feeding structure 1 and the ablation structure 2, form a needle rod 20; the side of the feeding structure 1 away from the ablation structure 2 is connected to an external power supply to supply power to the ablation structure 2, and the ablation structure 2 is used to use a superimposed electromagnetic field to form an ablation area with a preset radial diameter and a preset roundness.

[0030] Here, the insulating needle head 10 is a cone, the bottom diameter of the cone is the same as the diameter of the needle rod 20, and the bottom diameter of the cone or the diameter of the needle rod 20 is less than or equal to 1 mm. In addition, the ratio of the height of the cone to the bottom diameter is between 1 and 2.

[0031] Here, the outer insulating layer 3 is made of high-hardness, high-temperature-resistant Teflon with added fillers or reinforcing fibers.

[0032] Since the lesion area is inside the human body, by designing the insulating needle into a cone, it is convenient for the operator to extend the microwave ablation antenna into the lesion area, and the outer insulating layer 3 is pencil-shaped, that is, the bottom diameter of the cone is the same as the diameter of the needle rod 20, both are less than or equal to 1 mm. Compared with the existing microwave ablation antenna of about two millimeters, the wound area is small, which greatly reduces the risk of postoperative complications (such as fever, dull organ pain, etc.).

[0033] Figure 2 Schematic diagram of the ablation structure provided by an embodiment of the present invention. Figure 2 As shown, the ablation structure 2 includes: a first inner conductor 21 arranged along the axial direction of the needle rod 20, and a plurality of first outer conductors 22 distributed along the axial direction of the first inner conductor 21; each first outer conductor 22 is arranged around the first inner conductor 21 and is electrically connected to the first inner conductor 21, and the plurality of first outer conductors 22 can synchronously form an electromagnetic field.

[0034] It should be noted that the first outer conductor 22 can be arranged according to actual needs. In a possible implementation, the plurality of first outer conductors 22 at least include: a first ring conductor 221, a second ring conductor 222 and a third ring conductor 223. Moreover, the outer diameter width of each first outer conductor 22 is the same as the outer diameter width of the feed structure 1. Here, the first ring conductor 221, the second ring conductor 222 and the third ring conductor 223 are arranged in sequence along the axial direction of the ablation structure 2, wherein the first ring conductor 221 is closely arranged with the insulating needle 10, and the third ring conductor 223 is arranged close to the feed structure 1.

[0035] In a possible implementation, the plurality of first outer conductors 22 are integrally formed with the first inner conductor 21; or, each first outer conductor 22 is fixed to the first inner conductor 21 by a conductive tape. When the plurality of first outer conductors 22 are integrally formed with the first inner conductor 21, the inner diameter width of each first outer conductor 22 is the same as the outer diameter width of the first inner conductor 21; when each first outer conductor 22 is fixed to the first inner conductor 21 by a conductive tape, the inner diameter width of each first outer conductor 22 is slightly larger than the outer diameter width of the first inner conductor 21.

[0036] In a possible implementation, the feeding structure 1 includes: a second outer conductor 11; wherein, in the axial direction of the first inner conductor 21, the spacing distance between any two adjacent first outer conductors 22 among the plurality of first outer conductors 22, and the spacing distance between a first outer conductor 22 close to the second outer conductor 11 and the second outer conductor 11 are the same.

[0037] Here, the plurality of first outer conductors 22 are spaced apart along the axial direction of the ablation structure 2, and the spaced apart regions are filled with air, which acts as an equivalent inductor. This distribution method can be simplified into an equivalent circuit. Figure 3 Schematic diagram of an equivalent circuit of the ablation structure provided by an embodiment of the present invention. Figure 3 As shown, the first loop conductor 221, the second loop conductor 222 and the third loop conductor 223 are equivalent to capacitors C1, C2 and C3 respectively; the air between the first loop conductor 221 and the second loop conductor 222 is equivalent to inductance L1, the air between the second loop conductor 222 and the third loop conductor 223 is equivalent to inductance L2, the air between the third loop conductor 223 and the outer conductor 213 of the coaxial cable is equivalent to inductance L3, and the loss generated by the rest of the antenna is equivalent to resistance R. Among them, one end of C1 is electrically connected to one end of L1, the other end of L1 is electrically connected to one end of C2 and one end of L2 respectively, the other end of L2 is electrically connected to one end of L3 and one end of C3 respectively, one end of L3 is connected to a power supply, the other end of C1, the other end of C2 and the other end of C3 are connected to one end of R, the other end of R is respectively connected to the power supply and grounded.

