CN216908100U

CN216908100U - Cryoablation probe

Info

Publication number: CN216908100U
Application number: CN202122747699.6U
Authority: CN
Inventors: 胡艳艳; 王晓钫; 许金苗; 徐宏
Original assignee: Hangzhou Kunbo Biotechnology Co Ltd
Current assignee: Hangzhou Kunbo Biotechnology Co Ltd
Priority date: 2021-11-10
Filing date: 2021-11-10
Publication date: 2022-07-08
Anticipated expiration: 2031-11-10

Abstract

The application provides a cryoablation probe, including needle tubing, filler piece and connecting seat. The needle tube is provided with a near end and a far end which are opposite, an expansion cavity is arranged at the far end in the needle tube, an input channel and a backflow channel for flowing of freezing working media are arranged in the needle tube, and the input channel and the backflow channel are communicated through the expansion cavity. The filling piece is arranged in the expansion cavity and is made of porous materials. The connecting seat is fixed at the near end of the needle tube, and a fluid interface which is correspondingly communicated with the input channel and the return channel is arranged on the connecting seat. The cryoablation probe provided by the application is beneficial to fully utilizing the cold quantity of the freezing working medium.

Description

Cryoablation probe

Technical Field

The application relates to the technical field of medical instruments, in particular to a cryoablation probe.

Background

Cryoablation (cryosurgery), also known as cryosurgery or cryotherapy (cryotherapy), is a method of accurately puncturing a lesion under the guidance of modern medical imaging equipment and performing in-situ cryo-extinguishment on target tissue by using ultra-low temperature generated at the distal end of a probe. Compared with radio frequency ablation and microwave ablation, the cryoablation has the advantages of no pain, conformity, accurate and controllable ablation range and the like.

At present, the refrigeration modes of cryoablation include latent heat of vaporization and throttling refrigeration. The latent heat of vaporization is to utilize the vaporization heat absorption of liquid freezing working medium to reduce the temperature in the target area, and the freezing working medium with the latent heat of vaporization comprises liquid nitrogen and liquid CO₂And liquid N₂O, and the like. The throttling refrigeration utilizes Joule-Thomson effect, that is, high pressure gas flows into large space via small hole and expands to absorb heat, and the freezing working medium for throttling refrigeration includes nitrogen, argon, helium and CO₂Gases, and the like. Compared with throttling refrigeration, the efficiency of latent heat of vaporization refrigeration is higher, and a complex precooling system such as self-cascade refrigeration/GM refrigeration and the like is not needed due to the use of the liquid working medium.

In the existing cryoablation probe, the heat exchange efficiency of a remote freezing working medium is low, and the cold energy carried by the freezing working medium is not fully utilized.

SUMMERY OF THE UTILITY MODEL

To prior art's not enough, this application provides a cryoablation probe, helps the cold volume of make full use of freezing working medium.

The present application provides a cryoablation probe comprising:

the needle tube is provided with a near end and a far end which are opposite, an expansion cavity is arranged at the far end in the needle tube, an input channel and a backflow channel for flowing of freezing working media are arranged in the needle tube, and the input channel and the backflow channel are communicated through the expansion cavity;

the filling piece is arranged in the expansion cavity and is made of porous materials;

and the connecting seat is fixed at the near end of the needle tube, and a fluid interface which is correspondingly communicated with the input channel and the return channel is arranged on the connecting seat.

The filling piece is arranged in the expansion cavity, so that the absorption of the heat of the target tissue by the freezing working medium can be accelerated, and the treatment time is shortened.

Several alternatives are provided below, but not as an additional limitation to the above general solution, but merely as a further addition or preference, each alternative being combinable individually for the above general solution or among several alternatives without technical or logical contradictions.

Optionally, the filling member is porous metal or porous ceramic, and the average pore size is 0.05-200 microns.

The porous metal has higher heat conductivity, and is beneficial to the uniform distribution of heat in the expansion cavity. The porous ceramic has good corrosion resistance and stable structure.

