A combined low-impedance microwave ablation transmission component and impedance matching method thereof

Abstract

The present invention relates to a combined low-impedance microwave ablation transmission assembly, comprising a host output interface, a composite cable connector, and a composite cable. The host output interface is fixed to a microwave power generator, and the composite cable connector is fixed to both ends of the composite cable. The composite cable connection includes a microwave transmission channel, a signal transmission line, and a cooling medium transmission pipeline. Advantages: For low-impedance microwave ablation needles, the efficiency of the host's microwave output can be greatly improved, thereby improving the efficiency of microwave ablation surgery. Only a single composite cable is required, completely eliminating the problem of intertwined pipelines and reducing the difficulty of clinical use.

Description

Technical Field

[0001] The present invention relates to a combined low-impedance microwave ablation transmission component and an impedance matching method thereof, belonging to the technical field of microwave surgical equipment. Background Art

[0002] Microwave ablation has become an important treatment for solid tumors. Microwave ablation involves releasing microwave energy into tumor tissue using a microwave ablation needle. Polar molecules in the tumor tissue (mostly water) undergo high-speed rotation under the microwave field, rapidly generating heat and reaching a high temperature. This causes tissue dehydration, coagulation, and protein denaturation, thereby inactivating the tumor tissue and eliminating its ability to proliferate, achieving the therapeutic goal.

[0003] According to microwave energy transmission theory, to improve power transmission efficiency, the characteristic impedance of the entire microwave energy transmission channel must be as consistent as possible. Due to the unique characteristics of microwave transmission equipment, industry standards have been established for microwave power generators, microwave transmission cables, microwave component connectors, and microwave test loads, and the most commonly used characteristic impedance is 50 ohms.

[0004] However, the characteristic impedance of tumor tissue, serving as a microwave load, is not 50 ohms. However, the characteristic impedance of all current microwave ablation equipment, including the main unit's microwave output interface, transmission cables, and microwave connectors, is 50 ohms. This is primarily due to the limited availability of commercially available equipment. This inevitably results in microwave energy reflection within the transmission channel, particularly around the ablation needle tip. This can lead to reduced microwave transmission efficiency at best. In more severe cases, the resulting local standing waves from the reflected waves can cause a significant increase in needle shaft temperature, potentially breaking through the insulation and burning the ablation needle, leading to accidents. This factor is strongly associated with the detachment of some needle tips in clinical applications.

[0005] According to the industry standard "General Requirements for Accessories of Medical Microwave Equipment," internal tissue thermocoagulators must have a needle shaft cooling mechanism and a needle shaft or refrigerant temperature detection device to prevent excessive shaft temperatures from causing burns to non-surgical tissue. Current products all use normal saline as the cooling medium for the ablation needle shaft, requiring separate connections for the water supply and return pipes, detection circuits, and microwave transmission cables. This multitude of pipes can easily become tangled during surgery, making it extremely inconvenient.

[0006] Some institutions are currently developing low-impedance microwave ablation needles, but the peripheral microwave cables and connectors still use the industry-standard 50-ohm characteristic impedance, which inevitably reduces the output power efficiency of the microwave transmitter. Other institutions are developing a method that uses cold air from the operating room as a cooling medium within the ablation needle, which would be more convenient. The processing and delivery of the cold air is handled by the host computer. Summary of the Invention

[0007] The present invention proposes a combined low-impedance microwave ablation transmission cable and an impedance matching method thereof, which are used to connect a microwave power generator equipped with a cold air generating device and a low-impedance microwave ablation needle using air cooling, so as to improve the transmission efficiency of the host microwave power, simplify the pipelines that need to be connected to the ablation needle, and achieve the purpose of improving the efficiency of microwave ablation surgery.

