ELECTROSURGICAL SYSTEM

Abstract

An electrosurgical system for treating biological tissue that comprises: an electrosurgical generator to supply microwave energy; a surgical scoping device having a steerable insertion cord for insertion to a treatment site; and an electrosurgical instrument dimensioned to fit within an instrument channel that is located within the insertion cord. The electrosurgical instrument comprises: a flexible coaxial cable arranged to convey the microwave energy; and a radiating tip portion connected at an end of the coaxial cable and configured to receive microwave energy. The radiating tip portion comprises: a coaxial transmission line for conveying the microwave energy; and a needle tip mounted at an end of the proximal coaxial transmission line, wherein the electrosurgical instrument is slidable within the instrument channel to extend the needle tip beyond an end of the instrument channel to puncture biological tissue; the needle tip is arranged to deliver the microwave energy into biological tissue.

Claims

1. An electrosurgical system for treating biological tissue, the electrosurgical system comprising: an electrosurgical generator configured to supply microwave energy; a surgical scoping device having a steerable insertion cord for minimally invasive insertion to a treatment site within a body; and an electrosurgical instrument dimensioned to fit within an instrument channel that is located within the insertion cord, wherein the electrosurgical instrument comprises: a flexible coaxial cable arranged to convey the microwave energy; and a radiating tip portion connected at a distal end of the coaxial cable and configured to receive the microwave energy, wherein the radiating tip portion has a maximum outer diameter that is 1.0 mm or less, and wherein the maximum outer diameter of the radiating tip portion is smaller than an outer diameter of the coaxial cable, wherein the radiating tip portion comprising: a proximal coaxial transmission line for conveying the microwave energy; and a distal needle tip mounted at a distal end of the proximal coaxial transmission line, wherein the electrosurgical instrument is slidable within the instrument channel to extend the distal needle tip beyond a distal end of the instrument channel to puncture biological tissue, and wherein the distal needle tip is arranged to deliver the microwave energy into biological tissue.

2. An electrosurgical system according to claim 1, wherein the surgical scoping device is an ultrasound-enabled bronchoscope.

3. An electrosurgical system according to claim 1, wherein the electrosurgical instrument further comprises a protective catheter mounted around the radiating tip portion, wherein the catheter is movable within the instrument channel, and wherein the radiating tip portion is movable relative to the catheter.

4. An electrosurgical system according to claim 1, wherein the electrosurgical generator is configured to supply pulsed microwave energy having a pulse duration that is shorter than a thermal response time of the radiating tip portion.

5. An electrosurgical system according to claim 4, wherein the electrosurgical generator is configured to supply the pulsed microwave energy with a duty cycle of 25% or less.

6. An electrosurgical system according to claim 4, wherein a pulse duration of the pulsed microwave energy is between 10 ms and 200 ms.

7. An electrosurgical system according to claim 1, wherein a length of the radiating tip portion is equal to or greater than 140 mm.

8. An electrosurgical system according to claim 1, wherein the proximal coaxial transmission line comprises: an inner conductor that extends from a distal end of the flexible coaxial cable, the inner conductor being electrically connected to a centre conductor of the flexible coaxial cable; a proximal dielectric sleeve mounted around the inner conductor; and an outer conductor mounted around the proximal dielectric, wherein the distal needle tip comprises a distal dielectric sleeve mounted around the inner conductor, and wherein a distal portion of the outer conductor overlays a proximal portion of the distal dielectric sleeve.

9. An electrosurgical system according to claim 8, wherein distal dielectric sleeve is made from a different material compared to the proximal dielectric sleeve.

10. An electrosurgical system according to claim 9, wherein a proximal end of the distal dielectric sleeve includes a protrusion disposed around the inner conductor, and wherein the protrusion is received in a complementarily shaped cavity at a distal end of the proximal dielectric sleeve.

