GB2580424A - Microwave ablation antenna assemblies - Google Patents
Microwave ablation antenna assemblies Download PDFInfo
- Publication number
- GB2580424A GB2580424A GB1900424.1A GB201900424A GB2580424A GB 2580424 A GB2580424 A GB 2580424A GB 201900424 A GB201900424 A GB 201900424A GB 2580424 A GB2580424 A GB 2580424A
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- United Kingdom
- Prior art keywords
- assembly
- choke
- conductor
- longitudinally
- coaxial conductor
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- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
- A61B18/00—Surgical instruments, devices or methods for transferring non-mechanical forms of energy to or from the body
- A61B18/18—Surgical instruments, devices or methods for transferring non-mechanical forms of energy to or from the body by applying electromagnetic radiation, e.g. microwaves
- A61B18/1815—Surgical instruments, devices or methods for transferring non-mechanical forms of energy to or from the body by applying electromagnetic radiation, e.g. microwaves using microwaves
-
- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
- A61B18/00—Surgical instruments, devices or methods for transferring non-mechanical forms of energy to or from the body
- A61B2018/00005—Cooling or heating of the probe or tissue immediately surrounding the probe
- A61B2018/00011—Cooling or heating of the probe or tissue immediately surrounding the probe with fluids
- A61B2018/00023—Cooling or heating of the probe or tissue immediately surrounding the probe with fluids closed, i.e. without wound contact by the fluid
-
- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
- A61B18/00—Surgical instruments, devices or methods for transferring non-mechanical forms of energy to or from the body
- A61B2018/00571—Surgical instruments, devices or methods for transferring non-mechanical forms of energy to or from the body for achieving a particular surgical effect
- A61B2018/00577—Ablation
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- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
- A61B18/00—Surgical instruments, devices or methods for transferring non-mechanical forms of energy to or from the body
- A61B18/18—Surgical instruments, devices or methods for transferring non-mechanical forms of energy to or from the body by applying electromagnetic radiation, e.g. microwaves
- A61B18/1815—Surgical instruments, devices or methods for transferring non-mechanical forms of energy to or from the body by applying electromagnetic radiation, e.g. microwaves using microwaves
- A61B2018/183—Surgical instruments, devices or methods for transferring non-mechanical forms of energy to or from the body by applying electromagnetic radiation, e.g. microwaves using microwaves characterised by the type of antenna
- A61B2018/1838—Dipole antennas
-
- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
- A61B18/00—Surgical instruments, devices or methods for transferring non-mechanical forms of energy to or from the body
- A61B18/18—Surgical instruments, devices or methods for transferring non-mechanical forms of energy to or from the body by applying electromagnetic radiation, e.g. microwaves
- A61B18/1815—Surgical instruments, devices or methods for transferring non-mechanical forms of energy to or from the body by applying electromagnetic radiation, e.g. microwaves using microwaves
- A61B2018/1869—Surgical instruments, devices or methods for transferring non-mechanical forms of energy to or from the body by applying electromagnetic radiation, e.g. microwaves using microwaves with an instrument interstitially inserted into the body, e.g. needles
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- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
- A61B18/00—Surgical instruments, devices or methods for transferring non-mechanical forms of energy to or from the body
- A61B18/18—Surgical instruments, devices or methods for transferring non-mechanical forms of energy to or from the body by applying electromagnetic radiation, e.g. microwaves
- A61B18/1815—Surgical instruments, devices or methods for transferring non-mechanical forms of energy to or from the body by applying electromagnetic radiation, e.g. microwaves using microwaves
- A61B2018/1892—Details of electrical isolations of the antenna
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- Health & Medical Sciences (AREA)
- Surgery (AREA)
- Life Sciences & Earth Sciences (AREA)
- Biomedical Technology (AREA)
- Medical Informatics (AREA)
- Nuclear Medicine, Radiotherapy & Molecular Imaging (AREA)
- Electromagnetism (AREA)
- Engineering & Computer Science (AREA)
- Physics & Mathematics (AREA)
- Heart & Thoracic Surgery (AREA)
- Otolaryngology (AREA)
- Molecular Biology (AREA)
- Animal Behavior & Ethology (AREA)
- General Health & Medical Sciences (AREA)
- Public Health (AREA)
- Veterinary Medicine (AREA)
- Surgical Instruments (AREA)
Abstract