Optionally, the needle tube comprises an inner tube and an outer tube which are nested with each other, the conduit of the inner tube serves as the input channel, a gap between the inner tube and the outer tube in the radial direction serves as the return channel, and a gap between the distal end of the inner tube and the distal end of the outer tube in the axial direction serves as the expansion cavity; the far end of the inner pipe is a jet orifice communicated with the expansion cavity, and the far end of the outer pipe is a blind end.

The needle tube formed by combining the tubes allows different sections of the freezing working medium loop to be made of different materials so as to meet the requirements of difference of flexibility, heat conductivity and the like. The pipes can be bonded, sealed and fixed in the axial direction or the radial direction.

Optionally, a butt-joint groove is formed in the proximal end side of the filling member, and the jet orifice of the inner tube is fixedly inserted into the butt-joint groove.

The freezing working medium flowing out of the injection port is ensured to enter the filling part, and the heat exchange efficiency of the freezing working medium and the filling part is enhanced.

Optionally, the distal end of the inner tube is fixed in the outer tube by a support.

The support prevents the inner tube 14 from vibrating and affecting the flow of the refrigerant.

Optionally, the distal end of the outer tube is provided with a reinforced heat exchange layer, and the reinforced heat exchange layer is arranged in at least one of the following manners:

the reinforced heat exchange layer is a microporous structure layer positioned on the outer wall of the outer pipe, and the pore diameter of each micropore is 1-20 microns;

the reinforced heat exchange layer is a first heat conduction layer positioned on the outer wall of the outer pipe;

the reinforced heat exchange layer is a second heat conduction layer positioned on the inner wall of the outer pipe.

The heat exchange layer can strengthen the heat exchange between the expansion cavity and the target tissue.

Optionally, the cross-sectional area of the return channel increases gradually in the direction of fluid movement.

The freezing working medium is gradually expanded during backflow, so that the freezing working medium is convenient to discharge, and the situations that the air return is not smooth and the air return pressure is higher than a desired value are avoided.

Optionally, from the distal end to the proximal end, the backflow channel includes multiple sections with different cross-sectional areas, wherein the first section is located between the support and the outer tube and has a cross-sectional area of S1, the second section is located between the inner tube and the outer tube and has a cross-sectional area of S2, the third section is located between the inner tube and the connecting seat and has a cross-sectional area of S3, the fourth section is located in the connecting seat and is in cross communication with the third section and has a cross-sectional area of S4, S1 < S2 < S3 < S4.

The cross section area of the backflow channel is ensured to be increased, the expansion position of the freezing working medium in the backflow process is enabled to avoid the middle of the needle tube, and the freezing working medium is prevented from expanding and absorbing heat in the puncture channel.

Optionally, the outer tube is provided with a vacuum jacket at the periphery, and one end of the vacuum jacket is adjacent to the distal end of the outer tube in the length direction of the needle tube and exposes at least the part of the expansion cavity;

the other end of the vacuum jacket extends to the connecting seat, and a vacuum interface communicated with the vacuum jacket is arranged on the connecting seat.

The vacuum jacket has good heat insulation effect, is beneficial to ice balls to be concentrated at the far end of the needle tube 1, and prevents normal tissues from being frostbitten.

Optionally, the expansion chamber further comprises a sensing system for measuring the temperature or pressure in the input channel and the return channel for closed-loop control of the temperature in the expansion chamber.

The control system can conveniently control the ice ball to form an ice ball with a proper size, so that the diseased tissue is covered, and the normal tissue is not lost.

Optionally, the sensing system comprises at least one of the following temperature sensors, and at least one of the following pressure sensors:

the first temperature sensor is arranged close to the near end of the input channel and used for measuring the temperature of the freezing working medium in the near end of the input channel;

the second temperature sensor is arranged close to the far end of the input channel and used for measuring the temperature of the freezing working medium in the far end of the input channel;

the third temperature sensor is arranged close to the near end of the backflow channel and used for measuring the temperature of the freezing working medium in the near end of the backflow channel;

the first pressure sensor is arranged close to the far end of the input channel and used for measuring the pressure of the freezing working medium in the far end of the input channel;

and the second pressure sensor is arranged close to the near end of the return channel and used for measuring the pressure of the freezing working medium in the near end of the return channel.