11. An electrosurgical system according to claim 1, wherein the distal needle tip is configured to operate as a half wavelength transformer to deliver the microwave energy from the distal needle tip.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0048] Embodiments of the invention are discussed below with reference to the accompanying drawings, in which:

[0049] FIG. 1 is a schematic diagram of an electrosurgical system for tissue ablation that is an embodiment of the invention;

[0050] FIG. 2 is a schematic sectional view through an insertion cord of an endoscope that can be used with the present invention;

[0051] FIG. 3 is a schematic side view of an electrosurgical instrument that may be used in an electrosurgical system of the invention;

[0052] FIG. 4 is a cross-sectional diagram of the electrosurgical instrument of FIG. 3, where an outer conductor has been omitted for illustration purposes;

[0053] FIG. 5 is a cross-sectional diagram of a distal section of the electrosurgical instrument of FIG. 3;

[0054] FIG. 6 is a graph showing power delivery profile of pulsed microwave energy supplied by an electrosurgical generator that is part of an electrosurgical system of the invention;

[0055] FIG. 7 is a schematic cross-sectional diagram of a radiating tip portion that may be used in an electrosurgical system of the invention;

[0056] FIG. 8a is a schematic cross-sectional diagram of a radiating tip portion that may be used in an electrosurgical system of the invention;

[0057] FIG. 8b is a perspective view of a distal tip of the radiating tip portion of FIG. 8a;

[0058] FIG. 9a is a schematic cross-sectional diagram of a radiating tip portion that may be used in an electrosurgical system of the invention;

[0059] FIG. 9b is a schematic cross-sectional diagram of a distal portion of the radiating tip portion of FIG. 9a;

[0060] FIG. 10 is a schematic cross-sectional diagram of a radiating tip portion that may be used in an electrosurgical system of the invention;

[0061] FIG. 11 is a schematic cross-sectional diagram of a radiating tip portion that may be used in an electrosurgical system of the invention; and

[0062] FIG. 12 is a schematic cross-sectional diagram of an electrosurgical instrument located in an instrument channel of a surgical scoping device according to another embodiment of the invention.

DETAILED DESCRIPTION; FURTHER OPTIONS AND PREFERENCES

[0063] FIG. 1 is a schematic diagram of an electrosurgical system 100 that is an embodiment of the invention. The electrosurgical system 100 is capable of supplying microwave energy to a distal end of an invasive electrosurgical instrument to perform tissue ablation. The electrosurgical system is also capable of supplying a fluid, e.g. a liquid medicament or a cooling fluid, to a distal end of the invasive electrosurgical instrument. The system 100 comprises an electrosurgical generator 102 for controllably supplying microwave energy. The electrosurgical generator is configured to supply pulsed microwave energy, as discussed in more detail below. A suitable generator for this purpose is described in WO 2012/076844, which is incorporated herein by reference. The electrosurgical generator 102 may be arranged to monitor reflected signals received back from the instrument in order to determine an appropriate power level for delivery. For example, the generator 102 may be arranged to calculate an impedance seen at the distal end of the instrument in order to determine an optimal delivery power level.

[0064] The electrosurgical system 100 further includes an interface joint 106 that is connected to the electrosurgical generator 102 via an interface cable 104. The interface joint 106 is also connected via a fluid flow line 107 to a fluid delivery device 108, such as a syringe. In some examples, the system may be arranged, additionally or alternatively, to aspirate fluid from a treatment site. In this scenario, the fluid flow line 107 may convey fluid away from the interface joint 106 to a suitable collector (not shown). The aspiration mechanism may be connected at a proximal end of the fluid flow line 107.

[0065] The interface joint 106 may house an instrument control mechanism for controlling a position of the electrosurgical instrument. The control mechanism may be used to control a longitudinal position of the electrosurgical instrument, and/or bending of a distal end of the electrosurgical instrument. The Control mechanism is operable by sliding a trigger, to control a longitudinal (back and forth) movement of one or more control wires or push rods (not shown). If there is a plurality of control wires, there may be multiple sliding triggers on the interface joint to provide full control. A function of the interface joint 106 is to combine the inputs from the generator 102, fluid delivery device 108 and instrument control mechanism into a single flexible shaft (or electrosurgical instrument) 112, which extends from the distal end of the interface joint 106.

[0066] The electrosurgical system further includes a surgical scoping device 114, which in embodiment of the present invention may comprise an endoscopic ultrasound device. The flexible shaft 112 is insertable through an entire length of an instrument (working) channel of the surgical scoping device 114.

[0067] The surgical scoping device 114 comprises a body 116 having a number of input ports and an output port from which an insertion cord 120 extends. The insertion cord 120, which is illustrated in more detail in FIG. 2, comprises an outer jacket which surrounds a plurality of lumens. The plurality of lumens convey various things from the body 116 to a distal end of the insertion cord 120. One of the plurality of lumens is the instrument channel discussed above. Other lumens may include a channel for conveying optical radiation, e.g. to provide illumination at the distal end or to gather images from the distal end. The body 116 may include an eye piece 122 for viewing the distal end.