A microwave ablation antenna assembly 20 with an elongate coaxial conductor assembly 26, for connection to a source of microwave energy, extending from the proximal end 201 to the distal end 202 of the antenna body 22. The coaxial conductor assembly has an outer conductor 32 surrounding a dielectric layer 30, which surrounds an inner conductor 28. A distal dipole tip portion 36 extends from a feed point 34, defined by the inner conductor at the distal end 202, towards an applicator tip 24. A choke (or balun) assembly 40 comprises a conducting element 50 in the form of a longitudinally-extending sleeve which is electrically insulated from the outer conductor of the coaxial conductor assembly, such as by a choke dielectric portion 41. The choke sleeve comprises a second portion 52 which surrounds a first portion 51 which surrounds the coaxial conductor assembly 26. The first 51 and second 52 portions are radially connected by a third portion 53. The choke assembly minimises power reflected back to the microwave source which would affect tissue outside the desired ablation zone. There may be an adhesive sealant 60 or a dielectric fluid 25.
Description
MICROWAVE ABLATION ANTENNA ASSEMBLIES The present invention relates to microwave ablation antenna assemblies. BACKGROUND OF THE INVENTION In the treatment of tumours, for example tumours caused by a disease such as cancer, it is known to use microwave ablation techniques to ablate the tumour. Such microwave ablation techniques typically ablate the targeted tissue by delivering a controlled amount of microwave energy into the tumour.
Minimally-Invasive techniques for delivering such microwave energy have been shown to be effective in the treatment of tumours. In a minimally-invasive technique, a microwave emitter is inserted directly into a point of treatment, either using a normal body orifice or via percutaneous insertion. Such minimally-invasive procedures and devices provide a means of treating tumours in patients who either cannot undergo other forms of treatment (e.g. radiotherapy, surgical resection, chemotherapy) or where ablation is preferred as a therapy.
One type of microwave antenna assembly includes a dipole antenna, which consists of a coaxial construction having an inner conductor and an outer conductor with a dielectric junction (feed point) separating a portion of the inner conductor. The inner conductor may be coupled to a portion corresponding to a first dipole radiating portion, and a portion of the outer conductor may constitute a second dipole radiating portion. The dipole radiating portions may be configured such that one radiating portion is located forwardly of the dielectric junction (known as the feed-point), and the other portion is located rearwardly of the dielectric junction.
The dipole antenna is connected to a source of microwave energy using a coaxial conductor assembly.
In order for such a device to be controlled properly, and to improve the delivery of microwave energy into the tissue being treated, it is desirable for the antenna assembly to be impedance matched with the microwave energy generator. An ablation shape as close to spherical as possible is also desirable. Existing designs of antenna assemblies can be improved upon in these respects.
SUMMARY OF THE INVENTION
According to the present invention, there is provided a microwave ablation antenna assembly comprising: an elongate body with a longitudinal axis, a proximal end and a distal end, the elongate body having a hollow inner volume and defining a longitudinal axis of the antenna; an applicator tip portion mounted on, or mountable to, the distal end of the elongate body; an elongate coaxial conductor assembly for connection to a source of microwave energy having an operating frequency in the microwave frequency range, the coaxial conductor assembly extending from the proximal end of the elongate body towards the distal end of the elongate body through the inner volume, the coaxial conductor assembly having an inner conductor, a dielectric layer around the inner conductor and an outer conductor around the dielectric layer, the inner conductor defining a signal feed-point of the coaxial conductor assembly at a distal end thereof towards the distal end of the elongate body; a distal dipole tip portion which extends from the feed point of the coaxial conductor assembly towards the applicator tip, and which is electrically connected with the inner conductor of the coaxial conductor assembly; and a choke assembly comprising: a choke conducting element of electrically conductive material, the conducting element in the form of a longitudinally-extending sleeve which is electrically insulated from the outer conductor of the coaxial conductor assembly, the sleeve comprising a first longitudinally-extending portion which surrounds the coaxial conductor assembly, a second longitudinally-extending portion of greater diameter than the first portion which surrounds the first portion and a third portion which radially connects the first portion and the second portion at one end of the first and second longitudinally-extending portions.
