US 8,568,401 B2Grant

System for monitoring ablation size

Issue Date:2013-10-29

•8 Claims

•8 Drawing Sheets

Abstract

A system for monitoring ablation size is provided and includes a power source including a microprocessor for executing at least one control algorithm. A microwave antenna is configured to deliver microwave energy from the power source to tissue to form an ablation zone. An ablation zone control module is in operative communication with memory associated with the power source. The memory includes one or more data look-up tables including one or more electrical parameters associated with the microwave antenna. The one or more electrical parameters corresponding to an ablation zone having a radius. The one or more electrical parameters include a threshold value, wherein when the threshold value is met the power source is adjusted to form an ablation zone of suitable proportion.

Metadata

Assignee

Covidien LP

Inventor

Joseph D. Brannan

Application Information

Application Number:US 12/606,769

Filing Date:2009-10-27

Priority Date:2009-10-27

Art Unit:3739

Classifications

IPC:

A61B18/18

Patent Drawings (8 sheets)

Description

Background

[0001] 1. Technical Field

[0002] The present disclosure relates to systems and methods that may be used in tissue ablation procedures. More particularly, the present disclosure relates to systems and methods for monitoring ablation size during tissue ablation procedures in real-time.

[0003] 2. Background of Related Art

[0004] In the treatment of diseases such as cancer, certain types of cancer cells have been found to denature at elevated temperatures (which are slightly lower than temperatures normally injurious to healthy cells). These types of treatments, known generally as hyperthermia therapy, typically utilize electromagnetic radiation to heat diseased cells to temperatures above 41° C. while maintaining adjacent healthy cells at lower temperatures where irreversible cell destruction will not occur. Procedures utilizing electromagnetic radiation to heat tissue may include ablation of the tissue.

[0005] Microwave ablation procedures, e.g., such as those performed for menorrhagia, are typically done to ablate the targeted tissue to denature or kill the tissue. Many procedures and types of devices utilizing electromagnetic radiation therapy are known in the art. Such microwave therapy is typically used in the treatment of tissue and organs such as the prostate, heart, and liver.

[0006] One non-invasive procedure generally involves the treatment of tissue (e.g., a tumor) underlying the skin via the use of microwave energy. The microwave energy is able to non-invasively penetrate the skin to reach the underlying tissue. However, this non-invasive procedure may result in the unwanted heating of healthy tissue. Thus, the non-invasive use of microwave energy requires a great deal of control.

[0007] Currently, there are several types of systems and methods for monitoring ablation zone size. In certain instances, one or more types of sensors (or other suitable devices) are operably associated with the microwave ablation device. For example, in a microwave ablation device that includes a monopole antenna configuration, an elongated microwave conductor may be in operative communication with a sensor exposed at an end of the microwave conductor. This type of sensor is sometimes surrounded by a dielectric sleeve.

[0008] Typically, the foregoing types of sensor(s) are configured to function (e.g., provide feedback to a controller for controlling the power output of a power source) when the microwave ablation device is inactive, i.e., not radiating. That is, the foregoing sensors do not function in real-time. Typically, the power source is powered off (or pulsed off) when the sensors are providing feedback (e.g., tissue temperature) to the controller and/or other device(s) configured to control the power source.

Summary

[0009] The present disclosure provides a system for monitoring ablation size in real-time. The system includes a power source including a microprocessor for executing at least one control algorithm. The system includes a microwave antenna configured to deliver microwave energy from the power source to tissue forming an ablation zone. An ablation zone control module is in operative communication with a memory associated with the power source. The memory includes one or more data look-up tables including one or more electrical parameters associated with the microwave antenna. The electrical parameter(s) corresponding to a radius of the ablation zone, wherein the ablation zone control module triggers a signal when a predetermined threshold value of the electrical parameter(s) is measured corresponding to the radius of the ablation zone.

[0010] The present disclosure provides a microwave antenna adapted to connect to a power source configured for performing an ablation procedure. The microwave antenna includes a radiating section configured to deliver microwave energy from a power source to tissue to form an ablation zone. An ablation zone control module is in operative communication with a memory associated with the power source. The memory includes one or more data look-up tables including one or more electrical parameters associated with the microwave antenna. The electrical parameter(s) corresponding to a radius of the ablation zone, wherein the ablation zone control module triggers a signal when a predetermined threshold value of the electrical parameter(s) is measured corresponding to the radius of the ablation zone.

[0011] The present disclosure also provides a method for indirectly monitoring temperature of tissue undergoing ablation by way of probe impedance. The method includes an initial step of transmitting microwave energy from a power source to a microwave antenna to form a tissue ablation zone. A step of the method includes monitoring complex impedance associated with the microwave antenna as the tissue ablation zone forms. A step of the method includes communicating a control signal to the power source when a predetermined complex impedance is reached at the microwave antenna. Adjusting the amount of microwave energy from the power source to the microwave antenna is another step of the method.

Brief Description of the Drawings

[0012] The above and other aspects, features, and advantages of the present disclosure will become more apparent in light of the following detailed description when taken in conjunction with the accompanying drawings in which:

[0013] FIG. 1 is a perspective view of a system for monitoring ablation size according to an embodiment of the present disclosure;

[0014] FIG. 2 is a functional block diagram of a power source for use with the system depicted in FIG. 1;

[0015] FIG. 3A is a schematic, plan view of the tip of a microwave antenna depicted in FIG. 2A illustrating radial ablation zones having a spherical configuration;

[0016] FIG. 3B is a schematic, plan view of the tip of a microwave antenna depicted in FIG. 1 illustrating radial ablation zones having an ellipsoidal configuration;

[0017] FIG. 4A-1 is a graphical representation of a real impedance (Zr) versus time (t) curve;

[0018] FIG. 4A-2 a graphical representation of a corresponding ablation radii (Ar) versus time (t) curve;

[0019] FIG. 4B-1 is a graphical representation of the imaginary impedance (Zi) versus time (t) curve;

[0020] FIG. 4B-2 is a graphical representation of corresponding ablation radii (Ar) versus time (t) curve; and

[0021] FIG. 5 is a flow chart illustrating a method for monitoring temperature of tissue undergoing ablation in accordance with the present disclosure.

Detailed Description

[0022] Embodiments of the presently disclosed system and method are described in detail with reference to the drawing figures wherein like reference numerals identify similar or identical elements. As used herein and as is traditional, the term “distal” refers to the portion which is furthest from the user and the term “proximal” refers to the portion that is closest to the user. In addition, terms such as “above”, “below”, “forward”, “rearward”, etc. refer to the orientation of the figures or the direction of components and are simply used for convenience of description.

