Water-cooling-free microwave ablation needle based on monopole helical antenna

Abstract

The water-cooling-free microwave ablation needle comprises a microwave adapter, a medical stainless steel tube, a coaxial cable, a helical antenna and an insulating puncture sleeve, the coaxial cable penetrates through the medical stainless steel tube, one end of the coaxial cable is connected with the microwave adapter, and the other end of the coaxial cable is twisted into the helical antenna; the insulating puncture sleeve wraps the helical antenna and serves as a needle head at the front end of the ablation needle. The microwave ablation needle can achieve a carbonization-free ablation area with the long diameter of 2 cm at the power of 20 W, meanwhile, the microwave ablation needle does not need circulating water cooling, and the weight of the ablation needle can be reduced.

Description

Technical Field

[0001] The present invention relates to the technical field of microwave ablation, and particularly to a water-cooled-free microwave ablation needle based on a monopole spiral antenna. Background Art

[0002] Currently, the power selected for microwave ablation needles is mostly high power (such as 50W / 60W / 70W, etc.). This is because in order to reduce the temperature of the ablation needle rod, the current microwave ablation needles are designed with a circulating water cooling system. While reducing the temperature of the ablation needle rod, most of the heat energy is also taken away. Therefore, it is necessary to select a relatively high power (above 30W) for microwave ablation. However, using a relatively high power for microwave ablation will form a high temperature (above 160°C) within a few seconds after ablation, which will then form a large amount of carbonization, resulting in adhesion and restricting the size of the coagulation area.

[0003] Due to its special structure, the spiral antenna can achieve circular polarization of electromagnetic waves, has a wide beam width, and has a highly consistent input impedance in different frequency bands. In addition, due to its high gain and stable heating mode, it is also widely used in the field of microwave heating. Summary of the Invention

[0004] The present invention provides a water-cooled-free microwave ablation needle based on a monopole spiral antenna, which does not require a circulating water cooling system. It can not only reduce the weight of the ablation needle, but also does not need to take away heat energy due to water cooling circulation. It can select a relatively small power (below 20W) for ablation, so as to effectively reduce carbonization while taking into account the size of the ablation area.

[0005] An embodiment of the present invention provides a water-cooled-free microwave ablation needle based on a monopole spiral antenna, comprising:

[0006] A microwave adapter;

[0007] A medical stainless steel tube;

[0008] A coaxial cable, the coaxial cable passes through the medical stainless steel tube, one end is connected to the microwave adapter, and the other end is twisted into a spiral antenna;

[0009] An insulating puncture sleeve, the insulating puncture sleeve wraps the spiral antenna at the front end of the ablation needle as the needle tip.

[0010] Optionally, in an embodiment of the present invention, the diameter of the medical stainless steel tube is 2.0 mm and the thickness is 0.45 mm.

[0011] Optionally, in an embodiment of the present invention, the outer diameter of the coaxial cable is 1.1 mm, which includes an inner conductor, an intermediate insulating medium, and an outer shielding layer with diameters of 0.3 mm, 0.8 mm, and 1.1 mm respectively. The material of the outer shielding layer is seamless copper tube, the material of the intermediate insulating medium is polytetrafluoroethylene, and the material of the inner conductor is silver-plated copper-clad steel wire.

[0012] Optionally, in an embodiment of the present invention, the coaxial cable is a semi-rigid coaxial cable with a capacitance of 95.1 PF / M and an impedance of 50 Ω.

[0013] Optionally, in an embodiment of the present invention, the spiral antenna has a spiral diameter of 1.8 mm, a pitch of 0.5 mm, and 5 turns.

[0014] Optionally, in an embodiment of the present invention, the needle includes a puncture tip and a puncture needle rod. The puncture tip is conical with a length of 0.5 mm, and the puncture needle rod has a length of 2.5 mm. The material of the puncture sleeve is polytetrafluoroethylene with a relative dielectric constant of 2, and the material of the gap between the inside of the puncture sleeve and the spiral antenna is air.

[0015] Optionally, in an embodiment of the present invention, the maximum power of the microwave ablation needle is 20 W, and the maximum ablation duration is 600 s.