In one embodiment, the choke assembly comprises a choke dielectric element of dielectric 25 material arranged between the outer conductor of the coaxial conductor assembly and the choke conducting element.
In a further embodiment, the choke assembly comprises a layer of adhesive between the outer conductor of the coaxial conductor assembly and the choke conducting element.
In an antenna assembly in according with the present invention, the third portion connects the first and second longitudinally-extending portions at respective ends which are nearest to the feed point. Alternatively, the third portion connects the first and second longitudinally-extending portions at respective ends which are away from the feed point.
In a further embodiment of the present invention, the first longitudinally-extending portion and the second longitudinally-extending portion are cylindrical.
In one embodiment, the applicator tip surrounds the choke assembly.
In a further embodiment, at least part of the choke assembly is within the elongate body.
Preferably, at least part of the second longitudinally-extending portion of the choke assembly 10 is formed on an inner surface of the elongate body.
In one embodiment, the antenna assembly comprises a dielectric fluid in an inner volume of the body.
BRIEF DESCRIPTION OF THE DRAWINGS
Figure 1 is a schematic block diagram of a microwave ablation system; Figure 2 is a cross sectional view of part of a first example of a microwave ablation antenna assembly; Figure 3 is a cross sectional view of part of second example of a microwave ablation antenna assembly; Figure 4 is a cross sectional view of part of a third example of a microwave ablation antenna assembly; Figure 5 is a cross sectional view of part of a fourth example of a microwave ablation antenna assembly; Figure 6 is a cross sectional view of part of a fifth example of a microwave ablation antenna assembly.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
Figure 1 is a schematic diagram illustrating a microwave ablation system 1 comprising a controller unit 2, and a microwave power generator 4 which is connected to the controller via a control connection 6. An ablation antenna assembly 8 is connected to the microwave power generator 4 via a power connection 10. The antenna assembly includes a tip portion 12 which aids insertion of the antenna assembly into the tissue being treated, and enables a desired output pattern of microwave energy from the antenna assembly.
The controller unit 2 is operable to control the power generator 4 to supply the correct magnitude and operating frequency of microwave energy to the antenna assembly 8. Different control schemes are known in the art, and will not be described here for the sake of brevity. The present invention is concerned with the design of the antenna assembly, and such an assembly may be used with any appropriate control scheme and control hardware.
Figure 2 is a cross-sectional view of part of a first example of an antenna assembly 20. The antenna assembly 20 comprises a body 22, which is preferably cylindrical in form. The body 22 extends from a first (proximal) end 201 to a second (distal) end 202, and defines a longitudinal axis of the assembly. The body 22 defines an inner volume, in which most of the other components of the assembly are housed. The body 22 provides the assembly with the necessary rigidity for insertion into the tissue being treated. The body 22 is preferably of a rigid material, such as a composite material (for example glass fibre, carbon fibre, aramid fibre), stainless steel, other biocompatible metals (e.g. titanium) or combinations of, and is typically 1.5 to 3mm mm in diameter.
An applicator tip 24 is attached to, or forms part of, the second end 202 of the body, to close off the inner volume at the second end. The applicator tip 24 may be a faceted trocar with a relatively sharp distal end point. The applicator tip 24 is designed to be suitable for insertion into the tissue being treated, and partly to affect the transmission pattern for microwave energy into that tissue. The applicator tip 24 forms a water fight seal to the internal volume of the body 22.
