Microwave Ablation Probe

Abstract

A microwave ablation probe (100; 200; 300; 400; 500) comprising: a dipole antenna (106; 206; 306; 406; 506) configured to emit microwave radiation to heat surrounding tissue; and a feed cable configured to supply electromagnetic energy to the dipole antenna, the feed cable comprising a coaxial cable having an inner conductor (108; 208; 308; 408; 508) and an outer conductor (110; 210; 310; 410; 510) with a dielectric (112; 212; 312; 412; 512) therebetween. The dipole antenna (106; 206; 306; 406; 506) comprises a first antenna portion (106a; 206a; 306a; 406a; 506a) that forms a first pole of the dipole antenna and a second antenna portion (106b; 206b; 306b; 406b; 506b) that forms a second pole of the dipole antenna. The first antenna portion (106a; 206a; 306a; 406a; 506a) comprises one or more antenna elements (116a-i; 216a-i; 316a-i; 416a-h; 516a-h), each integrally formed with the outer conductor (110; 210; 310; 410; 510) and comprising an outwardly extending portion (117a) extending away from the longitudinal axis of the feed cable and folded back over the insulator (118; 318; 418; 518) to form an overlapping portion (117b) extending proximally along the length of the feed cable. The first antenna portion (106a; 206a; 306a; 406a; 506a) further comprises antenna insulation (118; 318; 418; 518) between the overlapping portions of each of the one or more antenna elements and the portions of the outer conductor they overlap.

Description

[Technical Field]

[0001] This application relates to microwave ablation probes and methods of manufacturing ablation probes. In particular, this application relates to antennas for ablation probes that can be used to generate heat in tissue to destroy tissue growth. [Background technology]

[0002] Thermal ablation can be used to destroy tissue growths in the body that may be malignant. Current ablation systems use applicators that deliver radio frequency (RF) energy, or more specifically, microwave energy, to the tissue surrounding the applicator tip. This results in localized heating and destruction of malignant cells.

[0003] Known ablation probes generally include an active tip (or applicator) made of a ceramic material coupled to a coaxial feed cable configured to deliver electromagnetic energy to the active tip, the inner conductor of which extends through the ceramic material to form a monopole antenna with the ceramic material that acts as a resonator.

[0004] When microwaves are applied to heat the surrounding tissue, it is advantageous to create a spherical ablation zone around the applicator where the tissue is ablated. This helps ensure that the ablation can be directed more precisely to the relevant tissue. To create a spherical ablation zone, a dipole antenna can be used. Such an antenna can have two antenna portions that radiate radiation from their central point. Summary of the Invention [Problem to be solved by the invention]

[0005] Designing a dipole antenna for an ablation probe is challenging due to the limited space available for components in a device that is small and flexible enough for insertion into the body, and the need to produce a stable, spherical ablation zone within these design constraints. The present application provides an ablation probe having an antenna that aims to overcome one or more of these challenges. [Means for solving the problem]

[0006] One aspect of the present disclosure provides a microwave ablation probe having any one or more of the following features: a dipole antenna configured to emit microwave radiation to heat surrounding tissue; and 1. A feeder cable configured to supply electromagnetic energy to a dipole antenna, the feeder cable comprising a coaxial cable having an inner conductor, an outer conductor and a dielectric therebetween, wherein: the dipole antenna comprises a first antenna portion forming a first pole of the dipole antenna and a second antenna portion forming a second pole of the dipole antenna; the first antenna portion comprises one or more antenna elements each integrally formed with the outer conductor and each having an outwardly extending portion extending away from the longitudinal axis of the feed cable and an overlapping portion extending proximally along the length of the feed cable; and The first antenna portion further comprises antenna insulation between the overlapping portions of each of the one or more antenna elements and the portions of the outer conductor they overlap.

[0007] Forming the antenna element integrally with the outer conductor in this manner may provide one or more of the following advantages: The electrical continuity between the antenna element and the outer conductor may be improved, which may improve the electrical performance of the ablation probe. Fewer components need to be manufactured and assembled to produce the antenna. It is easy to expose the cable dielectric without damaging it, which may also improve electrical performance and aid manufacturing. Using a portion of the outer conductor to form the antenna element helps avoid the need for machining of conductive antenna components, simplifying the manufacturing process. The flexibility of the ablation probe may be improved in the antenna, which may be particularly useful for delivery through an intraluminal delivery device. A small profile can also be achieved, which is advantageous for insertion into a working channel or into tissue. Numerous clinical advantages may also be achieved: for example, increased flexibility may allow access to difficult-to-reach anatomical structures, such as the periphery of the lung, a smaller profile may reduce tissue trauma, and improved electrical performance may allow for more stable and / or more spherical ablation zones to be precisely created in the target tissue.

[0008] The outer conductor may be a braided outer conductor. The braided outer conductor may comprise a plurality of braided wire strands. Each antenna element may be formed from one or more wire strands. The antenna elements may be formed by unbraiding a portion of the cable and reusing the strands that form the braid to be integrally formed with the outer conductor.

[0009] The wire strands forming the antenna element may be overlapped or interwoven together such that the first antenna portion is formed by a re-braided (or at least partially re-braided) portion of the outer conductor. The outer conductor may be unbraided and then at least partially re-braided to form the first antenna portion.

[0010] The outer conductor may comprise a solid conductive sheath or tube of material that surrounds the dielectric.

[0011] The antenna elements of the first antenna portion may each be formed by a portion of a solid conductive sheath shaped to form the outwardly extending and overlapping portions of the antenna element, respectively. The solid conductive sheath may be cut to form separate antenna elements that are integral with the sheath. For example, the solid sheath may be cut to form strips of material that can be formed into the antenna elements. Cutouts of material may be removed between the strips to allow the sheath to be more easily bent to the desired shape.

[0012] The first antenna portion may comprise at least two antenna elements, which may be circumferentially spaced (preferably equally spaced) around the feed cable.

[0013] The overlapping portions of the antenna elements may extend along a helical path along the longitudinal axis of the ablation probe, for example, they may extend helically around the outer surface of the antenna insulator.

[0014] The second antenna section is: an inner conductor extending distally along the length of the ablation probe beyond the antenna element of the first antenna portion; and A dielectric resonator having an inner conductor extending therethrough. The device may also include:

[0015] The proximal end of the dielectric resonator may be spaced apart from the antenna element of the first antenna portion along the length of the inner conductor to form a flexible hinge region therebetween that may allow the ablation probe to bend preferentially at that location along the length of the probe.

[0016] The microwave ablation probe may further comprise a catheter tube in which (at least part of) the coaxial cable and the antenna are located, the catheter tube therefore forming part of the feed cable.

[0017] The region of the catheter tube surrounding or adjacent to the antenna may be formed from a polymeric material and free of conductive components, which may help to make it transparent to microwave propagation and therefore not affect ablation in the surrounding tissue.

[0018] The entire length of the catheter tubing may be formed from a polymeric material and may not include conductive components, which may avoid the need to join sections of tubing made from different materials.

[0019] The polymeric material may include any one or more of the following: i) fluorinated polymers or fluoroelastomers, such as polymers such as fluorinated ethylene propylene (FEP) and / or polytetrafluoroethylene (PTFE); and / or ii) Polymer (e.g. PEEK) reinforced laminate tubing.

[0020] These materials may provide the desired level of flexibility and durability for the catheter tube where it will be stressed during use by high temperatures, pressures, and insertion and withdrawal forces, while also being transparent to microwave radiation.

[0021] The dielectric resonator may include a plurality of (e.g., radially extending) resonator protrusions, which may extend from an outer surface of the dielectric resonator.

[0022] The catheter tube may be spaced from the outer surface of the dielectric resonator by a plurality of resonator protrusions.

[0023] The resonator protrusion can be positioned to position the catheter tube concentrically with the dielectric resonator.

[0024] The first antenna portion may include a plurality of antenna elements, and the antenna insulation may include a plurality of (e.g., radially extending) insulation protrusions (e.g., insulation fins) extending between the antenna elements.

[0025] The insulator protrusions can be positioned to position the catheter tube concentrically with the antenna insulator.

[0026] The microwave ablation probe may further comprise one or more coolant channels between the resonator protrusions and / or between the insulator protrusions.

