Electrosurgical apparatus for generating radiofrequency energy and microwave energy for delivery into biological tissue

Patent metadata

Field	Value
Publication number	US-2016374752-A1
Application number	US-201415102845-A
Country	US
Kind code	A1
Filing date	Dec 4, 2014
Priority date	Dec 9, 2013
Publication date	Dec 29, 2016
Grant date	—

Abstract

An isolating circuit for electrosurgical generator arranged to produce radiofrequency (RF) energy and microwave energy for treating biological tissue. The generator has an RF channel and a microwave channel which are combined at signal combiner to enable the RF energy and microwave energy to be delivered into tissue along a common feed path. The isolating circuit comprises a tunable waveguide isolator at a junction between the microwave channel and signal combiner, and can include a capacitive structure between a ground conductor of the signal combiner and a conductive input section of the waveguide isolator to inhibit coupling of the RF energy and leakage of the microwave energy. The isolating circuit can combine into a single tunable unit all the necessary components to isolate the microwave and RF channels from one another whilst providing a high withstanding voltage.

First claim

1 . Electrosurgical apparatus for resection of biological tissue, the apparatus comprising:
a radiofrequency (RF) signal generator for generating RF electromagnetic (EM) radiation having a first frequency; a microwave signal generator for generating microwave EM radiation having a second frequency that is higher than the first frequency; a probe arranged to deliver the RF EM radiation and the microwave EM radiation separately or simultaneously from a distal end thereof; and a feed structure for conveying the RF EM radiation and the microwave EM radiation to the probe, the feed structure comprising an RF channel for connecting the probe to the RF signal generator, and a microwave channel for connecting the probe to the microwave signal generator, wherein the RF channel and microwave channel comprise physically separate signal pathways from the RF signal generator and microwave signal generator respectively, wherein the feed structure includes a combining circuit having a first input connected to the separate signal pathway on the RF channel, a second input connected to the separate signal pathway on the microwave channel, and an output connected to a common signal pathway for conveying the RF EM radiation and the microwave EM radiation separately or simultaneously along a single channel to the probe, wherein the microwave channel includes a waveguide isolator connected to isolate the separate signal pathway on the microwave channel from the RF EM radiation, and wherein the waveguide isolator has an adjustable impedance.

2 . Electrosurgical apparatus according to claim 1 , wherein the waveguide isolator includes a tuning portion that is adjustable to change the impedance of the waveguide isolator.

3 . Electrosurgical apparatus according to claim 2 , wherein the tuning unit comprising a plurality of tuning stubs that are adjustably insertable into the waveguide isolator.

4 . Electrosurgical apparatus according to claim 1 ,
wherein the waveguide isolator comprises a conductive input section, a conductive output section which mates with the input section to define a waveguide cavity within a volume enclosed by the input and output sections, and a DC isolation barrier arranged between the input and output sections, wherein the output on the common signal pathway includes a signal conductor and a ground conductor, and wherein the feed structure includes a capacitive structure between the ground conductor of the output on the common signal pathway and the conductive input section of the waveguide isolator, the capacitive structure being arranged to inhibit coupling of the RF EM energy and leakage of the microwave EM energy.

5 . Electrosurgical apparatus according to claim 4 , wherein the capacitive structure is provided by the DC isolation barrier and a microwave choke formed on the input section of the waveguide isolator.

6 . Electrosurgical apparatus according to claim 5 , wherein the inner and outer sections of the waveguide isolator define a cylindrical body, and wherein the microwave choke comprises an annular channel extending axially from the distal end of the inner section of the waveguide isolator.

7 . Electrosurgical apparatus according to claim 4 , wherein the DC isolation barrier includes a rigid insulating spacer element mounted between the inner and outer sections of the waveguide isolator.

8 . Electrosurgical apparatus according to claim 7 , wherein the DC isolation barrier includes an insulating film mounted on a portion of the inner surface of the input section at the junction with the rigid insulating spacer element.

