Tissue ablation device with broadband antenna

Abstract

A microwave ablation probe is provided that includes an antenna having a helical arm and a linear arm.

Description

This application is a divisional application of application number 201980023159.6, application date 2019.1.29, and application name “Tissue ablation device with broadband antenna”. Technical Field

[0001] The present invention generally relates to tissue ablation devices and methods of using the same. Background Art

[0002] In treating diseases such as cancer, it has been found that certain types of tissue denature at elevated temperatures. These types of treatments, often referred to as hyperthermia, typically utilize electromagnetic radiation to heat cancerous tissue to temperatures above 60°C while maintaining healthy tissue at lower temperatures where irreversible cell damage does not occur. Microwave ablation is one such therapy that utilizes electromagnetic radiation to heat tissue.

[0003] Microwave tissue ablation is less invasive than surgical resection and is preferred in many cases where the tumor is difficult to remove surgically, such as when the tumor is relatively small, near relatively small organs, or near large blood vessels. The method has been used in organs where it may be difficult to remove the tumor surgically, such as the prostate, heart, and liver.

[0004] In order to effectively plan and optimize surgery, it is desirable that an ablation device creates an ablation volume of predictable size and shape. Therefore, a regularly shaped, predictable ablation volume is preferred, and a spherical or nearly spherical ablation volume is particularly preferred. An ablation device with an ablation volume of predictable size and shape can simplify surgical procedures and reduce adverse medical complications.

[0005] One issue with microwave tissue ablation devices relates to the shape of the energy emission field, which is typically teardrop-shaped, with a larger head shape in the distal direction of the device and an elongated tail or cone in the proximal direction. The ablation device is typically positioned so that the head shape is applied to the target tissue. The elongated cone is typically undesirable because it can result in damage to non-target tissue along the insertion track.

[0006] Another problem associated with microwave ablation devices is that they must operate within a specified frequency range that is both suitable for dielectric heating and can be adjusted for medical use. Suitable frequency bands exist in the 915MHz range (902 to 928MHz), the 2.45GHz range (2.402 to 2.483GHz), and the 5.8GHz range (5.725 to 5.875GHz), although the 2.45GHz range is generally preferred. It is desirable to match the antenna to the tissue impedance so that the maximum peak of energy absorbed by the target tissue falls at or near the frequency at which the antenna operates. However, as the operation progresses, the tissue degenerates and the tissue impedance changes. In some cases, these changes in tissue impedance cause the absorption peak to deviate from the desired frequency. This makes tissue ablation less effective. In addition, unabsorbed microwave energy may be reflected. The reflected microwave energy can cause the device itself to overheat prematurely, thereby increasing the possibility of device failure.

[0007] The embodiments disclosed herein are intended to reduce the impact of the above-mentioned problems associated with microwave tissue ablation devices. More specifically, the embodiments disclosed herein provide microwave antennas and ablation devices that can operate over a wide frequency band and therefore can operate in more than one allowed spectrum. They produce a microwave emission field that is closer to an ideal sphere, and / or improve tissue impedance matching so that the energy absorption peak can be more closely maintained at or near the applied frequency during tissue ablation. Summary of the invention

[0008] The present invention particularly provides tissue ablation devices and methods of using the same. More particularly, the present invention relates to tissue ablation devices having an asymmetric dipole antenna.

[0009] A first aspect of the present invention provides a tissue ablation device including an asymmetric dipole antenna, which includes a feed line having an inner conductor, an outer conductor and a dielectric disposed therebetween; the asymmetric dipole antenna includes a spiral arm electrically connected to the outer conductor of the feed line at a junction and a linear arm extending distally from the end of the feed line and electrically connected to the inner conductor, the spiral arm extending proximally around the feed line in the form of a series of turns, and the proximal end of the spiral arm electrically floating; the linear arm includes two parts, a first part surrounded by a dielectric and a second part distal to the first part, the second part being exposed, that is, it lacks the dielectric.

[0010] In one aspect, the tissue ablation device of the present invention comprises a microwave tissue ablation device having a metal cover disposed at the distal end of the tissue ablation device. In one embodiment, the metal cover comprises a hollow cylindrical protrusion, wherein the proximal portion of the hollow cylindrical protrusion axially overlaps with the distal portion of the asymmetric dipole antenna. Alternatively, the metal cover comprises a hollow cylindrical protrusion, wherein a gap is axially disposed between the proximal end of the hollow cylindrical protrusion and the distal end of the helical antenna. Alternatively, the metal cover comprises a solid cylindrical protrusion, wherein a gap is axially disposed between the proximal end of the solid cylindrical protrusion and the distal end of the helical antenna.

[0011] In a preferred arrangement, the metal cover is configured to be electromagnetically coupled to the antenna via a linear arm. Preferably, it is not physically connected to the linear arm of the antenna. The closer the distal end of the linear arm of the antenna is to the metal cover, the more the metal cover is electromagnetically coupled as part of the antenna.

[0012] Most conveniently, the tissue ablation device is a microwave ablation probe comprising a feed line, which is usually coaxial and has an inner conductor, a dielectric coaxially arranged around the inner conductor, and an outer conductor coaxially arranged around the dielectric. The feed line may include a dielectric or insulator layer coaxially arranged around the outer conductor. The device includes an antenna, the antenna including a spiral arm electrically connected to the outer conductor of the feed line at a junction, the spiral arm coaxially arranged around the feed line and extending from the junction to the proximal direction. The antenna also includes a linear arm electrically connected to the inner conductor of the feed line, the linear arm extending from the distal end of the feed line to the distal direction, the linear arm also including a first portion surrounded by the dielectric, and a second portion without the dielectric, the second portion being distal to the first portion.

[0013] A more preferred device comprises a microwave ablation probe, preferably a needle. The microwave ablation probe comprises a feeder electrically connected to a microwave antenna. The microwave antenna is preferably configured to emit microwave radiation in a frequency band selected from 915 MHz (902 to 928 MHz), 2.45 GHz (2.402 to 2.483 GHz) and / or 5.8 GHz (5.725 to 5.875 GHz). The microwave ablation probe has a probe shaft comprising a distal cover preferably configured to penetrate tissue. The needle shaft surrounds at least the distal portion of the microwave antenna and the feeder and is preferably coaxial therewith. The needle shaft comprises a metal portion and a non-metal portion, the non-metal portion extending axially to extend coextensively with at least the radiating portion of the antenna. The non-metal portion extends axially and circumferentially so that the shaft is preferably non-metallic between the proximal and distal ranges of the non-metal portion. This arrangement is useful for the antenna further described herein.

[0014] The non-metallic portion may extend distally beyond the most distal portion of the antenna, and preferably extends distally to the cover.The non-metallic portion may extend proximally to a point between the hub and the most proximal point of the antenna, but in this embodiment does not extend to the hub.

[0015] In the case where the microwave ablation device has a shaft comprising a metallic portion and a non-metallic portion, the shaft may additionally include an elastic element between the metallic portion and the non-metallic portion, which is configured to provide elasticity to the joint. This reduces stress on the joint during use, such as during insertion of an ablation needle. Preferably, the tissue ablation device also includes a cooling system configured to cool the antenna and / or feeder line. The cooling system may be configured to cool the antenna and feeder line by flowing a cooling fluid through at least the distal-most portion of the antenna.

[0016] Other embodiments of the present invention are discussed throughout the application. Any embodiment discussed about one aspect of the present invention is also applicable to other aspects of the present invention, and vice versa. Each embodiment described herein should be understood as an embodiment of the present invention applicable to all aspects of the present invention. It is conceivable that any embodiment discussed in the present invention can be implemented for any method or composition of the present invention, and vice versa. In addition, the compositions and kits of the present invention can be used to implement the methods of the present invention. The following includes the definitions of various terms and phrases used throughout this specification.

[0017] The term "spherical" refers to a generally spherical three-dimensional shape.

[0018] The term "distal" refers to a position or portion farthest from a user, and the term "proximal" refers to a position or portion closest to a user.

[0019] The term "pitch" for a helical antenna is the height of one complete helical turn measured parallel to the helix axis.

[0020] The terms "electrically connected", "electrically coupled" or "electrically in contact" are defined as the ability of electrical current to pass from one object to another. Typically, the two objects are physically connected by or through a conductor, such as a metal wire.

[0021] The term "electromagnetic coupling" is defined as the ability of electromagnetic energy to be transferred from one object to another without physical contact to affect the shape of the energy field and the resulting ablation volume. The two objects do not need to be physically connected by or via conductors, but electromagnetic energy can be transferred from one object to another, such as by electromagnetic induction.

[0022] The terms "insulating layer", "dielectric" and "insulator" refer to a layer of non-conductive material that does not form any electrical contact under operational use of the device. In the embodiments disclosed herein, an insulating layer or dielectric layer is used to prevent undesired electrical contact.

[0023] As understood by one of ordinary skill in the art, the terms "about" and "approximately" are defined as close to, and in a non-limiting example, within 20%.

[0024] When used in conjunction with the term "comprising" in the claims or the specification, the use of the words "a" may mean "one", but is also consistent with the meaning of "one or more", "at least one", and "one or more".

[0025] The words "comprise" (and any form of including, such as the plural and singular form of "including"), "have" (and any form of having, such as the plural and singular form of "having"), "include" (and any form of including, such as the plural and singular form of "include"), or "contain" (and any form of containing, such as the plural and singular form of "containing") are inclusive or open-ended and do not exclude additional, unrecited elements or method steps.