The plurality of sensors are respectively arranged at different positions of the fluid loop, so that the influence of the change of the external environment of the cryoablation probe on the temperature monitoring in the expansion cavity is fully considered, and the temperature of the ice hockey is more stable and adjustable.

The cryoablation probe provided by the application has at least one of the following beneficial effects:

1) the length of time of cryoablation can be effectively reduced, and the operation efficiency is improved.

2) The lowest temperature in the target area after heat balance is reduced, and the cryoablation range is increased.

3) The total flow of the system consumed freezing working medium is reduced, and the excessively frequent canning of the freezing working medium is avoided.

Drawings

FIG. 1 is a perspective view of an embodiment of the present application;

FIG. 2 is an exploded view of the needle portion of FIG. 1;

FIG. 3 is a cross-sectional view of a portion of the coupling socket of FIG. 1;

FIG. 4 is a cross-sectional view of the distal end of the needle cannula of FIG. 1;

FIG. 5 is a cross-sectional view of a first segment of a return channel;

FIG. 6 is a cross-sectional view of a second segment of the return channel;

fig. 7 is a schematic structural diagram of a sensing system according to an embodiment of the present application.

The reference numerals in the figures are illustrated as follows:

1. a needle tube; 11. an expansion chamber; 12. an input channel; 13. a return channel; 131. a first stage; 132. a second stage; 133. a third stage; 134. a fourth stage; 14. an inner tube; 141. an ejection port; 15. an outer tube; 151. a flexible tube; 152. a metal probe; 16. a vacuum chamber; 2. a filling member; 21. a butt joint groove; 3. a connecting seat; 31. a first fluid interface; 32. a second fluid interface; 33. a vacuum interface; 4. a support; 41. positioning holes; 42. pipe sleeve; 5. a vacuum jacket; 6. a sensing system; 61. a first temperature sensor; 62. a second temperature sensor; 63. a third temperature sensor; 64. a first pressure sensor; 65. a second pressure sensor; 66. a third pressure sensor.

Detailed Description

The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application, and it is obvious that the described embodiments are only a part of the embodiments of the present application, and not all of the embodiments. All other embodiments obtained by a person of ordinary skill in the art based on the embodiments in the present application without making any creative effort belong to the protection scope of the present application.

It will be understood that when an element is referred to as being "connected" to another element, it can be directly connected to the other element or intervening elements may also be present. When a component is referred to as being "disposed on" another component, it can be directly on the other component or intervening components may also be present.

Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used in the description of the present application herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the application. As used herein, the term "and/or" includes any and all combinations of one or more of the associated listed items.

Referring to fig. 1 to 7, the cryoablation probe of the present application includes a needle tube 1, a filling member 2, and a connecting seat 3.

The needle tube 1 has a proximal end and a distal end opposite to each other, an expansion chamber 11 is provided at the distal end position in the needle tube 1, an inlet passage 12 and a return passage 13 for a refrigerant (not shown) to flow are provided in the needle tube 1, and the inlet passage 12 and the return passage 13 are connected to each other via the expansion chamber 11. The filling member 2 is installed in the expansion chamber 11 and is made of a porous material. The connecting seat 3 is fixed at the near end of the needle tube 1, and the connecting seat 3 is provided with a fluid interface which is correspondingly communicated with the input channel 12 and the return channel 13.

The lesion target tissue treated by the cryoablation probe is not limited, and can be tumor inside a body, and also can be lesion tissue of nasal cavity, oral cavity and skin. The freezing working medium used by matching the cryoablation probe is not limited, and can be liquid, such as liquid nitrogen, so that a refrigerating system is not needed, and the cryoablation probe can be applied to portable therapeutic apparatuses. The cryoablation probe can also be matched with gaseous refrigerant such as argon, so that the temperature reduction speed is high, the diameter of the needle tube is small, and the puncture treatment is facilitated.

The fluid ports on the connection socket 3 include a first fluid port 31 and a second fluid port 32. The first fluid interface 31 is used for the frozen working medium to enter the input channel 12, and the second fluid interface 32 is used for the frozen working medium to be discharged from the return channel 13. The first fluid interface 31 and the second fluid interface 32 may or may not dock with the pressure device.