9 . Electrosurgical apparatus according to claim 8 , wherein the insulating film extends away from the rigid insulating spacer element by a predetermined distance.

10 . Electrosurgical apparatus according to claim 1 , wherein the combining circuit is integrated with the waveguide isolator.

11 . Electrosurgical apparatus according to claim 10 , wherein the output connected to common signal pathway includes an output probe mounted on the output section of the waveguide isolator, the output probe having a coupling conductor extending into the waveguide isolator to couple the microwave EM energy therefrom, and wherein the first input includes an RF connector mounted on the waveguide isolator, the RF connector having a signal conductor that extends into the waveguide cavity to electrically contact the coupling conductor of the output probe.

12 . Electrosurgical apparatus according to claim 11 , wherein the position of the signal conductor extends substantially along an equipotential of the microwave EM field within the waveguide isolator.

13 . Electrosurgical apparatus according to claim 11 , wherein a proximal portion of the coupling conductor of the output probe that extends into the waveguide isolator is surrounded by an insulating sleeve.

14 . Electrosurgical apparatus according to claim 11 , wherein a proximal portion of the signal conductor of the RF connector that extends into the waveguide isolator is surrounded by an insulating sleeve.

15 . Electrosurgical apparatus according to claim 11 including a microwave choke mounted on the RF connector to prevent the microwave EM energy from leaking out of the waveguide isolator through the signal conductor of the RF connector.

16 . Electrosurgical apparatus according to claim 15 , wherein the microwave choke is radial or cylindrical.

17 . Electrosurgical apparatus according to claim 1 , wherein the RF channel includes a controllably adjustable reactance.

18 . Electrosurgical apparatus according to claim 17 , wherein the adjustable reactance comprises a capacitance or an inductance that is selectable switchable into the RF channel.

19 . Electrosurgical apparatus according to claim 17 , wherein the adjustable reactance is an electronically tunable capacitance or an electronically tunable inductance.

20 . Electrosurgical apparatus according to claim 4 , wherein the capacitive structure includes a coaxial isolator connected in series with the waveguide isolator.

21 . Electrosurgical apparatus according to claim 1 , wherein the combining circuit comprises a microstrip diplexer circuit.

22 . Electrosurgical apparatus according to claim 21 , wherein the RF channel includes a low pass, band pass, band stop or notch filter connected between the separate signal pathway on the RF channel and the combining circuit for blocking microwave EM radiation from entering the separate signal pathway on the RF channel.

23 . Electrosurgical apparatus according to claim 1 including a controller operable to select an energy delivery profile for the RF EM radiation and the microwave EM radiation.

24 . Electrosurgical apparatus according to claim 23 including an RF signal detector for sampling current and voltage on the RF channel and generating therefrom a RF detection signal indicative of the phase difference between the current and voltage, wherein the controller is in communication with the RF signal detector to receive the RF detection signal and is arranged to select the energy delivery profile for the RF EM radiation based on the RF detection signal.

25 . Electrosurgical apparatus according to claim 23 including a microwave signal detector for sampling forward and reflected power on the microwave channel and generating therefrom a microwave detection signal indicative of the magnitude and/or phase of microwave power delivered by th

Assignees

• Creo Medical Ltd

Inventors

• Hancock Christopher Paul
• White Malcolm
• Dharmisiri Nuwan

Classifications

• H01P1/36

  Isolators · CPC title

• H01P5/12

  Coupling devices having more than two ports (H01P5/04 takes precedence) · CPC title

• A61B18/1482 Primary

  having a long rigid shaft for accessing the inner body transcutaneously in minimal invasive surgery, e.g. laparoscopy · CPC title

• A61B18/1815 Primary

  using microwaves · CPC title

• H01P5/08

  for linking dissimilar lines or devices (H01P1/16, H01P5/04 take precedence; linking lines of the same kind but with different dimensions H01P5/02) · CPC title