WO2023115669A1

WO2023115669A1 - Microwave ablation needle adopting hollow inner conductor coaxial cable

Info

Publication number: WO2023115669A1
Application number: PCT/CN2022/071854
Authority: WO
Inventors: 刘文婕; 刘芳; 刘中一
Original assignee: 南京臻泰微波科技有限公司
Priority date: 2021-12-23
Filing date: 2022-01-13
Publication date: 2023-06-29
Also published as: CN114039209B; CN114039209A

Abstract

The present invention relates to a microwave ablation needle adopting a hollow inner conductor coaxial cable. The microwave ablation needle comprises a needle rod, a coaxial cable located in the needle rod, and a needle tip located at the front part of the needle rod. An inner conductor of the coaxial cable is a hollow tube. A first refrigerant channel is formed in the internal space of the hollow tube. A second refrigerant channel is formed in a gap between the needle rod and an outer conductor. According to the present invention, one refrigerant channel is realized by utilizing the hollow structure of the inner conductor of the coaxial cable, so that the space of one refrigerant is reduced, and the size of the cable conductor can be increased while the outer diameter of the needle rod is reduced. In this way, the ablation needle realizes high-power transmission without exceeding the rated power of the coaxial cable, the operation efficiency is improved, and the temperature rise and structure failure risks of the product are reduced.

Description

A microwave ablation needle adopting hollow inner conductor coaxial cable

technical field

The invention relates to a microwave ablation needle adopting a hollow inner conductor coaxial cable, belonging to the technical field of microwave ablation medical equipment.

Background technique

Microwave ablation has become one of the important methods for the treatment of solid tumor tissues. Microwave ablation uses a microwave ablation needle to release microwave energy to the tumor tissue. The polar molecules (mostly water) in the tumor tissue rotate at a high speed under the action of the microwave field to rapidly generate heat and reach a higher temperature, causing tissue dehydration. , coagulation, and protein denaturation, so that the tumor tissue is inactivated and loses its ability to proliferate, so as to achieve the purpose of treatment.

As shown in FIG. 1 , microwave energy transmission path: microwave power generator (host) 1 → microwave transmission cable 2 → microwave ablation needle 3 → tumor tissue 4 . 1-1 in the figure is the microwave output interface of the host, and 3-1 is the microwave input interface of the ablation needle handle. The current mainstream microwave ablation equipment operates at a frequency of 2.45 GHz.

The use of microwave energy to perform minimally invasive ablation of tumor soft tissue requires two points of clinical concern: first, the outer diameter of the ablation needle must be as small as possible, and second, the transmitted microwave power must be sufficiently large. The outer diameter of commonly used microwave ablation needles is basically not allowed to be larger than 2 mm. At present, there are no suitable products for microwave ablation needles less than 1.2mm, mainly due to the limitation of the coaxial cable that can be used for ablation needles.

Whether it is a rigid microwave ablation needle or a flexible microwave ablation needle, it is an essential part to transmit microwave energy to the target tissue. The needle bar structure of the ablation needle includes at least: an external stainless steel needle tube, an internal refrigerant inlet and outlet channel, and a coaxial cable. Additional requirements may also require the installation of a temperature sensor. The structure of the currently listed products is shown in Figure 2 and Figure 3. Fig. 2 is a cross-sectional view of the existing microwave ablation needle with a side-by-side layout. The built-in coaxial cable 5-5 of the ablation needle and the refrigerant input pipe 5-3 are arranged inside the stainless steel pipe 5-1 of the ablation needle, and the gap between them forms a refrigerant return channel 5-2. Since the refrigerant pipeline occupies the space of the stainless steel needle tube, the coaxial cable can only be selected with a smaller outer diameter. Figure 3 is a cross-sectional view of a microwave ablation needle with a coaxial layout inside. The refrigerant channel input tube 5-3 is set inside the stainless steel tube 5-1 of the ablation needle, and the coaxial cable 5-5 is set in the refrigerant channel input tube 5-1. 3 inside. Thus, the gap between the refrigerant channel input tube 5-3 and the coaxial cable 5-5 forms the cooling liquid input channel 5-4, while the gap between the refrigerant channel input tube 5-3 and the stainless steel tube 5-1 of the ablation needle forms Refrigerant return channel 5-2. Because the microwave coaxial cable has a solid core structure, an isolation tube (that is, the refrigerant channel input pipe 5-3) must be nested on the outer surface of the coaxial cable and the inner surface of the stainless steel tube to form a refrigerant inlet and outlet channel, and the coaxial cable can only A smaller outer diameter can be selected.