A coaxial conductor assembly 26 extends along the inner volume of the body 22 from the first end 201 towards the second end 202. The coaxial conductor assembly 26 is connectable, at a proximal end thereof, to the microwave energy generator 4 of Figure 1. The coaxial conductor assembly 26 extends substantially along the longitudinal axis of the body 22, and comprises an inner conductor 28. The inner conductor 28 is of an electrically conductive material such as copper. Surrounding the inner conductor 28 is a dielectric layer 30 which extends along the inner conductor 28, radially outwardly thereof. The dielectric layer 30 is of any appropriate dielectric material. Surrounding the dielectric layer 30, is an outer conductor 32, which is of an electrically conductive material such as copper. The outer conductor 32 extends along the dielectric layer 30, radially outwardly thereof. Typically, the
S
inner conductor 28 is a wire having a circular cross section, such that the dielectric layer 30 is a cylinder of dielectric material surrounding an outer surface of the inner conductor 28. The outer conductor 32 is then formed by a cylinder of electrically conductive material surrounding an outer surface of the dielectric layer 30.
The inner conductor 28 defines a signal feed-point 34 at its distal end (that is, the end towards the second end 202 of the body 22). A dipole tip portion 36 extends longitudinally from the distal end of the coaxial conductor assembly 36. The dipole tip portion 36 may extend into a reception aperture 23 in the applicator tip 24. The reception aperture may be located centrally with respect to the longitudinal axis of the assembly within the applicator tip 24. The reception aperture is designed so as to locate centrally the dipole tip portion 36 into the tip 24. The tip material is chosen for it mechanical and electrical properties, which have to be considered in the design. The applicator tip is preferably formed of an insulating or dielectric material. However, the applicator tip may comprise a metallic tip or a tip comprising a metallic portion in combination with a high permittivity ceramic material.
Both the dipole tip portion and the choke have a length of A/4. However, their physical length may vary depending on the surrounding material.
The dielectric layer 30 extends along the complete length of the inner conductor 28 to the distal end thereof adjacent the dipole tip portion 36. The outer conductor 32 stops short of the distal end of the inner conductor 28 and dielectric layer 30, and so is spaced apart 20 longitudinally from the signal feed-point 34 and dipole tip portion 36.
A dielectric fluid 25 may be provided within the inner volume of the body 22 to provide a cooling fluid for the antenna assembly. This fluid may be isotonic saline or deionised water.
The antenna assembly includes a choke assembly 40 (alternatively called a balun assembly) which acts to convert an unbalanced microwave input signal into a balanced signal suitable for driving a dipole antenna. Without this conversion, the shape of the ablated tissue extends up the shaft of the instrument and affects tissue which is outside the desired ablation zone. The choke assembly 40 acts to minimise power reflected back to the microwave source.
The choke assembly 40 is located within the body 22, around the coaxial conductor assembly 26, and is spaced apart from the distal end 202 of the coaxial conductor assembly 26. The choke assembly 40 comprises choke dielectric elements 41, 42 and a choke conductor element 50. A first choke dielectric element 41 is adjacent, and coaxial with, the outer conductor 32 of the coaxial conductor assembly 26. The choke dielectric element 41 is longitudinally spaced apart from the feed point 34 of the conductor assembly. In the case when the coaxial conductor assembly 26 has a circular cross section, the choke dielectric element 41 is in the form of a cylinder of dielectric material surrounding an outer surface of the outer conductor 32 of the coaxial conductor assembly 26. The choke dielectric element 41 has a proximal end towards the first end 201 of the body 22 and a distal end towards the second end 202 of the body 22.