[0068] An endoscopic ultrasound device typically provides an ultrasound transducer on a distal tip of the insertion cord, beyond an exit aperture of the instrument channel. Signals from the ultrasound transducer may be conveyed by a suitable cable 126 back along the insertion cord to a processor 124, which can generate images in a known manner. The instrument channel may be shaped within the insertion cord to direct an instrument exiting the instrument channel through the field of view of the ultrasound system, to provide information about the location of the instrument at the target site.

[0069] The flexible shaft 112 has a distal assembly 118 (not drawn to scale in FIG. 1) that is shaped to pass through the instrument channel of the surgical scoping device 114 and protrude (e.g. inside the patient) at the distal end of the insertion cord.

[0070] The structure of the distal assembly 118 discussed below may be particularly designed for use with an endoscopic ultrasound (EUS) device. The maximum outer diameter of the distal assembly 118 is equal to or less than 1.0 mm, e.g. less than 0.95 mm or 0.90 mm. The length of the flexible shaft can be equal to or greater than 1.2 m.

[0071] The body 116 includes an input port 128 for connecting to the flexible shaft 112. As explained below, a proximal portion of the flexible shaft may comprise a conventional coaxial cable capable of conveying the pulsed microwave energy from the electrosurgical generator 102 to the distal assembly 118. Example coaxial cables that are physically capable of fitting down the instrument channel of an EUS device are available with the following outer diameters: 1.19 mm (0.047″), 1.35 mm (0.053″), 1.40 mm (0.055″), 1.60 mm (0.063″), 1.78 mm (0.070″). Custom-sized coaxial cables (i.e. made to order) may also be used.

[0072] In order to control a position of a distal end of the insertion cord 120, the body 116 may further include a control actuator that is mechanically coupled to the distal end of the insertion cord 120 by one or more control wires (not shown), which extend through the insertion cord 120. The control wires may travel within the instrument channel or within their own dedicated channels. The control actuator may be a lever or rotatable knob, or any other known catheter manipulation device. The manipulation of the insertion cord 120 may be software-assisted, e.g. using a virtual three-dimensional map assembled from computer tomography (CT) images.

[0073] The invention may be particularly suited for treatment of the pancreas. In order to reach a target site in the pancreas, the insertion cord 120 may need to be guided through the mouth, stomach and duodenum. The electrosurgical instrument is arranged to access the pancreas by passing through the wall of the duodenum. The invention may also be particularly suited to treatment of tissue in the liver.

[0074] FIG. 2 is a view down the axis of the insertion cord 120. In this embodiment there are four lumens within the insertion cord 120. The largest lumen is the instrument channel 132 in which the flexible shaft 112 is received. The other lumens comprise an ultrasound signal channel 134, an illumination channel 136, and a camera channel 138 but the invention is not limited to this configuration. For example, there may be other lumens, e.g. for control wires or fluid delivery or suction.

[0075] We will now describe an electrosurgical instrument 300 that may be part of an electrosurgical system of the invention, with reference to FIGS. 3 and 4. FIGS. 3 and 4 show side views of a distal portion of the electrosurgical instrument 300, which may correspond to the distal assembly 118 referred to above. The electrosurgical instrument 300 includes a flexible coaxial cable 302, and a radiating tip portion 304 which is connected at a distal end of the coaxial cable 302. The coaxial cable 302 may be a conventional flexible 50Ω coaxial cable suitable for conveying microwave energy. The coaxial cable includes a centre conductor and an outer conductor that are separated by a dielectric material. The coaxial cable 302 is connectable at a proximal end to a generator, e.g. to generator 102, to receive the microwave energy.

[0076] The radiating tip portion 304 includes a proximal coaxial transmission line 306 and a distal needle tip 308 formed at a distal end of the proximal coaxial transmission line 306. The proximal coaxial transmission line 306 is electrically connected to the distal end of the coaxial cable 302 to receive the electromagnetic energy from the coaxial cable 302 and convey it to the distal needle tip 308. The distal needle tip 308 is configured to deliver the received electromagnetic energy into target biological tissue. In the present example, the distal needle tip 308 is configured as a half wavelength transformer to deliver microwave energy into target biological tissue, to ablate the target tissue. In other words, an electrical length of the distal needle tip 308 corresponds to a half wavelength of the microwave energy (e.g. at 5.8 GHz). When microwave energy is delivered to the distal needle tip 308 it may radiate the microwave energy along its length into surrounding biological tissue.