At present, the microwave transmission materials in all microwave ablation needles in the world use industrial standard microwave coaxial cables (semi-rigid, flexible), which are characterized by solid structures. Due to the limitation of the size of the ablation needle, it is necessary to choose a coaxial cable with a small outer diameter on the microwave ablation needle. The diameter of the inner and outer conductors of this cable is small, and the effective cross-sectional area is very limited. The rated transmission power of the cable cannot reach the ablation surgery To meet the requirements, the microwave power has to be overloaded, and the temperature of the needle bar is lowered by forced cooling of the refrigerant. Once the cooling fails, the temperature of the needle rod rises sharply in an instant, which will cause medical accidents such as burning the ablation needle, scalding the non-surgical site, and falling off the needle tip.

According to the currently published data, the commonly used microwave power for tumor ablation is 60-80W, and some even exceed 100W. The maximum outer diameter of the available coaxial cable cannot exceed 1.2mm (more than that will cause other components to fail to assemble). The nominal rated power of this coaxial cable is 56.6W at 1GHz, and it will be much smaller than this value at 2.45GHz. . For thinner microwave ablation needles (for example, the outer diameter of the 16G microwave ablation needle is 1.6mm, the outer diameter of the 17G microwave ablation needle is 1.4mm, and the outer diameter of the 18G microwave ablation needle is 1.2mm), the optional coaxial cable is more For example, the nominal rated power of the widely used 020-type coaxial cable with an outer diameter of 0.584mm will hardly exceed 12W. Such microwave ablation needles will inevitably be used with excess power. Most of the known failure phenomena of microwave ablation needles are similar to this. Related, there are security risks.

The optional coaxial cables on the market are all designed for industrial applications, and the structure, material and impedance parameters comply with international and national standards; their structures are all solid structures, the inner conductor is a single metal wire, the outer conductor and the inner conductor The conductor diameter ratio is greater than 3. Especially in microwave ablation application scenarios with strict restrictions on the outer diameter of the ablation needle, the coaxial cable specifications that can be selected by the industry standard coaxial cable have reached the limit, and the size of the outer diameter of the needle shaft cannot meet the requirements of microwave transmission power; otherwise If the microwave transmission power is satisfied, the outer diameter of the needle bar cannot be satisfied. Unfortunately, there is currently no coaxial cable suitable for microwave ablation in size and transmission power in the world, which needs to be specially designed and manufactured.

Contents of the invention

The object of the present invention is to solve the deficiencies in the above-mentioned prior art, and propose a hollow inner conductor coaxial cable that can not only increase the microwave transmission power but also meet the requirements of the outer diameter of the ablation needle. The hollow inner conductor coaxial cable utilizes coaxial The hollow structure of the inner conductor of the cable realizes one of the refrigerant passages, saving the space of one refrigerant, and can increase the size of the cable conductor while reducing the outer diameter of the needle bar. The ablation needle achieves high-power transmission without exceeding the rated power of the coaxial cable, improves surgical efficiency, and reduces product temperature rise and structural failure risks. And the present invention proposes a microwave ablation needle based on the hollow inner conductor coaxial cable.

In order to achieve the purpose of the present invention, the coaxial cable used for microwave ablation needles provided by the present invention includes: an inner conductor, an insulating layer and an outer conductor arranged coaxially from the inside to the outside, and is characterized in that: the inner conductor is provided with a first a refrigerant channel.

Preferably, the inner conductor is a hollow tube, and the space inside the hollow tube forms the refrigerant channel. This preferred solution is the easiest to think of and the easiest to implement. Seen from the section, the inner conductor, insulating layer and outer conductor are concentric circles.