[0023] Referring now to FIG. 1, a system for monitoring ablation size is designated 10. The system 10 includes a microwave antenna 100 that is adapted to connect to an electrosurgical power source, e.g., an RF and/or microwave (MW) generator 200 that includes or is in operative communication with one or more controllers 300 and, in some instances, a fluid supply pump 40. Briefly, microwave antenna 100 includes an introducer 116 having an elongated shaft 112 and a radiating or conductive section or tip 114 operably disposed within elongated shaft 112, a cooling assembly 120 having a cooling sheath 119, a handle 118, a cooling fluid supply 122 and a cooling fluid return 124, and an electrosurgical energy connector 126. Connector 126 is configured to connect the microwave antenna 100 to the electrosurgical power source 200, e.g., a generator or source of radio frequency energy and/or microwave energy, and supplies electrosurgical energy to the distal portion of the microwave antenna 100. Conductive tip 114 and elongated shaft 112 are in electrical communication with connector 126 via an internal coaxial cable 126a that extends from the proximal end of the microwave antenna 100 and includes an inner conductor tip that is operatively coupled to a radiating section 138 operably disposed within the shaft 112 and adjacent the conductive or radiating tip 114 (see FIG. 3A, for example). As is common in the art, internal coaxial cable 126a includes a dielectric material and an outer conductor surrounding each of the inner conductor tip and dielectric material. A connection hub (not shown) disposed at a proximal end of the microwave antenna 100 operably couples connector 126 to internal coaxial cable 126a, and cooling fluid supply 122 and a cooling fluid return 124 to a cooling assembly 120. Radiating section 138 by way of conductive tip 114 (or in certain instances without conductive tip 114) is configured to deliver radio frequency energy (in either a bipolar or monopolar mode) or microwave energy (having a frequency of about 500 MHz to about 10 GHz) to a target tissue site. Elongated shaft 112 and conductive tip 114 may be formed of suitable conductive material including, but not limited to copper, gold, silver or other conductive metals having similar conductivity values. Alternatively, elongated shaft 112 and/or conductive tip 114 may be constructed from stainless steel or may be plated with other materials, e.g., other conductive materials, such as gold or silver, to improve certain properties, e.g., to improve conductivity, decrease energy loss, etc. In an embodiment, the conductive tip may be deployable from the elongated shaft 112.

[0024] With reference to FIG. 2, a schematic block diagram of the generator 200 is illustrated. The generator 200 includes a controller 300 having one or more modules (e.g., an ablation zone control module 332 (AZCM 332), a power supply 237 and a microwave output stage 238). In this instance, generator 200 is described with respect to the delivery of microwave energy. The power supply 237 provides DC power to the microwave output stage 238 which then converts the DC power into microwave energy and delivers the microwave energy to the radiating section 138 of the microwave antenna 100. The controller 300 may include analog and/or logic circuitry for processing sensed values provided by the AZCM 332 and determining the control signals that are sent to the generator 200 and/or supply pump 40 via a microprocessor 335. The controller 300 (or component operably associated therewith) accepts one or more measured signals indicative of calculated complex impedance associated with the microwave antenna 100 and/or tissue adjacent an ablation zone when the microwave antenna is radiating energy.

[0025] One or more modules e.g., AZCM 332, of the controller 300 analyzes the measured signals and determines if a threshold complex impedance has been met. If the threshold complex impedance has been met, then the AZCM 332, a microprocessor 335 and/or the controller 300 instructs the generator 200 to adjust the microwave output stage 238 and/or the power supply 237 accordingly. Additionally, the controller 300 may also signal the supply pump to adjust the amount of cooling fluid to the microwave antenna 100 and/or the surrounding tissue. The controller 300 includes microprocessor 335 having memory 336 which may be volatile type memory (e.g., RAM) and/or non-volatile type memory (e.g., flash media, disk media, etc.). In the illustrated embodiment, the microprocessor 335 is in operative communication with the power supply 237 and/or microwave output stage 238 allowing the microprocessor 335 to control the output of the generator 200 according to either open and/or closed control loop schemes. The microprocessor 335 is capable of executing software instructions for processing data received by the AZCM 332, and for outputting control signals to the generator 200 and/or supply pump 40, accordingly. The software instructions, which are executable by the controller 300, are stored in the memory 336.

[0026] One or more control algorithms for predicting tissue ablation size is implemented by the controller 300. More particularly, the concept of correlating complex impedance (e.g., real and imaginary portions of the complex impedance) associated with a particular microwave antenna, e.g., the microwave antenna 100, with an ablation zone “A” having a radius “r” may be used to indicate tissue death or necrosis. More particularly, complex impedance associated with the microwave antenna 100 varies over the course of an ablation cycle due to tissue complex permittivity changes caused by temperature increase (see FIGS. 4A-1 and 4B-1, for example). A relationship of complex impedance as a function of time may be represented by the curves illustrated in FIGS. 4A-1 (real portion of complex impedance) and 4B-1 (imaginary portion of complex impedance). When the microwave antenna 100 has heated tissue to a maximum attainable temperature, an ablation zone “A” having a corresponding radius “r” (e.g., rss) is formed (see FIG. 3A in combination with FIGS. 4A-2 and 4B-2, for example). At this maximum temperature a dielectric constant and conductivity associated with the ablated tissue reach a steady-state condition (this steady-state condition occurs at time tss) that corresponds to a steady-state complex impedance Zss (hereinafter referred to simply as Zss) associated with the microwave antenna 100. That is, because the ablated tissue is in a “near field” of the microwave antenna 100, the ablated tissue essentially becomes part of the microwave antenna 100. Accordingly, when a dielectric constant and conductivity associated with the ablated tissue reaches a steady-state condition, the complex impedance at the microwave antenna 100 also reaches a steady-state condition, e.g., Zss, where Zss includes a real portion Zrss and an imaginary portion Ziss, see FIGS. 4A-1 and 4B-1, respectively.

[0027] It should be noted, that Zss may vary for a given microwave antenna. Factors that may contribute to a specific Zss for a given microwave antenna include but are not limited to: dimensions associated with the microwave antenna (e.g., length, width, etc.); type of material used to manufacture the microwave antenna (or portion associated therewith, e.g., a radiating section) such as copper, silver, etc; and the configuration of the radiating section (e.g., dipole, monopole, etc.) and/or a conductive tip (e.g., sharp, blunt, curved, etc) associated with the microwave antenna.

[0028] The control algorithm implements one or more model equations and/or curves, e.g., curves depicted in FIGS. 4A-1 and 4B-1, to calculate the Zss associated with the microwave antenna 100 within a specified time range (e.g., t1-tss) not exceeding tss, i.e., time when the ablated tissue is at the steady-state condition (see FIG. 4A-1 or FIG. 4B-1, for example). More particularly, the real and imaginary portions, Zrss and Ziss, respectively, of the Zss of the microwave antenna 100 may be calculated via monitoring and/or measuring of a signal (or pulse) generated by the generator 200. More particularly, a phase (for calculating an imaginary impedance Ziss of the complex impedance) and magnitude (for calculating a real impedance Zrss of the complex impedance) associated with a signal (or pulse) generated by the generator 200 during an ablation procedure may be sampled and monitored. For example, one or more electrical properties (e.g., voltage, current, power, impedance, etc.) associated with a signal (or pulse) generated by the generator 200 may be sampled and monitored. More particularly, electrical properties associated with a forward and reflected portion of the signal generated by the generator 200 is sampled and monitored. For example, in one particular embodiment, forward and reflected power, Pfwd and Pref, respectively, of a signal for ablating tissue is measured by the AZCM 332, controller 300, microprocessor 337 or other suitable module associated with the generator 200 and/or controller 300. Thereafter, the power standing wave ratio (Pswr) is calculated using the equation:

[0029]

\begin{matrix} P_{SWR} = \frac{P_{fwd} + P_{ref}}{P_{fwd} - P_{ref}} & (1) \end{matrix}