[0077] An inner conductor 310 of the proximal coaxial transmission line 306 is electrically connected to the centre conductor of the coaxial cable 302. The radiating tip portion 304 is secured to the coaxial cable 302 via a collar 312 mounted over a junction between the coaxial cable 302 and the radiating tip portion 304. The collar 312 is made of a conductive material (e.g. brass), and electrically connects the outer conductor of the coaxial cable 302 to an outer conductor 314 of the proximal coaxial transmission line 306. The outer conductor 314 is formed of a tube of nitinol, which is flexible and provides a sufficient longitudinal rigidity to pierce tissue (e.g. the duodenum wall). For illustration purposes, the outer conductor 314 is omitted from FIG. 4 to reveal an inner structure of the radiating tip portion 304. Also for illustration purposes, a length of the proximal coaxial transmission line 306 has been omitted in FIGS. 3 and 4, as indicated by broken lines 307.

[0078] The proximal coaxial transmission line 306 includes a proximal dielectric sleeve 320 which is disposed around the inner conductor 310 and which spaces the inner conductor 310 from the outer conductor 314. The outer conductor 314 is formed on an outer surface of the proximal dielectric sleeve 320. A distal dielectric sleeve 322 is disposed around a distal portion of the inner conductor 310 to form the distal needle tip 308. The distal needle tip 308 further includes a pointed tip 324 at its distal end, to facilitate insertion of the radiating tip portion into target tissue. The distal dielectric sleeve 322 may be made of a different dielectric material compared to the proximal dielectric sleeve 504. In one example, the proximal dielectric sleeve 504 may be made of PTFE (e.g. it may be a PTFE tube) and the distal dielectric sleeve may be made of PEEK. Specific examples of materials that may be used in the radiating tip portion 304 are discussed below in relation to FIGS. 7-11.

[0079] A distal portion of the outer conductor 314 overlays a proximal portion of the distal dielectric sleeve 322. In this manner, a distal portion of the proximal coaxial transmission line 306 includes the proximal portion of the distal dielectric sleeve 322. The materials of the proximal and distal dielectric sleeves and the length of the overlap between the outer conductor 314 and the distal dielectric sleeve 322 may be selected in order to adjust an electrical length of the radiating tip portion 308 and impedance matching with target tissue.

[0080] The collar 312 includes a substantially cylindrical body 316 which is mounted on the distal end of the coaxial cable 302 and which is electrically connected to the outer conductor of the coaxial cable 302. The collar 312 further includes a distal portion 318 which extends from the body 316 of the collar 312 to a proximal end of the outer conductor 314 of the proximal coaxial transmission line 306. The distal portion 318 of the collar 312 includes a distal surface which is rounded. This may reduce friction between the electrosurgical instrument 300 and an instrument channel of a surgical scoping device when the electrosurgical instrument 300 is moved along the channel, by avoiding sharp edges at the interface between the coaxial cable 302 and the radiating tip portion 304. This may also facilitate moving the electrosurgical instrument along the channel when the channel is in retroflex.

[0081] A maximum outer diameter of the radiating tip portion 304 is indicated in FIG. 3 by arrows 326. In the present example, the maximum outer diameter of the radiating tip portion 304 corresponds to an outer diameter of the outer conductor 314, as this is the component of the radiating tip portion 304 having the largest outer diameter. The maximum outer diameter of the radiating tip portion 304 is 1.0 mm or less. For example, it may be 1.0 mm, 0.95 mm or 0.90 mm. This may ensure that a size of an insertion hole produced by the radiating tip portion 304 when it is inserted into target tissue is small, which may minimise bleeding. This may make the electrosurgical instrument 300 particularly suited to use in highly vascularised regions of the body, e.g. in the liver, where excessive bleeding may be an issue.