When the needle tube is used, the freezing working medium enters the input channel 12 through the first fluid interface 31, and reaches the expansion cavity 11 in the input channel 12 along the direction indicated by a hollow arrow in figure 4, the distance between molecules in the expansion cavity 11 is increased, the heat of the target tissue contacted with the distal end of the needle tube 1 is absorbed, and the target tissue is frozen and necrosed.

By arranging the filling member 2 in the expansion chamber 11, the absorption of the heat of the target tissue by the freezing working medium can be accelerated. In one embodiment, the refrigerant is in a liquid state before entering the expansion chamber 11, and the porous structure of the filling member 2 provides the refrigerant with rich pore surfaces, which can enhance boiling heat transfer, so that the cold carried by the refrigerant can be rapidly transferred to the target tissue.

For the general form of the heat transfer equation:

wherein Q is heat transfer amount, k is heat transfer coefficient in infinitesimal, Δ t is temperature difference of infinitesimal cold and hot surfaces, d_FInfinitesimal heat transfer area. From the expression, the temperature difference delta t is increased by improving the heat transfer coefficient k, increasing the heat transfer area F and improving the boiling point temperature in the expansion cavity, so that the utilization rate of the cold quantity is increased. The liquid freezing working medium sprayed out from the input channel 12 forms vortex in the fluid under the action of the filling part 2, and the heat exchange between liquid phases is enhanced; the heat is absorbed and converted into gas state, and the gas state generates a flowing boiling phenomenon in the expansion cavity 11, so that the heat transfer coefficient is improved, and the effects of enhancing heat transfer and improving heat transfer capacity are achieved.

In another embodiment, the refrigerant is high-pressure gas or gas-liquid mixture before entering the expansion chamber 11, and under the guidance of the pore network in the filling member 2, the expansion position of the high-pressure gas can be relatively uniformly distributed in the expansion chamber 11, or more close to the chamber wall and the target tissue of the expansion chamber 11, and the temperature distribution in the ice ball is relatively uniform, so as to facilitate the control of the range of the effective freezing area. The filler 2 may be of a unitary or dispersed structure without affecting the formation of voids.

In one embodiment, the filling member 2 is made of porous metal, such as copper-zinc alloy, titanium-aluminum alloy, gold-silver alloy, etc., and has high thermal conductivity, which facilitates uniform distribution of heat in the expansion chamber 11. In another embodiment, the filling member 2 is a porous ceramic, such as silicon carbide, alumina, etc., which has better corrosion resistance, more stable structure, and less influence on the medical imaging equipment. In one embodiment, the average pore size of the filler 2 is 0.05-200 μm. When the pore space is small, the capillary action is obvious, and the density of the vaporization core is high. When the pore space is large, the convection heat transfer is facilitated.

Referring to fig. 2 and 4, in an embodiment, the needle cannula 1 includes an inner tube 14 and an outer tube 15 nested with each other, a conduit of the inner tube 14 is used as the input channel 12, a gap between the inner tube 14 and the outer tube 15 in a radial direction is used as the return channel 13, and a gap between a distal end of the inner tube 14 and a distal end of the outer tube 15 in an axial direction is used as the expansion cavity 11; the distal end of the inner tube 14 is a jet port 141 communicating with the expansion chamber 11, and the distal end of the outer tube 15 is a blind end.

The design of the inner tube 14 should meet the working condition of the selected freezing working medium, and for gas throttling refrigeration, the temperature difference after throttling is in a direct proportion relation with the pressure before and after throttling, and the working pressure is usually higher. The liquid phase freezing working medium is not throttling refrigeration, so the working pressure is far lower than that of the gas phase freezing working medium. Therefore, compared with a gas-phase refrigerant, the consumable is higher in safety in use.

The main body of the inner tube 14 and the outer tube 15 can be made of metal, braided or polymer, the braided tube has pebax/Ptfe/PI/FEP/Nylon, etc., which is easy to bend along the curvature of the natural orifice, and the distal end of the outer tube 15 can be made of metal to enhance the heat exchange between the inside of the expansion chamber 11 and the target tissue.