In the present invention, the insulator of the coaxial cable covers the inner conductor, and the outer conductor covers the insulator, thereby forming a coaxial structure. In the present invention, the refrigerant passage is arranged inside the inner conductor, and the inner conductor is a hollow tube structure, that is, a coaxial cable design using a hollow inner conductor is proposed. The invention uses the hollow tube of the inner conductor to realize one of the refrigerant passages, saves the water pipe used in the traditional water-cooled microwave antenna, and can adjust the size of the coaxial cable and the microwave transmission power by reducing the size ratio of the outer and inner conductors of the coaxial cable. balance. While maintaining the same outer diameter as the existing coaxial cable, the size of the inner conductor can be increased, which can not only increase the microwave transmission power, but also provide a refrigerant channel. On the contrary, under the condition of maintaining the same inner conductor diameter as the existing coaxial cable, the outer diameter of the coaxial cable can be greatly reduced, and a microwave ablation needle with a smaller outer diameter can be manufactured. The invention solves the contradiction between the structural size of the microwave ablation needle and the transmission power, realizes high-power transmission without exceeding the rated power of the coaxial cable, improves operation efficiency, and reduces product temperature rise and structural failure risks.

In addition, the present invention also claims a microwave ablation needle, which has a coaxial cable, and the coaxial cable includes an inner conductor, an insulating layer and an outer conductor arranged coaxially from the inside to the outside, and is characterized in that: the inner conductor is arranged There is a first refrigerant channel.

Further, the microwave ablation needle further includes a needle bar and a needle head located at the front of the needle bar, the coaxial cable is located in the needle bar, and the gap between the needle bar and the outer conductor forms a refrigerant channel B.

Preferably, the refrigerant channel A is used as an inlet channel for the refrigerant, and the refrigerant channel B is used as a return channel for the refrigerant. Of course, it is also feasible to use the refrigerant channel B as the refrigerant inlet channel and the refrigerant channel A as the refrigerant return channel.

Further, the front end of the inner conductor protrudes from the outer conductor and is fixed to the needle, and the front part of the inner conductor is provided with a communication structure of a refrigerant channel, and the refrigerant channel A communicates with the refrigerant channel B at the communication structure. The area where the inner conductor protrudes from the outer conductor is the radiation window of the antenna, and microwave energy is radiated outward from this area. The cooling water is guided to the front end of the antenna to effectively cool down the high temperature area of the antenna.

The ablation antenna of the present invention has the following advantages:

1. The structure of the ablation needle shaft is simplified. The present invention utilizes the gap between the needle bar of the ablation needle and the outer surface of the coaxial cable as one refrigerant channel, and utilizes the inner conductor hollow structure of the coaxial cable as another refrigerant channel, without any additional refrigerant pipeline. However, in the prior art, special refrigerant pipes must be used to realize refrigerant circulation (the solution mentioned in the background technology), and the extra refrigerant pipes take up space, which brings difficulties to reduce the outer diameter of the needle bar or increase the size of the coaxial cable. insurmountable difficulty. Experiments show that the present invention can reduce the diameter by at least 0.3 mm, which reduces the risk of failure caused by this part while reducing the material.

2. The range of action of the refrigerant is improved, the temperature of the needle bar is reduced, and the load of the refrigerant is reduced. During the operation, the main heating part of the coaxial cable is the inner conductor, and the main heating area of the ablation needle is the needle part. The refrigerant flowing in the hollow tube of the inner conductor of the present invention can completely reach the needle point, and then flow through the outside of the outer conductor to directly cool the inner conductor, the outer conductor, the needle tip, the needle head and the needle shaft. However, the cooling water in the existing microwave ablation needle cannot reach the needle head, nor can it directly cool down the inner conductor.

3. The space utilization rate of the needle bar is improved. Compared with the prior art, one channel of refrigerant is reduced on the outside of the built-in coaxial cable of the ablation needle, and the saved space can be used to increase the size of the coaxial cable or reduce the outer diameter of the needle rod. The coaxial cable used in the prior art is a solid structure, and the range of options can only be within several specifications stipulated by industrial standards, such as type 020 (outer diameter 0.5840mm), type 031 (outer diameter 0.7870mm), Type 047 (outer diameter 1.1940mm). There is no space inside the coaxial cable to use.

4. Increase the rated transmission power of the coaxial cable. Coaxial cable conductors have increased in size to more safely transmit greater microwave power. According to theoretical analysis and actual test, compared with the coaxial cable corresponding to the industrial standard, the rated transmission power of the microwave ablation needle of the present invention can be increased by 3 times, which meets the requirement of clinical microwave power. In the existing technology, the 047-type industrial standard coaxial cable with an inner conductor of 0.2870mm and an outer conductor of 1.194mm has reached the limit in the available size of microwave ablation needles. The rated transmission power of this cable is 56.6W/1GHz and 24.7W/5GHz .