[0082] An outer diameter of the coaxial cable 302 is indicated by arrows 328 in FIG. 3. The outer diameter of the coaxial cable 302 is larger than the maximum outer diameter of the radiating tip portion 304. For example, the outer diameter of the coaxial cable 302 may be between 1.19 mm and 2.0 mm, or it may be greater than 2.0 mm. By providing the radiating tip portion 304 with a smaller maximum outer diameter than the coaxial cable, it is possible to increase the flexibility of the radiating tip portion 304 relative to the coaxial cable 302. This may facilitate manoeuvring the radiating tip portion 304 to a particular treatment location. At the same time, by providing the coaxial cable 302 with a larger diameter, transmission losses (e.g. due to heating) in the coaxial cable 302 may be reduced, as transmission losses are generally related to the diameter of the coaxial cable 302. This may enable microwave energy to be conveyed more efficiently along the coaxial cable 302 to the radiating tip portion 304.

[0083] In some embodiments, the electrosurgical instrument 300 may be housed in a catheter (not shown). The electrosurgical instrument 300 may be movable relative to the catheter, so that the radiating tip portion 304 can be retracted inside the catheter when not in use. This may serve to protect the radiating tip portion, and prevent it from catching on the insertion cord when it is inserted into the insertion cord of a surgical scoping device.

[0084] The radiating tip portion 304 may have a length equal to or greater than 30 mm, e.g. 40 mm. In this manner, the radiating tip portion 304 may be long enough for the distal needle tip 308 to reach a treatment site, without having to insert a portion of the coaxial cable 302 into tissue. In some cases the radiating tip portion 304 may have a length of 140 mm or greater. The inventors have found that this may facilitate inserting the electrosurgical instrument 300 into an insertion cord where a distal portion of the insertion cord is in retroflex, as it may avoid having to push the more rigid coaxial cable 302 through the distal portion of the insertion cord.

[0085] FIG. 5 illustrates an interface between the proximal dielectric sleeve 320 and the distal dielectric sleeve 322 in more detail. FIG. 5 shows a cross-sectional view of a distal section of the radiating tip portion 304. For illustration purposes, the outer conductor 314 is omitted from FIG. 5. A proximal end of the distal dielectric sleeve 322 includes a protrusion 502 which extends from the proximal end of the distal dielectric sleeve 322. The protrusion 502 has a generally cylindrical shape, with an outer diameter smaller than that of the distal dielectric sleeve 322, and is disposed around the inner conductor 310. The proximal dielectric sleeve 320 includes a cavity having a shape complementary to that of the protrusion 502, in which the protrusion 502 is received. Thus, the proximal dielectric sleeve 320 steps around the protrusion 502. As the protrusion 502 of the distal dielectric sleeve 322 is received in the proximal dielectric sleeve 320, this serves to provide a strong mechanical connection between the distal and proximal dielectric sleeves. Additionally, the protrusion 502 may serve to increase a breakdown voltage of the radiating tip portion 304 at the interface between the distal dielectric sleeve 322 and the proximal dielectric sleeve 320. This may improve an electrical safety of the radiating tip portion 304.

[0086] As the radiating tip portion 304 of electrosurgical instrument has a small diameter (i.e. 1.0 mm or less), it may heat up rapidly when microwave energy is delivered to it. This may result in inefficient delivery of microwave energy to the distal needle tip. Heating of the radiating tip portion 304 may also cause damage to healthy surrounding tissue. The inventors have overcome this drawback by configuring the electrosurgical generator (e.g. electrosurgical generator 102) of the electrosurgical system of the invention to deliver the microwave energy in pulses. The inventors have found that pulsed delivery of microwave energy may avoid or reduce heating effects in the radiating tip portion, so that the radiating tip portion may be maintained at an acceptable temperature during a surgical procedure.

[0087] In order to avoid heating of the radiating tip portion during application of microwave energy, a pulse duration of the microwave pulses may be set to be greater than a thermal response time of the radiating tip portion. In this manner, the radiating tip portion may not have time to react thermally to the pulsed microwave energy on the timescale of the microwave pulses. The thermal response time of the radiating tip portion may be measured experimentally, by determining an amount of time taken for a temperature of the radiating tip portion to increase by a given amount (e.g. 5° C.) when microwave energy at a given power level (e.g. a power level to be used during an electrosurgical procedure) is delivered to the radiating tip portion. The pulse duration may then be set accordingly, to ensure that the temperature of the radiating tip portion remains at an acceptable temperature over the course of an electrosurgical procedure.