Referring to fig. 2 and 4, in one embodiment, the outer tube 15 includes a flexible tube 151 and a metal probe 152 secured to a distal end of the flexible tube 151, the return channel 13 is located within the flexible tube 151, and the expansion lumen 11 is located within the metal probe 152. The flexible tube 151 and the metal probe 152 may be fixed by adhesion, heat fusion, or the like.

The metal probe 152 is used as a medium for heat exchange between the cryoablation consumables and the tissue, and can be made of a material with a high thermal conductivity, such as silver, copper, stainless steel, etc.

In one embodiment, the distal side of the filling member 2 abuts the inner wall of the expansion chamber 11, facilitating the transfer of heat from the target tissue to the cryogenic working fluid within the filling member 2.

In another embodiment, a gap is provided between the distal side of the filling member 2 and the inner wall of the expansion chamber 11 to facilitate rapid backflow of the refrigerant.

In one embodiment, the proximal end side of the filler member 2 is provided with an abutting groove 21, and the injection port 141 of the inner tube 14 is fixedly inserted into the abutting groove 21.

The filling member 2 covers the distal end of the inner tube 14, so that the freezing working medium flowing out from the injection port 141 is ensured to enter the filling member 2, and the heat exchange efficiency between the freezing working medium and the filling member 2 is enhanced.

Referring to fig. 2 and 4, in one embodiment, the distal end of the inner tube 14 is secured within the outer tube 15 by an abutment 4.

The support 4 fixes the far end of the inner pipe 14, and prevents the inner pipe 14 from vibrating in the expansion cavity 11 when no supporting structure exists, so that the flow of the freezing working medium is influenced.

In one embodiment, the support 4 abuts against the outer tube 15 at two opposite sides in the radial direction, a positioning hole 41 is formed in the support 4, and the inner tube 14 is inserted into the positioning hole 41. The support 4 is extruded between the inner pipe 14 and the outer pipe 15, and has compact structure and good stability. The support 4 may be fixedly connected to the outer tube 15 by means of bonding, interference fit, or the like.

In one embodiment, the distal end of the support 4 is provided with a tube sleeve 42, the tube sleeve 42 is fixedly inserted into the butt-joint groove 21, and the inner tube 14 is inserted into the tube sleeve 42.

The inner tube 14 is covered by the sleeve 42, and when the inner tube 14 is made of a flexible material having a low strength, the inner tube 14 is less likely to be expanded, deformed or vibrated at the injection port 141, and has a high stability.

In one embodiment, the distal end of the outer tube 15 carries a heat transfer enhancement layer (not shown). The heat exchange between the expansion cavity 11 and the target tissue can be enhanced by strengthening the heat exchange layer.

In one embodiment, the reinforced heat exchange layer is a microporous structure layer located on the outer wall of the outer tube 15, and the pore diameter of the micropores is 1-20 microns. The microporous structure layer increases the contact heat exchange area between the target tissue and the far end of the outer tube 15, and achieves the effects of enhancing heat transfer and improving heat transfer capacity. A sand blasting, acid washing process may be applied to the distal end of the outer tube 15 to form a microporous structure layer.

In one embodiment, the enhanced heat transfer layer is the first heat transfer layer located on the outer wall of the outer tube 15. The thermal conductivity of the first thermally conductive layer is higher than the thermal conductivity of the distal end of the outer tube 15, which accelerates the heat exchange between the distal end of the outer tube 15 and the target tissue. For example, the distal end of the outer tube 15 is made of 304 stainless steel, which is a heat-conducting property and cost-effective material. The first heat conduction layer is made of gallium nitride, the heat conductivity of the gallium nitride is about 10 times of that of 304 stainless steel, and the effects of strengthening heat transfer and improving heat transfer capacity are achieved. The gallium nitride has good biocompatibility and is not easy to leave sequelae. The first heat conducting layer can be attached to the surface of the microporous structure layer to play a role in double heat transfer enhancement.

In one embodiment, the enhanced heat transfer layer is a second heat transfer layer (not shown) located on the inner wall of the outer tube 15. The second heat conducting layer may be a ceramic with a relatively high thermal conductivity, such as gallium nitride, or an inert metal. The heat exchange between the filler 2 and the outer tube 15 is accelerated by the medium of the second heat conducting layer.