[0008] The technical solution of the present invention is as follows: a combined low-impedance microwave ablation transmission component, including a host output interface 1-1, a composite cable connector 2-1 and a composite cable. The host output interface is fixed on the microwave power generator, including a microwave coaxial cable connection jack 1101, a signal cable connection jack 1102, a cold air output pipe jack 1103, a negative pressure pipe jack 1104 and a plastic insulating base for fixing the components. The composite cable connector is fixed at both ends of the composite cable, including a microwave coaxial cable connection plug 2101, a signal cable connection pin 2102, a cold air pipe plug 2103, a negative pressure pipe plug 2104 and a plastic insulating base for fixing the components. The composite cable connector at one end is connected to the output interface of the host, and the composite cable connector at the other end is connected to the input interface of the microwave ablation needle; the composite cable includes, from the inside to the outside, a microwave coaxial cable outer conductor 2211, a microwave coaxial cable insulator 2212, a microwave coaxial cable inner conductor 2213, a signal cable 222, a cold air duct 223, a negative pressure duct 224, a host-end cold air duct connecting nozzle 2231, an ablation needle-end cold air duct connecting nozzle 2232, a host-end negative pressure duct connecting nozzle 2241, and ablation needle-end negative pressure duct connecting nozzle 2242. The composite cable connection includes a microwave transmission channel, a signal transmission line, and a cooling medium transmission duct.

[0009] The length of the composite cable and the ratio of the radial dimensions of the inner and outer conductors are adjustable.

[0010] The signal cable 222 is made of a double-sided circuit board with a polyimide substrate, with an overall thickness of 0.2 to 0.5 mm, one side being full copper, and the other side being corroded into evenly distributed and mutually insulated conductors; the full copper surface is attached to the outer conductor 2211 of the microwave coaxial cable and rolled into a cylindrical surface, and the overlaps are glued together with an adhesive to form a whole with the outer conductor 2211 of the microwave coaxial cable, and the peripheral conductors of the signal cable 222 are electrically connected to the corresponding terminals of the signal cable connection pins 2102 in the composite cable connector.

[0011] The cooling medium transmission pipeline includes a cold air pipeline, a negative pressure pipeline, a transfer hose between the pipeline and the composite cable connector, and an air nozzle.

[0012] The cooling medium transmission pipeline adopts a flexible plastic tube, which also serves as the outer sheath of the composite cable. A gap of 0.5 to 1 mm is formed between its inner wall and the outer wall of the negative pressure pipeline 224, which serves as a circulation channel for cold air; both ends of the cold air pipeline 223 are sealed with adhesive, and are respectively provided with a host end cold air pipeline connecting nozzle 2231 and an ablation needle end cold air pipeline connecting nozzle 2232. The host end cold air pipeline connecting nozzle 2231 is connected to the cold air pipeline plug 2103 of the host end composite cable connector through a hose, and the ablation needle end cold air pipeline connecting nozzle 2232 is connected to the cold air pipeline plug of the ablation needle end composite cable connector through a hose.

[0013] The negative pressure pipe adopts a flexible plastic tube, and a gap of 0.5 to 1 mm is formed between its inner wall and the outer surface of the signal cable 222, which serves as an exhaust channel for the negative pressure device. The negative pressure pipe connecting nozzle 2241 at the main unit end is connected to the negative pressure pipe plug 2104 of the composite cable connector at the main unit end through a hose, and the negative pressure pipe connecting nozzle 2242 at the ablation needle end is connected to the negative pressure pipe plug of the composite cable connector at the ablation needle end through a hose.

[0014] The flexible plastic tube is PFA, FEP or PVC.

[0015] The outer conductor 2211 of the microwave coaxial cable is made of copper foil tape wrapped or tinned copper wire, the microwave coaxial cable insulator 2212 is made of low-density polytetrafluoroethylene material, and the inner conductor 2213 of the microwave coaxial cable is made of silver-plated copper wire or silver-plated copper-clad steel wire.

[0016] Impedance matching between a low-impedance microwave ablation needle and a microwave power generator is achieved by controlling the length of the composite cable and the ratio of the radial dimensions of the inner and outer conductors. The specific method includes the following steps:

[0017] 1) Determine the characteristic impedance of the microwave coaxial cable 221: The output impedance of the host is Z0, the input impedance of the microwave ablation needle is Z1, and the characteristic impedance of the microwave coaxial cable 221 is Z;

[0018] 2) Determine the length of the microwave coaxial cable 221: According to the coaxial line λ / 4 impedance transformation principle, as long as the total length of the cable is an integer multiple of λ / 4, the cable as a whole acts as an impedance converter, thus we can get The transmission speed of electromagnetic waves in a vacuum is c, and the dielectric constant of the microwave coaxial cable insulator 2212 is ε r , the microwave operating frequency f, the microwave wavelength λ in the microwave coaxial cable 221, and the length of the microwave coaxial cable 221 is L; wherein k is a positive integer, and its value depends on the required cable length L;

[0019] 3) Determine the radial dimensions of the microwave coaxial cable insulator 2212: The inner diameter is d and the outer diameter is D.