[0088] The inventors have found that configuring the electrosurgical generator to deliver pulsed microwave energy with a duty cycle of 25% or less may avoid or reduce heating effects in the radiating tip portion so that it may be maintained at an acceptable temperature during use. The electrosurgical generator may be configured to deliver microwave energy according to one of the following example cycles:

[0089] a) 10 ms pulse duration, with 90 ms between pulses;

[0090] b) 10 ms pulse duration, with 50 ms between pulses;

[0091] c) 10 ms pulse duration, with 30 ms between pulses;

[0092] d) 100 ms pulse duration, with 900 ms between pulses;

[0093] e) 100 ms pulse duration, with 500 ms between pulses;

[0094] f) 100 ms pulse duration, with 300 ms between pulses; and

[0095] g) 200 ms pulse duration, with 800 ms between pulses.

[0096] Cycles a) and d) correspond to a duty cycle of 10%; cycles b) and e) correspond to a duty cycle of 16.67%; cycles c) and f) correspond to a duty cycle of 25%; and cycle g) corresponds to a duty cycle of 20%.

[0097] FIG. 6 illustrates a power delivery profile according to cycle a) given above. The power delivery profile of FIG. 6 shows power of microwave energy supplied by the electrosurgical generator against time. The power delivery profile includes a series of microwave pulses 600, each having a duration of 10 ms. The microwave pulses 600 are separated by intervals 602, each having a duration of 90 ms. The microwave pulses 600 each have a power P, as indicated in FIG. 6. During the intervals 602, no microwave energy is supplied by the electrosurgical generator (i.e. the supplied power is 0 W). Each of the pulses 600 is identical, and includes a constant power level. Note that the power delivery profile of FIG. 6 is not drawn to scale. In other examples, the power level of a microwave pulse may vary over the course of the pulse, depending on a desired energy delivery profile. In some cases, a microwave pulse cycle may include pulses having different durations and/or power levels.

[0098] We will now describe specific examples of radiating tip portions of electrosurgical instruments that may be used in an electrosurgical system of the invention, with reference to FIGS. 7-11. The radiating tip portions described below may, for example, be used instead of the radiating tip portion 304 of electrosurgical instrument 300 discussed above. Radiating tip portions 700, 800, 900, 1000 and 1100 discussed below each have a similar overall configuration. Similarly to radiating tip portion 304, each of radiating tip portions 700, 800, 900, 1000 and 1100 has an inner conductor electrically connected to a centre conductor of a coaxial cable (not shown), and an outer conductor electrically connected to an outer conductor of the coaxial cable. The radiating tip portions 700, 800, 900, 1000 and 1100 each further include a proximal dielectric sleeve and a distal dielectric sleeve disposed around the inner conductor, in order to form a proximal transmission line and a distal needed tip as discussed above in relation to radiating tip portion 304.

[0099] FIG. 7 shows a cross-sectional view of a distal section of a radiating tip portion 700. A proximal dielectric sleeve 706 of radiating tip portion 700 may be made of a flexible insulating material, e.g. PTFE. A distal dielectric sleeve 708 of radiating tip portion 700 is made of a cylindrical piece of Zirconia. A distal tip 710 of the distal dielectric sleeve 708 is sharpened, to facilitate insertion of the radiating tip portion 700 into tissue. Making the distal dielectric sleeve 708 of Zirconia may provide a rigid distal needle tip to the radiating tip portion 700, which may facilitate piercing of tissue. Use of Zirconia may also enable a physical length of the radiating tip portion to be shortened, whilst maintaining a desired electrical length.

[0100] Example dimensions of the radiating tip portion 700 are shown in FIG. 7. The dimension indicated by reference numeral 712, which corresponds to a length of the proximal dielectric sleeve 706, may be 37 mm. Note the total length of the proximal dielectric sleeve 706 is not shown in FIG. 7. The dimension indicated by reference numeral 714, which corresponds to an overlap between an outer conductor 704 of the radiating tip portion 700 and the distal dielectric sleeve 708, may be 3.6 mm. The dimension indicated by reference numeral 716, which corresponds to a length of an inner conductor 702 of the radiating tip portion 700 that protrudes beyond a distal end of the outer conductor 704, may be 1.5 mm. The dimension indicated by reference numeral 718, which corresponds to a length of the distal tip 710, may be 1.5 mm. A maximum outer diameter of the radiating tip portion 700, indicated by reference numeral 720, is 1.0 mm or less.