The choke assembly 40 also includes a choke conducting element 50 of an electrically conductive material having a first portion 51 which is arranged adjacent, and coaxial with the choke dielectric element 41. The choke conducting element 50 has a second portion 52 which extends from the first portion 51 coaxially with the first portion 51 and the conductor assembly 26. The choke conducting element 50 has a third portion 53 which extends radially between the first portion 51 of the choke conducting element 50 and the second portion 52 of the choke conducting element 50. The third portion 53 of the choke conducting element 50 forms an electrical short between the first portion 51 and the second portion 52. The first portion 51, second portion 52 and third portion 52 are electrically connected together and form a single conducting element. In this example, the first portion 51 of the choke conducting element 50 has a length L1 and the second portion 51 of the choke conducting element 50 has a distance L2. Length L2 is shorter than Li. The choke assembly 40 comprises a second choke dielectric element 42 which is between the first portion 51 of the choke conducting element 50 and the second portion 52 of the choke conducting element 50.
The choke conducting element 50 forms a sleeve which surrounds, but without electrical connection/coupling to, the coaxial cable assembly 26. The first choke dielectric element 41 lies between the outer conductor 32 of the coaxial conductor assembly 26 and the first portion 51 of the choke conducting element 50. The first choke dielectric element 41 electrically insulates the choke conducting element 50 from the coaxial conductor assembly 26. The balun/choke performs its function without electrical connection or coupling to the coaxial cable assembly.
Adhesive sealant 60 surrounds the choke assembly 40. The adhesive sealant 60 also surrounds part of the coaxial conductor assembly 26 and the dipole tip portion 36.
In this example the choke conducting element 50 acts as the distal leg of the dipole antenna. RF cancellation takes place at the proximal edge of the sleeve between the direct signal and the signal which runs around the inside of the choke, if the round trip distance is made A/2 (i.e. internal length, L2, is A/4), where A is the wavelength of the microwave signal.
This presents a high impedance to microwaves which would otherwise extend up the device shaft. This has an effect of confining the radiation and give a more spherical ablation shape.
In the embodiment shown, the choke conducting element 50 is located partly behind the body 22 with the conductor 50 extending to one side so that the body 22 overlaps the conductor 50. This assists with the production of a tip with the shorted dimensions possible 10 without any effect on the radiation pattern.
Figure 3 is a cross-sectional view of part of a second example of an antenna assembly 20. Features which are common to the first example have the same reference numerals. In this example, the choke conducting element 50 forms a sleeve which surrounds, but without electrical connection/coupling to, the coaxial cable assembly 26. A short between a first (inner) portion 51 and a second (outer) portion 52 of the choke conducting element 50 is located nearest the proximal end 201 of the body 22.
In this example the choke conducting element 50 acts as the proximal leg of the dipole antenna. RE cancellation takes place at the distal mouth X of the sleeve between the direct signal and the signal which runs around the inside of the choke, if the round trip distance is made A/2 (i.e. internal choke length, L2, is A/4), where A is the wavelength of the microwave signal.
This presents a high impedance to microwaves which would otherwise extend up the device shaft. This has an effect of confining the radiation and give a more spherical ablation shape.
The length of the dielectric between the feed point and the conducting element 50 is A/4 and 25 constitutes the proximal leg of the dipole for the embodiments shown in figures 3 and 5. This results in cancellation at point X. Figure 4 is a cross-sectional view of part of a third example of an antenna assembly 20. Features which are common to the first example have the same reference numerals.
In this example, the choke conducting element 50 forms a sleeve which surrounds, but without electrical connection/coupling to, the coaxial cable assembly 26. Adhesive 60, rather than a dielectric element, is located between the choke conducting element 50 and the coaxial cable assembly 26. The adhesive is non-conductive with a low dissipation factor.
A short between a first (inner) portion 51 and a second (outer) portion 52 of the choke conducting element 50 is located nearest the distal end 202 of the body 22.