[0027] The antenna insulator may form a flexible region of the ablation probe.

[0028] The antenna insulator may comprise: a) a solid flexible material; or b) a plurality of rigid beads.

[0029] The antenna insulation may allow the flow of coolant therethrough. The antenna insulation may include one or more coolant channels extending therethrough to allow the coolant to pass through the antenna.

[0030] The antenna insulator may have one or more air gaps (e.g., air-filled cavities) and may be formed from a ribbed polymer having one or more air gaps, which may serve to improve the flexibility of the insulator and to improve the electrical insulation provided by the insulator.

[0031] The ablation probe may comprise a multi-lumen extrusion or tubing (e.g., the feed cable may comprise a multi-lumen extrusion), and the antenna insulator may be formed from a portion of the multi-lumen extrusion.

[0032] The multi-lumen extrusion may be a tube with multiple lumens formed from a single, unitary extrusion of material (e.g., a polymeric material). Forming the antenna insulation from a portion of the multi-lumen extrusion may reduce the number of components required.

[0033] The multi-lumen extrusion may include a central inner lumen defined by an inner extrusion wall. The coaxial cable may be disposed in the central inner lumen. A portion of the inner extrusion wall may form an antenna insulator.

[0034] The multi-lumen extrusion may further comprise one or more outer lumens. The outer lumens may be defined by an outer wall of the inner extrusion wall, an outer extrusion wall, and, optionally, one or more radially extending extrusion walls. An overlapping portion of the antenna member may be positioned in the outer lumen. The outer extrusion wall may form a catheter tube as described in any of the above descriptions.

[0035] One or more of the outer lumens may be arranged to carry a coolant flow along the length of the ablation probe. A first outer lumen may be arranged to carry a coolant flow distally along the ablation probe, and a second lumen may be arranged to carry a coolant flow proximally along the length of the ablation probe. This may allow a coolant circuit to be formed for cooling the antenna.

[0036] The overlapping portions of one or more antenna elements may be embedded within an antenna insulator.

[0037] The overlapping portions of one or more antenna elements may be crimped around the insulator.

[0038] The first antenna portion may further comprise a heat shrink sleeve positioned to surround and hold the overlapping portion of the one or more antenna elements around the antenna insulation.

[0039] The first antenna portion may further comprise a wire (eg, a polymeric or metallic wire) arranged to surround and hold the overlapping portion of the one or more antenna elements around the antenna insulation.

[0040] The first antenna portion may further comprise one or more radiopaque marker bands positioned to surround and retain the overlapping portions of the one or more antenna elements around the antenna insulation.

[0041] The first antenna portion may further include one or more conductive bands arranged to surround and hold the overlapping portions of the one or more antenna elements around the antenna insulator. The bands may be formed from strips of conductive material that extend around the antenna insulator and overlapping portions to hold them in place. The conductive bands may be formed by rings of solder around the antenna elements.

[0042] The antenna insulator of the first antenna portion may include one or more recesses in its surface, each recessed to receive a respective one of the antenna elements, which may help to hold the antenna elements in place.

[0043] The first antenna portion may include an adhesive disposed to hold the overlapping portions of the one or more antenna elements around the antenna insulation.

[0044] According to a second aspect, there is provided a method of manufacturing an ablation probe, the ablation probe comprising: a dipole antenna configured to emit microwave radiation to heat surrounding tissue, the dipole antenna comprising a first antenna portion forming a first pole of the dipole antenna and a second antenna portion forming a second pole of the dipole antenna; and A feeder cable comprising a coaxial cable arranged to feed electromagnetic energy to a dipole antenna. This method includes: providing a coaxial cable comprising an inner conductor, an outer conductor and a dielectric therebetween; forming a first antenna portion by shaping a portion of the outer conductor such that one or more antenna elements are formed, each antenna element comprising an outwardly extending portion of the outer conductor extending away from the longitudinal axis of the feed cable and an overlapping portion of the outer conductor extending proximally along the length of the coaxial cable; and providing an insulator between the overlapping portions of one or more antenna elements and the portions of the outer conductor where they overlap; Includes:

[0045] The outer conductor may comprise a plurality of braided conductive wire strands. The steps of forming the antenna element of the first antenna portion include: unbraiding a portion of the braided strands of the outer conductor of the coaxial cable; and shaping the unbraided strands to form one or more antenna elements of the first antenna portion; may also include:

[0046] The outer conductor may comprise a solid conductive sheath or tube of material around the dielectric body. The steps of forming the antenna element of the first antenna portion include: cutting the sheath or tube to form one or more bands integrally formed with the remainder of the cut-out outer conductor material; and Shaping each of the one or more strips to form one or more antenna elements of the first antenna portion. may also include:

[0047] Cutting the sheath may include laser cutting the sheath.

[0048] The ablation probe produced by the method of the second embodiment may be the ablation probe of the first embodiment.

[0049] Any feature described above in connection with one embodiment or description may be used in combination with any other embodiment or description, unless the features are mutually exclusive.

[0050] As used herein, ranges such as "from value X to value Y" or "between value X and value Y" refer to inclusive ranges that include the bounds X and Y. Angles are given in degrees unless otherwise specified.

[0051] Embodiments of the present invention will now be described, by way of example only, with reference to the accompanying drawings, in which: [Brief explanation of the drawings]

[0052] [Figure 1] FIG. 1 shows a schematic diagram of an ablation probe according to an embodiment. [Figure 2] FIG. 2 shows a cross-sectional view of the antenna of the ablation probe shown in FIG. [Figure 3] Figure 3a shows a cross-sectional view of the antenna of Figure 2 in the plane AA. Figure 3b shows a side view of the antenna of Figure 3a without the antenna insulation, including a close-up of the outer conductor. [Figure 4] Figure 4a shows a cross-sectional view corresponding to that of Figure 3a showing an alternative embodiment of the outer conductor, and Figure 4b shows a side view corresponding to that of Figure 3b illustrating an alternative embodiment of the outer conductor shown in Figure 4a. [Figure 5] FIG. 5 shows a side view of an alternative embodiment of the antenna shown in FIG. 2 having a solid outer conductor rather than a braided outer conductor. [Figure 6] Figures 6a and 6b show how the antenna elements are formed by cutting the outer conductor of a coaxial cable. [Figure 7] Figures 7a and 7b show the relative dimensions and spacing of the antenna elements of the antenna. [Figure 8] FIG. 8 shows a cross-sectional view of an antenna of an ablation probe according to another embodiment, having a hinge region. [Figure 9] FIG. 9 shows a cross-sectional view of an applicator portion of an ablation probe according to another embodiment. [Figure 10] FIG. 10 shows a cross-sectional view of the applicator portion shown in FIG. 9 in the CC plane. [Figure 11] FIG. 11 shows a cross-sectional view of the applicator portion shown in FIG. 9 in the plane DD. [Figure 12] FIG. 12 shows a perspective view of a portion of the antenna of the ablation probe shown in FIG. [Figure 13] FIG. 13 shows a side view of an antenna of an ablation probe according to another embodiment. [Figure 14] FIG. 14 shows a cross section of the antenna shown in FIG. 13 in the EE plane. [Figure 15] FIG. 15 shows an alternative view of that shown in FIG. 13, but without the heat shrink sleeve. [Figure 16] 16a-c show a multi-lumen tube disposed in the antenna insulator of an antenna of an ablation probe according to another embodiment. [Figure 17] FIG. 17 illustrates a method for manufacturing an ablation probe. DETAILED DESCRIPTION OF THE INVENTION

[0053] An embodiment of an ablation probe 100 is shown schematically in FIG. 1 . The ablation probe 100 of the present disclosure may be suitable for insertion into the body to reach a desired treatment site, such as a malignant tissue growth. To reach the desired treatment site, the ablation probe may be suitable for insertion through a working channel of an internal anatomical access device. By internal anatomical access device, we mean any device that can be placed in a patient's anatomy, the device having a working channel for inserting an instrument to a desired location within the body. The internal anatomical device may be an intraluminal delivery device configured to be delivered along a patient's anatomical lumen (e.g., the trachea and bronchial or esophageal passages in the lungs). The ablation probe 100 may be used to reach various disease sites within the body, for example, endoscopically or using an ENB (electromagnetic navigation bronchoscopy) system. The ablation probe may therefore be generally flexible so as to be insertable through the working channel of an endoscope or similar device. In other embodiments, the ablation probe may be used with other types of intraluminal delivery devices, such as certain types of endoscopes (e.g., bronchoscopes) or navigation systems, such as pulmonary navigation systems (e.g., ENB systems). In other examples, the ablation probe 100 may also be used percutaneously or using any other suitable technique, such as, for example, insertion through an existing opening in the body. For percutaneous use, the ablation probe may be generally rigid so as to be insertable.