[0020] The beneficial effects of this invention: Compared with existing microwave ablation output accessories, this patent only requires a single composite cable, completely eliminating the problem of intertwined cables and reducing the difficulty of clinical use. It also significantly improves the efficiency of the host's microwave output, simplifies the cables required to connect the ablation needle, and improves the efficiency of microwave ablation procedures. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Attachment Figure 1 This is a schematic diagram of the microwave energy transmission path.

[0022] Attachment Figure 2 This is a schematic diagram of the host output interface structure.

[0023] Attachment Figure 3 It is a schematic diagram of the structure of a composite cable connector.

[0024] Attachment Figure 4 It is a schematic diagram of the cross-sectional structure of the composite cable.

[0025] Attachment Figure 5 It is a structural diagram of the signal cable combination status.

[0026] Attachment Figure 6 This is a structural diagram of the signal cable in the unfolded state.

[0027] In the figure, 1 is the microwave power generator, 1-1 is the microwave output interface, 2 is the microwave transmission cable, 3 is the microwave ablation needle, 3-1 is the microwave input interface of the ablation needle handle, and 4 is the tumor tissue.

[0028] 1101 is the microwave coaxial cable connection jack, 1102 is the signal cable connection jack, 1103 is the cold air output pipe jack, and 1104 is the negative pressure pipe jack.

[0029] 2-1 is the composite cable connector, 2101 is the microwave coaxial cable connection plug, 2102 is the signal cable connection pin, 2103 is the cold air duct plug, and 2104 is the negative pressure duct plug.

[0030] 221 is the microwave coaxial cable, 2211 is the outer conductor of the microwave coaxial cable, 2212 is the insulator of the microwave coaxial cable, 2213 is the inner conductor of the microwave coaxial cable, 222 is the signal cable, 223 is the cold air duct, 224 is the negative pressure duct, 2241 is the negative pressure duct connecting nozzle at the host end, 2242 is the negative pressure duct connecting nozzle at the ablation needle end, 2231 is the cold air duct connecting nozzle at the host end, and 2232 is the cold air duct connecting nozzle at the ablation needle end.

[0031] 2221 is the signal cable flexible circuit board substrate, 2222 is the signal cable flexible circuit board copper foil surface, and 2223 is the signal cable flexible circuit board conductor surface. DETAILED DESCRIPTION

[0032] As attached Figure 1 As shown, the microwave energy transmission path is: microwave power generator (main unit) → microwave transmission cable → microwave ablation needle → tumor tissue. This application provides a combined low-impedance microwave ablation transmission cable for connecting a microwave power generator equipped with a cold air generator and a low-impedance microwave ablation needle using air cooling. This cable is used to improve the transmission efficiency of the main unit's microwave power, simplify the pipelines required to connect the ablation needle, and achieve the purpose of improving the efficiency of microwave ablation surgery.

[0033] It includes a host output interface, a composite cable connector, and a composite cable.

[0034] The host output interface is fixed on the host, including a microwave coaxial cable connection jack, a signal cable connection jack, a cold air output pipe jack, a negative pressure pipe jack, and a plastic insulating base for fixing these components.

[0035] The composite cable connector is fixed to each end of the composite cable and includes a microwave coaxial cable connector, a signal cable connector, a cold air duct connector, a negative pressure duct connector, and a plastic insulating base that secures these components. One end of the composite cable connector connects to the output port of the host device, while the other end connects to the input port of the microwave ablation needle.

[0036] The composite cable connection includes a microwave transmission channel, a signal transmission line and a cooling medium transmission pipeline.

[0037] The microwave transmission channel consists of an outer conductor, an insulator, and an inner conductor. Impedance matching between the low-input-impedance microwave ablation needle and the microwave power generator (host) is achieved by controlling the length of the composite cable and the ratio of the radial dimensions of the inner and outer conductors.

[0038] The signal transmission line uses a double-sided polyimide circuit board wrapped around the outer conductor of the microwave coaxial cable, with the full copper surface facing the outer conductor of the microwave coaxial cable to form a shielding layer. The conductor surface faces outward to reduce interference with the signal caused by microwave leakage from the microwave coaxial cable.