[0030] where Pfwd is the power associated with the generated signal (i.e., forward signal) and Pref is the power associated with the reflected signal. Those skilled in the relative art can appreciate that with the Pswr, Pfwd and Pref calculated the real portion of the complex impedance at the steady-state condition, e.g., Zss, of the microwave antenna 100 may be calculated. More particularly, the phase difference between the forward and reflected power may be used to calculate the imaginary portion Ziss of the complex impedance and the magnitude difference between the forward and reflected power may be used to calculate the real portion Zrss of the complex impedance. With Zrss and Ziss known, Zss may be calculated and, subsequently, communicated and/or relayed to one or more modules associated with the controller 300, e.g., AZCM 332, to determine if a predetermined threshold value Zss that corresponds to a desired ablation size has been met. For example, in certain instances, known characteristic impedance associated with connector 126 and/or internal cable 126a may be employed to determine Zss. More particularly, measurement of Zss may be determined using the equation:

[0031]

\begin{matrix} \frac{Z_{ss} - Z_{o}}{Z_{ss} + Z_{o}} = \frac{P_{SWR} - 1}{P_{SWR} + 1} & (2) \end{matrix}

[0032] where, Zo is the characteristic impedance associated with the connector 126 and/or internal cable 126a. The characteristic impedance Zo is an accurate measure of the impedance of the connector 126 and/or internal cable 126a and takes into account the line losses associated with the connector 126 and/or internal cable 126a. In this instance, after all the necessary calculations have been carried out, the measurement of Zss will be an accurate representation of the steady-state impedance Zss at the microwave antenna 100 adjacent the ablation zone.

[0033] The foregoing algorithms and/or equations are two of many algorithms and/or equations that may be employed to calculate the Zss associated with the microwave antenna 100 such that real-time monitoring of an ablation zone may be achieved. For example, one or more model functions ƒ(t) representative of the model curves illustrated in FIGS. 4A-1 and 4B-1 may be utilized in conjunction with the aforementioned equations (or alone) to obtain additional information relevant to Zss. More particularly, a measurement of a slope of a tangent line at a point along either of the curves (e.g., curve illustrated in FIG. 4A-1) is equal to a derivative (dz/dt) of the curve at that point. The calculation of the derivative at a particular point along the curve(s) may provide additional information, e.g., rate of change of complex impedance with respect to time. This rate of change associated with complex impedance with respect to time may be utilized, for example, to determine the time it takes to go from Z4 to Zss during an ablation procedure.

[0034] The microwave antenna 100 of the present disclosure may be configured to create an ablation zone “A” having any suitable configuration, such as, for example, spherical (FIG. 3A), hemispherical, ellipsoidal (FIG. 3B where the ablation zone is designated “A-2”), and so forth. In one particular embodiment, microwave antenna 100 is configured to create an ablation zone “A” that is spherical (FIG. 3A). As noted above, when the microwave antenna 100 has heated tissue in the “near field” to a maximum temperature, a dielectric constant and conductivity associated with the ablated tissue reaches a steady-state that corresponds to a steady-state complex impedance Zss associated with the microwave antenna 100. Correlating the Zss associated with the microwave antenna 100 with the ablated tissue (i.e., ablated tissue, where the dielectric constant and conductivity are in a steady-state condition), indicates a specific size (e.g., radius rss) and shape (e.g., spherical) of the ablation zone “A.” Thus, a measure of Zss associated with the microwave antenna 100 corresponds to an ablation zone “A” having a radius r, e.g., rss. The control algorithm of the present disclosure uses known or calculated steady state complex impedances associated with specific microwave antennas at specific radii to predict an ablation size. That is, complex impedances, e.g., Zss, associated with a specific microwave antenna, e.g., microwave antenna 100, and corresponding radius, e.g., rss, are compiled into one or more look-up tables “D” and are stored in memory, e.g., memory 336, accessible by the microprocessor 335 and/or the AZCM 332. Thus, when the complex impedance for a specific microwave antenna, e.g., microwave antenna 100, reaches Zss one or more modules, e.g. AZCM 332, associated with the controller 300, commands the generator 200 to adjust the power output to the microwave antenna 100 accordingly. This combination of events will provide an ablation zone “A” with a radius approximately equal to rss.

[0035] In an embodiment, for a given microwave antenna, e.g., microwave antenna 100, impedance measurements may be taken at times prior to tss, e.g., times t1-t4. In this instance, complex impedances, e.g., Z1-Z4 (for illustrative purposes and clarity, Z1-Z4 are defined by both the real and imaginary portions of the complex impedance), associated with the microwave antenna 100 may be correlated with an ablation zone “A” defined by a plurality of concentric ablation zones having radii r1-r4 (collectively referred to as radii “r”) when measured from the center of the ablation zone “A.” More particularly, the complex impedances Z1-Z4 and corresponding radii “r” may be correlated with each other in a manner as described above with respect to Zss and rss (see FIG. 3A in combination with FIGS. 4A-1 and 4B-1, for example). In this instance, when specific complex impedance, e.g., Z3, is met one or more modules, e.g. AZCM 332, associated with the controller 300, commands the generator 200 to adjust the power output to the microwave antenna 100 accordingly.

[0036] AZCM 332 may be a separate module from the microprocessor 335, or AZCM 332 may be included with the microprocessor 335. In an embodiment, the AZCM 332 may be operably disposed on the microwave antenna 100. The AZCM 332 may include control circuitry that receives information from one or more control modules and/or one or more impedance sensors (not shown), and provides the information to the controller 300 and/or microprocessor 335. In this instance, the AZCM 332, microprocessor 335 and/or controller 300 may access look-up table “D” and confirm that a particular complex impedance (e.g., Zss) associated with microwave assembly 100 that corresponds to a specific ablation zone, e.g., specific ablation zone having a radius rss has been met and, subsequently instruct the generator 200 to adjust the amount of microwave energy being delivered to the microwave antenna. In one particular embodiment, look-up table “D” may be stored in a memory storage device (not shown) associated with the microwave antenna 100. More particularly, a look-up table “D” may be stored in a memory storage device operatively associated with handle 118 and/or connector 126 of the microwave antenna 100 and may be downloaded, read and stored into microprocessor 335 and/or memory 336 and, subsequently, accessed and utilized in a manner described above; this would do away with reprogramming the generator 200 and/or controller 300 for a specific microwave antenna. The memory storage device may also be configured to include information pertaining to the microwave antenna 100. For example, information such as, the type of microwave antenna, the type of tissue that the microwave antenna is configured to treat, the type of ablation zone desired, etc. may be stored into the storage device associated with the microwave antenna. In this instance, for example, generator 200 and/or controller 300 of system 10 may be adapted for use with a microwave antenna configured to create an ablation zone, e.g. ablation zone “A-2,” different from that of microwave antenna 100 that is configured to create an ablation zone “A.”

[0037] In the embodiment illustrated in FIG. 1, the generator is shown operably coupled to fluid supply pump 40. The supply pump 40 is, in turn, operably coupled to the supply tank 44 (FIG. 2). In embodiments, the microprocessor 335 is in operative communication with the supply pump 40 via one or more suitable types of interfaces, e.g., a port 240 operatively disposed on the generator 200, which allows the microprocessor 335 to control the output of a cooling fluid 42 from the supply pump 40 to the microwave antenna 100 according to either open and/or closed control loop schemes. The controller 300 may signal the supply pump 40 to control the output of cooling fluid 42 from the supply tank 44 to the microwave antenna 100. In this way, cooling fluid 42 is automatically circulated to the microwave antenna 100 and back to the supply pump 40. In certain embodiments, a clinician may manually control the supply pump 40 to cause cooling fluid 42 to be expelled from the microwave antenna 100 into and/or proximate the surrounding tissue.

[0038] Operation of system 10 is now described. In the description that follows, it is assumed that the losses associated with the connector 126 and/or cable 126a of the microwave antenna 100 are negligible and thus, are not needed in calculating and/or determining a complex impedance of the microwave antenna 100 adjacent the ablation zone during the ablation procedure. Alternatively, the losses associated with the connector 126 and/or cable 126a of the microwave antenna 100 may be calibrated out of measurement (or other suitable methods) and utilized in calculating and/or determining a complex impedance of the microwave antenna 100 adjacent the ablation zone during the ablation procedure. Initially, microwave antenna 100 is connected to generator 200. In one particular embodiment, one or more modules, e.g., AZCM 332, associated with the generator 200 and/or controller 300 reads and/or downloads data from a storage device associated with the antenna 100, e.g., the type of microwave antenna, the type of tissue that is to be treated, etc. Microwave antenna 100 may then be positioned adjacent tissue (FIG. 3A). Thereafter, generator 200 may be activated supplying microwave energy to radiating section 138 of the microwave antenna 100 such that the tissue may be ablated. During tissue ablation, when a predetermined complex impedance, e.g., Zss, at the microwave antenna 100 is reached, the AZCM 332 instructs the generator 200 to adjust the microwave energy accordingly. In the foregoing sequence of events the AZCM 332 functions in real-time controlling the amount of microwave energy to the ablation zone such that a uniform ablation zone of suitable proportion (e.g., ablation zone “A” having a radius rss) is formed with minimal or no damage to adjacent tissue.

[0039] With reference to FIG. 5 a method 400 for monitoring temperature of tissue undergoing ablation is illustrated. At step 402, microwave energy from generator 200 is transmitted to a microwave antenna 100 adjacent a tissue ablation site. At step, 404, complex impedance associated with the microwave antenna is monitored. At step 406, a detection signal is communicated to the generator 200 when a predetermined complex impedance Zss is reached at the microwave antenna 100. At step 408, the amount of microwave energy from the generator 200 to the microwave antenna 100 may be adjusted.

[0040] From the foregoing and with reference to the various figure drawings, those skilled in the art will appreciate that certain modifications can also be made to the present disclosure without departing from the scope of the same. For example, one or more directional couplers (not shown) may be operatively associated with the generator 200, controller 300 and/or AZCM 332, and configured to sample the forward, reflected, and/or load power portions of an output signal (or pulse) and direct the sampled signal to the AZCM 332. More particularly, the directional coupler provides samples of the forward and reflected signal (or pulse) generated by the generator 200. The power, magnitude and phase of the generated output signal may be obtained or calculated from the measured forward and reflected signals by conventional algorithms that may employ one or both of the aforementioned equations (1) (2), or other suitable equation.

[0041] It should be noted that energy values or parameters (e.g., power, voltage, current, impedance, magnitude and phase) of an output pulse are valid at the output of generator 200. That is, the connector 126 and/or internal cable 126a may include transmission line losses. In order to get a more accurate reading and/or measurement of the energy values or parameters that are delivered to the microwave antenna 100 and/or reflected back to the generator 200, one would have to know the actual transmission line losses associated with connector 126 and/or internal cable 126a. Accordingly, in some instances, AZCM 332 (or other suitable module or component associated with the controller 300) may be configured to adjust and/or calibrate Zss to compensate for losses associated with connector 126 and/or internal cable 126a. For example, line loss information associated with the connector 126 and/or internal cable 126a may be determined and stored into memory 336 and accessed during an ablation procedure by the AZCM 332 and, subsequently, used in determining if a predetermined threshold value of Zss has been met. Thus, in an embodiment, loss information for connector 126 and/or internal cable 126a may be determined and, subsequently, stored in memory 336 and accessed by one or more modules, such as, for example, a calibration module 600 or other suitable module (e.g., AZCM 332) for later use. The loss information for connector 126 and/or internal cable 126a may be determined by any suitable device and/or method. For example, the loss information for connector 126 and/or internal cable 126a may be determined via network analyzer 602. In one particular embodiment, the network analyzer 602 may be an integral part of generator 200 (e.g., part of calibration module 600) or alternatively, the network analyzer 602 may be a separate handheld device that is in operative communication with generator 200. The network analyzer 602 may be used to perform a diagnostic test of connector 126 and/or internal cable 126a. The network analyzer 602 may function in a fashion similar to most conventional network analyzers that are known in the available art. That is, the network analyzer 602 may determine the properties that are associated with connector 126 and/or internal cable 126a, and more particularly, those properties that are associated with connector 126 and/or internal cable 126a that affect the reflection and/or transmission of an output signal, such as, for example, the characteristic impedance Zo of connector 126 and/or internal cable 126a. In embodiments, the network analyzer 602 may be narrow band or single frequency, e.g., microwave frequency utilized by system 10, which, in turn, may reduce the complexity of the system 10.

[0042] As noted above, the control algorithm of the present disclosure implements one or more model equations and/or curves to calculate Zss within the time range t1-tss. In certain instances, however, for a particular probe, system 10 and operative components associated therewith, e.g., AZCM 332, may be configured to monitor ablation zone size after time tss. More particularly, system 10 may be configured to deliver “x” amount of electrosurgical energy to microwave antenna 100 for “n” more seconds such that an ablation zone “A” having a radius “y” is achieved.

[0043] While several embodiments of the disclosure have been shown in the drawings and/or discussed herein, it is not intended that the disclosure be limited thereto, as it is intended that the disclosure be as broad in scope as the art will allow and that the specification be read likewise. Therefore, the above description should not be construed as limiting, but merely as exemplifications of particular embodiments. Those skilled in the art will envision other modifications within the scope and spirit of the claims appended hereto.

Claims

What is claimed is:

1. A system for monitoring ablation size, comprising:

a power source including a microprocessor for executing at least one control algorithm;

a microwave antenna including at least one memory storage device accessible by the microprocessor and including data specific to the microwave antenna, the microwave antenna configured to deliver microwave energy from the power source to tissue to form an ablation zone; and

an ablation zone control module in operative communication with a memory associated with the power source, the memory including at least one data look-up table including complex impedance associated with the data specific to the microwave antenna, complex impedance corresponding to a radius of the ablation zone, wherein the ablation zone control module is programmed to perform the following steps:

measure a phase difference between forward and reflected power generated by the power source to calculate an imaginary portion of the complex impedance;

measure a magnitude difference between the forward and reflected power to calculate a real portion of the complex impedance; and

trigger a signal when a predetermined threshold value of the complex impedance is measured corresponding to the radius of the ablation zone.

2. A system according to claim 1, wherein the complex impedance is measured during transmission of microwave energy to the microwave antenna when the microwave antenna is disposed near ablated tissue.

3. A system according to claim 2, wherein the at least one control algorithm calculates complex impedance associated with the microwave antenna when at least a portion of the microwave antenna and ablated tissue are in a steady-state condition relative to each other.

4. A system according to claim 1, wherein the microwave antenna is configured to produce an ablation zone that is one of spherical and ellipsoidal.

5. A system according to claim 1, further comprising: at least one fluid pump configured to supply a cooling fluid to the microwave antenna for facilitating cooling of one of the microwave antenna and tissue adjacent the ablation zone.

6. A system according to claim 1, further comprising:

a calibration module operably connected to a network analyzer configured to determined line losses associated with one of a connector and internal cable of the microwave antenna.

7. A microwave antenna adapted to connect to a power source configured for performing an ablation procedure, comprising:

a radiating section configured to deliver microwave energy from a power source to tissue to form an ablation zone;

at least one memory storage device accessible by a microprocessor of the power source and including data specific to the microwave antenna; and

an ablation zone control module operably coupled to a memory associated with the power source, the memory including at least one data look-up table including complex impedance associated with the data specific to the microwave antenna, the complex impedance corresponding to a radius of the ablation zone, wherein the ablation zone control module is programmed to perform the following steps:

measure a phase difference between forward and reflected power generated by the power source to calculate an imaginary portion of the complex impedance;

measure a magnitude difference between the forward and reflected power to calculate a real portion of the complex impedance; and

trigger a signal to the power source when a predetermined threshold value of the complex impedance is measured corresponding to the radius of the ablation zone.

8. A system according to claim 7, wherein the complex impedance is measured during transmission of microwave energy to the microwave antenna when the microwave antenna is disposed near ablated tissue.

Patent Citations (181)

Patent	Date	Inventor	Cited By
US4922210(A)	1990-05-01	Flachenecker et al.	Applicant
US5383874(A)	1995-01-01	Jackson et al.	Examiner
US5797902(A)	1998-08-01	Netherly	Applicant
US5800350(A)	1998-09-01	Coppleson et al.	Applicant
US5836943(A)	1998-11-01	Miller, III	Applicant
US6016452(A)	2000-01-01	Kasevich	Applicant
US6132425(A)	2000-10-01	Gough	Applicant
US6171304(B1)	2001-01-01	Netherly et al.	Applicant
US6238387(B1)	2001-05-01	Miller, III	Applicant
US6500175(B1)	2002-12-01	Gough et al.	Examiner
US6575969(B1)	2003-06-01	Rittman et al.	Examiner
US6692489(B1)	2004-02-01	Heim et al.	Applicant
US6733495(B1)	2004-05-01	Bek et al.	Examiner
US7041096(B2)	2006-05-01	Malis et al.	Applicant
US7048687(B1)	2006-05-01	Reuss et al.	Examiner
US7175621(B2)	2007-02-01	Heim et al.	Applicant
US7344533(B2)	2008-03-01	Pearson et al.	Applicant
US7419487(B2)	2008-09-01	Johnson et al.	Applicant
US7749011(B2)	2010-07-01	Arts et al.	Applicant
US7863984(B1)	2011-01-01	Behnke	Applicant
US8035570(B2)	2011-10-01	Prakash et al.	Applicant
US8038693(B2)	2011-10-01	Allen	Applicant
US8059059(B2)	2011-11-01	Bonn	Applicant
US8118808(B2)	2012-02-01	Smith et al.	Applicant
US8182480(B2)	2012-05-01	Huseman	Applicant
US8192427(B2)	2012-06-01	Buysse	Applicant
US8197473(B2)	2012-06-01	Rossetto et al.	Applicant
US8202270(B2)	2012-06-01	Rossetto et al.	Applicant
US8211098(B2)	2012-07-01	Paulus	Applicant
US8216227(B2)	2012-07-01	Podhajsky	Applicant
US8221418(B2)	2012-07-01	Prakash et al.	Applicant
US8235981(B2)	2012-08-01	Prakash et al.	Applicant
US8251987(B2)	2012-08-01	Willyard	Applicant
US8267927(B2)	2012-09-01	Dalal et al.	Examiner
US8282632(B2)	2012-10-01	Rossetto	Applicant
US8292881(B2)	2012-10-01	Brannan et al.	Applicant
US8346370(B2)	2013-01-01	Haley et al.	Examiner
US8382750(B2)	2013-02-01	Brannan	Examiner
US2002/0120262(A1)	2002-08-01	Bek et al.	Examiner
US2006/0224152(A1)	2006-10-01	Behnke et al.	Examiner
US2007/0282320(A1)	2007-12-01	Buysse et al.	Examiner
US2008/0125775(A1)	2008-05-01	Morris	Applicant
US2008/0227424(A1)	2008-09-01	Muhammad et al.	Applicant
US2008/0287944(A1)	2008-11-01	Pearson et al.	Examiner
US2008/0319434(A1)	2008-12-01	Rick et al.	Examiner
US2009/0076409(A1)	2009-03-01	Wu et al.	Examiner
US2009/0157071(A1)	2009-06-01	Wham et al.	Examiner
US2009/0306652(A1)	2009-12-01	Buysse et al.	Applicant
US2009/0326620(A1)	2009-12-01	Rossetto et al.	Applicant
US2010/0030206(A1)	2010-02-01	Brannan et al.	Applicant
US2010/0030208(A1)	2010-02-01	Manley	Applicant
US2010/0030210(A1)	2010-02-01	Paulus	Applicant
US2010/0045558(A1)	2010-02-01	Rossetto	Applicant
US2010/0045559(A1)	2010-02-01	Rossetto	Applicant
US2010/0057070(A1)	2010-03-01	Behnke et al.	Applicant
US2010/0076422(A1)	2010-03-01	Podhajsky	Applicant
US2010/0082022(A1)	2010-04-01	Haley et al.	Examiner
US2010/0087808(A1)	2010-04-01	Paulus	Applicant
US2010/0092939(A1)	2010-04-01	Belous et al.	Applicant
US2010/0094272(A1)	2010-04-01	Rossetto et al.	Applicant
US2010/0094273(A1)	2010-04-01	Rossetto et al.	Applicant
US2010/0097284(A1)	2010-04-01	Brannan et al.	Applicant