Referring to fig. 3-6, in one embodiment, the cross-sectional area of the return channel 13 increases gradually in the direction of fluid movement. Avoid the situation that the return air pressure is higher than the expected value due to the unsmooth return air

Specifically, in one embodiment, the backflow channel 13 includes a plurality of sections with different cross-sectional areas from the distal end to the proximal end, wherein the first section 131 is located between the holder 4 and the outer tube 15 and has a cross-sectional area of S1, the second section 132 is located between the inner tube 14 and the outer tube 15 and has a cross-sectional area of S2, the third section 133 is located between the inner tube 14 and the connecting seat 3 and has a cross-sectional area of S3, the fourth section 134 is located in the connecting seat and is in cross communication with the third section 133 and has a cross-sectional area of S4, and S1 < S2 < S3 < S4. Generally, the needle tube 1 is of a slender structure, and the arrangement of the embodiment ensures that the sectional area of the backflow channel 13 is increased, and the expanded position of the freezing working medium in the backflow process is avoided from the middle part of the needle tube 1, so that the freezing working medium is prevented from expanding and absorbing heat in the puncture channel.

Referring to FIGS. 2-4, in one embodiment, the outer tube 15 has a vacuum jacket 5 around its circumference, and the vacuum jacket 5 has one end adjacent to the distal end of the outer tube 15 and exposing at least the portion of the expansion chamber 11 along the length of the needle cannula 1. The other end of the vacuum jacket 5 extends to the connecting seat 3, and a vacuum interface 33 communicated with the vacuum jacket 5 is arranged on the connecting seat 3. In one embodiment, the vacuum jacket 5 is provided with a vacuum insulation layer inside, which is connected to the vacuum port 33. The freezing working medium in the return channel 13 still has lower temperature, and the vacuum jacket 5 prevents the freezing working medium in the return channel 13 from exchanging heat with the external tissue of the needle tube 1, so that the cold energy is intensively released at the far end of the needle tube 1, and the normal tissue near the puncture channel is prevented from being frostbitten.

In another embodiment, the outer circumference of the outer tube 15 is coated with a thermal insulation layer, such as polyurethane foam, fiberglass, thermal insulating polystyrene, or the like. In another embodiment, the outer tube 15 is provided with a thermal barrier coating, such as an aerogel coating, a nanocoating, or the like, on its outer circumference.

Referring to fig. 4, in an embodiment, the distal end of the outer tube 15 is provided with a metal probe 152, the proximal end of the metal probe 152 is a tubular structure and is inserted and fixed between the flexible tube 151 and the vacuum jacket 5, and the flexible tube 151, the metal probe 152 and the vacuum jacket 5 are sequentially sleeved and sealed and fixed. The space between the flexible tube 151 and the vacuum jacket 5 serves as the vacuum chamber 16. The vacuum chamber 16 is evacuated by a vacuum pump connected to the vacuum port 33, and the vacuum chamber 16 is not communicated with the return channel 13.

In one embodiment, the cryoablation probe further includes a sensing system 6, as shown in fig. 2 and 7, for measuring the temperature or pressure in the inlet 12 and return 13 channels for closed loop control of the temperature in the expansion chamber 11. Through gathering temperature and pressure everywhere of cryoablation probe and feeding back to the control system that cryoablation probe is connected with cryoablation, can make the temperature in the inflation intracavity remain stable, form the puck that the size is suitable, ensure that effective freezing zone surrounds the target tissue completely, avoid haring normal tissue as far as possible again.

In particular, the sensing system 6 comprises at least one of the following temperature sensors, and at least one of the following pressure sensors: a first temperature sensor 61, a second temperature sensor 62, a third temperature sensor 63, a first pressure sensor 64, a second pressure sensor 65.

A first temperature sensor 61 is provided near the proximal end of the inlet channel 12 for measuring the temperature of the refrigerant inside the proximal end of the inlet channel 12. A second temperature sensor 62 is disposed proximate the distal end of the input passage for measuring the temperature of the refrigerant within the distal end of the input passage 12. The third temperature sensor 63 is disposed near the proximal end of the return channel 13 for measuring the temperature of the refrigerant inside the proximal end of the return channel 13. A first pressure sensor 64 is disposed proximate the distal end of the inlet passage 12 for measuring the pressure of the refrigerant within the distal end of the inlet passage 12. A second pressure sensor 65 is provided near the proximal end of the return channel 13 for measuring the pressure of the refrigerant inside the proximal end of the return channel 13.