[0054] The ablation probe extends between a proximal end 100a and a distal end 100b. The terms "distal" and "proximal" are relative to the user manipulating the ablation probe and the treatment site when the ablation probe is positioned for use, with the distal end 100b of the ablation probe 100 being the end closest to the treatment site and the proximal end 100a being the end closest to the user. The ablation probe 100 has a longitudinal axis Y that extends along the length of the device between the distal and proximal ends. The radial direction R is defined as the direction perpendicular to the longitudinal axis Y, as shown in FIG. 1 . As used herein, references to being along the "length" of the ablation probe or other component refer to a length along or parallel to the longitudinal axis Y.

[0055] A handle 101 is provided at the proximal end of ablation probe 100 to allow manipulation and positioning by the user. The distal end 100b may be fed through the working channel of an endoscope or similar device to reach the target ablation site.

[0056] The ablation probe 100 generally comprises an applicator portion 102 and a power or feed cable 104. The terms "power cable" and "feed cable" are used interchangeably herein. The applicator 102 comprises an antenna 106 and is configured to emit radiation to heat surrounding tissue when the ablation probe is in use. The emitted radiation can be used to locally heat and destroy malignant cells around or near the applicator 102. The applicator 102 may be configured to apply any suitable form of radiation to the surrounding tissue to produce the desired heating. The applicator 102 may be configured to emit, for example, microwave or RF radiation, or any other suitable radiation that produces heating. The applicator 102 is positioned at or near the distal end of the ablation probe 100 so that it can be positioned at a desired location relative to the tissue to be treated.

[0057] The power feed cable 104 is positioned to supply electromagnetic energy to the applicator 102. Only a portion of one power feed cable is shown in the figures. The power feed cable 104 can be an elongated member suitable for supplying electromagnetic energy to the applicator (e.g., conductors), but may include additional components (e.g., coolant conduits). The power feed cable 104 may extend along at least a portion or all of the length of the ablation probe 100 to supply energy to the applicator 102. In the described embodiment, the applicator is located at the distal end of the power feed cable 104, and a generator (not shown) suitable for supplying energy to the applicator 102 and generating a desired frequency signal is connected to the proximal end of the power feed cable 104. In the described embodiment, the power feed cable 104 comprises a coaxial cable, as described in more detail below. An extension coaxial cable, not shown, may be used to connect the distal end of the power feed cable to a signal generator (e.g., in the handle 101). Similar additional connections may be provided for the coolant circuit, which is also not shown.

[0058] In this embodiment, an applicator tip 102a is attached to the distal end of the applicator 102. The tip 102a forms a sharp distal tip of the ablation probe 100 suitable for piercing tissue during use. In some embodiments, the tip may be a separate component. In other embodiments, a separate tip component may not be provided, such that the tip is integrally formed with the applicator 102. Thus, the tip may be integral with or connected to the applicator's dielectric resonator. In still other embodiments, the ablation probe may have an atraumatic distal tip rather than a sharp one.

[0059] Referring again to FIG. 1 , ablation probe 100 generally comprises two sections: a needle section 100c and a catheter section 100d. Needle section 100c may be located at the distal end of ablation probe 100 and is adapted to be inserted into tissue during use to reach a desired ablation location. Catheter section 100d may be located at the proximal end of ablation probe 100 and is configured to deliver electromagnetic energy to the needle section (and, optionally, to deliver coolant flow to and from needle section 100). Catheter section 100d may be long and flexible for endoscopic use. In other embodiments, a shorter, more rigid catheter section 134 may be provided for percutaneous use.

[0060] In some embodiments, the needle portion 100c may form a short portion of the overall length of the ablation probe. For example, the needle portion may be 5 mm to 2000 mm long, and preferably about 70 mm long. The length of the needle portion 100c may be selected depending on the anatomical structure to be accessed. For example, the needle portion may be approximately 10 to 100 mm long to perform treatment on organs including the pancreas or lungs, or may be longer (e.g., 100 to 400 mm long) for percutaneous treatment. For example, a longer needle portion may be more suitable for accessing a portion of the lung. The catheter portion may be approximately 1000 mm to 2000 mm long, and preferably about 1400 mm long. The length of the catheter portion may be selected depending on the location of the ablation site that must be reached.

[0061] In other embodiments, the needle portion 100c of the ablation probe may form a greater proportion of the length of the ablation probe. In some embodiments, the entire length of the ablation probe may be formed by the needle portion 100c (i.e., such that there is no separately defined catheter portion). For example, if the ablation probe is to be used percutaneously, the catheter portion 100d may be shorter than for endoscopic use, or may not be necessary.

[0062] Referring now to FIG. 2, a schematic cross-sectional view (in a plane passing through the longitudinal axis Y) of the antenna 106 of the ablation probe 100 is shown. FIG. 3a shows a cross-section taken along plane AA in FIG. 2. FIGS. 2 and 3a show the antenna 106 and a portion of the feed cable 104 separately for ease of illustration; other components may be present, but are not shown. The antenna 106 is a dipole antenna configured to emit microwave radiation to heat surrounding tissue, as described above. The dipole antenna includes a first antenna portion 106a that forms a first pole of the dipole antenna 106 and a second antenna portion 106b that forms a second pole of the dipole antenna. The antenna 106 is supplied with a microwave signal from a microwave generator by a coaxial cable attached to the feed cable 104. The coaxial cable includes an inner conductor 108, an outer conductor 110, and a dielectric 112. The dielectric is positioned between the inner conductor 108 and the outer conductor 110. Antenna 106 is configured to generate a spherical (or approximately spherical) ablation zone centered about a feed point 114 of antenna 106. Feed point 114 is the point along the length of the ablation probe where inner conductor 108 is first exposed outside of the outer conductor (i.e., just past the point where the outer conductor no longer extends along the longitudinal length of the ablation probe). First antenna portion 106a is electrically connected to outer conductor 110 of the coaxial cable, and second antenna portion 106b is electrically connected to inner conductor 108 to form a dipole antenna.

[0063] The first antenna portion 106a includes a plurality of antenna elements (or antenna members) 116a-i, each integrally formed with the outer conductor 110. Two such antenna elements, 116a and 116e, are shown in cross section in FIG. 2. In this embodiment, the first antenna portion 106a includes nine antenna elements, as shown in FIG. 3a. Other numbers of antenna elements may be provided in other embodiments. In some embodiments, the first antenna portion 106a may include only a single antenna element 116a, although it is preferred to include at least two, as described below. Each of the antenna elements 116a-i includes an outwardly extending portion 117a that extends outwardly away from the longitudinal axis of the ablation probe, e.g., in a direction having a component in a radial direction R away from the longitudinal axis Y of the ablation probe (corresponding to the longitudinal axis of the coaxial cable). The outwardly extending portion may therefore be referred to as a radially extending portion. Each antenna element 116a-i further includes an overlapping portion 117b extending proximally (e.g., parallel to the longitudinal axis Y) along the length of the coaxial cable. The radial and overlapping portions are integrally formed with the remainder of the outer conductor; i.e., they are continuous pieces of material with no joints (such as solder joints or welds) therebetween. The outwardly extending and overlapping portions are formed by shaping (e.g., bending) portions of the outer conductor so that they extend away from and back along the coaxial cable, exposing a portion of the dielectric, as shown in FIG. 2. Although the outwardly extending portions 117a are shown in FIG. 2 as extending perpendicular to the longitudinal axis Y, they may extend at any angle, so long as they are bent outward (e.g., in a direction having a component in the radial direction R) to extend away from the longitudinal axis of the coaxial cable. Similarly, these overlapping portions may have any shape that allows them to extend proximally back along the coaxial cable.

[0064] The first antenna section 106a further comprises antenna insulators 118 disposed to separate or space the overlapping portions 117b of each antenna element 116a-i from the overlapping portion of the outer conductor 110. As shown, the antenna elements 116a-i may be located on the outer surface of the insulator material. In other embodiments, they may be embedded in the insulator material or located in recesses in its surface, as described below. The insulators 118 are disposed to electrically insulate the overlapping portions 117b from adjacent portions of the outer conductor 110. In this embodiment, the insulators 118 comprise an annular component that fits around the outer conductor 110, thus forming an insulating layer between the outer conductor 110 and the overlapping portions 117b of the antenna elements 116a-i.

[0065] The insulator 118 generally forms a flexible structure that allows the ablation probe to bend and flex during use. This allows the ablation probe to follow a tortuous path through a patient's anatomy when used with an endoluminal delivery device. In this embodiment, the insulator is formed from a (solid) flexible insulator material. In other embodiments, the insulator may comprise a plurality of rigid beads or pellets. In such embodiments, each bead is rigid, but the overall structure is flexible.

[0066] By forming the first antenna portion by molding portions of the outer conductor 110 to form the antenna elements 116a-i, a number of advantages can be achieved: It may provide electrical continuity between the antenna portion and the rest of the outer conductor compared to separate components attached to the outer conductor, which may improve the electrical performance of the antenna (e.g., minimize losses and aid in creating a spherical ablation zone). By forming the antenna element as described above, it is easy to expose the dielectric layer of the coaxial cable without damaging it, which can also help maintain the electrical performance of the cable. Using a portion of the outer conductor helps to avoid machining a separate conductive component that would need to be soldered to the cable. Fewer components are required to form the antenna, which reduces the overall number of components and processes required to manufacture the antenna. The antenna element allows the antenna to be manufactured with a small cross-sectional profile, which is advantageous for allowing the ablation probe to be inserted into the body. - Forming the antenna element as described above can help improve the flexibility of the ablation probe compared to using a more rigid structure with an antenna formed using additional components.

[0067] Forming the first antenna portion as described herein can provide a number of clinical advantages during use of the ablation probe. For example, it can improve the flexibility of the applicator so that it can be navigated within the body to reach difficult-to-access locations, such as the periphery of the lung. It also helps maintain a small overall cross-sectional profile of the device so that it can be inserted into a working channel and / or tissue. This can also help provide stable, spherical ablation and aid in precisely targeting the ablation.

[0068] In some embodiments, the antenna insulation may be formed from a ribbed polymer having one or more air gaps, which may serve to improve the flexibility of the insulation and may also serve to improve the electrical insulation provided by the insulation (e.g., by taking advantage of the electrical insulating properties of air).

[0069] In some embodiments, the antenna insulation may be configured to allow coolant to flow through the antenna insulation (and thus through the first antenna portion), which may be achieved by providing coolant channels through the body of the antenna insulation material or by allowing coolant to flow between the beads that form the insulation.

[0070] In the embodiment described herein, the outer conductor 110 of the coaxial cable is a braided outer conductor. For clarity, the braided structure of the outer conductor is not shown in FIG. 2 but is visible in FIGS. 3a and 3b. In FIG. 3b, the antenna is shown without the insulation 118 so that the outer conductor is more easily visible. The enlarged view in FIG. 3b shows a portion of the braided structure of the outer conductor in more detail. The outer conductor 110 may be composed of multiple strands 110a woven or braided together to form the outer conductor 110, which extends around and protects the inner conductor 108. In the described embodiment, each of the strands 110a is formed by a single wire element as shown (two of which are labeled in the enlarged view in FIG. 3b). In this embodiment, each of the strands is a flat wire strand. Each of the antenna elements 116a-i is formed from a single flat wire strand that has been unbraided from its outer conductor and shaped to a predetermined shape. The shape, number, and size of the strands 110a shown in the figures should be understood as being by way of example only.

[0071] In other embodiments, each of the strands 110a braided together to form the outer conductor may itself each have multiple separate wire filaments. An example of this is shown in FIGS. 4a and 4b, which correspond to FIGS. 3a and 3b but show a different embodiment of the outer conductor. In the example shown in FIGS. 4a and 4b, each of the strands 110a forming the outer conductor comprises four separate wire filaments 110b (four of which are labeled in the enlarged view in FIG. 4b) that are grouped together to form each of the strands that make up the braid pattern around the dielectric 212. These wire filaments are also visible in FIG. 4a. In other embodiments, the strands 110a may be formed with a different number of filaments; only four are shown for clarity.

[0072] As can be seen in Figures 3a-4b, the antenna elements 116a-i of the first antenna portion are formed from an unbraided portion of the outer conductor 110. Specifically, in the described embodiment, each of the antenna elements is formed from one of the wire strands of the unbraided portion of the outer conductor. This allows the antenna elements to be formed by unbraiding (including at least partially unbraiding) the separate strands of the outer conductor so that they are free from one another and shaping (e.g., bending) them to extend away from the outer conductor and back proximally along the cable. This allows the antenna elements to be manufactured integrally with the outer conductor. In other embodiments, the outer conductor can be unbraided, and the wire strands forming it can be used in any other way to form the antenna elements; for example, one or more of the wire strands can be used to form each antenna element, or wire filaments of the unbraided strands can be separated to form one or more antenna elements. In some embodiments, the wire strands of the outer conductor that form the antenna elements may be re-braided so that they are interwoven together. For example, a portion of the outer conductor may be unbraided, and then the unbraided strands that form each antenna element may be re-braided or re-braided into a new braided portion of the outer conductor.

[0073] In other embodiments, the outer conductor is not a braided wire strand but comprises a solid conductive sheath or tube of material surrounding the dielectric. The outer conductor is thus a single, solid element rather than formed from individual strands. One embodiment of such an antenna 206 is shown in FIG. 5. The embodiment of FIG. 5 includes similar components (except for the outer conductor) to those shown in FIGS. 1-4b, and corresponding reference numerals are used where appropriate. The second antenna portion 206a includes nine antenna elements 216a-i integrally formed from the outer conductor 210, five of which are visible in FIG. 5. Each of the antenna elements 216a-i is formed from a portion of the outer conductor 210. For example, the outer conductor may be cut from a continuous strip of material. Each of the strips may then be shaped (e.g., bent) to form the outwardly extending and overlapping portions of each antenna element. In this embodiment, forming the antenna elements integral with the outer conductor 210 may provide advantages similar to those of the embodiment in FIGS. 1-4b.

[0074] An example of an antenna element formed from a solid sheathed outer conductor 210 is shown in FIGS. 6a and 6b. In both of these figures, only a portion of the outer conductor 210 is shown as a separate tubular piece of material. In this example, the outer conductor is cut to form six individual antenna elements 216, labeled in FIG. 6b. FIG. 6a shows cutouts 216' formed in the outer conductor by cutting along the dashed lines shown in the figure. The shaded cutout areas 216' are then removed to form gaps or voids between portions of the outer conductor from which the antenna elements are formed. FIG. 6b shows the outer conductor 210 after the shaded cutouts 216' have been removed. In this example, the cutouts 216' are slots cut (e.g., by laser cutting) into the end of the outer conductor 210, leaving elongated strips or fingers of antenna elements 216 extending from the end of the outer conductor 216. These antenna elements 216 may then be shaped to form the antenna members 216a-i shown in FIG. 5 (e.g., by cutting an appropriate number from the outer conductor). Figures 6a and 6b show one example of the shape of the antenna members that may be formed. In other embodiments, the cutouts may not be required, and the antenna elements may be formed by cutting without removing material. However, the cutouts may aid in bending the antenna elements into the desired shape.

[0075] In the embodiment shown in FIGS. 1-5, the first antenna portion 106a, 206a includes nine antenna elements 116a-i, 216a-i. In other embodiments, other numbers of antenna elements may be provided. The inventors have determined that the size and distribution of the antenna elements are important for providing the desired electrical characteristics of the antenna. More generally, the first antenna portion may include three or more antenna elements. This may result in suitable electrical characteristics of the antenna. An example of one of the embodiments having two antenna elements 116a, 116b is shown in FIG. 7a, which shows a cross-section corresponding to that of FIG. 3. In any of the embodiments described herein, each of the antenna elements may extend over an area that is 15% (or at least 15%) of the cross-sectional area of ​​the antenna insulation. By the inventors, the cross-sectional area of ​​the antenna insulation means the total area over which the antenna insulation extends in a plane perpendicular to the longitudinal axis of the ablation probe, i.e., the area between the dashed lines in FIG. 7a. In some embodiments, the antenna elements may additionally or alternatively extend over a total of at least 20% of the entire longitudinal area of ​​the antenna insulation 118. In other words, the percentage of the outer surface of the antenna insulation that is covered by the antenna elements is at least 20% of its total area. The longitudinal area of ​​the antenna insulation is defined as the area of ​​the outer surface of the antenna insulation (excluding the antenna elements), for example, the area of ​​the cylindrical surface enclosed by the dashed line in FIG. 7b, which shows the antenna insulation 118 in isolation with one of the antenna elements 116b overlaid on it.

[0076] It has been found that the combination of having at least two antenna elements, each covering at least 15% of the cross-sectional area of ​​the insulator, and evenly distributing the antenna elements results in efficient electrical contact between the outer conductor of the coaxial cable and the folded antenna elements, although any of these features can be achieved independently of one another.

[0077] The antenna elements may be evenly distributed around the longitudinal axis of the coaxial cable, i.e., they are equally spaced circumferentially around the outer conductor, as shown in the figures. This may help to create a uniform ablation zone around the antenna. In other embodiments, other configurations, including other sizes and spacings of the antenna elements, may be provided.

[0078] The thickness of the antenna insulation 118, 218 in any of the embodiments described herein may be selected to reduce the risk of an electrical short between the overlapping portions 117b, 217b of the antenna elements 116a-i, 216a-i and the portions of the outer conductor where they overlap. In preferred embodiments, the thickness "t" of the antenna insulation in any of the embodiments described herein may range from 0.05 mm to 0.5 mm, and preferably from 0.1 to 0.3 mm. The antenna insulation 118, 218 may extend proximally beyond the proximal-most extent / end of the antenna elements 116a-i, 216a-i. This may reduce the risk of an electrical short between the antenna elements and the outer conductor. In other embodiments, the proximal end of the insulation may be coincident with the proximal end of the antenna elements or may extend a shorter distance along the feed cable.

[0079] The ablation probe is configured to emit radiation at an operating frequency. The operating frequency may be a microwave frequency. In some embodiments, the operating frequency of the ablation probe may be in the range of 10.0 GHz to 0.5 GHz. In some embodiments, the operating frequency of the ablation probe may be in the range of 1.0 to 4.0 GHz, or more preferably, in the range of 2.4 GHz to 2.5 GHz. In particular, the operating frequency is approximately 2.45 GHz. The antenna elements 116a-i, 216a-i extend a length (L in FIG. 4) along the length of the feed cable to tune the antenna to the correct microwave frequency. The length L may be 25% of the wavelength of the radiation at the operating frequency propagating through the antenna insulator material. For example, the length L may be in the range of 8 to 12 mm, preferably 9 to 11 mm, and more preferably approximately 10 mm.

[0080] The shapes of the antenna elements 116, 216 shown in Figures 1-7b should be understood as examples only. In other embodiments, the overlapping portions of the antenna elements may not extend parallel to the longitudinal axis of the ablation probe as shown, and may have other shapes or configurations. For example, in some embodiments, the overlapping portions of the antenna elements may overlap one another and may be, for example, interwoven or braided. In some embodiments, the overlapping portions of the antenna elements may extend helically around the longitudinal axis of the ablation probe.

[0081] Referring again to FIGS. 2 and 3a, the first antenna portion 106a further includes a heat shrink sleeve 119 disposed to hold the overlapping portions 117b of the antenna elements 116a-i around the insulator. The heat shrink sleeve may form a tight-fitting layer of material over the antenna insulator 118 and the antenna elements 116a-i to secure them in place. While shown in conjunction with the embodiment of FIGS. 2 and 3a, the heat shrink layer may be provided to hold the antenna elements of any of the embodiments described herein. The heat shrink sleeve may extend proximally along the feed cable beyond the proximal end of the antenna elements to prevent the antenna elements from being exposed. This may reduce the risk of electrical shorting.

[0082] Other methods for holding the antenna elements 116a-i in place may be used. In yet other embodiments, the overlapping portions 117b of the antenna elements 116a-i may additionally or alternatively be embedded in the antenna insulation 118. This may be achieved by heating the antenna insulation to soften it so that the overlapping portions 117b can be pressed in, and then allowing it to cool. In yet other embodiments, the overlapping portions 117b of the antenna elements 116a-i may additionally or alternatively be crimped around the insulation. In yet other embodiments, the first antenna portion 106a may additionally or alternatively include one or more retaining bands positioned to secure the antenna elements 116a-i around the antenna insulation 118. The retaining bands may be radiopaque marker bands that may also add a visual reference, allowing a user to determine the position of the antenna during use (e.g., using x-ray imaging). The radiopaque marker band may be made of any suitable material that is opaque to x-rays and acts as a marker, as known in the art. The band may be a conductive band arranged to surround and hold the overlapping portions of one or more antenna elements around the antenna insulator. The band may be formed from a loop of solder applied around the antenna elements to hold them in place. Additionally or alternatively, the first antenna portion may further include a wire arranged to extend around and hold the overlapping portions of the antenna elements in place. Such a wire may be made of a polymer or metal and may be arranged to surround and hold the overlapping portions of the one or more antenna elements around the antenna insulator. Additionally or alternatively, the first antenna portion may include an adhesive (e.g., epoxy) arranged to hold the overlapping portions of the one or more antenna elements around the antenna insulator. For example, an adhesive may be used to secure the antenna elements to the antenna insulator material. Additionally or alternatively, the antenna insulator 118 may include one or more recesses, each positioned to receive a respective one of the antenna elements 116a-i.For example, one or more recesses may be machined or molded into the surface of the insulator. Each recess may be shaped to receive a respective one of the antenna elements (e.g., overlapping portions of each element) so that the antenna elements can be positioned within the recesses and held in place. In still other embodiments, the heat shrink sleeve 119, embedding in the antenna insulator, retaining bands, wires, adhesives, recesses, and / or crimping may be absent. The antenna element retention methods described in this paragraph may be applied to any of the embodiments described herein.

[0083] The first antenna portion 106a, 206a described above can be used in combination with many different types of second antenna portions electrically coupled to the inner conductor. In the embodiments described above, the second antenna portion 106a, 206a comprises a linear monopole antenna formed by a portion of the inner conductor 108, 208. The second antenna portion comprises a single inner conductor 108, 208 that extends distally along the length of the ablation probe 100, 200, beyond the antenna elements 116a-i, 216a-i. Thus, the second antenna portion is formed from a portion of the inner conductor that extends distally along the length of the ablation probe, distally from the antenna feed point, i.e., from the most distal extent of the outer conductor 110, 210.

[0084] In some embodiments, the second antenna portion further comprises a dielectric resonator into which the inner conductor is inserted. Such an embodiment is shown in FIG. 8, which shows an embodiment of an ablation probe 300 having an antenna 306 with a dielectric resonator 320, in addition to components corresponding to other embodiments described herein. Any of the embodiments described herein may include such a dielectric resonator. The distal end of the inner conductor 308 extends into the dielectric resonator, as shown in FIG. 8. The dielectric resonator may be made of a ceramic material; however, different materials may be used in other embodiments. The dielectric resonator may generally be made of a rigid material.

[0085] In embodiments in which the second antenna portion comprises a dielectric resonator within which the inner conductor is inserted, the antenna may further comprise a flexible hinge region 322. The proximal end of the dielectric resonator 320 is spaced apart from the distal end of the outer conductor 310 along the length of the coaxial cable, forming a hinge region 322 therebetween. As shown in FIG. 8 , the proximal end of the dielectric resonator 320 is spaced apart from the antenna elements 316a-i along the length of the coaxial cable. The hinge region is thus formed from the portion of the coaxial cable where the cable's dielectric layer 312 is exposed. The hinge region 322 comprises a region of increased flexibility relative to the portion of the antenna where the outer conductor is present, and relative to the dielectric resonator 320. This provides a preferential bending point for the ablation probe away from where the components are connected together (e.g., where the dielectric resonator is connected to the inner conductor). This can help avoid connection failures when the ablation probe is bent during use. Hinge region 322 may also protect feed point 314 of antenna 306, which is the center of the ablation zone and the most critical portion of the antenna exposed to the strongest electromagnetic field. The hinge region may extend, for example, a distance of 0.5 to 2 mm along the length of the ablation probe to achieve a suitable degree of flexibility.