US2010/0121318(A1)	2010-05-01	Hancock et al.	Examiner
US2010/0256624(A1)	2010-10-01	Brannan et al.	Applicant
US2010/0262134(A1)	2010-10-01	Jensen et al.	Applicant
US2010/0262139(A1)	2010-10-01	Beller et al.	Examiner
US2010/0286681(A1)	2010-11-01	Podhajsky	Applicant
US2010/0286683(A1)	2010-11-01	Podhajsky	Applicant
US2010/0305560(A1)	2010-12-01	Peterson	Applicant
US2010/0321192(A1)	2010-12-01	Brannan	Applicant
US2010/0321257(A1)	2010-12-01	Brannan	Applicant
US2010/0331834(A1)	2010-12-01	Peterson et al.	Applicant
US2011/0015628(A1)	2011-01-01	Dalal et al.	Examiner
US2011/0034913(A1)	2011-02-01	Brannan	Applicant
US2011/0034917(A1)	2011-02-01	Brannan	Applicant
US2011/0034919(A1)	2011-02-01	DeCarlo	Applicant
US2011/0040300(A1)	2011-02-01	Brannan	Applicant
US2011/0054458(A1)	2011-03-01	Behnke	Applicant
US2011/0054459(A1)	2011-03-01	Peterson	Applicant
US2011/0060325(A1)	2011-03-01	Bonn	Applicant
US2011/0060326(A1)	2011-03-01	Smith et al.	Applicant
US2011/0066144(A1)	2011-03-01	Bonn et al.	Applicant
US2011/0071511(A1)	2011-03-01	Brannan et al.	Applicant
US2011/0071512(A1)	2011-03-01	Behnke et al.	Applicant
US2011/0071516(A1)	2011-03-01	Gregg	Examiner
US2011/0071582(A1)	2011-03-01	Willyard et al.	Applicant
US2011/0073594(A1)	2011-03-01	Bonn	Applicant
US2011/0077633(A1)	2011-03-01	Bonn et al.	Applicant
US2011/0077634(A1)	2011-03-01	Brannan	Applicant
US2011/0077635(A1)	2011-03-01	Bonn	Applicant
US2011/0077636(A1)	2011-03-01	Brannan et al.	Applicant
US2011/0077637(A1)	2011-03-01	Brannan	Applicant
US2011/0077638(A1)	2011-03-01	Brannan	Applicant
US2011/0077639(A1)	2011-03-01	Brannan et al.	Applicant
US2011/0098695(A1)	2011-04-01	Brannan	Applicant
US2011/0098696(A1)	2011-04-01	Brannan	Applicant
US2011/0098697(A1)	2011-04-01	Brannan	Examiner
US2011/0118721(A1)	2011-05-01	Brannan	Applicant
US2011/0118731(A1)	2011-05-01	Ladtkow	Applicant
US2011/0184403(A1)	2011-07-01	Brannan	Examiner
DE390937	1924-03-01		Applicant
DE1099658	1961-02-01		Applicant
DE1139927	1962-11-01		Applicant
DE1149832	1963-06-01		Applicant
DE1439302	1969-01-01		Applicant
DE2439587	1975-02-01		Applicant
DE2455174	1975-05-01		Applicant
DE2407559	1975-08-01		Applicant
DE2415263	1975-10-01		Applicant
DE2429021	1976-01-01		Applicant
DE2460481	1976-06-01		Applicant
DE2602517	1976-07-01		Applicant
DE2504280	1976-08-01		Applicant
DE2627679	1977-01-01		Applicant
DE2540968	1977-03-01		Applicant
DE2820908	1978-11-01		Applicant
DE2803275	1979-08-01		Applicant
DE2823291	1979-11-01		Applicant
DE2946728	1981-05-01		Applicant
DE3143421	1982-05-01		Applicant
DE3045996	1982-07-01		Applicant
DE3120102	1982-12-01		Applicant
DE3510586	1986-10-01		Applicant
DE3604823	1987-08-01		Applicant
DE8712328	1988-03-01		Applicant
DE3711511	1988-06-01		Applicant
DE3904558	1990-08-01		Applicant
DE3942998	1991-07-01		Applicant
DE4238263	1993-05-01		Applicant
DE4303882	1994-08-01		Applicant
DE4339049	1995-05-01		Applicant
DE29616210	1997-01-01		Applicant
DE19608716	1997-04-01		Applicant
DE19751106	1998-05-01		Applicant
DE19717411	1998-11-01		Applicant
DE19751108	1999-05-01		Applicant
DE19801173	1999-07-01		Applicant
DE19848540	2000-05-01		Applicant
DE10224154	2003-12-01		Applicant
DE10328514	2005-03-01		Applicant
DE102004022206	2005-12-01		Applicant
DE202005015147	2006-03-01		Applicant
EP246350	1987-11-01		Applicant
EP521264	1993-01-01		Applicant
EP556705	1993-08-01		Applicant
EP558429	1993-09-01		Applicant
EP836868	1998-04-01		Applicant
EP1159926	2001-05-01		Applicant
EP1707144(A1)	2006-10-01		Applicant
FR179607	1906-11-01		Applicant
FR1275415	1960-09-01		Applicant
FR1347865	1963-11-01		Applicant
FR2276027	1974-06-01		Applicant
FR2235669	1975-01-01		Applicant
FR2313708	1976-12-01		Applicant
FR2502935	1982-10-01		Applicant
FR2517953	1983-06-01		Applicant
FR2573301	1984-11-01		Applicant
FR2862813	2005-05-01		Applicant
FR2864439	2005-07-01		Applicant
JP5-5106	1993-01-01		Applicant
JP5-40112	1993-02-01		Applicant
JP6343644	1994-12-01		Applicant
JP7265328	1995-10-01		Applicant
JP8056955	1996-03-01		Applicant
JP8252263	1996-10-01		Applicant
JP9010223	1997-01-01		Applicant
JP11244298	1999-09-01		Applicant
JP2000342599	2000-12-01		Applicant
JP2000350732	2000-12-01		Applicant
JP2001008944	2001-01-01		Applicant
JP2001029356	2001-02-01		Applicant
JP2001128990	2001-05-01		Applicant
SU166452	1964-11-01		Applicant
SU401367	1974-11-01		Applicant
SU727201	1980-04-01		Applicant
WO97/37719	1997-10-01		Applicant
WO99/09899	1999-03-01		Applicant
WO99/11187	1999-03-01		Applicant
WO2004086995	2004-10-01		Applicant
WO2008043999(A2)	2008-04-01		Examiner

Non-Patent Literature (220)

European Search Report for European Application No. 11001596.3 dated Jun. 27, 2011.Applicant
International Search Report EP10014042 dated Feb. 18, 2011.Applicant
Alexander et al., “Magnetic Resonance Image-Directed Stereotactic Neurosurgery: Use of Image Fusion with Computerized Tomography to Enhance Spatial Accuracy” Journal Neurosurgery, 83 (1995), pp. 271-276.Applicant
Anderson et al., “A Numerical Study of Rapid Heating for High Temperature Radio Frequency Hyperthermia” International Journal of Bio-Medical Computing, 35 (1994), pp. 297-307.Applicant
Anonymous. (1999) Auto Suture MIBB Site Marker: Single Use Clip Applier, United States Surgical (Product instructions), 2 pages.Applicant
Anonymous. (2001) Disposable Chiba Biopsy Needles and Trays, Biopsy and Special Purpose Needles Cook Diagnostic and Interventional Products Catalog (products list), 4 pages.Applicant
Anonymous. (1987) Homer Mammalok™ Breast Lesion Needle/Wire Localizer, Namic® Angiographic Systems Division, Glens Falls, New York, (Hospital products price list), 4 pages.Applicant
Anonymous. (1999) MIBB Site Marker, United States Surgical (Sales brochure), 4 pages.Applicant
Anonymous. Blunt Tubes with Finished Ends. Pointed Cannula, Popper & Sons Biomedical Instrument Division, (Products Price List), one page, Jul. 19, 2000.Applicant
Anonymous. Ground Cannulae, ISPG, New Milford, CT, (Advertisement) one page, Jul. 19, 2000.Applicant
B. Levy M.D. et al., “Randomized Trial of Suture Versus Electrosurgical Bipolar Vessel Sealing in Vaginal Hysterectomy” Obstetrics & Gynecology, vol. 102, No. 1, Jul. 2003.Applicant
B. Levy M.D. et al., “Update on Hysterectomy New Technologies and Techniques” OBG Management, Feb. 2003.Applicant
B. Levy M.D., “Use of a New Vessel Ligation Device During Vaginal Hysterectomy” FIGO 2000, Washington, D.C.Applicant
B. F. Mullan et al., (May 1999) “Lung Nodules: Improved Wire for CT-Guided Localization,” Radiology 211:561-565.Applicant
B. T. Heniford M.D. et al., “Initial Research and Clinical Results with an Electrothermal Bipolar Vessel Sealer” Oct. 1999.Applicant
Bergdahl et al., “Studies on Coagulation and the Development of an Automatic Computerized Bipolar Coagulator” Journal of Neurosurgery 75:1 (Jul. 1991), pp. 148-151.Applicant
Bulletin of the American Physical Society, vol. 47, No. 5, Aug. 2002, p. 41.Applicant
C. F. Gottlieb et al., “Interstitial Microwave Hyperthermia Applicators having Submillimetre Diameters”, Int. J. Hyperthermia, vol. 6, No. 3, pp. 707-714, 1990.Applicant
C. H. Durney et al., “Antennas for Medical Applications”, Antenna Handbook: Theory Application and Design, p. 24-40, Van Nostrand Reinhold, 1988 New York, V.T. Lo, S.W. Lee.Applicant
Carbonell et al., “Comparison of the Gyrus PlasmaKinetic Sealer and the Valleylab LigaSure™ Device in the Hemostasis of Small, Medium, and Large-Sized Arteries” Carolinas Laparoscopic and Advanced Surgery Program, Carolinas Medical Center, Charlotte, NC 2003.Applicant
Carus et al., “Initial Experience With the LigaSure™ Vessel Sealing System in Abdominal Surgery” Innovations That Work, Jun. 2002.Applicant
Chicharo et al., “A Sliding Goertzel Algorithm” Aug. 1996 DOS pp. 283-297 Signal Processing, Elsevier Science Publishers B.V. Amsterdam, NL, vol. 52, No. 3.Applicant
Chou, C.K., (1995) “Radiofrequency Hyperthermia in Cancer Therapy,” Chapter 941n Biologic Effects of Nonionizing Electromagnetic Fields, CRC Press, Inc., pp. 1424-1428.Applicant
Chung et al., “Clinical Experience of Sutureless Closed Hemorrhoidectomy with LigaSure™” Diseases of the Colon & Rectum, vol. 46, No. 1, Jan. 2003.Applicant
Cosman et al., “Methods of Making Nervous System Lesions” In William RH, Rengachary SS (eds): Neurosurgery, New York: McGraw-Hill, vol. 111, (1984), pp. 2490-2499.Applicant
Cosman et al., “Radiofrequency Lesion Generation and its Effect on Tissue Impedence”, Applied Neurophysiology, 51:230-242, 1988.Applicant
Cosman et al., “Theoretical Aspects of Radiofrequency Lesions in the Dorsal Root Entry Zone” Neurosurgery 15:(1984), pp. 945-950.Applicant
Crawford et al., “Use of the LigaSure™ Vessel Sealing System in Urologic Cancer Surger” Grand Rounds In Urology 1999, vol. 1, Issue 4, pp. 1 0-17.Applicant
Dulemba et al., “Use of a Bipolar Electrothermal Vessel Sealer in Laparoscopically Assisted Vaginal Hysterectomy” Sales/Product Literature; Jan. 2004.Applicant
E. David Crawford, “Evaluation of a New Vessel Sealing Device in Urologic Cancer Surgery” Sales/Product Literature 2000.Applicant
E. David Crawford, “Use of a Novel Vessel Sealing Technology in Management of the Dorsal Veinous Complex” Sales/Product Literature 2000.Applicant
Esterline, “Light Key Projection Keyboard” 2004 Advanced Input Systems, located at: <http://www.advanced-input.com/lightkey> last visited on Feb. 10, 2005.Applicant
Esterline Product Literature, “Light Key: Visualize a Virtual Keyboard. One With No Moving Parts”, Nov. 1, 2003; 4 pages.Applicant
Geddes et al., “The Measurement of Physiologic Events by Electrical Impedence” Am. J. MI, Jan. Mar. 1964, pp. 16-27.Applicant
Goldberg et al., “Image-guided Radiofrequency Tumor Ablation: Challenges and Opportunities—Part I”, (2001) J Vasc. lnterv. Radiol, vol. 12, pp. 1021-1032.Applicant
Goldberg et al., “Tissue Ablation with Radiofrequency: Effect of Probe Size, Gauge, Duration, and Temperature on Lesion Volume” Acad Radio (1995) vol. 2, No. 5, pp. 399-404.Applicant
H. Schwarzmaier et al., “Magnetic Resonance Imaging of Microwave Induced Tissue Heating” Dept. of Laser Medicine & Dept. of Diagnostic Radiology; Heinrich-Heine-University, Duesseldorf, Germany; Dec. 8, 1994; pp. 729-731.Applicant
Heniford et al., “Initial Results with an Electrothermal Bipolar Vessel Sealer” Surgical Endoscopy (2001) 15:799-801.Applicant
Herman at al., “Laparoscopic Intestinal Resection With the LigaSure™ Vessel Sealing System: A Case Report” Innovations That Work, Feb. 2002.Applicant
Humphries Jr. et al., “Finite-Element Codes To Model Electrical Heating and Non•Llnear Thermal Transport In Biological Media”, Proc. ASME HTD-355, 131 (1997).Applicant
Ian D. McRury et al., The Effect of Ablation Sequence and Duration on Lesion Shape Using Rapidly Pulsed Radiofrequency Energy Through Electrodes, Feb. 2000, Springer Netherlands, vol. 4; No. 1, pp. 307-320.Applicant
Jarrett et al., “Use of the LigaSure™ Vessel Sealing System for Peri-Hilar Vessels in Laparoscopic Nephrectomy” Sales/Product Literature 2000.Applicant
Johnson et al., “Evaluation of a Bipolar Electrothermal Vessel Sealing Device in Hemorrhoidectomy” Sales/Product Literature, Jan. 2004.Applicant
Johnson, “Evaluation of the LigaSure™ Vessel Sealing System in Hemorrhoidectormy” American College of Surgeons (ACS) Clinic La Congress Poster (2000).Applicant
Johnson, “Use of the LigaSure™ Vessel Sealing System in Bloodless Hemorrhoidectomy” Innovations That Work, Mar. 2000.Applicant
Joseph G. Andriole M.D. et al., “Biopsy Needle Characteristics Assessed in the Laboratory”, Radiology 148: 659-662, Sep. 1983.Applicant
Joseph Ortenberg, “LigaSure™ System Used in Laparoscopic 1st and 2nd Stage Orchiopexy” Innovations That Work, Nov. 2002.Applicant
Kennedy et al., “High-burst-strength, feedback-controlled bipolar vessel sealing” Surgical Endoscopy (1998) 12: 876-878.Applicant
Kopans, D.B. et al., (Nov. 1985) “Spring Hookwire Breast Lesion Localizer: Use with Rigid-Compression. Mammographic Systems,” Radiology 157(2):537-538.Applicant