[0039] The cooling medium transmission pipeline includes a cold air pipeline, a negative pressure pipeline, and a transfer hose and an air nozzle between the pipeline and the composite cable connector.

[0040] The cooling medium transmission pipeline adopts a flexible plastic tube such as PFA, FEP, and PVC, which also serves as the outer sheath of the composite cable. A gap of 0.5 to 1 mm is formed between its inner wall and the outer wall of the negative pressure pipeline 224, which serves as a circulation channel for cold air. The two ends of the cold air pipeline 223 are sealed with adhesive, and a host end cold air pipeline connecting nozzle 2231 and an ablation needle end cold air pipeline connecting nozzle 2232 are respectively provided. The host end cold air pipeline connecting nozzle 2231 is connected to the cold air pipeline plug 2103 of the host end composite cable connector (2-1) through a hose, and the ablation needle end cold air pipeline connecting nozzle 2232 is connected to the cold air pipeline plug of the ablation needle end composite cable connector (3-1) through a hose.

[0041] The negative pressure pipe is made of a flexible plastic tube such as PFA, FEP, or PVC. A gap of 0.5 to 1 mm is formed between its inner wall and the outer surface of the signal cable 222, serving as a vacuum channel for the negative pressure device. The host-side negative pressure pipe connection nozzle 2241 is connected to the negative pressure pipe plug 2104 of the host-side composite cable connector (2-1) via a hose, and the ablation needle-side negative pressure pipe connection nozzle 2242 is connected to the negative pressure pipe plug of the ablation needle-side composite cable connector (3-1) via a hose.

[0042] The technical solution of the present invention is further described below with reference to the accompanying drawings.

[0043] As attached Figure 2 As shown, the host output interface (1-1) is fixed to the microwave power generator (host) and is an integrated microwave, signal, and gas connector. It includes a microwave coaxial cable connection jack 1101 located at the center of the connector, signal cable connection jacks 1102 distributed around the microwave coaxial cable connection jack 1101, a cold air output duct jack 1103, a negative pressure duct jack 1104, and a plastic insulating base that fixes these jack components.

[0044] The microwave coaxial cable connection jack 1101 uses an industrial standard 50-ohm female plug-in RF connector and is connected to the microwave output coaxial cable of the microwave power generator in the main unit. It is used to output microwaves to the microwave ablation needle.

[0045] The signal cable connection jack 1102 is a brass hole structure, and each terminal is connected to the power terminal and signal input and output terminal corresponding to the monitoring circuit in the host, and is used to connect to the sensor circuit in the microwave ablation needle.

[0046] The cold air output duct jack 1103 is made of plastic and is integrally formed during the injection molding of the insulating base. It is connected to the output duct of the cold air generator within the main unit and is used to output cooling medium to the microwave ablation needle.

[0047] The negative pressure pipe jack 1104 is made of plastic and is integrally molded during the injection molding of the insulating base. It is connected to the suction pipe of the negative pressure generator in the main unit and is used to generate negative pressure in the cooling circuit of the microwave ablation needle.

[0048] The same structure is also provided on the microwave ablation needle handle, and each functional component is connected to the built-in functional component of the microwave ablation needle.

[0049] Implementation example: Composite cable connector

[0050] As attached Figure 3 As shown, the composite cable connectors are fixed at both ends of the composite cable (2), the connector at one end of the composite cable is connected to the host output interface (1-1) of the microwave power generator (host), and the connector at the other end of the composite cable is connected to the ablation needle input interface (3-1).

[0051] The composite cable connector (2-1) is designed to complement the corresponding structure of the host output interface (1-1) in terms of style and size to achieve plug-in connection between the two. It includes a microwave coaxial cable connection plug 2101 located at the center of the connector, signal cable connection pins 2102 distributed around the periphery of the microwave coaxial cable connection plug 2101, a cold air output duct hollow pin 2103, a negative pressure duct hollow pin 2104, and a plastic insulating base for fixing these jack parts.

[0052] The microwave coaxial cable connection plug 2101 uses an industrial standard 50-ohm pin-type plug-in RF connector and is connected to the microwave coaxial cable 221 in the composite cable. It is used to transmit microwaves to the microwave ablation needle.

[0053] The signal cable connection pins 2102 are brass pin-type structures, and each terminal is connected to the wire on the outer surface of the signal cable 222 in the composite cable. They are used to deliver power and signal transmission to the sensor circuit in the microwave ablation needle.

[0054] The cold air output duct hollow pin 2103 is made of plastic material and is integrally formed during the injection molding of the insulating base. It is used to output cooling medium to the microwave ablation needle.

[0055] The hollow negative pressure pipe pin 2104 is made of plastic and is integrally formed during the injection molding of the insulating base. It is used to generate negative pressure in the cooling circuit of the microwave ablation needle.

[0056] Implementation example: composite cable

[0057] As attached Figure 4As shown, the composite cable is composed of the following components from the inside to the outside: microwave coaxial cable outer conductor 2211, microwave coaxial cable insulator 2212, microwave coaxial cable inner conductor 2213, signal cable 222, cold air duct 223, negative pressure duct 224, host end cold air duct connecting nozzle 2231, ablation needle end cold air duct connecting nozzle 2232, host end negative pressure duct connecting nozzle 2241, and ablation needle end negative pressure duct connecting nozzle 2242.

[0058] The microwave coaxial cable's outer conductor 2211 is made of copper foil tape or tinned copper wire. The microwave coaxial cable's insulator 2212 is made of low-density polytetrafluoroethylene (PTFE) material. The microwave coaxial cable's inner conductor 2213 is made of silver-plated copper wire or silver-plated copper-clad steel wire. This structure ensures the cable maintains good flexibility.

[0059] The signal cable 222 is made of a double-sided polyimide substrate circuit board with an overall thickness of 0.2 to 0.5 mm. One side is full copper, and the other side is etched into evenly distributed, mutually insulated wires. Figure 5 、 6 As shown. The full copper surface is placed against the outer conductor 2211 of the microwave coaxial cable and rolled into a cylindrical surface. The overlapped seams are glued together with the outer conductor 2211 of the microwave coaxial cable to form a whole. The full copper surface acts as a shielding layer for the outer conductor 2211 of the microwave coaxial cable. The outer peripheral conductors of the signal cable 222 are electrically connected to the corresponding terminals of the signal cable connection pins 2102 in the composite cable connector (2-1).

[0060] The cold air duct 223 is made of a flexible plastic tube such as PFA, FEP, or PVC, which also serves as the outer sheath of the composite cable. A gap of 0.5 to 1 mm is formed between its inner wall and the outer wall of the negative pressure duct 224 to serve as a circulation channel for the cold air. Both ends of the cold air duct 223 are sealed with adhesive, and are respectively provided with a host-end cold air duct connecting nozzle 2231 and an ablation needle-end cold air duct connecting nozzle 2232. The host-end cold air duct connecting nozzle 2231 is connected to the cold air duct plug 2103 of the host-end composite cable connector (2-1) through a hose, and the ablation needle-end cold air duct connecting nozzle 2232 is connected to the cold air duct plug of the ablation needle-end composite cable connector (3-1) through a hose.

[0061] The negative pressure pipe 224 is made of a flexible plastic tube such as PFA, FEP, or PVC. A gap of 0.5 to 1 mm is formed between its inner wall and the outer surface of the signal cable 222, serving as a vacuum channel for the negative pressure device. The host-side negative pressure pipe connection nozzle 2241 is connected to the negative pressure pipe plug 2104 of the host-side composite cable connector (2-1) via a flexible hose, and the ablation needle-side negative pressure pipe connection nozzle 2242 is connected to the negative pressure pipe plug of the ablation needle-side composite cable connector (3-1) via a flexible hose.

[0062] Example 1: Low Impedance Conversion

[0063] Since the microwave coaxial cable connection jack 1101 in the host output interface (1-1) and the microwave coaxial cable connection plug 2101 in the host-end composite cable connector (2-1) still use industrial standard 50Ω characteristic impedance microwave connectors, the microwave coaxial cable 221 in the composite cable (2-1) is used to achieve impedance matching between the host and the microwave ablation needle.

[0064] Step 1: Determine the characteristic impedance of the microwave coaxial cable 221.

[0065] The output impedance of the host is Z0, which is a known value of 50Ω.

[0066] The input impedance of the microwave ablation needle is Z1, which is a known quantity and is assumed to be 30Ω.

[0067] The characteristic impedance of the microwave coaxial cable 221 is Z.

[0068] According to the coaxial line impedance transformation principle, we can get

[0069] Step 2: Determine the length of the microwave coaxial cable 221.