[0038] Figure 4 Schematic diagram of the feeding structure provided by the embodiment of the present invention. Figure 4 As shown, the feeding structure 1 includes: a second outer conductor 11, a dielectric layer 12 and a second inner conductor 13; the second inner conductor 13 is an extension of the first inner conductor 21, the second outer conductor 11 is sleeved on the second inner conductor 13, and the dielectric layer 12 is filled between the second outer conductor 11 and the second inner conductor 13; a current loop is formed between the second outer conductor 11 and the second inner conductor 13.

[0039] Here, the second inner conductor 13 and the first inner conductor 21 are integrally formed. In addition, the second outer conductor 11 is in a ring shape. The second outer conductor 11 and the dielectric layer 12, as well as the dielectric layer 12 and the second inner conductor 13 are fixed by conductive tape.

[0040] Here, a second outer conductor 11 is provided to form a circulating circuit with the second inner conductor 13, and the current mainly enters the microwave ablation antenna along the second inner conductor 13 and flows out along the second outer conductor 11; and the second outer conductor 11 is provided to prevent the electromagnetic wave signal inside the microwave ablation antenna from leaking and interfering with surrounding equipment, and also to prevent external electromagnetic interference from entering the microwave ablation antenna and interfering with the integrity of the electromagnetic wave signal.

[0041] Here, the dielectric layer 12 is filled with Teflon, a high temperature resistant material with a relative dielectric constant of 2.03. The second outer conductor 11 and the second inner conductor 13 are made of copper.

[0042] In a possible implementation, the preset radial diameter ranges from 33 mm to 40 mm, and the preset roundness ranges from 0.999 to 1.005. Roundness refers to the ratio of the diameter of the radial ablation zone of the antenna to the diameter of the axial ablation zone of the antenna. When the diameter of the ablation zone produced by the existing microwave ablation antenna exceeds 30 mm, the structure is often complex. Compared with the existing microwave ablation antenna, the ablation zone produced by the microwave ablation antenna provided by the present invention is larger and rounder, and has a simple structure and is easy to process.

[0043] The above is an introduction to the structure of the microwave ablation antenna provided by the present invention. Correspondingly, the control method of the microwave ablation antenna provided by the present invention is now described in detail. The method includes: feeding power to the microwave ablation antenna; controlling the size and roundness of the ablation area generated by the microwave ablation antenna by controlling the input power of the microwave ablation antenna; wherein the input power is positively correlated with the size and roundness of the ablation area.

[0044] To verify the effect of input power on the ablation area, Figure 5 The simulation diagram of the effect of input power on the ablation area provided by the embodiment of the present invention is shown in FIG. COMSOL simulation software is used to simulate the microwave ablation antenna provided by the present invention operating on the human liver. Initial parameters are first set. Specifically, the blood density is 1000 kg / m 3, blood specific heat capacity is 3639 J / (kg·K), blood perfusion rate is 0.0036 (l / s), blood temperature is 37°C; set the relative dielectric constant of human liver, where when the temperature T is between 37°C and 100°C, the relative dielectric constant of human liver is 47.043-0.042×(T+273.15), when the temperature T is between 100°C and 101°C, the relative dielectric constant of human liver is 5459.8-14.55× (T+273.15), when the temperature T exceeds 101°C, the relative dielectric constant of human liver is 16.67; set the conductivity of human liver, when the temperature T is between 37°C and 100°C, the conductivity of human liver is 1.7381-0.0004×(T+273.15), when the temperature T exceeds 100°C, the conductivity of human liver is 2.173×{1-1 / [1+exp(5.9506-0.0697T)]}. Figure 5 As shown in the figure, when the input power is 10W, the corresponding maximum radial diameter is 18.567mm and the roundness is 0.820; when the input power is 20W, the corresponding maximum radial diameter is 25.754mm and the roundness is 0.891; when the input power is 30W, the corresponding maximum radial diameter is 29.984mm and the roundness is 0.928; when the input power is 45W, the corresponding maximum radial diameter is 34.329mm and the roundness is 0.962; when the input power is 60W, the corresponding maximum radial diameter is 37.575mm and the roundness is 0.987. In other words, the greater the input power, the greater the corresponding maximum radial diameter and roundness.