5. Reduce input power and improve operation efficiency. In the existing technology, due to the superpower loading, most of the energy is lost by the transmission channel and heats up, aggravating and deteriorating the working condition of the coaxial cable, and the energy that can be transmitted to the soft tissue is limited, forming a vicious circle. The invention increases the size of the inner conductor of the coaxial cable, improves the rated transmission power of the coaxial cable, loads the microwave power under the condition of the rated transmission power, the line loss is very small, and most of the power input by the host is transmitted to the soft tissue, which can Rapid ablation can be achieved with a small input power, forming a virtuous circle.

6. The temperature rise of the coaxial cable is reduced. In the prior art, in order to meet the requirements of the outer diameter of the needle bar, only small-sized coaxial cables can be used. The rated power of the coaxial cable itself is insufficient. If the input power is increased, the loss of the coaxial cable will be aggravated and serious heating will be caused. On the one hand, the invention increases the rated transmission power of the coaxial cable, and the microwave power loaded under the condition of the rated transmission power can meet the needs of the ablation operation and reduce the transmission loss; on the other hand, it can fully cool the inner conductor of the coaxial cable , thereby reducing the temperature rise of the ablation needle.

7. The connection strength between the inner conductor and the needle tip is enhanced. When the ablation needle is in use, the needle tip may be subjected to force due to changing the puncture direction. The inner conductors of several industrial standard coaxial cables available in existing technologies are 0.127mm, 0.2032mm, and 0.2870mm, and the inner conductors need to be connected with the metal needle tip. , the connection strength is very limited, and it is easy to break when subjected to external force. At the same time, when the cooling fails, it is easy to be burned because the inner conductor is too thin. The inner conductor of the present invention is a hollow tube inner conductor, and its size can reach more than 0.4mm, which greatly enhances the mechanical connection strength with the needle tip. Combined with measures such as low heat generation and complete cooling range of the cable under rated power, it fundamentally solves the hidden danger of connection failure when the needle tip is high temperature, and prevents needle breakage accidents.

The technical core of the invention is a coaxial cable with a hollow inner conductor structure, which can guide and promote the manufacture of a brand new coaxial cable product suitable for microwave ablation needles. Using the coaxial cable for microwave transmission and refrigerant exchange not only simplifies the structure of the microwave ablation needle, but also reduces the difficulty of product manufacturing. It can also further reduce the outer diameter of the ablation needle, reduce the temperature of the needle body, increase the power of microwave ablation, improve the mechanical strength of the needle body, and improve the efficiency of clinical operations. Whether it is the transmission principle, core structure or key materials, it is a brand-new design, which is conducive to the further development of microwave ablation, a minimally invasive technology.

Description of drawings

The present invention will be further described below in conjunction with the accompanying drawings.

Fig. 1 is a schematic diagram of microwave energy transmission path.

Fig. 2 is the cross-sectional structure of the existing microwave ablation needles arranged in parallel.

Fig. 3 is a cross-sectional structure of a conventional microwave ablation needle with a coaxial layout inside.

Fig. 4 is a cross-sectional view of the coaxial cable of the present invention.

Figure 5 is a cross-sectional view of the coaxial cable of the present invention.

Fig. 6 is a cross-sectional view of the microwave ablation needle of the present invention.

Fig. 7 is a cross-sectional view of the microwave ablation needle of the present invention.

Fig. 8 is a schematic diagram of refrigerant circulation (refrigerant flows in from the center of the inner conductor and returns from the periphery of the outer conductor).

Fig. 9 is a schematic diagram of refrigerant circulation (refrigerant flows in from the periphery of the outer conductor and flows out from the center of the inner conductor).