Figure 5 is a cross-sectional view of part of a fourth example of an antenna assembly 20. Features which are common to the first example have the same reference numerals. In this example, the choke conducting element 50 forms a sleeve which surrounds, but without electrical connection/coupling to, the coaxial cable assembly 26. Adhesive 60, rather than a dielectric element, is located between the choke conducting element 50 and the coaxial cable assembly 26. A short between a first (inner) portion 51 and a second (outer) portion 52 of the choke conducting element 50 is located nearest the proximal end 201 of the body 22.
Figure 6 is a cross-sectional view of part of a fifth example of an antenna assembly 20. Features which are common to the first example have the same reference numerals.
As with other examples, the antenna assembly includes a choke assembly 40 which acts to convert an unbalanced microwave input signal into a balanced signal suitable for driving a dipole antenna. The choke assembly 40 comprises a choke dielectric element 41 and a choke conductor element 50. The choke assembly 40 also includes a choke conducting element 50 of an electrically conductive material. The choke conducting element 50 may be in the form of a conducting layer, or plate. The conducting layer is a continuous layer. The choke conducting element 50 is generally in the form of a sleeve with a longitudinally-extending inner portion 151, longitudinally-extending outer portions 153, 155 and radially-extending portions 152, 154 which connect the inner portion 151 to the outer portion 155. Portions 152, 153, 154 form an electrical short. The short is located nearest the proximal end 201 of the body 22. The longitudinally-extending portion 153 is adjacent the inner surface of the body 22. In the embodiment shown, the stepped profile of the choke is to allow engagement with the antenna shaft. Tip portion 70 comprises an insulating ceramic onto which conductive layers 151, 152, 153, 154 and 155 are deposited.
A choke dielectric element 41 surrounds the coaxial conductor assembly 26. The choke dielectric element 41 extends towards the tip 24 for a longitudinal distance beyond the choke conducting element 50 for a distance of A/4, based on the electrical length for the ceramic material permittivity.
The choke dielectric element 41 is adjacent, and coaxial with, the outer conductor 32 of the coaxial conductor assembly 26. The choke dielectric element 41 is longitudinally spaced apart from the feed point 34 of the conductor assembly. In the case when the coaxial conductor assembly 26 has a circular cross section, the choke dielectric element 41 is in the form of a cylinder of dielectric material surrounding an outer surface of the outer conductor 32 of the coaxial conductor assembly 26. The choke dielectric element 41 has a proximal end towards the first end 201 of the body 22 and a distal end towards the second end 202 of the body 22.
The tip 24 may take any suitable form, such as a needle or bullet. In this example, the tip is an embedded tip which locates in a reception aperture. The reception aperture extends for a distance along a longitudinal axis of the assembly. Adhesive 61 may be provided around the embedded end 241 of the tip 24. Adhesive 61 retains tip 24 in place whilst avoiding an air gap which would impact on the effective permittivity of the ceramic tip portion 70.
Adhesive 62 may be provided between the choke conducting element 50 and the proximal 15 interior chamber of the body 22. Adhesive 62 retains the metal plated ceramic tip in place relative to the antenna shaft and seals choke assembly 40 from the circulating coolant.
In the example of figure 6, the proximal leg is defined by the distance from the mouth of the choke to the gap. RE cancellation takes place at the distal mouth of the sleeve between the direct signal, and the signal which runs around the inside of the choke, if the round-trip distance is made A/2 (i.e. internal length A14), where A is the wavelength of the microwave signal. This presents a high impedance to microwaves which would otherwise extend up the device shaft. This has an effect of confining the radiation and give a more spherical ablation shape.
This example has an advantage of simplifying construction and can allow a smaller diameter 25 of the overall assembly.