[0070] Assume that the transmission speed of electromagnetic waves in vacuum is c, which is 299792458m / s.

[0071] The dielectric constant of the microwave coaxial cable insulator 2212 is ε r , take 1.7.

[0072] The operating frequency f of the microwave takes the commonly used frequency 2450 MHz for microwave ablation as an example.

[0073] The wavelength λ of microwaves in the microwave coaxial cable 221 .

[0074] The length of the microwave coaxial cable 221 is L.

[0075] According to the theory of electromagnetic wave transmission in coaxial line, we can get

[0076] According to the coaxial cable λ / 4 impedance transformation principle, as long as the total length of the cable is an integer multiple of λ / 4, the entire cable will act as an impedance transformer. Where k is a positive integer, and its value depends on the required cable length L.

[0077] Step 3: Radial dimensions of microwave coaxial cable insulator 2212.

[0078] Assume: inner diameter is d, outer diameter is D

[0079] According to the formula It can be obtained that D≈2.32d.

[0080] Example 2: Radial dimensions of composite cables

[0081] Assume that d=0.5 mm is selected, which is the inner diameter of the microwave coaxial cable insulator 2212 , and the outer diameter of the microwave coaxial cable inner conductor 2213 .

[0082] Then D=1.16 mm, which is the outer diameter of the microwave coaxial cable insulator 2212 , and also the inner diameter of the microwave coaxial cable outer conductor 2211 .

[0083] Assuming that the wall thickness of the microwave coaxial cable outer conductor 2211 is 0.1 mm, the outer diameter after wrapping the signal cable 222 = 1.16 + 2 × 0.1 + 2 × 0.3 = 1.96 mm. The thickness of the signal cable 222 is selected to be 0.3 mm.

[0084] The outer diameter of the negative pressure pipe 224 is 1.96+2×(0.8+0.2)=3.96 mm, wherein the gap of the negative pressure pipe is 0.8 mm, and the wall thickness of the negative pressure pipe 224 is 0.2 mm.

[0085] The outer diameter of the cold air duct 223 (i.e., the sheath of the composite cable 2) is 3.96+2×(0.8+0.2)=5.96 mm, wherein the cold air duct gap is 0.8 mm and the wall thickness of the cold air duct 223 is 0.2 mm.

[0086] The outer diameter of the industrial standard flexible microwaves currently widely used in microwave ablation equipment is generally greater than 5mm. Therefore, the solution implemented in this invention does not increase the size of the connecting cable between the host and the ablation needle. Instead, it achieves the connection that currently requires three sets of cables with a single composite cable, which has great clinical application value.

Claims

1. A combined low-impedance microwave ablation transmission component, characterized by The invention comprises a host output interface (1-1), a composite cable connector (2-1) and a composite cable. The host output interface is fixed on a microwave power generator. The host output interface comprises a microwave coaxial cable connection jack (1101), a signal cable connection jack (1102), a cold air output pipe jack (1103), a negative pressure pipe jack (1104) and a plastic insulation base for fixing the microwave coaxial cable connection jack (1101), the signal cable connection jack (1102), the cold air output pipe jack (1103), and the negative pressure pipe jack (1104). The composite cable connector is fixed at both ends of the composite cable. The composite cable connector comprises a microwave coaxial cable connection plug (2101), a signal cable connection pin (2102), a cold air pipe plug (2103), a negative pressure pipe plug (2104) and a plastic insulation base for fixing the microwave coaxial cable connection plug (2101), the signal cable connection pin (2102), the cold air pipe plug (2103), the negative pressure pipe plug (2104) The composite cable connector at one end is connected to the output interface of the host, and the composite cable connector at the other end is connected to the input interface of the microwave ablation needle; the composite cable comprises, from the inside to the outside, a microwave coaxial cable (221), a signal cable (222), a cold air duct (223), and a negative pressure duct (224); wherein, the microwave coaxial cable (221) comprises, from the inside to the outside, a microwave coaxial cable outer conductor (2211), a microwave coaxial cable insulator (2212), and a microwave coaxial cable inner conductor (2213); the signal cable (222) and the cold air duct (223) comprise a host-end cold air duct connecting nozzle (2231) and an ablation needle-end cold air duct connecting nozzle (2232); the negative pressure duct (224) comprises a host-end negative pressure duct connecting nozzle (2241) and an ablation needle-end negative pressure duct connecting nozzle (2242); and the composite cable connection comprises a microwave transmission channel, a signal transmission line, and a cooling medium transmission duct; The cooling medium transmission pipe forms a gap of 0.5 to 1 mm between its inner wall and the outer wall of the negative pressure pipe (224) to serve as a circulation channel for cold air; The signal cable (222) is made of a double-sided circuit board with a polyimide substrate, with an overall thickness of 0.2 to 0.5 mm, one side being full copper, and the other side being corroded into evenly distributed mutually insulated conductors; the full copper surface is attached to the outer conductor (2211) of the microwave coaxial cable and rolled into a cylindrical surface, and the overlap is glued together with the outer conductor (2211) of the microwave coaxial cable with an adhesive to form a whole; the peripheral conductors of the signal cable (222) are respectively electrically connected to the corresponding terminals of the signal cable connection pins (2102) in the composite cable connector; Impedance matching between a low-impedance microwave ablation needle and a microwave power generator is achieved by controlling the length of the composite cable and the ratio of the radial dimensions of the inner and outer conductors.