Detailed ways

The present invention will be further described below in conjunction with the accompanying drawings and specific embodiments.

coaxial cable embodiment

As shown in Fig. 4 and Fig. 5, the coaxial cable used for the microwave ablation needle in this embodiment includes: an inner conductor 3401 coaxially arranged from inside to outside, an insulating layer 3402 and an outer conductor 3403, and the improvement lies in the inner conductor 3401 is provided with a first refrigerant channel 3-6. In this example, the inner conductor 3401 is a hollow tube (hollow tube), and the inner space of the hollow tube forms the first refrigerant passage 3-6. The insulating layer 3402 covers the inner conductor 3401, and the outer conductor 3403 covers the insulating layer 3402, thereby forming a coaxial structure. The inner conductor 3401 and the outer conductor 3403 of the coaxial cable can be made of copper, silver or a composite material whose surface is copper or silver. The wall thickness of the inner conductor 3401 and the outer conductor 3403 ranges from 0.04 mm to 0.1 mm, and the diameter of the through hole of the inner conductor 3401 ranges from 0.2 mm to 0.8 mm. The inner diameter of the outer conductor 3403 is 1.6-2.0 times the outer diameter of the inner conductor 3401 . The characteristic impedance range of the coaxial cable is 15Ω-40Ω. Preferably, the characteristic impedance range of the coaxial cable is 20Ω-30Ω.

The insulating layer 3402 between the inner and outer conductors can be made of fluoroplastics, and is manufactured using the semi-steel coaxial cable production process, so that the inner conductor 3401, the insulator 3402, and the outer conductor 3403 are combined to form a coaxial structure, forming a non-standard microwave transmission line (same as shaft cable).

According to the specific size of ablation needles with different outer diameter specifications, within the above parameters and ratio range, the most suitable inner conductor and outer conductor size can be matched, so as to meet the requirements of ablation needle outer diameter and transmission power.

According to the selected outer conductor size D, inner conductor size d and dielectric constant ε of the insulating medium, the characteristic impedance Z and rated transmission power P _br of the coaxial cable can be obtained by the following calculation formula.

The above parameters can ensure that the diameter of the outer conductor is less than 1.6mm, and the outer diameter of the ablation needle can be controlled within 2.0mm under the premise of satisfying the assembly and refrigerant passage. Even if the coaxial cable is designed with the smallest inner conductor of 0.4mm, its transmission power can still exceed the rated power of the 056 type industrial standard semi-steel coaxial cable with a cable inner conductor of 0.2870mm and an outer diameter of 1.422mm (34.0W@5GHz) , at a microwave frequency of 2450GHz, the measured stable transmission power exceeds 100W.

As shown in FIG. 4 , the front end of the inner conductor 3401 protrudes from the outer conductor 3403 , and the front end of the inner conductor 3401 is provided with a communication structure 3601 for the refrigerant channel. An alternative solution is to replace the part of the front end of 3401 protruding from the outer conductor 3403 with a metal tube, one end of the metal tube is inserted into the inner conductor 3401 for fixing, and the other end is provided with a communication structure 3601 . When the refrigerant is a conductive liquid (such as physiological saline), it is necessary to insulate between the inner conductor 3401 and the outer conductor 3403 . Therefore, preferably, the surface of the outer conductor 3403 is coated with an insulating coating (not labeled in the figure), so as to ensure the insulation between the inner and outer conductors. Alternatively, an insulating coating is applied to the inner and outer surfaces of the inner conductor 3401 .

Examples of microwave ablation needles

As shown in Figure 6 and Figure 7, the microwave ablation needle of this embodiment includes a needle bar 3-3 (coated with a protective layer on the outside), a needle head 3-8 located at the front of the needle bar 3-3 and a needle placed on the needle bar 3-3. The inner coaxial cable 3-4 and the structure of the coaxial cable 3-4 refer to the coaxial cable embodiment above, which will not be repeated here. The front end of the inner conductor 3401 protrudes from the outer conductor 3403 and is fixed with the needle 3-8.

The needle bar 3-3 is made of a stainless steel tube suitable for manufacturing medical devices, the outer diameter of which meets clinical requirements, preferably within 2.0 mm, and the wall thickness is preferably between 0.05 mm and 0.15 mm. The stainless steel tube plays the role of installing the built-in coaxial cable of the ablation needle, fixing the needle head of the ablation needle, maintaining a certain rigidity to meet clinical puncture, and providing a refrigerant channel. The outer surface of the stainless steel tube is coated with Teflon coating or similar anti-stick coating to prevent tissue adhesion during surgery. The front end of the stainless steel tube (needle bar 3-3) is connected with the insulating connecting sleeve 3-7, and the stainless steel tube at the handle end is connected with the coaxial transfer converter 3-2. The length depends on clinical requirements, usually within 10cm to 30cm.