The plurality of sensors are respectively arranged at different positions of the fluid loop, so that the influence of the change of the external environment of the cryoablation probe on the temperature monitoring in the expansion cavity 11 is fully considered, and the temperature of the ice ball is more stable and adjustable.

In one embodiment, the sensing system 6 further comprises a third pressure sensor 66, the third pressure sensor 66 being disposed proximate to the vacuum port 33 for measuring the pressure of the refrigerant at the vacuum port 33.

In one embodiment, second temperature sensor 62 is a T-type thermocouple with the cold end of the T-type thermocouple disposed around the outer circumference of shroud 42. The T-shaped thermocouple is suitable for working in a low-temperature environment and has higher sensitivity. The T-type thermocouple is located close to the injection port 141 and the temperature measurement is closer to the actual value in the expansion chamber 11.

During operation, the return air pressure, namely the pressure in the expansion cavity 11, is controlled to further obtain the saturation temperature of the expected freezing working medium under the current pressure, the return air pressure is made to be close to the atmospheric pressure as far as possible, or the return air pressure is made to be lower than the local atmospheric pressure through a vacuum auxiliary device, so that a lower saturation temperature is obtained in the expansion cavity 11, namely the temperature difference delta t is increased, and the effects of enhancing heat transfer and increasing heat transfer quantity are achieved.

The technical features of the embodiments described above may be arbitrarily combined, and for the sake of brevity, all possible combinations of the technical features in the embodiments described above are not described, but should be considered as being within the scope of the present specification as long as there is no contradiction between the combinations of the technical features. When technical features in different embodiments are represented in the same drawing, it can be seen that the drawing also discloses a combination of the embodiments concerned.

The above-mentioned embodiments only express several embodiments of the present application, and the description thereof is more specific and detailed, but not construed as limiting the claims. It should be noted that, for a person skilled in the art, several variations and modifications can be made without departing from the concept of the present application, which falls within the scope of protection of the present application. Therefore, the protection scope of the present patent shall be subject to the appended claims.

Claims

1. A cryoablation probe, comprising:

2. The cryoablation probe of claim 1, wherein the filler is a porous metal or ceramic having an average pore size of 0.05-200 microns.

3. The cryoablation probe of claim 1 wherein the needle cannula comprises an inner tube and an outer tube nested within one another, the inner tube having a conduit as the input channel, the inner tube and the outer tube having a radial gap as the return channel, the inner tube having a distal end and the outer tube having a distal end axially spaced as the expansion lumen; the far end of the inner pipe is a jet orifice communicated with the expansion cavity, and the far end of the outer pipe is a blind end.

4. The cryoablation probe of claim 3, wherein the proximal end of the filling member is provided with an abutment groove in which the ejection opening of the inner tube is fixedly inserted.

5. The cryoablation probe of claim 3, wherein the distal end of the outer tube carries a heat transfer enhancement layer disposed in at least one of:

the reinforced heat exchange layer is a microporous structure layer positioned on the outer wall of the outer pipe, and the pore diameter of each micropore is 1-20 micrometers;

6. The cryoablation probe of claim 3, wherein the distal end of the inner tube is secured within the outer tube by a holder.

7. The cryoablation probe of claim 6, wherein the return channel has a cross-sectional area that gradually increases in the direction of fluid movement.

8. The cryoablation probe of claim 3, wherein the outer tube has a vacuum jacket around its circumference, said vacuum jacket having one end adjacent to the distal end of the outer tube and exposing at least the region of the expansion lumen along the length of the needle cannula;

9. The cryoablation probe of claim 8 further comprising a sensing system for measuring temperature or pressure within the input and return channels for closed loop control of temperature within the expansion chamber.

10. The cryoablation probe of claim 9, wherein the sensing system comprises at least one of the following temperature sensors and at least one of the following pressure sensors: