System and method for directing energy to tissue

Abstract

An electrosurgical system includes an electrosurgical power generating source, an energy applicator operably associated with the electrosurgical power generating source, a processor unit, and a data acquisition module configured to receive a reflected signal. The processor unit is disposed in operative communication with the data acquisition module and adapted to determine a tissue desiccation rate around at least a portion of the energy applicator based on one or more signals received from the data acquisition module.

Claims

1. An electrosurgical system, comprising: an electrosurgical energy source including an output stage; an energy applicator configured to couple to the electrosurgical energy source; a data acquisition module including a diplexer and a dual directional coupler, the data acquisition module separate from and operably coupled to the energy applicator, wherein the diplexer is configured to: receive a reflected signal generated by transmission of electrosurgical energy from the energy applicator to tissue; generate a first signal based on the received reflected signal; receive electrosurgical energy generated by the electrosurgical energy source from the output stage: and wherein the dual directional coupler is configured to receive the first signal and generate a second signal based on the first signal; and a processor operably coupled to the diplexer and the dual directional coupler of the data acquisition module and configured to calculate a desiccation rate based on the second signal and adjust electrosurgical energy output by the electrosurgical energy source based on the calculated desiccation rate.

2. The electrosurgical system of claim 1, wherein the reflected signal is transmitted by the energy applicator to the data acquisition module.

3. The electrosurgical system of claim 1, wherein the energy applicator includes a microwave antenna.

4. The electrosurgical system of claim 1, wherein the processor is configured to control at least one operating parameter of the electrosurgical energy source based on the calculated desiccation rate.

5. A method for monitoring tissue desiccation, comprising: applying electrosurgical energy to tissue via an energy applicator to generate a reflected signal; transmitting the reflected signal to a diplexer of a data acquisition module, wherein the data acquisition module is separate from the energy applicator; generating, with the diplexer, a first signal based on the reflected signal; receiving, with a dual directional coupler of the data acquisition module, the first signal; generating, with the dual directional coupler, a second signal based on the first signal; calculating a desiccation rate based on the second signal; and adjusting the applied electrosurgical energy based on the calculated desiccation rate.

6. The method of monitoring tissue desiccation of claim 5, further comprising controlling at least one operating parameter of an electrosurgical energy source coupled to the energy applicator based on the calculated desiccation rate.

7. The method of monitoring tissue desiccation of claim 5, wherein applying electrosurgical energy to the tissue via the energy applicator includes applying microwave energy to tissue via the energy applicator.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) Objects and features of the presently-disclosed data acquisition module operably associated with an energy applicator, electrosurgical power generating source operably associated therewith, and electrosurgical systems including the same, and methods of directing energy to tissue will become apparent to those of ordinary skill in the art when descriptions of various embodiments thereof are read with reference to the accompanying drawings, of which:

(2) FIG. 1 is a schematic diagram of an electrosurgical system, such as a monopolar electrosurgical system, according to an embodiment of the present disclosure;

(3) FIG. 2 is a schematic diagram of an electrosurgical system, such as an bipolar electrosurgical system, according to an embodiment of the present disclosure;

(4) FIG. 3 is a schematic diagram of another embodiment of an electrosurgical system according to the present disclosure;

(5) FIG. 4 is a schematic diagram of an energy applicator with indicia graduation marks according to an embodiment of the present disclosure;

(6) FIG. 5 is a schematic block diagram of an electrosurgical power generating source according to an embodiment of the present disclosure;

(7) FIG. 6 is a schematic block diagram of an electrosurgical system according to an embodiment of the present disclosure;

(8) FIG. 7 illustrates a clocking signal, such as a continuous output of the RF output stage shown in FIG. 5, according to an embodiment of the present disclosure;

(9) FIG. 8 illustrates a sensor signal, such as an input signal to the reference detection shown in FIG. 5, according to an embodiment of the present disclosure;

(10) FIG. 9 is illustrates a reflected signal, such as a feedback signal of the detection source shown in FIG. 5, according to an embodiment of the present disclosure;

(11) FIG. 10 is a diagrammatic representation of a radiation pattern of electromagnetic energy delivered into tissue by an energy applicator, such as the energy applicator of FIG. 4, in accordance with the present disclosure;

(12) FIG. 11 is a flowchart illustrating a method of directing energy to tissue in accordance with an embodiment of the present disclosure; and

(13) FIG. 12 is a flowchart illustrating a method of directing energy to tissue in accordance with another embodiment of the present disclosure.

DETAILED DESCRIPTION

(14) Hereinafter, embodiments of the presently-disclosed data acquisition module operably associated with an energy applicator, electrosurgical power generating source operably associated therewith, and electrosurgical systems including the same, and the presently-disclosed methods of directing energy to tissue, are described with reference to the accompanying drawings. Like reference numerals may refer to similar or identical elements throughout the description of the figures. As shown in the drawings and as used in this description, and as is traditional when referring to relative positioning on an object, the term “proximal” refers to that portion of the device, or component thereof, closer to the user and the term “distal” refers to that portion of the device, or component thereof, farther from the user.

(15) This description may use the phrases “in an embodiment,” “in embodiments,” “in some embodiments,” or “in other embodiments,” which may each refer to one or more of the same or different embodiments in accordance with the present disclosure.

(16) Electromagnetic energy is generally classified by increasing energy or decreasing wavelength into radio waves, microwaves, infrared, visible light, ultraviolet, X-rays and gamma-rays. As it is used in this description, “microwave” generally refers to electromagnetic waves in the frequency range of 300 megahertz (MHz) (3×10.sup.8 cycles/second) to 300 gigahertz (GHz) (3×10.sup.11 cycles/second).

(17) As it is used in this description, “ablation procedure” generally refers to any ablation procedure, such as microwave ablation, radio frequency (RF) ablation or microwave ablation assisted resection. As it is used in this description, “energy applicator” generally refers to any device that can be used to transfer energy from a power generating source, such as a microwave or RF electrosurgical generator, to tissue. As it is used in this description, “transmission line” generally refers to any transmission medium that can be used for the propagation of signals from one point to another.

(18) For the purposes herein, the term “electrosurgical desiccation” or, simply, “desiccation”, is intended to encompass any tissue desiccation procedure, including electrosurgical coagulation, desiccation, vessel sealing, and tissue fusion. As it is used in this description, the term “thermal spread” refers generally to the heat transfer (e.g., heat conduction, heat convection or electrical current dissipation) traveling along the periphery of the electrically-conductive, tissue-contacting surfaces.

(19) Various embodiments of the present disclosure provide a data acquisition module operably associated with an energy applicator. Various embodiments of the present disclosure provide electrosurgical systems and instruments suitable for sealing, cauterizing, coagulating/desiccating and/or cutting vessels and vascular tissue, ablating tissue, or otherwise modifying a tissue or organ of a patient, wherein the presently-disclosed data acquisition module receives a reflected signal from an energy applicator and provides a signal used to determine the rate of desiccation of tissue, which, in turn, may be used to determine one or more operating parameters of an electrosurgical power generating source.

(20) Various embodiments of the presently-disclosed electrosurgical systems and instruments use the frequency of a signal reflected from target tissue to determine the rate of desiccation of tissue and/or hydration level of the tissue around at least a portion of an energy applicator. Embodiments may be implemented using electromagnetic radiation at RF or microwave frequencies or at other frequencies.

(21) In accordance with embodiments of the present disclosure, one or more operating parameters of an electrosurgical power generating source are adjusted and/or controlled based on the determined desiccation rate, e.g., to maintain a proper desiccation rate, or to determine when tissue has been completely desiccated and/or the procedure has been completed.

(22) Various embodiments of the presently-disclosed electrosurgical systems employ a secondary frequency, wherein the secondary frequency is different than the primary power source frequency, to determine a type of tissue, a condition of tissue, and/or a tissue response. In accordance with embodiments of the present disclosure, a secondary frequency may be used to assist in determining when the energy applicator has been removed from the target tissue, which may trigger safety procedures and/or controls, e.g., control that reduces power level and/or shuts off the power delivery to the energy applicator.

(23) FIG. 1 schematically illustrates a monopolar electrosurgical system (shown generally as 1) configured to selectively apply electrosurgical energy to target tissue of a patient P. Electrosurgical system 1 includes a monopolar electrosurgical instrument 2 having one or more electrodes for treating tissue of the patient P (e.g., electrosurgical pencil, electrosurgical cutting probe, ablation electrode(s), etc.). Electrosurgical energy is supplied to the instrument 2 by an electrosurgical power generating source 20 capable of generating. Power generating source 20 may be any generator suitable for use with electrosurgical devices to generate energy having a controllable frequency and power level, and may be configured to provide various frequencies of electromagnetic energy. Power generating source 20 may be configured to operate in a variety of modes, such as ablation, monopolar and bipolar cutting, coagulation, and other modes.

(24) The instrument 2 is connected via a transmission line, e.g., supply line 4, to an active terminal 23 of the electrosurgical power generating source 20, allowing the instrument 2 to coagulate, ablate and/or otherwise treat tissue. The energy is returned to the electrosurgical power generating source 20 through a return electrode 6 via a transmission line, e.g., return line 8, which is connected to a return terminal 22 of the power generating source 20. In some embodiments, the active terminal 23 and the return terminal 22 may be configured to interface with plugs (not shown) associated with the instrument 2 and the return electrode 6, respectively, e.g., disposed at the ends of the supply line 4 and the return line 8, respectively.

(25) The system 1 may include a plurality of return electrodes 6 that are arranged to minimize the chances of tissue damage by maximizing the overall contact area with the patient P. The power generating source 20 and the return electrode 6 may additionally, or alternatively, be configured for monitoring so-called “tissue-to-patient” contact to ensure that sufficient contact exists therebetween to further minimize chances of tissue damage. The active electrode may be used to operate in a liquid environment, wherein the tissue is submerged in an electrolyte solution.

(26) FIG. 2 schematically illustrates a bipolar electrosurgical system (shown generally as 3) configured to selectively apply electrosurgical energy to target tissue of a patient P. Electrosurgical system 3 includes a bipolar electrosurgical forceps 12 having one or more electrodes for treating tissue of a patient P. The electrosurgical forceps 12 includes opposing jaw members 11 and 13 including an active electrode 14 and a return electrode 16, respectively, associated therewith. The active electrode 14 and the return electrode 16 are connected to the electrosurgical power generating source 20 through cable 18. Cable 18 may include the supply and return lines 4 and 8 electrically-coupled to the active and return terminals 23 and 22, respectively (shown in FIG. 1). The electrosurgical forceps 10 is coupled to the power generating source 20 at a connector 21 having connections to the active and return terminals 23 and 22 (e.g., pins) via a plug (not shown) disposed at the end of the cable 18, wherein the plug includes electrical contacts associated with the supply and return lines 4 and 8.

(27) FIG. 3 schematically illustrates an electrosurgical system (shown generally as 10) including an energy applicator or probe 100. Probe 100 generally includes an antenna assembly 112 having a radiating portion connected by a feedline 110 (or shaft) via a transmission line 15 to a connector 17, which further operably connects the probe 100 to an electrosurgical power generating source 28, e.g., a microwave or RF electrosurgical generator. Power generating source 28 may be any generator suitable for use with electrosurgical devices, and may be configured to provide various frequencies of energy. An embodiment of an electrosurgical power generating source, such as the power generating source 28 of FIG. 3, in accordance with the present disclosure, is shown in more detail in FIG. 6. It will be understood, however, that other power generating source embodiments (e.g., power generating source 500 shown in FIG. 5) may also be used.

(28) Feedline 110 electrically connects the antenna assembly 12 via the transmission line 15 to the electrosurgical power generating source 28, and may include a coaxial cable, which may be semi-rigid or flexible. Feedline 110 may be cooled by fluid, e.g., saline or water, to improve power handling, and may include a stainless steel catheter. Transmission line 15 may additionally, or alternatively, provide a conduit (not shown) configured to provide coolant from a coolant source 18 to the probe 100.

(29) Antenna assembly 112, as shown in FIG. 3, is a dipole microwave antenna assembly, but other antenna assemblies, e.g., monopole or leaky wave antenna assemblies, may also utilize the principles set forth herein. Located at the distal end of the antenna assembly 112 is an end cap or tapered portion 120, which may terminate in a sharp tip 123 to allow for insertion into tissue with minimal resistance. One example of a straight probe with a sharp tip that may be suitable for use as the energy applicator 100 is commercially available under the trademark EVIDENT™ offered by Covidien. The end cap or tapered portion 120 may include other shapes, such as without limitation, a tip 123 that is rounded, flat, square, hexagonal, or cylindroconical.

(30) In some variations, the antenna assembly 112 includes a distal radiating portion 105 and a proximal radiating portion 140. In some embodiments, a junction 130 couples the proximal radiating portion 140 and the distal radiating portion 105. In some embodiments, the distal and proximal radiating portions 105, 140 align at the junction 130, which is generally made of a dielectric material, e.g., adhesives, and are also supported by the inner conductor that extends at least partially through the distal radiating portion 105. In some embodiments, the antenna assembly 112 may be provided with a coolant chamber (not shown). Additionally, the junction 130 may include coolant inflow and outflow ports (not shown) to facilitate the flow of coolant into, and out of, the coolant chamber. In some embodiments, the antenna assembly 112 may be provided with an outer jacket (not shown) disposed about the distal radiating portion 105, the junction 130 and/or the proximal radiating portion 140. The outer jacket may be a water cooled catheter formed of a material having low electrical conductivity.

(31) During microwave ablation, e.g., using the electrosurgical system 10, the probe 100 is inserted into or placed adjacent to tissue and microwave energy is supplied thereto. Probe 100 may be placed percutaneously or atop tissue, e.g., using conventional surgical techniques by surgical staff. A clinician may pre-determine the length of time that microwave energy is to be applied. The duration of microwave energy application using the probe 100 may depend on the progress of the heat distribution within the tissue area that is to be destroyed and/or the surrounding tissue.

(32) A plurality of probes 100 may be placed in variously arranged configurations to substantially simultaneously ablate a target tissue region, making faster procedures possible. Multiple probes 100 can be used to synergistically create a large ablation or to ablate separate sites simultaneously. Ablation volume is correlated with antenna design, antenna performance, number of energy applicators used simultaneously, ablation time and wattage, and tissue characteristics, e.g., time impedance.

(33) In operation, microwave energy having a wavelength, lambda (λ), is transmitted through the antenna assembly 112, e.g., along the proximal and distal radiating portions 140, 105, and radiated into the surrounding medium, e.g., tissue. The length of the antenna for efficient radiation may be dependent on the effective wavelength, λ.sub.eff, which is dependent upon the dielectric properties of the treated medium. Antenna assembly 112 through which microwave energy is transmitted at a wavelength, λ, may have differing effective wavelengths, λ.sub.eff, depending upon the surrounding medium, e.g., liver tissue, as opposed to breast tissue.

(34) According to an embodiment of the present disclosure, an energy applicator shown generally as 400 in FIG. 4 includes an antenna assembly 412 having a radiating portion 405 connected by a feedline 411 (or shaft) via a transmission line 15 to an energy source (e.g., 28 shown in FIG. 3). The energy applicator 400 includes a plurality of indicia graduation marks 480 disposed on at least a portion of the antenna assembly 412 and/or the feedline 411. The indicia graduation marks 480 may be etched, stamped, formed or the like, and may be disposed in fixed relationship with a known point on the antenna assembly 412, such as without limitation, the distal tip 423.

(35) The visual assistance provided by the indicia graduation marks 580 may allow the surgeon to selectively position the antenna assembly 412 in tissue. Antenna assembly 412 is similar to the antenna assembly 112 shown in FIG. 3, except for the indicia graduation marks 480, and further description thereof is omitted in the interests of brevity. The shape and size of the indicia graduation marks 480 may be varied from the configuration depicted in FIG. 4.

(36) FIG. 5 schematically illustrates an electrosurgical power generating source (shown generally as 500) according to an embodiment of the present disclosure including a controller 524, a DC power supply 527, and a data acquisition module 590. Data acquisition module 590 includes a diplexer 530 and a circulator/dual directional coupler 540. In some embodiments, as shown in FIG. 5, the electrosurgical power generating source 500 includes a signal source 560 coupled via a transmission line 561 to the controller 524.

(37) The DC power supply 527 is connected to an AC power source (not shown) and includes a high-voltage DC power supply, e.g., to provide high-voltage DC power via a transmission line 529 to an RF output stage 528 of the power generating source 500, and may include a low-voltage power supply, e.g., to provide power to various components of the power generating source 500 (e.g., input controls, displays, etc.).

(38) RF output stage 528 converts the high-voltage DC power into RF energy. The RF energy output by the RF output stage 528 is supplied via a transmission line 533 to a diplexer 530. The diplexer 530 is a multi-port network. In some embodiments, as shown in FIG. 5, the diplexer 530 includes an input port electrically-coupled through the return terminal 32 of the power generating source 500 to the return line 8, and an output port electrically-coupled through the active terminal 23 to the supply line 4. The diplexer 530 combines two different frequencies together, e.g., into a common output. The diplexer 530 provides a low impedance electrical pathway (at the operating frequency of the RF output stage 528) from the transmission line 533 to the supply line 4 and the return line 8 while providing a high impedance electrical pathway from the transmission line 533 to the transmission line 531. The diplexer 530 also may provide low impedance (at the operating frequency of the sensor frequency) from the transmission line 531 to the supply line 4 and the return line 8 but maintain the high impedance from the transmission line 531 to the transmission line 533.

(39) The RF output stage 528 is capable of generating waveforms (e.g., sinusoidal, square, or any type of AC waveform) of high RF energy. The RF output stage 528 may be configured to generate a plurality of waveforms having various duty cycles, peak voltages, crest factors, and other suitable parameters. Certain types of waveforms are suitable for specific electrosurgical modes. For instance, the RF output stage 528 may generate a 100% duty cycle sinusoidal waveform in cut mode, which is normally suitable for ablating, fusing and dissecting tissue. The RF output stage 528 may generate a 1-25% duty cycle waveform in coagulation mode, which is normally suitable for cauterizing tissue to stop bleeding.

(40) In some embodiments, as shown in FIG. 5, the diplexer 530 is coupled via a transmission line 531 to a circulator/dual directional coupler 540.

(41) The electrosurgical power generating source 500 may include a plurality of connectors to accommodate various types of electrosurgical instruments, such as without limitation, instrument 2 shown in FIG. 1, electrosurgical forceps 10 shown in FIG. 2, energy applicator 100 shown in FIG. 3, and/or energy applicator 400 of FIG. 4. The power generating source 500 may be configured to operate in a variety of modes such as ablation, monopolar and bipolar cutting coagulation, etc. The electrosurgical power generating source 500 may include a switching mechanism (e.g., relays) to switch the supply of electrosurgical energy, e.g., RF energy, between the connectors, such that, for instance, when the monopolar electrosurgical instrument 2 is connected to the power generating source 500, only the monopolar connector receives RF energy.

(42) The controller 524 includes a processor unit 525 operably connected to a memory 526, which may be any device or medium that can store code and/or data). The processor unit 525 may include any type of computing device, computational circuit, or any type of processor or processing circuit capable of executing a series of instructions that are stored in a computer-readable storage medium (e.g., memory 526). In some embodiments, the processor unit 525 is communicatively coupled to the DC power supply 527 and/or the RF output stage 528 allowing the processor unit 525 to control the output of the power generating source 500. In some embodiments, the processor unit 525 is configured to control the output of the power generating source 500 according to open and/or closed control loop schemes.

(43) In a closed feedback control loop configuration, sensor circuitry 522 and/or the sensor circuit 570 may each include a plurality of sensors. In some embodiments, the sensor circuitry 522 may be the main sensor in the feedback control loop. The sensor circuitry 522 may additionally be used in conjunction with the sensor circuit 570 for measuring a variety of tissue and/or energy properties (e.g., tissue impedance, tissue temperature, output current and/or voltage, voltage and current passing through the tissue, etc.) provide feedback to the controller 524. The sensor circuit 570 may also be used to determine if the instrument (e.g., instrument 2 shown in FIG. 1, energy applicator 100 shown in FIG. 3, and/or energy applicator 400 of FIG. 4) is moving towards or away from the patient, using the Doppler theory of the frequency shift of the reflected signal 900 (FIG. 9). Based on one or more signals received by the controller 524 from the sensor circuitry 522 and/or sensor circuit 570, the controller 524 may signal the DC power supply 527 and/or the RF output stage 528 which, in turn, adjusts DC and/or RF power supply, respectively. The controller 524 may receive input signals from a user interface (e.g., user interface 81 shown in FIG. 6) and/or input controls (e.g., controls 83 shown in FIG. 6) associated with the power generating source 500 and/or input signals from an electrosurgical instrument, e.g., instrument 2. Based on the input signals, the controller 524 may adjust operating parameters of the power generating source 500 and/or perform other control functions, alarming functions, or other functions in association therewith. Some examples of operating parameters associated with an electrosurgical power generating source 28 that may be adjusted include temperature, impedance, power, current, voltage, mode of operation, and duration of application of electromagnetic energy.

(44) In some embodiments, as shown in FIG. 5, the data acquisition module 590 includes a reference detection 550 coupled via a transmission line 547 to the circulator/dual directional coupler 540 and coupled via a transmission line 551 to a signal source 560. The reflected signal 900 (FIG. 9) is separated from the sensor signal 800 (FIG. 8) by the circulator/dual directional coupler 540, this signal can be communicated via differential pairs 545, 543 to detection source 570 which may be adapted to analyze the signal, e.g., using an internal processor (not shown), and/or condition the signal (e.g., filtering noise) and send the signal to the controller 524. The reference detection 550 can split the sensor signal for reference to the reflected signal.

(45) FIG. 6 schematically illustrates an electrosurgical system (shown generally as 600) including an embodiment of the electrosurgical power generating source 28 of FIG. 3 that includes a generator module 86 in operable communication with a processing unit 82. Generator module 86 may be configured to provide various frequencies of energy. In some embodiments, the generator module 86 may be configured to provide energy at an operational frequency from about 300 MHz to about 10 GHz.

(46) In some embodiments, as shown in FIG. 6, the data acquisition module 590 of FIG. 5 is coupled to the processing unit 82 and the generator module 86, and may be coupled to the energy applicator 400 of FIG. 4. It is to be understood, however, that other energy applicator embodiments (e.g., instrument 2 shown in FIG. 1, electrosurgical forceps 10 shown in FIG. 2, and energy applicator 100 shown in FIG. 3) may also be used. A suitable flexible, semi-rigid or rigid cable assembly 19 may be provided to electrically-couple the energy applicator 400 to the data acquisition module 590.

(47) Processing unit 82 may be communicatively coupled to a user interface 81. User interface 81 may include a display (not shown), such as without limitation a flat panel graphic LCD (liquid crystal display). User interface 81 may additionally, or alternatively, include one or more controls 83 that may include without limitation a switch (e.g., pushbutton switch, toggle switch, slide switch) and/or a continuous actuator (e.g., rotary or linear potentiometer, rotary or linear encoder). In some embodiments, one or more controls 83 may have a dedicated function, e.g., display contrast, power on/off, and the like. One or more controls 83 may have a function that may vary in accordance with an operational mode of the electrosurgical power generating source 28.

(48) In some embodiments, a storage device 88 is operably coupled to the processing unit 82, and may include random-access memory (RAM), read-only memory (ROM), and/or non-volatile memory (NV-RAM, Flash, and disc-based storage). Storage device 88 may include a set of program instructions executable on the processor 82 for executing a method for displaying and controlling ablation patterns in accordance with the present disclosure. Power generating source 28 may include a data interface 90 that is configured to provide a communications link to an external device 91. In an embodiment, the data interface 90 may be any of a USB interface, a memory card slot (e.g., SD slot), and/or a network interface (e.g., 100BaseT Ethernet interface or an 802.11 “Wi-Fi” interface). External device 91 may be any of a USB device (e.g., a memory stick), a memory card (e.g., an SD card), and/or a network-connected device (e.g., computer or server).

(49) Processing unit 82 may include any type of computing device, computational circuit, or any type of processor or processing circuit capable of executing a series of instructions that are stored in a memory, e.g., storage device 88 or external device 91. Generator assembly 10 may also include a database 84 communicatively coupled to the processing unit 82 and configured to store and retrieve data, e.g., parameters associated with one or energy applicators (e.g., energy applicator 400). Parameters stored in the database 84 in connection with an energy applicator, or energy applicator array assembly, may include, but are not limited to, energy applicator (or applicator array assembly) identifier, energy applicator (or applicator array assembly) dimensions, a frequency, an ablation length (e.g., in relation to a radiating section length), an ablation diameter, a gap distance at the feed point (e.g. in relation to an ablation geometry), a temporal coefficient, a shape metric, and/or a frequency metric. Database 84 may be maintained at least in part by data provided by the external device 91 via the data interface 90. For example without limitation, energy applicator data and/or other data may be uploaded from the external device 91 to the database 84 via the data interface 90.

(50) FIG. 7 illustrates a clocking signal 700, such as a continuous output of the RF output stage 528 shown in FIG. 5. FIG. 8 illustrates a sensor signal 800, such as an input signal to the reference detection 550 shown in FIG. 5. FIG. 9 illustrates a reflected signal 900, such as a feedback signal of the sensor circuit 570 shown in FIG. 5.

(51) FIG. 10 shows a diagrammatic representation of a radiation pattern “R” of electromagnetic energy delivered into tissue “T” by the energy applicator 400 of FIG. 4. Energy applicator 400 may be placed percutaneously or surgically. Ultrasound or computed tomography (CT) guidance may be used to accurately guide the energy applicator 400 into the area of tissue “T” to be treated. The shape and size of the emitted radiation pattern “R” may be varied from the configuration depicted in FIG. 10.

(52) In some embodiments, as shown in FIG. 10, the energy applicator 400 is coupled via a transmission line 15 to a connector 17, which further operably connects the energy applicator 400 to the data acquisition module 590 of FIG. 6 which, in turn is coupled to the electrosurgical power generating source 28. It will be understood, however, that other power generating source embodiments (e.g., power generating source 500 of FIG. 5) may also be used.

(53) Hereinafter, methods of directing energy to tissue are described with reference to FIGS. 11 and 12. It is to be understood that the steps of the methods provided herein may be performed in combination and in a different order than presented herein without departing from the scope of the disclosure.

(54) FIG. 11 is a flowchart illustrating a method of directing energy to tissue according to an embodiment of the present disclosure. In step 1110, an energy applicator 400 is positioned for delivery of energy to a target tissue “T”. The energy applicator may be inserted directly into tissue, inserted through a lumen, e.g., a vein, needle or catheter, placed into the body during surgery by a clinician, or positioned in the body by other suitable methods. The energy applicator 400 is operably associated with a data acquisition module 590. The data acquisition module 590 is operably associated with one or more components of an electrosurgical power generating source 28, such as without limitation, a processor unit 82.

(55) In step 1120, energy from the electrosurgical power generating source 28 is transmitted through the energy applicator 400 to the target tissue “T”. The electrosurgical power generating source 28 may be capable of generating energy at RF or microwave frequencies or at other frequencies.

(56) In step 1130, a signal reflected from the target tissue “T” is transmitted to the data acquisition module 590. A cable assembly 19 may electrically-couple the energy applicator 400 to the data acquisition module 590.

(57) In step 1140, one or more operating parameters associated with the electrosurgical power generating source 28 are determined based on a tissue desiccation rate which is determined by the processor unit 82 based on at least one signal received from the data acquisition module 590. Some examples of operating parameters associated with an electrosurgical power generating source 28 that may be determined include temperature, impedance, power, current, voltage, mode of operation, and duration of application of electromagnetic energy.

(58) FIG. 12 is a flowchart illustrating a method of directing energy to tissue according to an embodiment of the present disclosure. In step 1210, an energy applicator 400 is positioned for delivery of energy to a target tissue “T”. The energy applicator 400 is operably associated with an electrosurgical power generating source 500.

(59) In step 1220, energy from the electrosurgical power generating source 500 is transmitted through the energy applicator 400 to the target tissue “T”.

(60) In step 1230, data including a frequency of a signal reflected from the target tissue “T” is acquired.

(61) In step 1240, a tissue desiccation rate is calculated as a function of the frequency of the signal reflected from the target tissue “T”.

(62) In step 1250, one or more operating parameters associated with the electrosurgical power generating source are determined based on the calculated tissue desiccation rate. In some embodiments, the position of the energy applicator may be adjusted based on the calculated tissue desiccation rate. For example, an energy applicator with a directional radiation pattern may be rotated either manually, or automatically, based on the calculated specific absorption rate, e.g., to avoid ablating sensitive structures, such as large vessels, healthy organs or sensitive membrane barriers.

(63) The above-described electrosurgical systems for treating tissue and methods of directing energy to a target tissue may be suitable for various open and endoscopic surgical procedures.

(64) In the above-described embodiments, signals reflected by a target tissue are transmitted from an energy applicator to a data acquisition module, which may be operably associated with one or more components of an electrosurgical power generating source. The above-described energy applicators may be inserted into or placed adjacent to tissue. The above-described data acquisition module receives a reflected signal and provides a signal that may be used to determine the rate of desiccation of tissue and/or to determine one or more operating parameters of an electrosurgical power generating source.

(65) Various embodiments of the above-disclosed electrosurgical systems employ a secondary frequency, wherein the secondary frequency is different than the primary power source frequency, to determine a type of tissue, a condition of tissue, and/or a tissue response. In the above-described embodiments, a secondary frequency may be used to assist in determining when the energy applicator has been removed from the target tissue, which may trigger safety procedures and/or controls, e.g., control that reduces power level and/or shuts off the power delivery to the energy applicator.

(66) Although embodiments have been described in detail with reference to the accompanying drawings for the purpose of illustration and description, it is to be understood that the inventive processes and apparatus are not to be construed as limited thereby. It will be apparent to those of ordinary skill in the art that various modifications to the foregoing embodiments may be made without departing from the scope of the disclosure.