The needle head 3-8 can be made of metal material, and is integrated with the inner conductor 3401 of the built-in coaxial cable 3-4 of the ablation needle through laser welding or brazing. Connect with the stainless steel pipe through the insulating sleeve 3-7. The needle-point insulating sleeves 3-7 use high-temperature-resistant insulating materials such as PTFE, polyimide, or ceramics to support the hollow tubular structure. The needle head 3-8 can also be made of ceramic material, and the needle point and the needle point needle bar insulating connecting sleeve are used as an integral part, embedded in a stainless steel tube (needle bar 3-3) and connected by high-temperature glue.

In this embodiment, the insulating sleeve 3-7 is embedded in the stainless steel pipe to a depth of 3-10 mm.

The realization method of the refrigerant channel in the ablation needle: keep a gap of 0.1 mm to 0.2 mm between the inner wall of the stainless steel tube (needle bar 3-3) and the outer surface of the built-in coaxial cable 3-4 of the ablation needle, and the inner wall of the insulating sleeve 3-7 and the outer surface of the inner wall of the ablation needle Keep a gap of 0.1 mm to 0.2 mm between the outer surfaces of the inner conductor 3401 of the coaxial cable built in the ablation needle, and keep a distance of about 1 mm between the insulating sleeve 3-7 and the end position of the insulating layer 3402 of the coaxial cable built in the ablation needle, thus forming a refrigerant channel ( The second refrigerant channel 3-5), the internal space of the inner conductor 3401 of the coaxial cable 3-4 inside the ablation needle forms another refrigerant channel (the first refrigerant channel 3-6). Holes are opened on the inner conductor 3401 of the built-in coaxial cable of the ablation needle near the needle tip to form a refrigerant input or return channel communication structure 3601 . In this way, the communication between the two refrigerant channels is realized. Preferably, the first refrigerant channel 3-6 is used as a refrigerant injection channel, and the second refrigerant channel 3-5 is used as a refrigerant return channel. FIG. 8 is a schematic diagram of the refrigerant flow direction (indicated by arrows) of this design. As shown in Figure 9, it is a feasible alternative, that is, it is a feasible alternative to use the second refrigerant channel 3-5 as a refrigerant injection channel, and the first refrigerant channel 3-6 as a refrigerant return channel, as shown in Figure 9 The direction of the arrow is the direction of refrigerant flow. In the microwave ablation needle of the present invention, the refrigerant can reach the front end of the antenna, which can more effectively cool down the temperature of the ablation needle, especially the heating area.

If the needle head 3-8 is made of metal material, it is suggested that the needle head 3-8 and the needle bar 3-3 be fixedly connected through an insulating sleeve 3-7. If the needle head 3-8 is made of ceramic material, the needle head 3-8 can be integrally formed with the insulating sleeve 3-7, and then directly connected with the needle bar 3-3. In this example, the needle head 3-8 is fixedly connected to the needle bar 3-3 through an insulating sleeve 3-7. In addition, there is an alternative solution: the needle head 3-8 is directly fixedly connected with the needle bar 3-3.

Since the central hole of the inner conductor of the coaxial cable inside the ablation needle is a refrigerant channel, the outer diameter of the needle bar of the ablation needle is very small, and the injection and return of the refrigerant cannot be realized directly from the ablation needle bar. Shaft cable converter 3-2 (see Figure 6) to complete. The rear end of the coaxial cable 3-4 is connected to the microwave input connector 3-1 through the coaxial cable converter 3-2. A coaxial transition converter is equivalent to a section of coaxial cable with radially enlarged dimensions. The coaxial adapter is fixed in the handle of the ablation needle, and the inner space of the handle is large, which can be realized in engineering, and is no longer subject to the strict limitation of the structure size of the needle bar. This embodiment lists a feasible coaxial cable converter scheme, and there are other feasible schemes besides this, and the applicant will file a patent application separately.

The coaxial cable in the ablation needle needs to be connected to the output coaxial cable of the host, and the characteristic impedance of the output coaxial cable of the host is 50Ω. According to the implementation of the built-in coaxial cable of the ablation needle, it is obvious that the characteristic impedance of this coaxial cable is not 50Ω, and impedance transformation is required when connecting. However, the characteristic impedance of the industry standard coaxial cable used in the prior art is 50Ω, so this impedance transformation is not required.

The coaxial cable converter 3-2 includes an insulating tube 3202 fixed at the tail end of the insulating layer 3402 of the coaxial cable 3-4, an inner conductor 3201 and an outer conductor 3203 respectively located on the inner and outer surfaces of the insulating layer 3202, and the coaxial cable converter 3-2 The outer conductor 3203 of the coaxial cable 3-4 is electrically connected with the outer conductor 3403 of the coaxial cable 3-4 and the outer conductor of the microwave input connector 3-1, and the inner conductor 3201 of the coaxial cable converter 3-2 is connected with the coaxial cable 3-4 respectively. The inner conductor 3401 of the coaxial cable converter 3-2 is electrically connected to the inner conductor of the input socket 3204.

Inner conductor 3201 of the coaxial switching converter: a hollow tube made of copper, silver or a composite material whose surface is copper or silver.

The insulating layer 3202 of the coaxial switching converter 3-2: filled with fluoroplastics, such as PTFE, PFA, and FEP materials.

The outer conductor 3201 of the coaxial switching converter 3-2: a hollow tube made of copper, silver or a composite material whose surface is copper or silver.

The inner conductor input socket 3204 of the coaxial cable converter 3-2: made of copper alloy or silver alloy material with strong rigidity.

The inner conductor input socket 3204 of the coaxial cable converter 3-2 is conductively connected with the inner conductor of the microwave input connector 3-1. A refrigerant injection chamber a connected to the first refrigerant passage 3-6 is formed in the inner conductor 3201 of the coaxial cable converter 3-2, a refrigerant return chamber b is provided at the tail of the second refrigerant passage 3-5, and a refrigerant injection pipe connector 3211 1. The refrigerant return pipe connector 3212 is respectively connected to the refrigerant injection chamber a and the refrigerant return chamber b.

The dimensions of the components of the microwave ablation needle in this embodiment are as follows:

Taking the microwave ablation needle with a finished outer diameter of 2.0mm as an example, the main dimensions of the components of the microwave ablation needle in this implementation example are as follows:

Needle bar 3-3: stainless steel capillary, outer diameter 2.0mm, wall thickness 0.1mm, inner diameter 1.8mm, length 250mm.

The built-in coaxial cable 3-4 of the ablation needle has an outer diameter of 1.5mm, wherein, the outer conductor 3403 is a silver-plated capillary copper tube with an outer diameter of 1.50mm, a wall thickness of 0.10mm, and a central through hole diameter D=1.30mm. Inner conductor 3401: silver-plated capillary copper tube, outer diameter d=0.72mm, wall thickness 0.10mm, central through hole diameter 0.52mm. Insulating layer 3402: polytetrafluoroethylene, with an outer diameter of 1.30 mm and an inner diameter of 0.72 mm.

Needle 3-8: silver-plated hard copper, outer diameter 2.0mm, length 4mm.

Insulating sleeve 3-7: ceramic, outer diameter 1.8mm, inner diameter 1.00mm, length 6mm.

Aperture diameter of the first refrigerant channel 3-6: 0.52mm.

The gap between the second refrigerant channel 3-5: 0.15mm.

The measured data of the microwave ablation needle assembled according to the above dimensions are as follows:

The characteristic impedance of the ablation needle is 25.7Ω～26.0Ω;

The standing wave ratio of the ablation needle in the microwave phantom is 1.40-1.50;

With physiological saline as the refrigerant, the forward flow rate is 62-65mL/min, and the reverse flow rate is 55-57mL/min;

When the microwave power is 100W, the temperature of the needle bar is 32-35°C when the test is carried out at room temperature;

Microwave power 100W was applied to simulate the ablation test of the isolated pig liver, and the ablation range was >5cm in 5 minutes.

Conclusion: The ablation range, ablation efficiency, and cooling effect have obvious advantages.

In addition to the above-mentioned embodiments, the present invention can also have other implementations. All technical solutions formed by equivalent replacement or equivalent transformation fall within the scope of protection required by the present invention.