[0016] The water-cooled-free microwave ablation needle based on a monopole spiral antenna according to the embodiment of the present invention has the following beneficial effects:

[0017] 1. By using the spiral antenna, a tail-free ablation with a smaller ablation dose of less than 20 W can be achieved, with no carbonization in the ablation area within 2 cm and less carbonization within 3 cm.

[0018] 2. The spiral antenna is sheathed with a polytetrafluoroethylene puncture sleeve, which is easy to pull out and does not adhere.

[0019] 3. There is no need to build a water-cooling circulation structure inside the needle body, which reduces the weight of the ablation needle.

[0020] Some of the additional aspects and advantages of the present invention will be given in the following description, some will become obvious from the following description, or be understood through the practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] The above and / or additional aspects and advantages of the present invention will become obvious and easy to understand from the following description of the embodiments in conjunction with the drawings, where:

[0022] Figure 1 is a structural diagram of a water-cooled-free ablation needle based on a monopole spiral antenna provided by an embodiment of the present invention;

[0023] Figure 2Physical diagram of the waterless ablation needle based on a monopole spiral antenna according to an embodiment of the present invention;

[0024] Figure 3 Geometric model diagram of in vitro porcine liver needle ablation of the waterless ablation needle based on a monopole spiral antenna according to an embodiment of the present invention;

[0025] Figure 4 Reflection coefficient curve graph of antenna electromagnetic performance simulation analysis of the waterless ablation needle based on a monopole spiral antenna according to an embodiment of the present invention;

[0026] Figure 5 Simulation effect diagram of in vitro liver microwave ablation of the waterless ablation needle based on a monopole spiral antenna according to an embodiment of the present invention;

[0027] Figure 6 Actual effect diagram of in vitro liver microwave ablation of the waterless ablation needle based on a monopole spiral antenna according to an embodiment of the present invention.

[0028] Explanation of reference numerals: microwave adapter 1, medical stainless steel tube 2, coaxial cable 3, spiral antenna 4, insulating puncture sleeve 5. Detailed description of the specific implementation

[0029] The embodiments of the present invention will be described in detail below. Examples of the embodiments are shown in the drawings, where the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the drawings are exemplary and are intended to explain the present invention and should not be construed as limiting the present invention.

[0030] Figure 1 Structural diagram of a waterless ablation needle based on a monopole spiral antenna provided by an embodiment of the present invention.

[0031] As Figure 1 shown, the waterless ablation needle based on a monopole spiral antenna includes:

[0032] Microwave adapter 1;

[0033] Medical stainless steel tube 2;

[0034] Coaxial cable 3, the coaxial cable 3 passes through the medical stainless steel tube 2, one end is connected to the microwave adapter 1, and the other end is twisted into a spiral antenna 4;

[0035] Insulating puncture sleeve 5, the insulating puncture sleeve 5 wraps the spiral antenna 4 at the front end position of the ablation needle as the needle tip.

[0036] The microwave adapter of the embodiment of the present invention is a standard SMA RF connector.

[0037] In one embodiment of the present invention, the diameter of the medical stainless steel tube is 2.0 mm and the thickness is 0.45 mm.

[0038] In one embodiment of the present invention, the outer diameter of the coaxial cable is 1.1 mm, which includes an inner conductor, an intermediate insulating medium, and an outer shielding layer. The diameters are respectively: 0.3 mm, 0.8 mm, and 1.1 mm. The material of the outer shielding layer is seamless copper tube, the material of the intermediate insulating medium is polytetrafluoroethylene, and the material of the inner conductor is silver-plated copper-clad steel wire. The coaxial cable is a semi-rigid coaxial cable, with a capacitance of 95.1 PF / M and an impedance of 50 Ω.

[0039] In one embodiment of the present invention, the helix diameter of the helical antenna is 1.8 mm, the pitch is 0.5 mm, and the number of turns is 5.