[0086] Although the hinge region is shown for use with the folded antenna element of the present invention, it may also be used with other antenna designs, for example, more generally, the hinge region may be used between the dielectric resonator and the outer conductor in any other antenna design.

[0087] Another embodiment of an ablation probe 400 according to the present invention is shown in Figures 9, 10, and 11. Figure 9 shows a cross section through the distal end of ablation probe 400 where antenna 406 is located. Figures 10 and 11 show cross sections in the CC and DD planes in Figure 8. Figure 12 shows the components of antenna 406 of ablation probe 400, excluding the catheter tube shown in Figures 9, 10, and 11.

[0088] Ablation probe 400 includes features corresponding to those of other embodiments disclosed herein, and corresponding reference numerals are used for these. Ablation probe 400 includes a catheter tube 430 in which the antenna components and coaxial cable are disposed. The catheter tube may therefore be considered to form part of the ablation probe's power cable. Such a catheter tube may also be provided for any of the other embodiments described herein.

[0089] The catheter tube 430 may be a tubular shaft, such as a sheath or other hollow, elongated component. The catheter tube 430 may extend along the length of the ablation probe from its proximal end, where it connects to the handle, to its distal end, where the antenna is located. The catheter tube 430 may be formed from a material that is sufficiently stiff to allow the ablation probe to be inserted into tissue, yet flexible enough to pass through a working channel of a delivery device. In other embodiments, the catheter tube may be more rigid to allow the ablation probe to be used percutaneously. The catheter tube may be made of a superelastic material. The catheter tube may be a single length of tube, or in some embodiments, may comprise multiple separate lengths of tube.

[0090] In some embodiments, the catheter tube 430 in the region of the antenna 406 may be transparent to allow microwave propagation, facilitating the radiation of energy to the target tissue and creating ablation. The portion of the catheter tube 430 extending around or directly adjacent to the antenna 406 may therefore be completely devoid of conductive components. This helps to avoid blocking the microwaves emitted from the antenna 430. In some embodiments, the catheter tube may comprise one or more polymeric materials. The polymeric materials may be fluorinated polymers or fluoroelastomers, such as fluorinated ethylene propylene (FEP) and / or polytetrafluoroethylene (PTFE). In some embodiments, the catheter tube may comprise a polymer (e.g., PEEK) reinforced laminate tube. The entire length of the catheter tube may be formed solely from polymeric materials (i.e., no metallic or other conductive materials are present), such as those described in this paragraph or elsewhere herein. These materials can provide a desired level of flexibility and durability for the catheter tube in areas where it will be stressed by high temperatures, pressure, and insertion and withdrawal forces during use, while also being transparent to microwave radiation. In some embodiments, only the portion of the catheter tube surrounding the antenna may be formed exclusively from a polymeric material, such as a fluorinated polymer or fluoroelastomer-based polymeric material (e.g., fluorinated ethylene propylene (FEP) or polytetrafluoroethylene (PTFE)), or a polymer (e.g., PEEK) reinforced laminate tubing. In such embodiments, other materials can be used in other portions of the catheter tube (e.g., away from the distal end) where microwave radiation is not present to be interfered with.

[0091] 10 and 11, the outer surface of the dielectric resonator 420 of the second antenna portion includes a plurality of resonator protrusions 420a-420d. As shown in FIG. 12, the resonator protrusions may be fins extending from the surface of the dielectric resonator and extending along the length of the dielectric resonator. While four such protrusions are provided in the described embodiment, other numbers may be provided in other embodiments. The resonator protrusions 420a-420d may extend radially from the outer surface (e.g., the outer cylindrical surface) of the dielectric resonator 420. The resonator protrusions 420a-420d are spaced apart from the surface of the dielectric resonator 420 and from the inner wall of the catheter tube 430 (or other surrounding tubes). The resonator protrusions 420a-420d may be positioned to position the catheter tube 430 concentrically with the dielectric resonator 420. For example, resonator protrusions 420a-d may be equally spaced around the circumference of the dielectric resonator and extend an equal distance from the longitudinal axis of the ablation probe to concentrically position the catheter tube 430. Resonator protrusions 420a-d may be integrally formed with the body of the dielectric resonator, e.g., the dielectric resonator shape, including the protrusions, may be machined from a continuous piece of material, which may facilitate manufacturing. In other embodiments, the protrusions may be separate components bonded to the surface of the dielectric resonator.

[0092] The first antenna portion 406a of the ablation probe shown in FIGS. 9-12 includes an antenna insulator 418 having multiple insulator protrusions 418a-d. The insulator protrusions are formed by protrusions extending radially from the surface of the antenna insulator 418. The antenna protrusions may be fins shaped similar to the resonator protrusions, as shown in FIG. 12. In this embodiment, four insulator protrusions 418a-d are provided, although other numbers may be provided in other embodiments. The insulator protrusions 418a-d extend from the outer surface of the antenna insulator 418 around which the antenna elements 416a-h are disposed. In this embodiment, the antenna protrusions 418a-d are positioned between adjacent antenna elements (eight antenna elements are provided in this embodiment, rather than nine as in the previous embodiment, to allow for equal spacing of the antenna protrusions). The insulator protrusions 418a-d are positioned to position the catheter tube 430 around the feed cable and around the first antenna portion 406a. The insulator protrusions 418a-d may be positioned to position the catheter tube 430 concentrically with the antenna insulator 418 and, therefore, with the other components of the first antenna portion. The insulator protrusions 418a-d may be equally spaced around the circumference of the antenna insulator 418 and extend equal radial distances from the longitudinal axis of the coaxial cable to concentrically position the catheter tube 430.

[0093] In embodiments having protrusions in the antenna insulator 418, the shrink sleeve 119 may not be provided and other means of holding the antenna element in place as described elsewhere herein may be used (e.g., one or more of embedding in the insulator material, adhesive, or recesses in the surface of the insulator material).

[0094] 10 and 11, antenna projections 218a-d and resonator projections 220a-d are each positioned to form a gap between the inner wall of catheter tube 430 and the first antenna portion or other components of the dielectric resonator. In this embodiment, this gap is used for one or more coolant channels through which coolant can flow to cool the antenna. The flow of coolant can help control the temperature of the ablation probe during use, allowing energy to reach surrounding tissue over an extended period of time without overheating and damaging ablation probe 100 or damaging healthy tissue. The coolant can be a fluid and can be water, saline solution, cryogenic gas, or any other suitable coolant known in the art.

[0095] This embodiment includes a first coolant channel or tube 432 extending along the length of the feed cable. The first coolant channel is disposed in the catheter tube 430 to extend between the two antenna lobes 418a, 418b and between the two resonator lobes 420a, 420b. The first coolant channel 432 is configured to convey a flow of coolant distally along the feed cable to (and through) the antenna 406. The first coolant channel is therefore a coolant supply channel. A similar second coolant channel or tube 434 is provided to act as a coolant return channel. The coolant flow is indicated by arrows in FIG. 9 . The second coolant channel 434 is disposed to extend along the length of the feed cable between the two antenna lobes 418c, 418d and between the two resonator lobes 420c, 420d. The distal end of the coolant conduit is fluidly coupled (e.g., by a cavity surrounding the dielectric resonator or additional coolant conduit or coolant transport structure) to form a coolant circuit, allowing coolant to be circulated to and from the antenna. For example, the proximal end of the coolant conduit may be connected to a coolant pump or circulation device. This use of space between the resonator and the antenna protrusion ensures a suitable location for the coolant conduit while minimizing the overall cross-section of the ablation probe.

[0096] While Figures 9, 10, and 11 show separate coolant conduits or tubes for carrying coolant, in other embodiments, these components may not be present; i.e., the coolant may flow along a coolant channel defined by the inner wall of the catheter tube and the surface of the resonator and / or antenna protrusion. While two coolant channels are shown in these figures, in other embodiments, more may be provided to allow for greater volumes of coolant to be carried. In the embodiments described herein, the antenna protrusion and the resonator protrusion are aligned at the same angle with respect to the longitudinal axis of the ablation probe. This may allow for continuous coolant channels in a straight line parallel to the longitudinal axis of the ablation probe in the gaps between the protrusions. This may reduce coolant backpressure. In other embodiments, this may not be the case, and other configurations of coolant channels are possible. In some embodiments, only antenna protrusions or only dielectric protrusions may be provided with coolant channels disposed therein.

[0097] In any of the embodiments described herein, the antenna insulation can be positioned to allow coolant to flow through each first antenna portion, which can help reduce backpressure in the coolant flow circuit. For example, a coolant channel can be provided through the antenna insulation between the outer conductor of the coaxial cable and the overlapping portion of the antenna element to allow coolant to flow through the first antenna portion.

[0098] 13 and 14 illustrate a portion of an ablation probe 500 according to another embodiment. In this embodiment, the antenna 506 includes a second antenna portion 506b configured differently compared to other embodiments described herein. The embodiment illustrated in FIGS. 13 and 14 includes components corresponding to those of the previously described embodiments, and corresponding reference numerals are used accordingly. The second antenna portion 506b illustrated in FIG. 13 includes a helical portion 508a of the inner conductor 508. The helical portion extends from the distal-most point of the straight portion of the inner conductor to form a helix around the inner conductor, extending back proximally along the length of the inner conductor. The second antenna portion 506b may additionally include a dielectric resonator between the straight portion of the inner conductor 508 and the helical portion 508a.

[0099] Figure 15 shows the same view as Figure 13, but without the heat shrink 519 that is present, allowing the antenna elements 516a-d to be more clearly visible as they extend along the length of the ablation probe, with the underlying antenna insulation 518 visible in the gaps between them.

[0100] In the above embodiments, the antenna insulator and the catheter tube are separate components. In some embodiments, the catheter tube may comprise a multi-lumen extrusion (MLE). A portion of the multi-lumen extrusion may be used to form the antenna insulator. The multi-lumen extrusion may be an extruded tube or a structure having multiple lumens extending along the length of the ablation probe, where the lumens are defined by walls formed by the tube of extruded material. The multi-lumen extrusion may be formed from an extruded polymeric material.

[0101] An example of a multi-lumen extrusion 140 that may form part of an ablation probe is shown in Figure 16a. For ease of illustration, Figure 16a shows the multi-lumen extrusion alone, without other components of the ablation probe, and shows a cross-section of the extrusion in a plane perpendicular to the longitudinal axis of the ablation probe (e.g., corresponding to section AA in Figure 2 or section CC in Figure 8). Figures 16b and 16c show the multi-lumen extrusion 140 of Figure 16a together with components of a first antenna portion. Numbers corresponding to those in Figures 1-4 are used in Figures 16a-c, and it should be understood that the multi-lumen extrusion 140 may be used in any of the embodiments shown in these figures or other embodiments described herein.

[0102] The multi-lumen extrusion 140 includes an outer extrusion wall 130 corresponding to the catheter tubes of other embodiments described herein (e.g., the catheter tube 430 shown in FIGS. 9-11). The multi-lumen extrusion 140 includes an inner central lumen 142 extending along the longitudinal axis of the ablation probe. The inner lumen 142 is defined by an inner extrusion wall 144 of the multi-lumen extrusion 140. In this embodiment, the inner extrusion wall 144 forms a lumen having a generally circular cross-section as shown. As shown in FIGS. 16b and 16c, a coaxial cable can be positioned within the central lumen 142. The multi-lumen extrusion 140 further includes two outer lumens 146, 148, each of which partially surrounds the inner central lumen 142 in this embodiment. Each outer lumen 146, 148 is defined by the outer surface of the inner extruded wall 144, the inner surface of the outer extruded wall 130, and two radial partition walls 150a, 150b.

[0103] The antenna insulation 118 of the first antenna portion 106a may be formed by a portion of the inner extrusion wall 144 of the multi-lumen extrusion 140. As can be seen in FIGS. 16b and 16c, the portion of the outer conductor 110 forming the antenna elements 116a, 116b, 116c, and 116d may extend through or around the inner extrusion wall 144 and then extend back proximally along the outer surface of the inner extrusion wall 144. The portion of the inner extrusion wall 144 thus extends between the overlapping portions of the antenna elements and the coaxial cable they overlap, providing electrical insulation therebetween. FIG. 16b shows an example in which the first antenna portion has two antenna elements 116a and 116b, and FIG. 16c shows an example in which the first antenna portion has four antenna elements 116a-d. In the embodiment shown in Figure 16b, one of the antenna elements 116a, 116b is positioned in each of the outer lumens 146, 148. In the embodiment shown in Figure 16c, two of the antenna elements 116a-d are positioned in each of the outer lumens 146, 148.

[0104] Forming the antenna insulation from a portion of a multi-lumen extrusion can reduce the number of components required to form the first antenna portion (e.g., eliminating the need for separate antenna components). In some embodiments, the outer lumens 146, 148 can be configured to carry a coolant flow along the length of the ablation probe. For example, the first outer lumen 146 can carry a coolant flow distally along the length of the ablation probe, and the second outer lumen 148 can carry a coolant flow back proximally, forming a coolant circuit as described elsewhere herein. In some embodiments, the lumens can include a coolant flow tube or channel through which coolant flows (e.g., corresponding to the coolant conduits 432, 434 described in connection with FIGS. 9-11). The lumens can be fluidly coupled to a coolant pump, as previously described, to circulate the coolant.

[0105] 16a-c show only one example of a configuration of lumens that may be provided in a multi-lumen extrusion. In other embodiments, additional outer lumens may be provided, for example, there may be four outer lumens. In other examples, any other number of outer lumens may be provided (for example, there may be only one). In still other examples, additional lumens may be provided in additional layers around the outer lumen shown in the figures.

[0106] FIG. 17 illustrates a method for fabricating an ablation probe, specifically, fabricating an antenna component of the ablation probe. The ablation probe can be any of those described herein. Method 1000 includes step 1002 of providing a coaxial cable including an inner conductor, an outer conductor, and a dielectric therebetween. Method 1000 further includes step 1004 of forming a first antenna portion by shaping a portion of the outer conductor of the coaxial cable to form an antenna element. According to any of the embodiments described herein, each of the antenna elements includes an outwardly extending portion of the outer conductor that extends radially away from the longitudinal axis of the feed cable and an overlapping portion of the outer conductor that extends proximally along the coaxial cable. The antenna element can be formed by bending a portion of the outer conductor to a desired shape, i.e., extending outward and then back along the length of the coaxial cable.

[0107] The method 1000 further includes providing antenna insulation positioned to space the overlapping portions of the antenna element from the portions of the outer conductor that they overlap. According to any of the embodiments described herein, the insulation may be inserted between the overlapping portions of the antenna element and the outer conductor to provide electrical insulation therebetween. In other embodiments, the antenna insulation may be placed around the outer conductor before the antenna element is formed. This may allow the portion of the outer conductor that forms the antenna element to be bent or formed around the antenna insulation.

[0108] As noted above, in some embodiments, the outer conductor may comprise a plurality of braided conductive wire strands, with each antenna element formed from one or more of these strands. Step 1004 of forming one or more antenna elements may therefore include: unbraiding a portion of the braided strands of the outer conductor of the coaxial cable; and shaping or bending the unbraided strands to form one or more antenna elements of the first antenna portion. As noted above, the unbraided strands may be bent into a desired shape to extend away from and back along the coaxial cable. Each strand of the wire braid may be used to form each antenna element. However, this is not necessarily the case; the strands may be partially rebraided to form each of the antenna elements. In some embodiments, the antenna elements may be overlapped or interwoven together to form a new braided portion of the outer conductor, as described above.

[0109] In embodiments in which the outer conductor comprises a solid conductive sheath or tube of material around a dielectric, step 1004 of forming the antenna elements of the first antenna portion includes: cutting the sheath or tube to form one or more bands integrally formed with the remainder of the cut-out outer conductor material; and shaping each of the one or more bands to form one or more antenna elements of the first antenna portion. The outer conductor material may be cut using any suitable method. Preferably, laser cutting may be used so that a precise cut can be achieved. Laser cutting may also avoid damage to the cable's dielectric by using a laser at a suitable frequency to cut only the metal of the outer conductor.