[0045] It should be noted that, in addition to adjusting the input power, the size and circularity of the generated ablation area can also be controlled by adjusting the heating time of the microwave ablation antenna.

[0046] To verify the effect of heating time on the ablation area, Figure 6 It is a simulation schematic diagram of the effect of heating time on the ablation area provided by an embodiment of the present invention. Figure 6 The initial parameters in Figure 5 The initial parameters are the same as in , and will not be repeated here. Figure 6 As shown in the figure, when the heating time is 3 minutes, the corresponding maximum radial diameter is 26.477mm and the roundness is 0.883; when the heating time is 5 minutes, the corresponding maximum radial diameter is 30.913mm and the roundness is 0.934; when the heating time is 8 minutes, the corresponding maximum radial diameter is 35.239mm and the roundness is 0.968; when the heating time is 10 minutes, the corresponding maximum radial diameter is 37.575mm and the roundness is 0.987. In other words, the longer the heating time, the larger the corresponding maximum radial diameter and roundness.

[0047] Figure 7Schematic diagram of the effect of the ablation area produced when the input power is 60W and the heating time is 10 minutes provided by the embodiment of the present invention. Figure 7 As shown, an ablation zone with a diameter of 37.575 mm and a roundness of 0.987 was generated, indicating that the microwave ablation antenna provided by the present invention has a good ablation effect.

[0048] In order to verify the association between the ablation area of ​​the microwave ablation antenna provided by the present invention and the ablation structure 2, specifically, by adjusting the axial width of each annular conductor in the ablation structure 2, the distance between the first annular conductor 221 and the insulating needle 10, the distance between the first annular conductor 221, the second annular conductor 222 and the third annular conductor 223, and the distance between the third annular conductor 223 and the feeding structure 1 in the range of 0.1 mm to 1.0 mm with a step length of 0.1 mm, the association between the ablation area and the ablation structure 2 is verified. Here, simulation and Figure 4 The parameters are the same as those in Table 1, Table 2 and Table 3.

[0049] Table 1 Effect of the axial width of the annular conductor on the size and roundness of the ablation area

[0050]

[0051] Table 2 Effect of the distance between the first annular conductor and the needle on the size and roundness of the ablation area

[0052]

[0053] Table 3 Effect of the distance between the annular conductors and the distance between the third annular conductor and the second outer conductor on the size and roundness of the ablation area

[0054]

[0055] Based on Table 1, Table 2 and Table 3, it can be seen that by only changing the axial width of the annular conductor, the larger the axial width of the annular conductor, the larger the maximum radial diameter of the ablation area; by only changing the distance between the first annular conductor and the needle, as the distance between the first annular conductor and the needle increases, the maximum radial diameter of the ablation area tends to increase as a whole; by only changing the distance between the annular conductors and the third annular conductor and the outer conductor of the coaxial cable, as the distance between the annular conductors and the third annular conductor and the outer conductor of the coaxial cable increases, the maximum radial diameter of the ablation area tends to increase as a whole. In addition, it can be seen from Table 1, Table 2 and Table 3 that the maximum radial diameter of the ablation area of ​​the microwave ablation antenna provided by the present invention is greater than 35 mm, and the roundness is greater than 0.96, which can meet the ablation range requirements under different operating environments.