[0101] FIG. 8a shows a cross-sectional view of a distal section of a radiating tip portion 800. A proximal dielectric sleeve 806 of radiating tip portion 800 may be made of a flexible tube of insulating material, e.g. PTFE. A distal dielectric sleeve 808 of radiating tip portion 800 is made of a cylindrical piece of Zirconia. The distal dielectric sleeve 808 includes a bore in which the inner conductor is received. A distal tip 810 made of Zirconia is mounted at a distal end of the distal dielectric sleeve 808. A perspective view of the distal tip 810 is shown in FIG. 8b. The distal tip 810 has a conical body 812 forming a pointed tip, to facilitate insertion of the radiating tip portion 800 into tissue. The distal tip 810 includes a protrusion 814 extending from a proximal face 816 of the conical body 812. The protrusion of the distal tip 810 is received in the bore in the distal dielectric sleeve 808, where it is secured in placed (e.g. with an adhesive).

[0102] Example dimensions of the radiating tip portion 800 are shown in FIG. 8a. The dimension indicated by reference numeral 818, which corresponds to a length of the proximal dielectric sleeve 806, may be 37 mm. Note the total length of the proximal dielectric sleeve 806 is not shown in FIG. 8a. The dimension indicated by reference numeral 820, which corresponds to an overlap between an outer conductor 804 of the radiating tip portion 800 and the distal dielectric sleeve 808, may be 3.6 mm. The dimension indicated by reference numeral 822, which corresponds to a length of the distal dielectric sleeve 808 that protrudes beyond a distal end of the outer conductor 804, may be 2.0 mm. The dimension indicated by reference numeral 824, which corresponds to a length of the conical body 812 of the distal tip 810, may be 1.5 mm. The dimension indicated by reference numeral 826, which corresponds to a length of the protrusion 814, may be 0.5 mm. A maximum outer diameter of the radiating tip portion 800, indicated by reference numeral 828, is 1.0 mm or less.

[0103] FIG. 9a shows a cross-sectional view of a distal section of a radiating tip portion 900. A proximal dielectric sleeve 906 of the radiating tip portion 900 may be made of a flexible tube of insulating material, e.g. PTFE. A distal dielectric sleeve 908 of the radiating tip portion 900 is made of a cylindrical piece of Polyether ether ketone (PEEK). The distal dielectric sleeve 908 includes a cavity at a distal end thereof in which a distal tip 910 made of Zirconia is received. A “push-fit” connection is formed between the distal tip 910 and the distal dielectric sleeve 908.

[0104] FIG. 9b shows the connection between the distal tip 910 and the distal dielectric sleeve 908 in greater detail. The distal tip includes a body 912 which is received in the cavity in the distal dielectric sleeve 908. The body 912 includes a bump 914 on its outer surface, which is arranged to press outwards against the distal dielectric sleeve 908, in order to retain the distal tip 910 in the cavity. Thus, the distal tip 910 may be automatically retained within the cavity once it has been inserted into the cavity. The distal tip 910 may further be secured in the cavity using adhesive. The distal tip 910 further includes a conical portion 916, which forms a pointed tip a distal end of the radiating tip portion 900. An outer surface of the distal dielectric sleeve 908 is tapered at an angle matching a tapering angle of the conical portion 916, so that an outer surface of the radiating tip portion 900 is smooth. Making the distal tip 910 out of Zirconia may enable a sharper distal tip to be provided, as Zirconia may have a higher rigidity than PEEK.

[0105] Example dimensions of the radiating tip portion 900 are shown in FIG. 9a. The dimension indicated by reference numeral 918, which corresponds to a length of the proximal dielectric sleeve 906, may be 37 mm. Note the total length of the proximal dielectric sleeve 906 is not shown in FIG. 9a. The dimension indicated by reference numeral 920, which corresponds to an overlap between an outer conductor 904 of the radiating tip portion 900 and the distal dielectric sleeve 908, may be 7.0 mm. The dimension indicated by reference numeral 922, which corresponds to a length of an inner conductor 902 of the radiating tip portion 900 that protrudes beyond a distal end of the outer conductor 904, may be 5.0 mm. The dimension indicated by reference numeral 924, which corresponds to a length of distal tip 910, may be 2.0 mm. A maximum outer diameter of the radiating tip portion 900, indicated by reference numeral 926, is 1.0 mm or less.