2. A combined low-impedance microwave ablation transmission component according to claim 1, characterized in that The cooling medium transmission pipeline includes a cold air pipeline, a negative pressure pipeline, a transfer hose between the pipeline and the composite cable connector, and an air nozzle.

3. A combined low-impedance microwave ablation transmission component according to claim 1, characterized in that The cooling medium transmission pipeline adopts a flexible plastic tube, which also serves as the outer sheath of the composite cable; the two ends of the cold air pipeline (223) are sealed with adhesive, and are respectively provided with a host end cold air pipeline connecting nozzle (2231) and an ablation needle end cold air pipeline connecting nozzle (2232); the host end cold air pipeline connecting nozzle (2231) is connected to the cold air pipeline plug (2103) of the host end composite cable connector through a hose, and the ablation needle end cold air pipeline connecting nozzle (2232) is connected to the cold air pipeline plug of the ablation needle end composite cable connector through a hose.

4. A combined low-impedance microwave ablation transmission component according to claim 3, characterized in that The negative pressure pipe adopts a flexible plastic pipe, and a gap of 0.5~1mm is formed between its inner wall and the outer surface of the signal cable (222), which serves as an air extraction channel of the negative pressure device. The negative pressure pipe connecting nozzle (2241) at the host end is connected to the negative pressure pipe plug (2104) of the composite cable connector at the host end through a hose, and the negative pressure pipe connecting nozzle (2242) at the ablation needle end is connected to the negative pressure pipe plug of the composite cable connector at the ablation needle end through a hose.

5. A combined low-impedance microwave ablation transmission component according to any one of claims 3 or 4, characterized in that The flexible plastic tube is PFA, FEP or PVC.

6. The combined low-impedance microwave ablation transmission component according to claim 1, characterized in that The outer conductor (2211) of the microwave coaxial cable is made of copper foil tape wrapped or copper wire braided and tinned, the insulator (2212) of the microwave coaxial cable is made of low-density polytetrafluoroethylene material, and the inner conductor (2213) of the microwave coaxial cable is made of silver-plated copper wire or silver-plated copper-clad steel wire.

7. The combined low-impedance microwave ablation transmission component according to claim 1, characterized in that: The specific method for achieving impedance matching between a low-impedance microwave ablation needle and a microwave power generator by controlling the length of the composite cable and the ratio of the radial dimensions of the inner and outer conductors includes the following steps: 1) Determine the characteristic impedance of microwave coaxial cable: , the output impedance of the host is Z0, the input impedance of the microwave ablation needle is the set value Z1, and the characteristic impedance of the microwave coaxial cable 221 is Z; 2) Determine the length of microwave coaxial cable: According to the coaxial cable λ / 4 impedance transformation principle, as long as the total length of the cable is an integer multiple of λ / 4, the cable as a whole acts as an impedance converter, thus we can get , the transmission speed of electromagnetic waves in a vacuum is c, and the dielectric constant of the microwave coaxial cable insulator is ε r , microwave operating frequency f, microwave wavelength λ in microwave coaxial cable, microwave coaxial cable length L; where k is a positive integer, and its value depends on the required cable length L; 3) Determine the radial dimensions of the microwave coaxial cable insulator: , the inner diameter is d and the outer diameter is D.

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