[0056] The above contents are further detailed descriptions of the present invention in combination with specific preferred embodiments, and it cannot be determined that the specific implementation of the present invention is limited to these descriptions. For ordinary technicians in the technical field to which the present invention belongs, several simple deductions or substitutions can be made without departing from the concept of the present invention, which should be regarded as falling within the scope of protection of the present invention.

Claims

1. A microwave ablation antenna, characterized in that: include: A feeding structure (1) and an ablation structure (2), wherein the feeding structure (1) and the ablation structure (2) are electrically connected, the feeding structure (1) and the ablation structure (2) are wrapped by an outer insulating layer (3), and the outer insulating layer (3) forms an insulating needle head (10) on a side of the ablation structure (2) away from the feeding structure (1), and the feeding structure (1), the ablation structure (2) and the outer insulating layer (3) wrapping the feeding structure (1) and the ablation structure (2) form a needle rod (20); an external power source is connected to a side of the feeding structure (1) away from the ablation structure (2) to supply power to the ablation structure (2), and the ablation structure (2) is used to form an ablation area with a preset radial diameter and a preset roundness by using a superimposed electromagnetic field.

2. The microwave ablation antenna according to claim 1, characterized in that: The ablation structure (2) comprises: a first inner conductor (21) arranged along the axial direction of the needle rod (20), and a plurality of first outer conductors (22) distributed along the axial direction of the first inner conductor (21); each first outer conductor (22) is arranged around the first inner conductor (21) and is electrically connected to the first inner conductor (21); the plurality of first outer conductors (22) can synchronously form an electromagnetic field.

3. The microwave ablation antenna according to claim 2, characterized in that: The feeding structure (1) comprises: a second outer conductor (11); wherein, in the axial direction of the first inner conductor (21), the spacing distance between any two adjacent first outer conductors (22) among the plurality of first outer conductors (22) and the spacing distance between a first outer conductor (22) close to the second outer conductor (11) and the second outer conductor (11) are the same.

4. The microwave ablation antenna according to claim 2 or 3, characterized in that: The plurality of first outer conductors (22) include at least a first annular conductor (221), a second annular conductor (222) and a third annular conductor (223).

5. The microwave ablation antenna according to claim 2, characterized in that: The outer diameter width of each first outer conductor (22) is the same as the outer diameter width of the feeding structure (1).

6. The microwave ablation antenna according to claim 2, characterized in that: The plurality of first outer conductors (22) are integrally formed with the first inner conductor (21); or, each first outer conductor (22) is fixed to the first inner conductor (21) by means of a conductive tape.

7. The microwave ablation antenna according to claim 2, characterized in that: The feeding structure (1) comprises: a second outer conductor (11), a dielectric layer (12) and a second inner conductor (13); the second inner conductor (13) is an extension of the first inner conductor (21); the second outer conductor (11) is sleeved on the second inner conductor (13); the dielectric layer (12) is filled between the second outer conductor (11) and the second inner conductor (13); and a current loop is formed between the second outer conductor (11) and the second inner conductor (13).

8. The microwave ablation antenna according to claim 1, characterized in that: The insulating needle head (10) is a cone, the bottom diameter of the cone is the same as the diameter of the needle rod (20), and the bottom diameter of the cone or the diameter of the needle rod (20) is less than or equal to 1 mm.

9. The microwave ablation antenna according to claim 1, characterized in that: The preset radial diameter has a value range of 33 mm to 40 mm, and the preset roundness has a value range of 0.999 to 1.

005.

10. A method for controlling a microwave ablation antenna, characterized in that: Applied to the microwave ablation antenna as described in any one of claims 1 to 9 above, the method comprises: feeding power to the microwave ablation antenna; By controlling the input power of the microwave ablation antenna, the size and circularity of the ablation area generated by the microwave ablation antenna are controlled; wherein the input power is positively correlated with the size and circularity of the ablation area.

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