Claims

A coaxial cable for a microwave ablation needle, comprising: an inner conductor (3401), an insulating layer (3402) and an outer conductor (3403) coaxially arranged from inside to outside, characterized in that: the inner conductor (3401) A first refrigerant channel (3-6) is arranged inside.
The coaxial cable for microwave ablation needle according to claim 1, characterized in that: the inner conductor (3401) is a hollow tube, and the space inside the hollow tube forms the first refrigerant channel (3- 6).
The coaxial cable for microwave ablation needle according to claim 2, characterized in that: the front end of the inner conductor (3401) protrudes from the outer conductor (3403).
The coaxial cable for microwave ablation needle according to claim 3, characterized in that: the front end of the inner conductor (3401) is provided with a communication structure (3601) of a refrigerant channel.
The coaxial cable for microwave ablation needle according to claim 3, characterized in that: the surface of the outer conductor (3403) is coated with an insulating coating.
The coaxial cable for microwave ablation needle according to claim 3, characterized in that: the wall thickness of the inner conductor (3401) and the outer conductor (3403) ranges from 0.04 mm to 0.1 mm, and the thickness of the inner conductor (3401) The diameter range of the through hole is: 0.2mm-0.8mm; the inner diameter of the outer conductor (3403) is 1.6-2.0 times the outer diameter of the inner conductor (3401); the characteristic impedance range of the coaxial cable (3-4) is 15Ω- 40Ω.
The coaxial cable for microwave ablation needle according to claim 6, characterized in that: the characteristic impedance of the coaxial cable (3-4) preferably ranges from 20Ω to 30Ω.
A microwave ablation needle, characterized by comprising the coaxial cable according to any one of claims 1-6.
The microwave ablation needle according to claim 8, characterized in that it further comprises a needle bar (3-3) and a needle head (3-8) located at the front of the needle bar (3-3), the coaxial cable (3 -4) Located in the needle bar (3-3), the front end of the inner conductor (3401) protrudes from the outer conductor (3403) and is fixed with the needle head (3-8).
The microwave ablation needle according to claim 9, characterized in that: the gap between the needle shaft (3-3) and the outer conductor (3403) and the periphery of the part where the inner conductor (3401) protrudes from the outer conductor (3403) The space forms the second refrigerant channel (3-5).
The microwave ablation needle according to claim 10, characterized in that: the front part of the inner conductor (3401) is provided with a communication structure (3601), and the first refrigerant channel (3-6) and the second refrigerant channel ( 3-5) Connect at the connection structure (3601).
The microwave ablation needle according to claim 10, characterized in that: the tail of the needle (3-8) has a blind hole, and the front end of the inner conductor (3401) is welded or glued to the bottom of the blind hole fixed.
The microwave ablation needle according to claim 12, characterized in that: the needle head (3-8) is directly fixedly connected to the needle bar (3-3), or the needle head (3-8) is connected to the needle bar (3-3) They are fixedly connected by insulating sleeves (3-7).
The microwave ablation needle according to claim 10, characterized in that it further comprises a coaxial cable converter (3-2) arranged at the rear of the needle bar (3-3), the coaxial cable (3-4) The rear end is connected to the microwave input connector (3-1) through the coaxial cable converter (3-2).
The microwave ablation needle according to claim 14, characterized in that: the coaxial cable converter (3-2) includes an insulating tube (3202) fixed to the tail end of the insulating layer (3402) of the coaxial cable (3-4) , the inner conductor (3201) and the outer conductor (3203) respectively arranged on the inner and outer surfaces of the insulating layer (3202), the outer conductor (3203) of the coaxial cable converter (3-2) and the outer conductor (3203) of the coaxial cable (3-4) respectively The outer conductor (3403) and the outer conductor of the microwave input connector (3-1) are conductively connected, and the inner conductor (3201) of the coaxial cable converter (3-2) is respectively connected to the inner conductor of the coaxial cable (3-4). (3401), the inner conductor input socket (3204) of the coaxial cable converter (3-2) is conductively connected.
The microwave ablation needle according to claim 15, characterized in that: the inner conductor input socket (3204) of the coaxial cable converter (3-2) is electrically connected to the inner conductor of the microwave input connector (3-1) .
The microwave ablation needle according to claim 15, characterized in that: a refrigerant injection cavity (a) connected to the first refrigerant channel (3-6) is formed in the inner conductor (3201) of the coaxial cable converter (3-2) , the tail of the second refrigerant channel (3-5) is provided with a refrigerant return chamber (b), and the refrigerant injection pipe connector (3211) and the refrigerant return pipe connector (3212) are respectively connected to the refrigerant injection chamber (a) and the refrigerant return chamber (b).