[0026]

[00136] Components, apparatuses or methods disclosed herein may "comprise," "consist essentially of," or "consist of" particular method steps, ingredients, components, components or the like.

[0027] Other objects, features and advantages disclosed herein will become apparent from the following drawings, detailed descriptions and examples. However, it should be understood that although the drawings, detailed descriptions and examples illustrate specific embodiments of the present invention, they are given by way of example only and are not intended to be limiting. In addition, it is expected that changes and modifications within the spirit and scope of the present invention will become apparent to those skilled in the art based on this detailed description. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Advantages of the present invention will become apparent to those skilled in the art upon benefit of the following detailed description and with reference to the accompanying drawings.

[0029] Figure 1 is a simplified cross-sectional view of a microwave tissue ablation device according to one embodiment of the present disclosure.

[0030] Figure 1a is a simplified cross-sectional view of a microwave tissue ablation device with a cooling system according to one embodiment of the present disclosure.

[0031] Figure 1b is a simplified cross-sectional view of a microwave tissue ablation device having an alternative cooling system according to one embodiment of the present disclosure.

[0032] Figure 1c is a simplified cross-sectional view of a microwave tissue ablation device having another alternative cooling system according to one embodiment of the present disclosure.

[0033] Figure 1d is a simplified cross-sectional view of a microwave tissue ablation device having another alternative cooling system according to one embodiment of the present disclosure.

[0034] Figure 2aSchematic diagram of a microwave tissue ablation device with a metal cover according to one embodiment of the present invention.

[0035] Figure 2b Schematic diagram of a microwave tissue ablation device with a metal cover according to one embodiment of the present invention.

[0036] Figure 2c Schematic diagram of a microwave tissue ablation device with a metal cover according to one embodiment of the present invention.

[0037] Figure 2d Schematic diagram of a microwave tissue ablation device with a metal cover according to one embodiment of the present invention.

[0038] Figure 3 is a stereoscopic view of a microwave tissue ablation device with its handle according to one embodiment of the present disclosure.

[0039] Figure 4A is a stereoscopic view of a microwave tissue ablation device according to an embodiment of the present disclosure.

[0040] Figure 4B is a schematic cross-sectional view of a microwave tissue ablation device according to an embodiment of the present disclosure. Figure 4A XY intercept in.

[0041] Figure 5 is a side view of a handle of a microwave tissue ablation device according to one embodiment of the present disclosure.

[0042] Fig. 6A An ultrasound image of a tissue ablation probe without an echogenic coating is shown according to one embodiment of the present disclosure.

[0043] Figure 6B An ultrasound image of a tissue ablation probe having an echogenic coating according to one embodiment of the present disclosure is shown.

[0044] Fig. 7A Graph 1 is an energy absorption spectrum of a tissue ablation probe according to an embodiment of the present disclosure.

[0045] Figure 7B is a picture showing the energy emission field of a tissue ablation probe according to one embodiment of the present disclosure.

[0046] Figure 7C is a picture showing the energy emission field of a tissue ablation probe according to one embodiment of the present disclosure.

[0047] Fig. 8A is a picture showing an ablation pattern produced in a bovine liver by an ablation probe according to one embodiment of the present disclosure.

[0048] Figure 8Bis a picture showing an ablation pattern produced in a bovine liver by a tissue ablation probe according to one embodiment of the present disclosure.

[0049] Figure 8C is a picture showing an ablation pattern produced in a bovine liver by a tissue ablation probe according to one embodiment of the present disclosure.

[0050] Fig. 9 The present invention provides a method for using a microwave ablation device according to an embodiment of the present invention.

[0051] Fig.10 is an enlarged view of a section of an ablation device shaft showing the junction between the metal and ceramic portions of the shaft.

[0052] While the invention is susceptible to various modifications and alternative forms, specific embodiments thereof have been shown by way of example in the drawings. The drawings may not be to scale. DETAILED DESCRIPTION

[0053] The size and dimensions of the ablation zone produced by a microwave tissue ablation device depends on, among other factors, the type of microwave antenna. The clinician may select a microwave antenna that is capable of producing an ablation zone that is larger than the size and dimensions of the target tissue, and insert the microwave antenna so that the ablation zone produced by the microwave antenna includes the target tissue. When the tissue to be ablated is larger than the size of the ablation volume produced by the device, more than one device may be used and the ablation volume may be combined to cover the tissue to be ablated. Embodiments of the microwave tissue ablation devices described herein may be used to produce ablation zones of predictable shapes with reduced tailing, which aids in ablation planning and prevents damage to tissue outside the volume to be treated.

[0054] The ablation devices disclosed herein are microwave ablation devices; that is, they cause ablation by emitting microwave energy, which kills tissue by heating. Typically, the device is a microwave ablation needle having a microwave antenna, such as those described herein. The microwave energy can be generated by a microwave generator and supplied to the antenna by wires electrically connecting the microwave generator to a feeder wire of the antenna within the needle. The microwave ablation device also has a shaft surrounding at least a distal portion of the microwave antenna and the feeder wire and generally coaxial therewith. The shaft generally extends from a proximal hub to a distal cap.

[0055] The microwave antenna is configured to emit microwave radiation in a frequency band selected from the 915MHz band (902 to 928MHz), the 2.45GHz band (2.402 to 2.483GHz) and / or the 5.8GHz band (5.725 to 5.875GHz). Preferably the wavelength is within the 2.45GHz band, in particular the antenna is preferably configured to emit microwave energy at 2.45Ghz or about 2.45GHz. The device is configured to operate to supply up to 150 watts of power to the antenna.

[0056] The feed line preferably includes an inner conductor, an outer conductor, and a dielectric disposed therebetween. The feed line may include another dielectric or insulator that insulates the outer conductor from the rest of the device and serves as an outer insulator for the feed line, but this is not required in all embodiments. In some embodiments, the feed line may be free of additional dielectric at least in the distal portion of the junction. The feed line may lack such additional dielectric within the device shaft (such as between the junction of the proximal feed line connector of the distal hub and the antenna). The feed line is typically a coaxial cable having a center conductor surrounded by a first dielectric or insulator, the first dielectric being surrounded by a second conductor, which may be covered by another dielectric or insulator as described above. The inner conductor is typically a power conductor.

[0057] The device of the present invention may include an asymmetric dipole antenna. The antenna preferably includes two arms, a spiral arm and a linear arm as further described herein. The distal end of the spiral arm is electrically connected to the outer conductor of the feed line at a junction. The junction is conveniently towards or located at the farthest end of the feed line. The feed line may extend beyond the junction to provide appropriate mechanical support for the electrical junction, but preferably, it extends no more than 5 mm, especially no more than 1 mm beyond the junction.

[0058] The spiral arm extends proximally from the junction point around the feeder in the form of a series of turns, and is therefore coaxially arranged around the feeder. The spiral arm is preferably not wound in a manner that directly contacts the feeder. It can, for example, form turns at a position radially offset from the feeder. The spiral arm is preferably wound around a substrate that supports it. In the case where the feeder includes an outer insulator, the outer insulator can be a substrate for the spiral arm, and the spiral arm can form turns around the outer insulator. Alternatively, the spiral arm can, for example, be wound around a tubular substrate, such as a cooling tube positioned around the feeder. The cooling tube is further described below. The spiral arm can be fixed to its substrate by an adhesive to keep it in place and make assembly simpler. The spiral arm can be embedded in a matrix such as a polymer layer or coating to protect it, insulate it from other parts of the device, or provide a seal as further described below.

[0059] Typically, the spiral arm is in the form of a single conductor. The spiral arm of the antenna may be in the form of a wire or strip, but is typically a wire or strip with a circular cross-section. The spiral arm is preferably in the form of a cylindrical conductor with a spiral gap extending from its proximal end to its distal end to provide a spiral conductor with a planar conductor surface that curves around the feed line. The spiral arm does not make any other contact with the inner conductor or the outer conductor except at the junction.

[0060] The linear arm of the antenna described herein is a conductor that is electrically connected to the inner conductor of the feed line and extends distally therefrom, preferably along an axis coaxial with the spiral arm and / or the feed line. The conductor is preferably in the form of a straight line. In a particularly preferred embodiment, the linear arm includes a first proximal insulating portion and a second distal non-insulated portion. Typically, the first portion is surrounded by a dielectric, and there is no dielectric in the second portion distal to the first portion. The second portion extends to the end of the arm. The dielectric surrounding the first portion of the linear arm preferably extends from the distal end of the feed line. In its simplest form, the linear arm of the antenna can be an extension of the inner conductor of the feed line. Then, the dielectric can be an extension of the dielectric arranged between the center conductor and the outer conductor of the coaxial feed line.

[0061] Preferably, the linear arm and the helical arm of the antenna are coaxial with the axis of the ablation device, such that the linear arm is coaxial with the helical arm and extends distally therefrom.

[0062] Preferably, the total length (Lba) of the spiral arms may be in the range of 1 to 18 mm, preferably the spiral arms are in the range of 4 to 10 mm. In a preferred embodiment, the spiral arms are in the range of 4 to 7 mm.

[0063] The total number of turns (N) is in the range of 1 to 12, but is not limited to an integer. In a preferred embodiment, N is typically 4 to 8.

[0064] For each complete helical turn, the axial distance is the pitch (P), which may be in the range of 0.7-1.5 mm, preferably the pitch is in the range of 1-1.5 mm, and in a preferred embodiment the pitch (P) of the helical arms is 1.2-1.25 mm.

[0065] The number of helical rings (N) and the pitch (P) affect the microwave energy output, the shape of the emission field, and the energy absorption spectrum. Judicious selection of the combination of variables can provide an ablation device with favorable characteristics for tissue ablation.

[0066] The length (L1a) of the linear arm is preferably 4 mm to 14 mm, preferably 8 mm to 10 mm. The length (L2) of the second exposed portion is preferably 0.1 mm to 2 mm, preferably 0.3 mm to 0.5 mm.

[0067] Thus, in a preferred embodiment, the helical arm of the antenna is in the form of a strip having a length (Lha) of 1 to 18 mm and comprising 1 to 14 turns, the linear arm of the antenna is 4 to 14 mm long and has a second distal portion lacking a dielectric and having a length of 0.1 to 3 mm.

[0068] In a more preferred embodiment, the helical arm of the antenna is in the form of a strip having a length (Lha) of 4 to 10 mm and comprising 4 to 8 turns, the linear arm of the antenna is 7 to 10 mm long and has a second distal portion lacking a dielectric and having a length of 0.3 to 0.5 mm.

[0069] In a particularly preferred embodiment, the helical arm of the antenna is in the form of a strip having a length (Lha) of 4 to 6 mm and comprising 3 to 5 turns. The linear arm has a length of 7 to 10 mm, the second distal portion lacking dielectric for a length of 0.3 to 0.5 mm.

[0070] Reference Figure 1 Dimensions are described purely for ease of reference.

[0071] The ablation device comprises a device shaft, which preferably terminates at the distal end in a device cap. The shaft is preferably cylindrical. The feed wire and antenna are preferably arranged in the device shaft. The device shaft generally extends from the proximal hub and terminates at the distal end in the distal cap. The diameter of the shaft is not limited and is generally suitable for the intended purpose, such as an ablation needle, where it is important to have a narrow needle to limit damage caused by insertion and provide well-controlled positioning, so the needle shaft diameter is between 1.4 and 3 mm, preferably between 1.5 and 2.5 mm, and particularly 2 to 2.5 mm.

[0072] The hub includes electrical connections to the electronics of the shaft, such as feed lines, and may also include cooling fluid inlet and outlet connections if necessary.

[0073] The shaft is typically cylindrical and is typically made of a biocompatible polymer, a biocompatible composite material, such as a glass fiber reinforced polymer or a carbon fiber reinforced polymer, a ceramic, or a metal (such as stainless steel). The shaft is preferably made of ceramic or metal, but in a preferred embodiment, the shaft includes a metal portion and a non-metal portion. The non-metal portion can be a biocompatible composite material, such as a glass fiber reinforced polymer or a carbon fiber reinforced polymer, or a ceramic, but ceramic is preferred because of its improved performance and strength. The ceramic is preferably an aluminum oxide or zirconium oxide ceramic.

[0074] Where the shaft has a non-metallic portion, the non-metallic portion preferably extends axially to cover the antenna and is therefore at least coextensive with the radiating portion of the antenna. In one embodiment, the non-metallic portion extends at least from the proximal point of the helical arm to the distal end of the shaft (i.e., the attachment point of the device tip). The non-metallic portion extends axially and circumferentially, so that the shaft is preferably non-metallic between the proximal and distal extents of the non-metallic portion.

[0075] The shaft may also include an echogenic region on the outer surface that is configured to be visible under ultrasound imaging. In one embodiment, the region includes a coating that includes acoustically reflective microspheres. The echogenic region extends over at least the region of the shaft radially outward from the antenna. In the case where the shaft includes a metallic portion and a non-metallic portion, the joint between the two portions (where the metallic portion and the non-metallic portion adjoin) may be a potential weak point, particularly in the case where the non-metallic portion is ceramic, as ceramics are generally less flexible than metals (such as stainless steel) and more brittle. Therefore, preferably, the shaft further includes an elastic element between the portion and the metallic portion, which is configured to provide elasticity to the joint between the non-metallic portion and the metallic portion of the probe shaft when in use. Although an elastic element may also be present between the non-metallic region and the cover, this is not necessary as the stress on the shaft is lower there. The elastic element may include, for example, an elastic annular gasket, which may be made of an elastic thermoplastic elastomer, such as a trade name ELASTOMER. or E (Evonik Industries) polyether block amide (PEBA) or polyaryletherketone (PAEK) such as polyetheretherketone (PEEK). The gasket is preferably shaped and configured to space the proximal end of the non-metallic part from the distal end of the metal part. The elastic element is preferably adjacent to the metal part on the proximal side and adjacent to the non-metallic part on the distal side. The elastic annular gasket usually extends radially outward to form a surface flush with the outer surface of the probe shaft. The radial inner portion of the annular gasket may extend proximally and / or distally to provide an annular step configured to support the inner surface of the proximal end of the non-metallic part and / or the distal end of the metal part. In a preferred embodiment, the annular gasket extends proximally to provide an inner surface configured to support the distal end of the metal part, but does not extend distally. The device shaft may also include an adapter sleeve to support the joint between the non-metallic part and the metal part of the shaft. The adapter can be configured to take into account any difference in thickness between the non-metallic part and the metal part of the shaft so as to provide a smooth surface transition between the metal part and the non-metallic part. It may be metallic, or non-metallic, such as a thermoplastic elastomer, e.g. or The adapter is particularly important where the non-metallic part is ceramic, due to the thickness required for the additional strength of the ceramic and the risk of cracking here due to shaft flexure. Conveniently, the sleeve extends sufficiently on each side of the joint to provide support to the joint and is typically located radially inwardly of the shaft, typically between the feed wire and the inner wall of the shaft. The adapter sleeve is preferably metallic.

[0076] The elastic element and the adapter sleeve together form a strain relief area. The elastic element and the adapter sleeve can be a single piece or separate.

[0077] In a preferred embodiment, the stress relief area includes a resilient element as described above, which includes a resilient annular gasket shaped and configured to space the proximal end of the non-metallic part from the distal end of the metal part, the gasket being configured to abut the metal part at the proximal side and the non-metallic part at the distal side, the gasket extending radially outward to form a surface flush with the outer surface of the probe shaft, and the radially innermost portion of the gasket extending proximally to provide an annular step configured to support the inner surface of the distal end of the metal part; the stress relief area also includes an adapter sleeve extending radially inward of the annular gasket on each side of the joint. Preferably, the sleeve extends proximally of the annular gasket and is configured to contact and support the inner surface of the distal end of the metal part of the shaft, and preferably extends distally of the gasket and is configured to contact and support the inner surface of the proximal end of the ceramic part of the shaft.

[0078] The ablation device preferably includes a distal cover, which can be configured to seal the distal end of the device to prevent leakage of cooling fluid or penetration of tissue fluid. The cover can be manufactured as a separate component and can be configured to be attached to the shaft. The cover is preferably configured to facilitate insertion into the tissue and penetrate the patient's skin, so that it can reach the distal point, for example, or is configured as a sleeve needle. The cover can be made of any suitable biocompatible material, such as a biocompatible polymer, a composite material, a ceramic or a metal such as stainless steel. In the case where the cover is metal, the cover and the distal end of the antenna (i.e., the distal end of the antenna linear arm) can be configured to be electromagnetically coupled. This can be achieved by adjusting the distance between the distal end of the antenna and the cover so that they are electromagnetically coupled at the frequency and power at which the antenna is intended to work. This effect can be used to adjust the shape of the distal part of the energy field generated by the antenna, thereby adjusting the shape of the ablation zone. However, the cover and the antenna do not need to be so connected, that is, the antenna can be electromagnetically separated from the cover. Preferably, the end and the cover do not touch. In practice, the gap between the end and the cover is 0.2 mm or more, in particular 0.2 mm to 3 mm, and most preferably 1 to 2 mm. Most preferably it is at or about 1.5 mm.

[0079] In one aspect, the portion of the linear arm lacking the dielectric is partially or completely inserted into the metal cover, but does not touch the cover. This can be achieved by forming an open pocket at the base of the cover into which this portion of the antenna or a portion thereof is inserted. The degree of insertion of the exposed distal tip affects the shape of the distal portion of the energy field and, therefore, the shape of the ablation zone. Effects such as Figures 7A-7C shown.

[0080] With distances greater than 3 mm between the tip and cap, they are not believed to be sufficiently coupled to be useful for ablation shaping, especially at 2.45 GHz.

[0081] Thus, in a preferred embodiment, the helical arm of the antenna is ribbon-shaped, having a length (Lha) of 1 to 18 mm and comprising 1 to 14 turns, the linear arm of the antenna is 4 to 14 mm long and has a second distal portion lacking dielectric and being 0.1 to 3 mm long, the portion lacking dielectric being spaced 0.2 to 3 mm from the base of the cover.

[0082] In a more preferred embodiment, the helical arm of the antenna is ribbon-shaped, has a length (Lha) of 4 to 10 mm and includes 4 to 8 turns, and the linear arm of the antenna is 7 to 10 mm long and has a second distal portion lacking dielectric and being 0.3 to 0.5 mm long, the portion lacking dielectric being spaced 1 to 2 mm from the base of the cover.

[0083] In a more preferred embodiment, the helical arm of the antenna is in the form of a ribbon having a length (Lha) of 4 to 6 mm and comprising 3 to 5 turns. The linear arm has a length of 7 to 10 mm and has a second distal portion lacking dielectric and having a length of 0.3 to 0.5 mm, the portion lacking dielectric being spaced 1 to 2 mm, preferably 1.5 mm or about 1.5 mm, from the base of the cap.

[0084] The shape of the energy field and therefore the ablation volume can also be influenced by providing a metal sheath concentric with the feed line. The sheath is preferably cylindrical and extends proximally to the antenna over at least a portion of the feed line. The sheath may also extend over at least a portion of the antenna, but preferably it terminates at a point proximal to the distal-most point of the antenna's spiral arm and does not extend over the antenna. Preferably, the gap between the sheath and the distal-most portion of the spiral arm is at least 0.1 mm. The gap may, for example, be between 0.1 and 2 mm or between 0.1 and 1 mm, preferably 0.5 mm or about 0.5 mm. The sheath is preferably not placed on the outer surface of the shaft, but is preferably radially offset from the feed line and coaxial with it. Preferably, it is placed between the feed line and the inner wall of the shaft. In one arrangement, the metal sheath may be the adapter sleeve described above.

[0085] The ablation device described herein is preferably configured to operate at a power of up to 150 watts for 20 minutes or more. The device becomes hot during use due to the resistive heating of the antenna and the energy reflected from the tissue, so typically the device, including the distal portion of the feeder and at least the distal portion of the antenna, will need to be cooled. Conveniently, the entire feeder and antenna are cooled. Cooling the antenna prevents damage to the device itself and prevents overheating or burning of tissue near the antenna. This changes the physical properties of the tissue, including its energy absorption and reflection characteristics, thereby reducing the efficiency of the antenna and can change the ablation zone. Therefore, in one embodiment, the above tissue ablation device may additionally include a cooling system to cool at least a portion of the antenna and / or the feeder. Such a cooling system is typically configured to allow a coolant such as a cooling fluid (e.g., water) to flow through at least a portion of the feeder and the antenna. Typically, such a system includes a coolant inlet and a coolant outlet, which cooperate to allow the coolant to flow through the antenna and optionally at least a portion of the feeder to cool the antenna, and optionally at least a portion of the feeder, preferably all. The antenna and feeder are typically in contact with the coolant.

[0086] In one option, the cooling system includes a cooling chamber surrounding at least a distal portion of the antenna and the feeder line, the cooling chamber having a coolant inlet conduit configured to supply coolant to the cooling chamber and a coolant outlet conduit configured to carry coolant away from the cooling chamber, the coolant inlet conduit and the coolant outlet conduit being configured to flow coolant through at least a portion of the feeder line and at least a portion of the antenna.

[0087] Preferably, the cooling chamber is defined between the inner walls of the device shaft. The chamber may be limited by a cover on the distal side and by one or more proximal seals on the proximal side, which close the cooling chamber on the proximal side. One or more seals are preferably formed at the hub or at a point between the hub and the proximal portion of the spiral arm of the antenna. The cooling system includes at least one coolant inlet conduit configured to deliver cooling fluid to the cooling chamber and at least one coolant outlet conduit for removing cooling fluid from the chamber. The coolant inlet conduit and the coolant outlet conduit typically pass through the proximal seal. In one method, the coolant inlet conduit is a coolant inlet tube configured to deliver coolant to an adjacent antenna and / or feeder and at a radially outward position thereof. In this case, the coolant inlet tube is preferably arranged in the cooling chamber, between the antenna and the inner wall of the shaft. Preferably, it is arranged radially outwardly away from the feeder.

[0088] In an alternative arrangement, the cooling system includes a coolant inlet conduit and a coolant outlet conduit, each conduit being arranged around at least a portion of the feeder and a portion of the antenna. Each conduit is arranged in a spiral form, and the coolant inlet conduit and the coolant outlet conduit are interlaced with each other to form a double helix. In a preferred arrangement, the cooling system includes a pair of spiral separators arranged in a double helix around at least a portion of the feeder and the antenna, each separator extending radially outward toward the inner wall of the shaft and radially inward toward the antenna and / or the feeder, so that the coolant inlet conduit and the coolant outlet conduit are formed between the two separators, and the coolant inlet conduit and the coolant outlet conduit form a double helix. The separator can be in the form of a filament or a band, or a combination of the two. In the case where the separator includes a band, the band is preferably substantially perpendicular to the inner wall of the shaft. The filament can be formed by metal or an elastic polymer. The separator preferably extends to seal the inner wall and at least a portion of the antenna and / or the feeder.

[0089] The cooling system may further include a coolant mixing chamber in fluid communication with both the coolant inlet duct and the coolant outlet duct, such that the coolant inlet and the coolant outlet are in fluid communication via the coolant mixing chamber. The coolant mixing chamber is preferably configured to allow coolant to flow through at least a portion of the antenna, in particular at least a portion of the linear arm of the antenna. The coolant mixing chamber is particularly configured to allow coolant to flow through at least a portion of the distal portion of the linear arm of the antenna and the cover.

[0090] Alternatively and preferably, the cooling system comprises a cooling chamber defined between the inner walls of the device shaft. The chamber may be defined distally by a cover and proximally by a seal between the hub and the shaft, or at a point distal to the hub and between the antenna and the hub (as previously described). The cooling chamber surrounds at least the distal portion of the antenna and feeder line.

[0091] The cooling system also includes a cooling tube arranged around the feeder, which preferably extends distally around the feeder and is preferably coaxial therewith. The cooling tube preferably divides the cooling chamber into a first cooling duct and a second cooling duct, the first cooling duct being arranged between the feeder and the inner wall of the cooling tube, and the second cooling duct being arranged between the outer wall of the cooling tube and the inner wall of the device axis. The cooling tube preferably extends over the distal portion of the feeder and extends distally around at least a portion of the antenna, preferably, the cooling tube extends at least to the end of the linear arm of the antenna. A variety of materials are suitable for the cooling tube, but non-metallic materials are preferred. Conveniently, the cooling tube can be made of a thermosetting polymer (e.g., polyimide) or a thermoplastic polymer resin (e.g., polyethylene terephthalate (PET)) or a fluoropolymer (e.g., polytetrafluoroethylene (PTFE)) or PAEK (e.g., PEEK).

[0092] The spiral arm of the antenna may be arranged in the first cooling conduit, for example, the distal portion of the feeder may include the second insulator as described above, and the spiral arm of the antenna is directly wound around the feeder, the second insulator extending axially at least between the spiral arm and the second conductor of the feeder. In this case, the cooling conduit may extend to cover a portion of the spiral arm, but preferably covers a portion of the spiral arm and the linear arm, but most preferably, the cooling conduit extends at least to the distal end of the antenna, so that the first cooling conduit extends at least to the distal end of the antenna.

[0093] Otherwise, the cooling tube extends to cover a distal portion of the feeder and a portion of the linear arm, but most preferably the cooling tube extends at least to the distal end of the antenna so that the first cooling duct extends at least to the tip of the antenna.

[0094] The cooling system may additionally include a coolant mixing chamber in fluid communication with both the first cooling conduit and the second cooling conduit, such that the first cooling conduit and the second cooling conduit are in fluid communication via the coolant mixing chamber.The coolant mixing chamber is preferably configured to allow coolant to contact a portion of the cover.

[0095] The first or second cooling conduit may serve as a coolant input conduit or a coolant output conduit.The first and second cooling conduits are open at distal ends, allowing cooling fluid to circulate through a coolant mixing chamber between the cooling tube distal end and the base of the applicator cap.

[0096] The cooling tube preferably extends proximally towards the hub.The first cooling fluid conduit and the second cooling fluid conduit are in fluid communication with cooling fluid input and output connectors of the hub to supply cooling fluid and to exhaust cooling fluid during use.

[0097] In a particularly preferred method, the spiral arm of the antenna, preferably in the form of a ribbon, is wound around the cooling tube. In this case, as described above, the spiral arm is in electrical contact with the outer conductor of the feeder line at the junction and extends distally around the cooling tube in a series of turns. In this case, the cooling tube preferably extends at least to the junction of the antenna and the feeder line, preferably it extends further to cover at least a part of the linear arm, but most preferably, the cooling tube extends to the end of the linear arm, so that the first cooling duct extends at least to the end of the antenna. Preferably, the electrical contact between the distal end of the spiral arm and the outer conductor of the feeder line passes through the cooling tube.

[0098] In this method, preferably, the outer insulator does not extend over the distal portion of the feeder wire. Preferably, it does not extend over at least the portion extending from a point on the feeder wire immediately proximal to the antenna helical arm to the junction point. The entire feeder wire may be free of the outer insulator within the shaft of the ablation device.

[0099] In embodiments where the cooling system comprises a cooling tube as described above, the spiral arm may be a wire or a ribbon, but is most preferably a ribbon. The spiral arm is preferably in the form of a cylindrical conductor having a spiral gap extending from its proximal end to its distal end to provide a spiral conductor disposed around the feed line and preferably coaxial therewith, having a planar conductor surface.

[0100] The cooling systems described herein cause a coolant (usually water) to flow through at least a portion of the feeder and the antenna, preferably the entire antenna. Normal operation does not require the antenna to be insulated from the cooling fluid. In some embodiments described herein, some portions of the feeder lack an outer insulator surrounding the feeder. The feeder may lack insulation over its entire length between the hub and the junction or within the device shaft. The spiral arms of the antenna may also lack any insulation, especially if they are wrapped around a cooling tube.

[0101] The ablation devices described herein may additionally include one or more temperature sensors, such as thermocouples, to measure the temperature at points along the shaft. Typically, the thermocouples may be located within the cooling system and configured to measure the temperature of the coolant or other parts of the device (e.g., the feed line or the device shaft) during operation of the device.

[0102] The ablation devices described herein typically include a proximal hub as briefly discussed above. The hub typically includes connectors for connecting the feed lines to the energy supply lines and for connecting the electrical devices within the device shaft to the control system. Such connectors can be permanent or removable. The hub may also include a coolant manifold having input and output connectors for connecting the coolant input to the coolant supply and the coolant output to a waste or recirculation system. The hub may also form part of a handle that is configured to provide a surgeon with a more secure grip for manipulating the tissue ablation device.

[0103] In another aspect, the present invention provides a system for microwave ablation of tissue, the system comprising one or more microwave ablation devices, such as the probe or needle described herein, the microwave ablation device comprising a microwave antenna configured to transmit microwave energy to tissue, a power module configured to provide microwave energy to the microwave antenna, and one or more power cables configured to connect the power module to the microwave antenna of the ablation device and to deliver the microwave energy provided by the power module to the antenna to ablate tissue.

[0104] The power module is preferably configured to provide microwave energy to the antenna in one or more of the 915 MHz range, the 2.45 GHz range, or the 5.8 GHz range, preferably the 2.45 GHz range and most preferably at or about 2.45 GHz. The power module may be configured to provide microwave energy to an antenna having five microwave ablation probes, preferably one, two, or three probes.

[0105] The system may also include a control module configured to control the output of the power module. The control module may be configured to control one or more of the following parameters: output wavelength, output power, time period over which microwave energy is delivered to one or more antennas, time period over which energy is delivered at the output power. Where the ablation device includes a temperature sensor, the control module may be configured to control any one or more of the parameters in response to a signal from the temperature sensor. For example, the control module may be configured to cut off power to one or more of the antennas in response to an overheat condition.

[0106] The power cable is preferably a coaxial cable, preferably rated at least 30 Watts, preferably at least 100 Watts, preferably at least 150 Watts. The cable may be a cooled cable configured to be cooled by a supply of coolant, preferably by circulating the coolant along the cable between a cable coolant inlet and a cable coolant outlet.

[0107] In particular, where the ablation device includes a cooling system, the system for microwave ablation may include a cooling system configured to deliver a coolant to the microwave ablation device to cool the device. The cooling system may include a coolant supply reservoir and a cooling line configured to deliver a coolant to the ablation device to cool the device as described herein. The system preferably also includes at least one pump configured to pump cooling fluid from the coolant supply reservoir to the ablation device to cool the device. The system preferably also includes a coolant outlet line configured to carry the coolant out of the ablation device. The coolant outlet line may deliver the coolant to waste, or the system may include a coolant recirculation system, whereupon the coolant is delivered to the coolant recirculation system. For example, the coolant may be returned to the coolant reservoir for recirculation.

[0108] A system for microwave ablation may include a cooling system configured to cool a power cable. The system configured to cool a power cable may include a coolant reservoir and a cooling line configured to deliver coolant to the power cable to cool the cable. The system preferably also includes at least one pump configured to pump cooling fluid from the coolant supply reservoir to the cable to cool the cable. The system preferably also includes a coolant outlet line configured to take the coolant away from the cable. The coolant outlet line may deliver the coolant to waste, or the system may include a coolant recirculation system for cooling the cable, whereupon the coolant is delivered to the coolant recirculation system. For example, the coolant may be returned to the coolant reservoir for recirculation.

[0109] In a further configuration, the system includes a cooling system, and the cooling system is configured to cool both the cable and the microwave ablation device.

[0110] Another aspect of the invention is a method of using a microwave ablation device according to the invention.

[0111] The method includes the steps of preparing a console, wherein the console connects the microwave tissue ablation device to a power source and a coolant source. In one embodiment, the console can support more than one microwave tissue ablation device. For example, one console can support three or four tissue ablation devices, providing sufficient power and coolant supply to each tissue ablation device.

[0112] Method 1000 includes step 1010 of preparing a microwave tissue ablation device, wherein the microwave tissue ablation device includes an asymmetric dipole antenna. The microwave tissue ablation device in method 1000 may be Figure 1-7C The microwave tissue ablation device is shown.

[0113] Step 1010 may also include collecting other necessary supplies; obtaining room temperature sterile saline / water; obtaining an IV stand; placing the IV stand close to the operating table; identifying the target tissue location; determining the number of microwave tissue ablation devices required; obtaining the required microwave tissue ablation devices from the warehouse; obtaining a temperature probe from the warehouse; unpacking the microwave tissue ablation device; inserting the manifold into the console; connecting the saline / water source to the manifold connector; locking the perfusion pump to the console, etc.

[0114] Method 1000 includes step 1015 of activating a control console and a microwave tissue ablation device.

[0115] Step 1015 may further include confirming that the pump is working; confirming that the temperature of the water / saline is operational; confirming that the coolant is circulating properly in the microwave tissue ablation device; confirming that the asymmetric dipole antenna of the microwave tissue ablation device is operational; operating the pump for a period of time to prepare the pump and the microwave tissue ablation device; inserting the distal portion of the tissue ablation device into the water, etc.

[0116] Method 1000 includes step 1020 of bringing a microwave tissue ablation device into proximity with target tissue under ultrasound visual guidance.

[0117] Step 1020 may also include starting an ultrasound imaging system (the ultrasound imaging system can be 2D or 3D); inserting a microwave tissue ablation device into the patient's body under ultrasound visual guidance; securing the microwave tissue ablation device with a fixation device to prevent accidental movement of the device in the patient's body; securing cables and tubes attached to the microwave tissue ablation device to prevent unwanted torque; positioning a temperature sensor at a desired location; performing a CT scan to verify the position of the microwave tissue ablation device and the target tissue; and repeating any steps as needed if the position of the microwave tissue ablation device is not as desired.

[0118] Method 1000 includes step 1025 of activating the microwave tissue ablation device to emit microwaves to heat the target tissue.

[0119] Step 1025 may also include selecting parameters for ablation, wherein the parameters include organ type, organ size, output power and / or output time; conducting the necessary power to the microwave tissue ablation device to heat the target tissue. Note that the steps listed in method 1000 are not in order.

[0120] While the invention is susceptible to various modifications and alternative forms, specific embodiments thereof have been shown by way of example in the drawings. The drawings may not be to scale.

[0121] The present invention will now be further described by the following non-limiting examples with reference to the accompanying drawings. These are provided for illustrative purposes only, and from these examples, one skilled in the art will recognize other examples that fall within the scope of the claims.

[0122] Figure 1 1 is a schematic side view of the distal end of a microwave tissue ablation device 100 (hereinafter referred to as “ablation device”) according to one embodiment of the present disclosure. For ease of explanation, the device is simplified. Figure 1 Shows the characteristics of an asymmetric antenna.

[0123] like Figure 1 As shown, the ablation device 100 includes a coaxial feed line 110. The feed line 110 includes an inner conductor 102. The feed line 110 includes a first insulator 104 disposed concentrically and circumferentially around the inner conductor 102. The inner conductor 102 may be a power line. The feed line 110 includes an outer conductor 106 disposed concentrically around the first insulator 104. The outer conductor 106 may be a ground line. The feed line 110 includes a second insulator 108 disposed concentrically around the outer conductor 106.

[0124] Ablation device 100 includes an asymmetric dipole antenna 120. Asymmetric dipole antenna 120 includes a spiral arm 118. Distal end 500 of the spiral arm is electrically connected to outer conductor 106 of feed line 110 at junction 117. Spiral arm 118 extends proximally from junction 117 around the feed line in a series of turns. Apart from junction 117, spiral arm 118 does not make other electrical contact with inner conductor 102 or outer conductor 106.

[0125] The helical arm 118 has a length Lha 124. For each complete helical turn, the height measured axially is the pitch P 122.

[0126] The number of helical turns and the pitch (P) affect the microwave energy output, the shape of the emission field, and the energy absorption spectrum. Judicious selection of the combination of variables can provide an ablation device with favorable properties for tissue ablation. See above.

[0127] The asymmetric dipole antenna 120 further includes a linear arm 119. The linear arm 119 is electrically connected to the inner conductor 102 of the feed line 110. The linear arm 119 extends distally from the distal end of the inner conductor 102. The linear arm 119 further includes a first portion 131 surrounded by a dielectric 135. The dielectric 135 may be an extension of the first insulator 104 disposed between the inner conductor 102 and the outer conductor 106 of the feed line 110. The linear arm 119 further includes a second portion 133 without a dielectric. The second portion 133 is distal to the first portion 131.

[0128] The linear arm 119 has a length L1a 126. The first portion 131 of the linear arm 119 has a length L1 127. The second portion 133 of the linear arm 119 has a length L2 128.

[0129] The linear arms do not contact the base 134 of the applicator cap 130 .

[0130] The antenna and feeder are contained within the shaft 114 having a separate distal applicator cap 130, attached and sealed to the shaft 114. The applicator cap 130 is made of a biocompatible metal or ceramic, for example, preferably stainless steel or ceramic. The portion of the applicator cap 130 distal to the circular base 134 is tapered. The applicator cap 130 includes a sharp tip 132 disposed at the distal end of the applicator cap 130 and configured to penetrate tissue. The applicator cap 130 includes a circular base 134 configured to seal the sheath 114.

[0131] Ablation device 100 may include a cooling system configured to cool the antenna and / or the feed line. Figure 1a to Figure 1d Illustrative embodiments of apparatuses including cooling systems are provided.

[0132] Figure 1a An embodiment of the device of the present invention having a cooling system is shown. Figure 1a The other features of the device are illustrative. Figure 1 The device shown, Figure 1a The illustrated device 100 includes a coaxial feed line 110 having an inner conductor 102 , a first insulator 104 disposed concentrically about the inner conductor 102 , an outer conductor 106 disposed concentrically about the first insulator 104 , and a second insulator 108 disposed concentrically about the outer conductor 106 .