[0106] FIG. 10 shows a cross-sectional view of a distal section of a radiating tip portion 1000. A proximal dielectric sleeve 1006 of radiating tip portion 1000 may be made of a flexible tube of insulating material, e.g. PTFE. A distal dielectric sleeve 1008 of radiating tip portion 1000 is made of a cylindrical piece of PEEK. Similarly to radiating tip portion 800, radiating tip 1000 includes a distal tip 1010 made of Zirconia mounted at a distal end of the distal dielectric sleeve 1008. The distal tip 1010 has a similar configuration to distal tip 810 shown in FIG. 8b, i.e. it includes a conical body and a protrusion 1014 that is received in a bore in the distal dielectric sleeve 1008.

[0107] Example dimensions of the radiating tip portion 1000 are shown in FIG. 10. The dimension indicated by reference numeral 1018, which corresponds to a length of the proximal dielectric sleeve 1006, may be 37 mm. Note the total length of the proximal dielectric sleeve 1006 is not shown in FIG. 10. The dimension indicated by reference numeral 1020, which corresponds to an overlap between an outer conductor 1004 of the radiating tip portion 1000 and the distal dielectric sleeve 1008, may be 6.0 mm. The dimension indicated by reference numeral 1022, which corresponds to a length of the distal dielectric sleeve 1008 that protrudes beyond a distal end of the outer conductor 1004, may be 5.5 mm. The dimension indicated by reference numeral 1024, which corresponds to a length of the conical body of the distal tip 810, may be 1.5 mm. The dimension indicated by reference numeral 1026, which corresponds to a length of the protrusion 1014, may be 0.5 mm. A maximum outer diameter of the radiating tip portion 1000, indicated by reference numeral 1028, is 1.0 mm or less.

[0108] FIG. 11 shows a cross-sectional view of a distal section of a radiating tip portion 1100. A proximal dielectric sleeve 1106 of radiating tip portion 1100 may be made of a flexible tube of insulating material, e.g. PTFE. A distal dielectric sleeve 1108 of radiating tip portion 1100 is made of a cylindrical piece of PEEK. A distal tip 1110 of the distal dielectric sleeve 1108 is sharpened, to facilitate insertion of the radiating tip portion 1100 into tissue.

[0109] Example dimensions of the radiating tip portion 1100 are shown in FIG. 11. The dimension indicated by reference numeral 1118, which corresponds to a length of the proximal dielectric sleeve 1106, may be 37 mm. Note the total length of the proximal dielectric sleeve 1106 is not shown in FIG. 11. The dimension indicated by reference numeral 1120, which corresponds to an overlap between an outer conductor 1104 of the radiating tip portion 1000 and the distal dielectric sleeve 1108, may be 6.0 mm. The dimension indicated by reference numeral 1122, which corresponds to a length of an inner conductor 1102 of the radiating tip portion 1100 that protrudes beyond a distal end of the outer conductor 1004, may be 5.5 mm. The dimension indicated by reference numeral 1024, which corresponds to a length of the distal tip 1110, may be 1.5 mm. A maximum outer diameter of the radiating tip portion 1100, indicated by reference numeral 1028, is 1.0 mm or less.

[0110] FIG. 12 is a schematic cross-sectional view of a distal end of an insertion cord 120 of a surgical scoping device, such as a ultrasound-enabled bronchoscope. The insertion cord 120 includes a lumen therethrough that forms an instrument channel 132 for receiving an electrosurgical instrument 700. The instrument from FIG. 7 is shown in this example, but any of the configurations discussed above can be used. The electrosurgical instrument 700 in this example includes a protective catheter 1202, which is a flexible tube that lies around an outer surface of the electrosurgical instrument 700. The protective catheter 1202 protects the inner surface of the instrument channel 132 from the pointed tip 710 of the instrument. This may be particularly useful if the insertion cord is bent on its route to the treatment site. The protective catheter 1202 may assist the radiating tip in curving around in the instrument channel without catching on the inner surface of the instrument channel.

[0111] In use, the instrument 700 may be extendable (e.g. slidable) beyond the protective catheter 1202 to protrude from the distal end of the insertion cord 120, where it is able to penetrate tissue to recite the treatment site. The radiating tip may be observed using the ultrasound imaging capability of the bronchoscope to assist in accurate location at the treatment site.