[0040] In one embodiment of the present invention, the needle is 3 mm long and includes a puncture tip and a puncture needle rod. The puncture tip is conical, with a length of 0.5 mm, and the puncture needle rod has a length of 2.5 mm. The material of the puncture sleeve is polytetrafluoroethylene, which has a non-sticking function and a relative dielectric constant of 2. The material of the gap between the inside of the puncture sleeve and the helical antenna is air.

[0041] The maximum ablation power of the waterless-cooled microwave ablation needle based on a monopole helical antenna in the embodiment of the present invention is 20 W, and the maximum ablation duration is 600 s. This microwave ablation needle can achieve a tail-free ablation with less carbonization in an ablation area of less than 2 cm and less carbonization in an ablation area of less than 3 cm at a relatively low ablation dose of less than 20 W.

[0042] In the embodiment of the present invention, the waterless-cooled microwave ablation needle based on a monopole helical antenna does not require an internal water-cooling circulation structure inside the needle body, which reduces the weight of the ablation needle.

[0043] As Figure 2 shows a physical diagram of the waterless-cooled microwave ablation needle based on a monopole helical antenna. 1 is a microwave adapter, 2 is a medical stainless steel tube, 3 is a coaxial cable, 4 is a helical antenna, and 5 is an insulating puncture sleeve.

[0044] Select two powers of 10 W and 20 W as the ablation power and set different times for ablation.

[0045] As Figure 3 shows a geometric model diagram of in vitro porcine liver simulation ablation of the waterless-cooled microwave ablation needle based on a monopole helical antenna. The in vitro porcine liver ablation thermal field simulation of the ablation needle of the present invention is carried out based on the COMSOL Multiphysics software. The ablation needle is mainly composed of a coaxial cable (inner conductor, intermediate insulating medium, and outer shielding layer), a helical antenna (the coaxial cable is twisted at the front end of the needle), a stainless steel tube, and a polytetrafluoroethylene insulating puncture sleeve. The porcine liver tissue is set to be isotropic and homogeneous, and the shape is cylindrical.

[0046] As shown in Figure 4 Figure 1, it shows the reflection coefficient curve of the antenna electromagnetic performance simulation analysis of the waterless-cooled microwave ablation needle based on the monopole spiral antenna, where the input reflection coefficient S at 2.45 GHz 11 is -5 dB, that is, less than half of the energy is used for heating, and no large ablation damage and carbonization area will be generated.

[0047] As shown in Figure 5 Figure 2, it shows the in vitro liver microwave ablation simulation effect diagram of the waterless-cooled microwave ablation needle based on the monopole spiral antenna. Figure 5 For the (a) in Figure 2, the simulated ablation power is 10 W and the time is 300 s. The area outlined by 55 °C (cell inactivation threshold temperature) and 130 °C (carbonization threshold temperature) is the coagulation area and the carbonization area; the major axis and minor axis of the measured coagulation area in the simulation results are 19.5 mm and 10.5 mm respectively, and the axial ratio is 53.8%. Figure 5 For the (b) in Figure 2, the simulated ablation power is 20 W and the time is 300 s. The area outlined by 55 °C (cell inactivation threshold temperature) and 130 °C (carbonization threshold temperature) is the coagulation area and the carbonization area; the major axis and minor axis of the measured coagulation area in the simulation results are 25.1 mm and 13 mm respectively, and the axial ratio is 51.8%.

[0048] As shown in Figure 6 Figure 3, it shows the in vitro liver microwave ablation actual effect diagram of the waterless-cooled microwave ablation needle based on the monopole spiral antenna. Figure 6 For the (a) in Figure 3, the actual ablation power is 10 W and the time is 300 s. The measured major axis of the actual coagulation area is 19 mm, the minor axis is 10 mm, and the axial ratio is 52.6%. There is no carbonization component (charcoal black) in the coagulation area after ablation; compared with the simulation results, the absolute error of the major axis between the coagulation area in the simulation results and the actual coagulation area is 0.5 mm, and the absolute error of the minor axis is 0.5 mm. Figure 6 For the (b) in Figure 3, the actual ablation power is 20 W and the time is 300 s. The measured major axis of the actual coagulation area is 26 mm, the minor axis is 13 mm, and the axial ratio is 50.0%. There is no carbonization component in the coagulation area after ablation; compared with the simulation results, the absolute error of the major axis between the coagulation area in the simulation results and the actual coagulation area is 0.9 mm, and the minor axis is consistent with the simulation result data.

[0049] A waterless-cooled microwave ablation needle based on a monopole spiral antenna provided by the embodiments of the present invention can form an ellipsoidal carbonization-free coagulation area with a major axis of 19 mm and a minor axis of 10 mm at an ablation dose of 10 W - 300 s; at an ablation dose of 20 W - 300 s, an ellipsoidal carbonization-free coagulation area with a major axis of 26 mm and a minor axis of 13 mm can be formed.

[0050] According to an embodiment of the present invention, a water-free microwave ablation needle based on a monopole helical antenna comprises a microwave adapter, a medical stainless steel tube, a coaxial cable, a helical antenna, and an insulating puncture sleeve. The coaxial cable passes through the medical stainless steel tube at one end and connects to the microwave adapter at the other end, where it is twisted into a helical antenna. The insulating puncture sleeve wraps around the helical antenna and serves as the needle tip at the front end of the ablation needle. At a power of 20W, this microwave ablation needle can achieve a carbon-free ablation area with a long diameter of 2cm. Furthermore, no water-cooling circulation structure is required within the needle body, reducing the weight of the ablation needle.

[0051] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" 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 expressions of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or N embodiments or examples in a suitable manner. In addition, those skilled in the art can combine and combine different embodiments or examples described in this specification and the features of different embodiments or examples without contradiction.

[0052] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be understood to indicate or imply relative importance or implicitly specify the number of technical features indicated. Thus, a feature specified as "first" or "second" may explicitly or implicitly include at least one such feature. In the description of the present invention, "N" means at least two, such as two, three, etc., unless otherwise specifically defined.

Claims

1. An air-cooled microwave ablation needle based on a monopole helical antenna, characterized in that Comprising: Microwave adapter; Medical stainless steel tube; Coaxial cable, the coaxial cable passes through the medical stainless steel tube, one end is connected to the microwave adapter, and the other end is twisted into a spiral antenna; Insulating puncture sleeve, the insulating puncture sleeve wraps the spiral antenna at the front end position of the ablation needle as the needle tip.

2. The waterless-cooling microwave ablation needle based on a monopole helix antenna according to claim 1, wherein The diameter of the medical stainless steel tube is 2.0 mm and the thickness is 0.45 mm.

3. The waterless cooled microwave ablation needle based on a monopole helical antenna according to claim 1, wherein The outer diameter of the coaxial cable is 1.1 mm, including an inner conductor, an intermediate insulating medium and an outer shielding layer, with diameters of: 0.3 mm, 0.8 mm, 1.1 mm respectively. The material of the outer shielding layer is seamless copper tube, the material of the intermediate insulating medium is polytetrafluoroethylene, and the material of the inner conductor is silver-plated copper-clad steel wire.

4. The waterless-cooling microwave ablation needle based on a monopole helix antenna according to claim 1, characterized in that, The coaxial cable is a semi-rigid coaxial cable, with a capacitance of 95.1 PF / M and an impedance of 50 Ω.

5. The waterless cooled microwave ablation needle based on a monopole helix antenna according to claim 1, wherein The spiral diameter of the spiral antenna is 1.8 mm, the pitch is 0.5 mm, and the number of turns is 5.

6. The waterless cooled microwave ablation needle based on a monopole helix antenna according to claim 1, characterized in that, The needle tip includes a puncture tip and a puncture needle rod. The puncture tip is conical, with a length of 0.5 mm, and the length of the puncture needle rod is 2.5 mm. The material of the puncture sleeve is polytetrafluoroethylene, with a relative dielectric constant of 2. The gap material between the inside of the puncture sleeve and the spiral antenna is air.

7. The waterless cooled microwave ablation needle based on a monopole helix antenna according to any one of claims 1-6, characterized in that The maximum power of the microwave ablation needle is 20 W, and the maximum ablation duration is 600 s.

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