Claims (10)
- CLAIMS: 1. A microwave ablation antenna assembly comprising: an elongate body with a longitudinal axis, a proximal end and a distal end, the elongate body having a hollow inner volume and defining a longitudinal axis of the antenna; an applicator tip portion mounted on, or mountable to, the distal end of the elongate body; an elongate coaxial conductor assembly for connection to a source of microwave energy having an operating frequency in the microwave frequency range, the coaxial conductor assembly extending from the proximal end of the elongate body towards the distal end of the elongate body through the inner volume, the coaxial conductor assembly having an inner conductor, a dielectric layer around the inner conductor and an outer conductor around the dielectric layer, *the inner conductor defining a signal feed-point of the coaxial conductor assembly at a distal end thereof towards the distal end of the elongate body; a distal dipole tip portion which extends from the feed point of the coaxial conductor assembly towards the applicator tip, and which is electrically connected with the inner conductor of the coaxial conductor assembly; and a choke assembly comprising: a choke conducting element of electrically conductive material, the conducting element in the form of a longitudinally-extending sleeve which is electrically insulated from the outer conductor of the coaxial conductor assembly, the sleeve comprising a first longitudinally-extending portion which surrounds the coaxial conductor assembly, a second longitudinally-extending portion of greater diameter than the first portion which surrounds the first portion and a third portion which radially connects the first portion and the second portion at one end of the first and second longitudinally-extending portions.
- 2. An antenna assembly as claimed in claim 1, wherein the choke assembly comprises a choke dielectric element of dielectric material arranged between the outer conductor of the coaxial conductor assembly and the choke conducting element.
- 3. An antenna assembly as claimed in claim 1, wherein the choke assembly comprises a layer of adhesive between the outer conductor of the coaxial conductor assembly and the choke conducting element
- 4. An antenna assembly as claimed in any one of the preceding claims, wherein the third portion connects the first and second longitudinally-extending portions at respective ends which are nearest to the feed point.
- 5. An antenna assembly as claimed in any one of claims 1 to 3, wherein the third portion connects the first and second longitudinally-extending portions at respective ends which are away from the feed point.
- 6. An antenna assembly as claimed in any one of the preceding claims wherein the first longitudinally-extending portion and the second longitudinally-extending portion are cylindrical.
- 7. An antenna assembly as claimed in any one of claims 1 to 6 wherein the applicator tip surrounds the choke assembly.
- 8. An antenna assembly as claimed in any one of claims 1 to 6 wherein at least part of the choke assembly is within the elongate body.
- 9. An antenna assembly as claimed in claim 8 wherein at least part of the second longitudinally-extending portion of the choke assembly is formed on an inner surface of the elongate body.
- 10. An antenna assembly as claimed in any one of the preceding claims comprising a dielectric fluid in an inner volume of the body.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB1900424.1A GB2580424B (en) | 2019-01-11 | 2019-01-11 | Microwave ablation antenna assemblies |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB1900424.1A GB2580424B (en) | 2019-01-11 | 2019-01-11 | Microwave ablation antenna assemblies |
Publications (3)
| Publication Number | Publication Date |
|---|---|
| GB201900424D0 GB201900424D0 (en) | 2019-02-27 |
| GB2580424A true GB2580424A (en) | 2020-07-22 |
| GB2580424B GB2580424B (en) | 2023-02-01 |
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| Application Number | Title | Priority Date | Filing Date |
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| GB1900424.1A Active GB2580424B (en) | 2019-01-11 | 2019-01-11 | Microwave ablation antenna assemblies |
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| Country | Link |
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| GB (1) | GB2580424B (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2024081287A1 (en) * | 2022-10-11 | 2024-04-18 | Stryker Corporation | Systems for microwave ablation of tissue |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN109907822B (en) * | 2019-04-09 | 2023-10-20 | 北京博海康源医疗器械有限公司 | Radio frequency ablation closed microcatheter |
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- 2019-01-11 GB GB1900424.1A patent/GB2580424B/en active Active
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| WO2024081287A1 (en) * | 2022-10-11 | 2024-04-18 | Stryker Corporation | Systems for microwave ablation of tissue |
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| Publication number | Publication date |
|---|---|
| GB201900424D0 (en) | 2019-02-27 |
| GB2580424B (en) | 2023-02-01 |
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