[0133] Ablation device 100 also includes antenna 120 having a spiral arm 118, the distal end 500 of the spiral arm being electrically connected to outer conductor 106 of feed line 110 at junction 117 toward the distal end of the feed line. Spiral arm 118 extends proximally from junction 117 around feed line 110 in a series of turns. Antenna 120 also includes linear arm 119. Linear arm 119 is electrically connected to inner conductor 102 of feed line 110. Linear arm 119 extends distally from the distal end of inner conductor 102 and includes a first portion 131 surrounded by dielectric 135 and a second portion 133 lacking dielectric. Figure 1 As shown, the linear arms do not contact the applicator cap 130 .

[0134] The antenna and feed lines are contained within a shaft (shown simplified in this figure) 114 which terminates distally in a separate metal applicator cap 130 having a Figure 1 The device has a sharp tip 132 disposed at its distal end.

[0135] A cooling chamber 163 is defined between the inner wall 160 of the shaft 114. The cooling chamber 163 is defined distally by the base 134 of the cover 130 and proximally by a seal 162 located at a point distal to the hub (not shown) and the antenna 120, through which the feed line 110 passes. A coolant inlet conduit 164 and a coolant outlet conduit 167 also pass through the seal 162. The coolant inlet conduit 164 is in the form of a coolant inlet tube 167 disposed within the cooling chamber 163 and radially outwardly offset from the feed line 110. The cooling tube is sized and configured to pass between the antenna 120 and the inner wall 160 of the shaft and deliver coolant from the coolant outlet 165 to a location adjacent to a portion of the antenna 120.

[0136] The coolant inlet conduit may terminate near seal 162 or may extend to deliver cooling fluid to any portion of the chamber. Delivery close to antenna 165 is advantageous because it ensures that fresh cooling fluid flows through the antenna. Coolant return conduit 167 receives coolant flowing from cooling chamber 163. By flowing cooling fluid through the cooling chamber in this manner, at least a portion of the heat generated by the antenna and / or feeder lines may be dissipated.

[0137] Figure 1b Another embodiment of the ablation device according to the present invention is shown. Figure 1b The device 100 shown in FIG. 1 includes a coaxial feed line 110 having a Figure 1a Describes the same component.

[0138] The device also includes an asymmetric dipole antenna 120 having a spiral arm 118, in this case formed from a metal strip as described herein, with its distal end 500 electrically connected to the outer conductor 106 of the feed line 110 at a junction 117. The spiral arm 118 extends proximally around the feed line 110 in a series of turns from the junction 117. The strip of the spiral arm is embedded in a bonding matrix 170, which bonds the strip to the outer insulator 108 of the feed line and protects it from damage during the manufacturing process. The antenna 120 also includes a linear arm 119. The linear arm 119 is electrically connected to the inner conductor 102 of the feed line 110. The linear arm 119 extends distally from the distal end of the inner conductor 102 and includes a first portion 131 surrounded by a dielectric 135 and a second portion 133 without a dielectric. As shown in FIG. Figure 1 As shown, the linear arms are spaced apart from the base 134 of the applicator cap 130 .

[0139] according to Figure 1 The antenna, antenna and feed line are contained within a shaft (shown simplified in this figure) that terminates distally in a pointed metal or ceramic applicator cap for tissue penetration.

[0140] A cooling system is provided that is configured to circulate a coolant over at least a portion of an antenna and a feeder line. The cooling system includes a pair of cooling pipes 171, 172, each arranged around a portion of the feeder line and a spiral portion of the antenna and coaxial therewith. Each pipe is in the form of a spiral, and the two pipes are staggered with each other to form a double spiral. The coolant is delivered to the inlet of the first pipe 171 through the coolant inlet pipe 173. The coolant passes through the first cooling pipe 171, passes through the antenna and the feeder line, and exits from the outlet hole 174 into the coolant mixing chamber 175, where the coolant immerses the rest of the antenna (in this case, the linear arm) until the antenna cover base 134. The coolant then enters the coolant return pipe 172 via the coolant return hole 176, passes through the coolant return pipe, returns via the coolant return pipe 172, and leads to the coolant return pipe 177. The spiral cooling channels 171, 172 are separated by proximal and distal walls 178, 900, which form a pair of spiral dividing strips extending perpendicularly from the inner surface 160 of the shaft 114 and extending distally in a double helix, thereby forming two spiral channels 171, 172 between them. The innermost end 179 of the dividing strip seals the matrix 170 of strips around the antenna to form two spiral channels.

[0141] Figure 1c Another embodiment of the ablation device according to the present invention is shown. Figure 1c The device 100 shown in FIG. 1 includes a coaxial feed line 110 having a Figure 1a The same components as described.

[0142] The device includes an asymmetric dipole antenna 120 having a helical arm 118 formed of a metal strip attached, for example, by an adhesive (not shown), to an outer insulator 108. The distal end 500 of the helical portion makes electrical connection with the outer conductor 106 of the feed line 110 at a junction 117. The helical arm 118 extends proximally from the junction 117 around the feed line 110 in a series of helical turns.

[0143] Antenna 120 also includes a linear arm 119. Linear arm 119 is electrically connected to inner conductor 102 of feed line 110. Linear arm 119 extends distally from the distal end of inner conductor 102 and includes a first portion 131 surrounded by dielectric 135 and a second portion 133 without dielectric. The linear arm does not contact applicator cap 130.

[0144] The cooling chamber 163 surrounds the feed line 183 and the antenna 120. The cooling chamber is defined between the inner wall 160 of the shaft 114 and the antenna 120 and feed line 183 and the base 134 of the applicator cap 130. The device includes a cooling tube 182, which is coaxial with the feed line 110 and the antenna 120 and extends distally to a point toward the end of the linear arm of the antenna 184. The cooling tube 182 divides the cooling chamber 163 into a first cooling conduit 180, which is coaxial with the distal portion of the feed line 183 and extends over the helical portion 118 and the linear portion 119 of the antenna 120, and a second cooling conduit coaxial with the first cooling conduit and extends between the outer wall of the cooling tube 182 and the inner wall 160 of the sheath 114. The cooling tube 182 and the first and second conduits are open at the distal end, allowing a cooling fluid to circulate through a cooling fluid mixing chamber 185 between the base 134 of the applicator cap 130 and the distal end of the cooling tube 182. The first and second cooling ducts cooperate to provide circulation of coolant over the antenna. The first cooling duct may be coolant inflow and the second cooling duct may be coolant outflow, or vice versa. This arrangement of cooling ducts allows cooling of the antenna to the end.

[0145] Figure 1d A further embodiment of an ablation device according to the present invention is shown. Figure 1d The device 100 shown in FIG. 1 comprises a coaxial feed line 110 having an inner conductor 102, a first insulator 104 arranged concentrically around the inner conductor 102, and an outer conductor 106 arranged concentrically around the first insulator 104. The feed line is shown without an outer insulating layer and is thus in contact with a coolant in use.

[0146] The device includes an asymmetric dipole antenna 120 having a spiral arm 118, which is formed of a wire in this example, but can also be in the form of a ribbon. Antenna 120 also includes a linear arm 119. Linear arm 119 is electrically connected to the inner conductor 102 of feed line 110. Linear arm 119 extends distally from the distal end of feed line inner conductor 102 and includes a first portion 131 surrounded by a dielectric 135 and a second portion 133 without a dielectric. Figure 1 As shown, the linear arms do not contact the applicator cap 130 .

[0147] A cooling chamber 163 is defined between the inner surface 160 of the shaft 144 and the base 134 of the applicator cap 130 and surrounds the antenna 120. The distal portion of the feed line and the antenna are located within the cooling chamber 163. The device includes a cooling tube 182 that is coaxial with the feed line 110 and extends distally to a point toward the distal end 184 of the antenna linear arm 119. The cooling tube 182 divides the cooling chamber 163 into a first cooling duct 180 that is coaxial with the distal portion of the feed line 183 and extends over the linear portion 119 of the antenna 120 and a second cooling duct 181 that is coaxial with the first cooling duct 180 and extends between the outer wall of the cooling tube 182 and the inner wall 160 of the shaft 114. The cooling tube 182 and the first and second conduits are open at the distal end, thereby allowing cooling fluid to circulate through a cooling fluid mixing chamber 185 between the base 134 of the applicator cap 130 and the distal end 186 of the cooling tube 182 .

[0148] The spiral arm 118 of the antenna 120 is wound on the outer surface of the cooling tube. The distal end 500 of the spiral arm 118 is electrically connected to the outer conductor 106 of the feed line 110 at the junction 117. The spiral arm 118 extends proximally from the junction 117 around the feed line 110 in the form of a series of spiral turns on the surface of the cooling tube. The first cooling duct and the second cooling duct cooperate to provide circulation of the coolant on the antenna. The first cooling duct can be a coolant inflow and the second cooling duct can be a coolant outflow, or vice versa. This allows cooling of the antenna to the end.

[0149] Figure 2a-2d A schematic diagram of the distal portion of a microwave tissue ablation device is shown, and four embodiments of the relationship between the metal cover and the distal end of the antenna and the cover 202 are shown.

[0150] Figure 2aA schematic diagram of a microwave tissue ablation device 200 having a metal cover 202 according to one embodiment of the present invention is shown. The metal cover 202 is conical and has a circular base 203. A solid cylindrical protrusion 204 is suspended from the base 203 and has a base 214, and the cover has a shoulder 205 that allows the cover 202 to be inserted into the distal end of the device shaft 206, which can be metal or ceramic. The cover can be fixed to the shaft by an adhesive (not shown). The microwave tissue ablation device 200 also includes an asymmetric dipole antenna 207, which is shown in a simplified form here and discussed in detail elsewhere in this article. The antenna includes a spiral arm 211 and a linear arm 208. The linear arm has a proximal portion 209 surrounded by a dielectric 212 and a free distal portion 210 without a dielectric. The distal portion of the linear arm 210 has a tip 213, which is separated from the cover by a distance Hg. Adjusting the distance between the tip 213 and the cap changes the degree to which the metal cap electromagnetically couples to the antenna, which changes the shape of the energy emission field and thus the shape of the ablation zone (see also Figures 8A-8C ).

[0151] Figure 2b Another embodiment is shown. A microwave tissue ablation device 225 includes a metal cap 226 that is conical and has a circular base. The metal cap 226 includes a base 227 from which a hollow cylindrical protrusion 228 depends downwardly. The cap has a shoulder 231 that allows the cap 226 to be inserted into the distal end of the device shaft 232. The cap can be secured to the shaft by an adhesive (not shown). The microwave tissue ablation device 225 also includes a Figure 2a An asymmetric dipole antenna 229 having the characteristics described in.

[0152] like Figure 2b As shown, a gap H is provided between the proximal end of the hollow cylindrical protrusion 228 and the distal end 230 of the asymmetric dipole antenna. g 229.

[0153] Figure 2c 2 is a schematic diagram of a microwave tissue ablation device 235 having a metal cover 236 according to an embodiment of the present invention. The metal cover 236 is a round-bottomed cone having a base 237. The microwave tissue ablation device 225 also includes a Figure 2a An asymmetric dipole antenna 239 having the same features as described in.

[0154] The metal cap 236 is fixed directly to the distal end 240 of the device shaft 241. The distal end of the linear arm of the antenna 239 is a distance H from the base of the cap 236. g 238. Gap H g 238 is axially disposed between the proximal end of the base 237 and the distal end of the asymmetric dipole antenna 239 .

[0155] Figure 2d2 is a schematic diagram of a microwave tissue ablation device 245 having a metal cap 246 according to one embodiment of the present invention. The metal cap 246 is conical and has a circular base 248. A cylindrical protrusion 249 depends downwardly from the center of the circular base 247, forming a shoulder 248 that allows the cylindrical protrusion to be inserted into the distal end of the device shaft 255. A blind ending cylindrical void or pocket 250 is formed at the center of the base of the cylindrical protrusion, which is configured to receive a length Hp 259 of a distal portion 252 of the antenna linear arm, which is axially and radially spaced from the wall 258 of the void 250.

[0156] Other features of the antenna are Figure 2a Described in.

[0157] Figure 3 is a perspective view of a microwave tissue ablation device 300 having a handle 305 according to one embodiment of the present disclosure.

[0158] The microwave tissue ablation device 300 includes a handle 305. The handle 305 is configured to provide a surgeon with a more secure grip to manipulate the tissue ablation device 300. The handle is further configured to house a fluid manifold for coolant circulation and a coaxial connector for supplying power to a feed line.

[0159] The microwave tissue ablation device 300 includes a probe 307. The probe 307 is configured to be inserted into a patient's body to heat the target tissue. In one embodiment, the probe 307 includes Figure 1 And all components of the ablation device 100 shown in 1a to 1d, such as the feed line, the asymmetric dipole antenna, the cooling system with the inflow tube and the coolant outflow tube, etc.

[0160] The probe 307 includes a surface 315. The surface 315 is configured to contact human tissue and is made of a biocompatible material. The device shaft 315 is at least partially metal, such as stainless steel, and includes markings 311, such as laser markings. The markings 311 are configured to inform the surgeon of the depth of penetration of the probe into the body. It may include a smooth surface layer, such as PTFE, to aid insertion and prevent tissue from adhering thereto.

[0161] Probe 307 also includes a trocar tip 330. In one embodiment, trocar tip 330 may be, for example Figures 1 to 1d , Figure 2a -d or Figures 4A-4B Applicator cap 130 is shown.

[0162] The probe 307 also includes an echogenic region 325 that extends over at least the region of the probe surrounding the antenna. The echogenic region 325 is configured to be visible under ultrasound imaging and, in one embodiment, includes a coating having acoustically reflective microspheres.

[0163] The probe 307 also includes a region 320 configured to relieve stress induced on the probe during use, such as stress caused by the flexure of the shaft. As described above, this stress relief region is particularly useful when the distal portion of the probe sheath is ceramic. The stress relief region 320 is configured to provide increased flexibility for the probe 307 to avoid fracture of the probe 307 during medical operation.

[0164] The microwave tissue ablation device 300 includes a housing 310. The housing 310 accommodates coaxial cables, fluid lines, electrical wires, and the like.

[0165] Figure 4A is a stereoscopic view of a microwave tissue ablation device 400 according to an embodiment of the present disclosure. Figure 4B is a cross-sectional view along line XY to illustrate one embodiment of a cooling feature.

[0166] The tissue ablation device has a shaft 401 having a metal portion 445 and a ceramic portion 402. The ceramic portion extends from a distal end 406 of a collar 405 to a base 441 of a cap 440. The ceramic portion is shown displaced to show internal features of the device.

[0167] The tissue ablation device 400 includes a resilient element 405 and an adapter 410 that joins the metal portion 445 of the shaft to the ceramic portion 402. In the device of the present invention, the adapter accounts for the difference in shaft thickness between the two portions and additionally serves to reduce flexure between the metal portion 445 and the ceramic portion. In the device of the present invention, as shown here, a resilient annular spacer between the ceramic and metal portions of the shaft serves to provide elasticity to this area, thereby reducing the risk of fracture at this point due to stress on the shaft during use.

[0168] The tissue ablation device 400 may include a temperature sensor 450 positioned beside the internal adapter 410 and having an electrical connection 451 to the control unit via the hub.

[0169] The tissue ablation device 400 has an antenna 452 that includes a spiral arm 412 and a linear arm 420. The distal end 435 of the spiral arm 412 is electrically connected to the outer conductor 430 of the feed line 432 at a junction 436. The spiral arm 412 extends proximally from the junction 436 around the feed line 432 in a series of turns. Other than the junction 436, the spiral arm 412 does not make other electrical contacts with the inner conductor 427 or the outer conductor 430. The spiral arm is wrapped around a tube 426 that extends from a hub (not shown) through a metal portion 445 of the shaft to the end 428 of the antenna. The electrical connection between the spiral arm 412 of the antenna and the outer conductor of the feed line 432 passes through the tube at the junction 436. The spiral arm 412 has a length (Lha), the size of which is discussed elsewhere herein.

[0170] The tube 426 defines a first cooling duct 448 between the inner wall 454 of the tube 426 and the feeder 432, and a second cooling duct 460 between the outer wall 455 of the tube 426 and the inner wall 453 of the shaft. The cooling fluid can be pumped through the space between the tube 426 and the feeder 432 to the mixing chamber 429 between the tube 426 and the cover 440, and back to the space between the outside of the tube 426 and the ceramic portion of the shaft, through the space 411 between the inside of the shaft and the adapter 410, down the shaft 445 and back to the hub.

[0171] The linear arm 420 is an extension of the inner conductor 427 of the feed line 432 and is surrounded by a dielectric layer 425 except for a distal portion 423 which is free of dielectric.

[0172] The linear arm 420 of the asymmetric dipole antenna has a length L1a. The linear arm comprises a first portion L1 421 coated with an insulator, which is an extension of the first dielectric layer where the feed line 432 is arranged between the inner conductor 427 and the outer conductor 430, not visible in this view.

[0173] The linear arm 420 also includes a second portion 423 having a length L2 422 and not coated with an insulator. In one embodiment, the second portion L2 422 is exposed to the circulating coolant.

[0174] Device 400 includes a trocar tip 440. In one embodiment, trocar tip 440 may be Figure 1 The applicator cap 130 shown, Figure 2a-2d The metal cover shown in Figure 3 The trocar tip 330 is shown in FIG. The trocar tip 440 may be made of stainless steel and / or ceramic.

[0175] Figure 5 500 is a side view of a microwave tissue ablation device 500 of the present invention. The ablation device 500 includes a handle 501. The handle 501 accommodates a manifold 505.

[0176] Manifold 505 is electrically connected to a power source (not shown) and tissue ablation probe 530 via coaxial cable connector 515. Tissue ablation probe 530 includes markings 535 configured to inform the surgeon of the probe penetration depth during the procedure.

[0177] The manifold 505 also fluidly connects a coolant source (not shown) and a tissue ablation probe 530. The manifold 505 includes a coolant inlet 520 and a coolant outlet 525. The coolant inlet 520 is fluidly connected to a coolant inflow conduit, and the coolant outlet 525 is fluidly connected to a coolant outflow conduit.

[0178] Tissue ablation device 500 also includes a tubular housing 540 that houses electrical wires and fluid tubes.

[0179] Fig. 6A and 6B The results compared the echogenic coating (6A) with the echogenic coating ( Figure 6B ). The echogenic coating provides additional assistance in accurately placing the tissue ablation probe in the patient's tissue.

[0180] Fig. 7A Graph 1 is an energy absorption spectrum of a tissue ablation probe according to an embodiment of the present disclosure. Fig. 7A The x-axis is frequency (GHz). Fig. 7A The y-axis is energy absorption (dB). Fig. 7A Energy absorption at different microwave frequencies is shown. Fig. 7A Mark 1 in the figure shows a microwave frequency of 2.12158 GHz; the energy absorption by the surrounding tissue is -27.951 dB. Fig. 7A Mark 2 in the figure shows a microwave frequency of 2.40553 GHz; the energy absorption by the surrounding tissue is -27.951 dB. Fig. 7A Mark 3 in the figure shows a microwave frequency of 2.48694 GHz; the energy absorption by the surrounding tissue is -27.951 dB. Fig. 7A Marker 4 in the figure shows a microwave frequency of 2.63119 GHz; the energy absorption by the surrounding tissue is -13.276 dB.

[0181] Figure 7B is a picture showing the energy emission field of a tissue ablation probe according to one embodiment of the present disclosure. Figure 7B The ablation device tested in has an asymmetric dipole antenna with a 1 mm gap between the distal end of the linear arm of the tissue ablation device and the proximal end of the metal cover. Figure 7B The division grid shown in is 10 mm x 10 mm.

[0182] Figure 7C is a picture showing the energy emission field of a tissue ablation probe according to one embodiment of the present disclosure. Figure 7C The ablation device tested in had an axial overlap distance of 1.5 mm between the distal portion of the linear arm of the asymmetric dipole antenna and the proximal portion of the metal cover. Figure 7C The division grid shown in is 10mm x 10mm.

[0183] Fig. 8A FIG. 1 is a diagram showing the ablation effect of a tissue ablation probe according to an embodiment of the present disclosure on a bovine liver. The animal tissue was heated at 40 W for 4 minutes. The ablation size was 2.5 cm x 2.5 cm.

[0184] Figure 8B FIG. 1 is a diagram showing the ablation effect of a tissue ablation probe according to an embodiment of the present disclosure on a bovine liver. The animal tissue is heated at 40 W for 10 minutes. The ablation size is 3.7 cm×3.7 cm.

[0185] Figure 8C FIG. 1 is a diagram showing the ablation effect of a tissue ablation probe according to an embodiment of the present disclosure on a bovine liver. The animal tissue was heated at 100 W for 10 minutes. The ablation size was 5.0 cm x 5.2 cm.

[0186] Fig. 9 A method 1000 of using a microwave ablation device according to one embodiment of the present disclosure is provided.

[0187] Method 1000 includes a step 1005 of preparing a console, wherein the console connects the microwave tissue ablation device to a power source and a coolant source. In one embodiment, the console can support more than one microwave tissue ablation device. For example, one console can support three or four tissue ablation devices, thereby providing sufficient power and coolant supply to each tissue ablation device.

[0188] Method 1000 includes step 1010 of preparing a microwave tissue ablation device, wherein the microwave tissue ablation device includes an asymmetric dipole antenna. The microwave tissue ablation device in method 1000 may be Figure 1-7C The microwave tissue ablation device is shown.

[0189] Step 1010 may also include collecting other necessary supplies; obtaining sterile saline / water at room temperature; obtaining an IV stand; placing the IV stand close to the operating table; identifying the target tissue location; Determine the number of microwave tissue ablation devices required; obtain the required microwave tissue ablation devices from warehouse; obtain temperature probes from warehouse; unpack the microwave tissue ablation devices; insert the manifold into the console; connect the saline / water source to the manifold connector; lock the perfusate to the console, etc.

[0190] Method 1000 includes step 1015 of activating a control console and a microwave tissue ablation device.

[0191] Step 1015 may also include confirming that the pump is working; confirming that the temperature of the water / saline is operational; confirming that the coolant is circulating properly within the microwave tissue ablation device; confirming that the asymmetric dipole antenna of the microwave tissue ablation device is operational; operating the pump for a period of time to prepare the pump and the microwave tissue ablation device; inserting the distal portion of the tissue ablation device into the water; and the like.

[0192] Method 1000 includes step 1020 of bringing a microwave tissue ablation device into proximity with target tissue under ultrasound visual guidance.

[0193] Step 1020 may also include starting an ultrasound imaging system (the ultrasound imaging system can be 2D or 3D); inserting a microwave tissue ablation device into the patient's body under ultrasound visual guidance; securing the microwave tissue ablation device with a fixation device to prevent accidental movement of the device in the patient's body; securing cables and tubes attached to the microwave tissue ablation device to prevent unwanted torque; positioning a temperature sensor at a desired location; performing a CT scan to verify the position of the microwave tissue ablation device and the target tissue; and repeating any steps as needed if the position of the microwave tissue ablation device is not ideal.

[0194] The method 1000 includes a step 1025 of activating a microwave tissue ablation device to emit microwaves to heat the target tissue.

[0195] Step 1025 may also include selecting parameters for ablation, wherein the parameters include organ type, organ size, output power and / or output time; conducting the necessary electricity to the microwave tissue ablation device to heat the target tissue. Note that the steps listed in method 1000 are not in order.

[0196] Fig.10 A cross section of one embodiment of a device shaft 1200 is shown. The proximal end is indicated by A and the distal end is indicated by B. Other features such as coaxial cables, antennas, and cooling systems are omitted for clarity. The shaft has a proximal metallic portion 1201 and a distal non-metallic portion, which is preferably made of ceramic 1202. The shaft includes a stress relief region 1216 having an elastic element 1203 located between the metallic and non-metallic portions of the shaft and an adapter sleeve 1214 radially inward of the elastic element 1203.

[0197] The resilient element comprises a resilient annular gasket 1204 shaped and configured to space the proximal end of the non-metallic portion 1205 from the distal end of the metal portion 1206. The gasket is configured to abut the metal portion at a proximal side 1207 and to abut the non-metallic portion at a distal side 1208. The gasket extends radially outward to form a surface 1209 that is flush with the outer surface of the probe shaft 1210. The radially innermost portion 1211 of the annular gasket extends proximally to provide an annular step 1212 that is configured to support the inner surface of the distal end of the metal portion 1213. An adapter sleeve 1214 extends on each side of the joint between the metal and non-metallic portions and extends radially inward of the annular gasket 1203. Preferably, the sleeve extends proximally of the annular gasket 1203 and is configured to contact and support the inner surface of the distal end of the shaft metal portion 1213. The sleeve extends distally of the spacer 1203 and is configured to contact and support the inner surface of the proximal end of the shaft ceramic portion 1215 .

[0198] While the invention is susceptible to various modifications and alternative forms, certain specific embodiments thereof have been shown by way of example in the drawings. The drawings may not be drawn to scale.

Claims

1. A microwave ablation probe, comprising: A feeder line having an inner conductor, an outer conductor and a dielectric disposed therebetween; antenna; and a shaft, wherein the antenna and the feed line are disposed within the shaft; wherein the shaft comprises a metal portion and a ceramic portion, the ceramic portion extending axially to be at least coextensive with the antenna, and wherein the antenna comprises: a helical arm having a distal end electrically connected to the outer conductor of the feed line at a junction, the helical arm being coaxially disposed about the feed line and extending in a proximal direction from the junction; and a linear arm electrically connected to the inner conductor of the feed line, the linear arm extending distally from the distal end of the feed line, the linear arm further comprising: a first portion surrounded by the dielectric, and A second portion is free of dielectric, the second portion being distal to the first portion. 2 . The microwave ablation probe according to claim 1 , further comprising a cooling system configured to flow a cooling fluid through at least a portion of the feed line or through the antenna. 3 . The microwave ablation probe of claim 2 , wherein the cooling system comprises a cooling chamber defined between inner walls of a device shaft and a cooling tube arranged around the feed line.

4. The microwave ablation probe according to claim 3, wherein the cooling tube divides the cooling chamber into a first cooling pipe and a second cooling pipe, the first cooling pipe is arranged between the feed line and the inner wall of the cooling pipe, and the second cooling pipe is arranged between the outer wall of the cooling pipe and the inner wall of the device axis. 5 . The microwave ablation probe according to claim 3 , wherein the cooling tube extends over a distal portion of the feed line and extends distally around at least a portion of the antenna. 6 . The microwave ablation probe according to claim 3 , wherein the cooling tube is coaxial with the feed line or the cooling tube extends axially to the end of the linear arm of the antenna or extends beyond the end of the linear arm of the antenna.

7. The microwave ablation probe of any one of claims 3 to 6, wherein the helical arm of the antenna is wrapped around the cooling tube and extends proximally from the junction in a series of turns around the cooling tube.

8. The microwave ablation probe of any one of claims 3 to 6, wherein the helical arm of the antenna is wound around the feed line and extends proximally from the junction in a series of turns around the feed line.

9. The microwave ablation probe according to any one of claims 1 to 8, wherein the spiral arm of the antenna is a ribbon. 10 . The microwave ablation probe according to claim 1 , wherein the length of the spiral arm is 1 to 18 mm, preferably 4 to 14 mm, or 1 to 14 turns.

11. The microwave ablation probe according to any one of claims 1 to 10, wherein the length of the second portion of the linear arm is 0.1 to 2 mm.

12. The microwave ablation probe according to any one of claims 1 to 11 comprising a metal cover.

13. The microwave ablation probe of claim 12, wherein the linear arms of the antenna are electromagnetically coupled to the metal cover but are not connected to the cover.

14. The microwave ablation probe according to claim 12 or 13, wherein the distal tip of the antenna is separated from the cover by a distance of 0.2 mm to 3 mm.

15. A microwave ablation system, comprising: One or more microwave ablation probes according to any one of claims 1 to 14; a power module configured to provide microwave energy to each microwave ablation probe or its microwave antenna; as well as One or more power cables are configured to connect the power modules to the microwave antennas and deliver microwave energy provided by the power modules to the antennas to ablate tissue.

Images