[0110] 17 should be understood as providing steps for fabricating a first antenna portion of an antenna according to any of the ablation probes described herein, and should be understood to include additional steps required for fabrication / assembly of other components of the ablation probe as would be apparent to one skilled in the art.

[0111] Various modifications will be apparent to those skilled in the art without departing from the scope of the claims. Any feature disclosed with respect to one embodiment may be used in combination with features from other embodiments.

[0112] Although the appended claims are directed to particular combinations of features, the scope of the present disclosure should also be understood to include any novel feature or any novel combination of features disclosed herein, either explicitly or implicitly, or any generalization thereof, whether or not it relates to the same invention claimed herein in any claim and whether or not it solves any or all of the same technical problems as the present invention.

[0113] Features that are described in the context of separate embodiments may also be provided in combination in a single embodiment. Conversely, various features that are, for brevity, described in the context of a single embodiment may also be provided separately or in any suitable subcombination. Applicant hereby notifies that new claims may be formulated to such features and / or combinations of such features during prosecution of this application or any further application derived therefrom.

[0114] For the sake of completeness it is also mentioned that the word "comprising" does not exclude other elements or steps, the words "a" or "an" do not exclude a plurality, and a single processor or other unit may fulfill the functions of several means recited in the claims, and that any reference signs in the claims are not to be construed as limiting the scope of the claims.

Claims

1. a dipole antenna configured to emit microwave radiation to heat surrounding tissue; and a feeder cable configured to supply electromagnetic energy to the dipole antenna, the feeder cable comprising a coaxial cable having an inner conductor, an outer conductor and a dielectric therebetween; A microwave ablation probe comprising: the dipole antenna comprises a first antenna portion forming a first pole of the dipole antenna and a second antenna portion forming a second pole of the dipole antenna; the first antenna portion comprises one or more antenna elements each integrally formed with the outer conductor and each having an outwardly extending portion extending away from a longitudinal axis of the feed cable and an overlapping portion extending proximally along a length of the feed cable; and The microwave ablation probe, wherein the first antenna portion further comprises antenna insulation between the overlapping portions of each of the one or more antenna elements and the portions of the outer conductor with which they overlap.

2. the outer conductor is a braided outer conductor; and The microwave ablation probe of claim 1 , wherein the braided outer conductor comprises a plurality of braided wire strands, and wherein each antenna element is formed by one or more of the wire strands.

3. 3. The microwave ablation probe of claim 2, wherein the wire strands forming the antenna element are overlapped or interwoven together such that the first antenna portion is formed by an at least partially re-braided portion of the outer conductor.

4. 2. The microwave ablation probe of claim 1, wherein the outer conductor comprises a solid conductive sheath or tube of material surrounding the dielectric, and the antenna elements of the first antenna portion are each formed by a portion of the solid conductive sheath shaped to form the outwardly extending and overlapping portions of the antenna element, respectively.

5. 5. The microwave ablation probe of claim 1, wherein the first antenna portion comprises at least two antenna elements, the antenna elements being circumferentially spaced apart around the feed cable, preferably equidistantly spaced apart around the feed cable.

6. The second antenna portion: the inner conductor extending distally along the length of the ablation probe and beyond the antenna element of the first antenna portion; and a dielectric resonator into which the inner conductor extends and optionally a proximal end of the dielectric resonator is spaced from the antenna element of the first antenna portion along the length of the inner conductor to form a flexible hinge region therebetween.

7. further comprising a catheter tube in which the coaxial cable and the antenna are disposed, wherein optionally: a) the region of the catheter tube surrounding or adjacent to the antenna is formed from a polymeric material and does not contain any conductive components; or b) the entire length of the catheter tube is formed from a polymeric material and does not include any conductive components; and further optionally, the polymeric material comprises: i) fluorinated polymers or fluoroelastomers, for example polymers such as fluorinated ethylene propylene (FEP) and / or polytetrafluoroethylene (PTFE); and / or ii) Polymer (e.g. PEEK) reinforced laminate tube The microwave ablation probe according to any one of claims 1 to 6, comprising:

8. the dielectric resonator comprises a plurality of radially extending resonator protrusions, the resonator protrusions extending from an outer surface of the dielectric resonator; and 8. The microwave ablation probe of claim 7, optionally when dependent on claim 7, wherein the catheter tube is spaced from the outer surface of the dielectric resonator by the plurality of resonator protrusions, and further optionally, the resonator protrusions are arranged to position the catheter tube concentrically with the dielectric resonator.

9. 9. The microwave ablation probe of claim 1, wherein the first antenna portion comprises a plurality of antenna elements, and the antenna insulator comprises a plurality of radially extending insulator protrusions extending between the antenna elements, and optionally, when dependent on claim 7 or claim 8, the insulator protrusions are arranged to position the catheter tube concentrically with the antenna insulator.

10. 10. The microwave ablation probe of claim 8 or claim 9, further comprising one or more coolant channels between the resonator protrusions and / or between the insulator protrusions.

11. a) the antenna insulator forms a flexible region of the ablation probe; and i) a solid flexible material; or ii) a plurality of rigid beads Equipped with c) the antenna insulation is capable of permitting the flow of coolant therethrough; d) the antenna insulation may comprise one or more air gaps; and / or e) the power supply cable comprises an extruded multi-lumen extrusion, and the antenna insulator is formed by a part of the multi-lumen extrusion.

11. The microwave ablation probe according to claim 1, wherein the probe has one or more of the following characteristics:

12. a) the overlapping portions of the one or more antenna elements are embedded within the antenna insulator; b) the overlapping portions of the one or more antenna elements are crimped around the antenna insulator; c) the first antenna portion further comprising a heat shrink sleeve positioned to surround and retain the overlapping portions of the one or more antenna elements around the antenna insulator; d) the first antenna portion comprises a wire arranged to surround and hold the overlapping portions of the one or more antenna elements around the antenna insulator; e) the first antenna portion further comprising one or more radiopaque marker bands positioned to surround and retain the overlapping portions of the one or more antenna elements around the antenna insulator; f) the first antenna portion comprising an adhesive disposed to hold the overlapping portions of the one or more antenna elements around the antenna insulation; g) the first antenna portion further comprises one or more conductive bands arranged to surround and hold the overlapping portions of the one or more antenna elements around the antenna insulator, optionally the bands being formed from a ring of solder around the antenna elements; and / or h) the antenna insulator of the first antenna portion may include one or more recesses each positioned to receive a respective one of the antenna elements; 12. The microwave ablation probe according to claim 1, wherein the probe has one or more of the following characteristics:

13. 1. A method of manufacturing an ablation probe, the ablation probe comprising: a dipole antenna configured to emit microwave radiation to heat surrounding tissue, the dipole antenna comprising a first antenna portion forming a first pole of the dipole antenna and a second antenna portion forming a second pole of the dipole antenna; and a feeder cable comprising a coaxial cable arranged to supply electromagnetic energy to said dipole antenna; Features: providing a coaxial cable comprising an inner conductor, an outer conductor and a dielectric therebetween; forming the first antenna portion by shaping a portion of an outer conductor such that one or more antenna elements are formed, each antenna element comprising an outwardly extending portion of the outer conductor extending away from the longitudinal axis of the feeder cable and an overlapping portion of the outer conductor extending proximally along the length of the coaxial cable; and providing insulation between the overlapping portions of the one or more antenna elements and the portions of the outer conductor that they overlap; A method comprising:

14. The outer conductor comprises a plurality of braided conductive wire strands, and forming the antenna element of the first antenna portion comprises: unbraiding the braided strands of a portion of the outer conductor of the coaxial cable; and shaping the unbraided strands to form the one or more antenna elements of the first antenna portion. The method of manufacturing an ablation probe of claim 13 , comprising:

15. The outer conductor comprises a solid conductive sheath or tube of material around the dielectric, and the steps of forming the antenna element of the first antenna portion include: cutting the sheath or tube to form one or more bands integrally formed with the remainder of the outer conductor material that is cut out; and Shaping each of the one or more strips to form the one or more antenna elements of the first antenna portion. The method of manufacturing an ablation probe of claim 13 , comprising:

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