Koyle et al., “Laparoscopic Palomo Varicocele Ligation in Children and Adolescents” Pediatric Endosurgery & Innovative Techniques, vol. 6, No. 1, 2002.Applicant
LigaSure™ Vessel Sealing System, the Seal of Confidence in General , Gynecologic, Urologic, and Laparaoscopic Surgery, Sales/Product Literature, Jan. 2004.Applicant
Livraghi et al., (1995) “Saline-enhanced RF Tissue Ablation in the Treatment of Liver Metastases”, Radiology, pp. 205-210.Applicant
Lyndon B. Johnson Space Center, Houston, Texas, “Compact Directional Microwave Antenna for Localized Heating,” NASA Tech Briefs, Mar. 2008.Applicant
M. A. Astrahan, “A Localized Current Field Hyperthermia System for Use with 192-Iridium Interstitial Implants” Medical Physics. 9(3), May/Jun. 1982.Applicant
Magdy F. Iskander et al., “Design Optimization of Interstitial Antennas”, IEEE Transactions on Biomedical Engineering, vol. 36, No. 2, Feb. 1989, pp. 238-246.Applicant
McGahan et al., (1995) “Percutaneous Ultrasound-guided Radiofrequency Electrocautery Ablation of Prostate Tissue in Dogs”, Acad Radiol, vol. 2, No. 1: pp. 61-65.Applicant
McLellan et al., “Vessel Sealing for Hemostasis During Pelvic Surgery” Int'l Federation of Gynecology and Obstetrics FIGO World Congress 2000, Washington, DC.Applicant
MDTECH product literature (Dec. 1999) “FlexStrand”: product description, 1 page.Applicant
MDTECH product literature (Mar. 2000) I'D Wire: product description, 1 page.Applicant
Medtrex Brochure “The O.R. Pro 300” 1 page, Sep. 1998.Applicant
Michael Choti, “Abdominoperineal Resection with the LigaSure™ Vessel Sealing System and LigaSure™ Atlas 20 cm Open Instrument” Innovations That Work, Jun. 2003.Applicant
Muller et al., “Extended Left Hemicolectomy Using the LigaSure™ Vessel Sealing System” Innovations That Work. LJ, Sep. 1999.Applicant
Murakami, R. et al., (1995). “Treatment of Hepatocellular Carcinoma: Value of Percutaneous Microwave Coagulation,” American Journal of Radiology (AJR) 164:1159-1164.Applicant
Ni Wei et al., “A Signal Processing Method for the Coriolis Mass Flowmeter Based on a Normalized . . . ” Journal of Applied Sciences•Yingyong Kexue Xuebao, Shangha CN, vol. 23, No. 2:(Mar. 2005); pp. 160-184.Applicant
Ogden, “Goertzel Alternative to the Fourier Transform” Jun. 1993 pp. 485-487 Electronics World; Reed Business Publishing, Sutton, Surrey, BG, vol. 99, No. 9, 1687.Applicant
Olsson M.D. et al., “Radical Cystectomy in Females” Current Surgical Techniques in Urology, vol. 14, Issue 3, 2001.Applicant
Organ, L W., “Electrophysiologic Principles of Radiofrequency Lesion Making” Appl. Neurophysiol, vol. 39: pp. 69-76 (1976/77).Applicant
P.R. Stauffer et al., “Interstitial Heating Technologies”, Thermoradiotheray and Thermochemotherapy (1995) vol. I, Biology, Physiology, Physics, pp. 279-320.Applicant
Palazzo et al., “Randomized clinical trial of LigaSure™ versus open haemorrhoidectomy” British Journal of Surgery 2002,89,154-157 “Innovations in Electrosurgery” Sales/Product Literature; Dec. 31, 2000.Applicant
Paul G. Horgan, “A Novel Technique for Parenchymal Division During Hepatectomy” The American Journal of Surgery, vol. 181, No. 3, Apr. 2001, pp. 236-237.Applicant
Peterson et al., “Comparison of Healing Process Following Ligation with Sutures and Bipolar Vessel Sealing” Surgical Technology International (2001).Applicant
R. Gennari et al., (Jun. 2000) “Use of Technetium-99m-Labeled Colloid Albumin for Preoperative and Intraoperative Localization of Non palpable Breast Lesions,” American College of Surgeons. 190(6):692-699.Applicant
Valleylab Brochure, “Reducing Needlestick Injuries in the Operating Room” 1 page, Mar. 2001.Applicant
Reidenbach, (1995) “First Experimental Results with Special Applicators for High-Frequency Interstitial Thermotherapy”, Society Minimally Invasive Therapy, 4(Suppl 1):40 (Abstr).Applicant
Richard Wolf Medical Instruments Corp. Brochure, “Kleppinger Bipolar Forceps & Bipolar Generator” 3 pages, Jan. 1989.Applicant
Rothenberg et al., “Use of the LigaSure™ Vessel Sealing System in Minimally Invasive Surgery in Children” Int'l Pediatric Endosurgery Group (1 PEG) 2000.Applicant
Sayfan et al., “Sutureless Closed Hemorrhoidectomy: A New Technique” Annals of Surgery, vol. 234, No. 1, Jul. 2001, pp. 21-24.Applicant
Sengupta et al., “Use of a Computer-Controlled Bipolar Diathermy System in Radical Prostatectomies and Other Open Urological Surgery” ANZ Journal of Surgery (2001) 71.9 pp. 538-540.Applicant
Sigel et al., “The Mechanism of Blood Vessel Closure by High Frequency Electrocoagulation” Surgery Gynecology & Obstetrics, Oct. 1965 pp. 823-831.Applicant
Solbiati et al., (2001) “Percutaneous Radio-frequency Ablation of Hepatic Metastases from Colorectal Cancer: Long-term Results in 117 Patients”, Radiology, vol. 221, pp. 159-166.Applicant
Strasberg et al., “Use of a Bipolar Vassel-Sealing Device for Parenchymal Transection During Liver Surgery” Journal of Gastrointestinal Surgery, vol. 6, No. 4, Jul./Aug. 2002 pp. 569-574.Applicant
Sugita et al., “Bipolar Coagulator with Automatic Thermocontrol” J. Neurosurg., vol. 41, Dec. 1944, pp. 777-779.Applicant
Sylvain Labonte et al., “Monopole Antennas for Microwave Catheter Ablation”, IEEE Trans. on Microwave Theory and Techniques, vol. 44, No. 10, pp. 1832-1840, Oct. 1995.Applicant
T. Matsukawa et al., “Percutaneous Microwave Coagulation Therapy in Liver Tumors”, Acta Radiologica, vol. 38, pp. 410-415, 1997.Applicant
T. Seki et al., (1994) “Ultrasonically Guided Percutaneous Microwave Coagulation Therapy for Small Hepatocellular Carcinoma,” Cancer 74(3):817•825.Applicant
Urologix, Inc.-Medical Professionals: Targis™ Technology (Date Unknown). “Overcoming the Challenge” located at: <http://www.urologix.com!medicaUtechnology.html > last visited on Apr. 27, 2001, 3 pages.Applicant
Urrutia et al., (1988). “Retractable-Barb Needle for Breast Lesion Localization: Use in 60 Cases,” Radiology 169(3):845-847.Applicant
Valleylab Brochure, “Valleylab Electroshield Monitoring System” 2 pages, Nov. 1995.Applicant
ValleyLab Brochure, “Electosurgery: A Historical Overview”, Innovations in Electrosurgery, 1999.Applicant
Vallfors et al., “Automatically Controlled Bipolar Electrocoagulation-‘COA-COMP’” Neurosurgical Review 7:2-3 (1984) pp. 187-190.Applicant
W. Scott Helton, “LigaSure™ Vessel Sealing System: Revolutionary Hemostasis Product for General Surgery” Sales/Product Literature 1999.Applicant
Wald et al., “Accidental Burns”, JAMA, Aug. 16, 1971, vol. 217, No. 7, pp. 916-921.Applicant
Walt Boyles, “Instrumentation Reference Book”, 2002, Butterworth-Heinemann, pp. 262-264.Applicant
European Search Report EP 98300964.8 dated Dec. 13, 2000.Applicant
European Search Report EP 98944778 dated Nov. 7, 2000.Applicant
European Search Report EP 98958575.7 dated Oct. 29, 2002.Applicant
European Search Report EP 03721482 dated Feb. 6, 2006.Applicant
European Search Report EP 04009964 dated Jul. 28, 2004.Applicant
European Search Report EP 04013772 dated Apr. 11, 2005.Applicant
European Search Report EP 04015980 dated Nov. 3, 2004.Applicant
European Search Report EP 04015981.6 dated Oct. 25, 2004.Applicant
European Search Report EP 04027314 dated Mar. 31, 2005.Applicant
European Search Report EP 04027479 dated Mar. 17, 2005.Applicant
European Search Report EP 04027705 dated Feb. 10, 2005.Applicant
European Search Report EP 04710258 dated Oct. 15, 2004.Applicant
European Search Report EP 04752343.6 dated Jul. 31, 2007.Applicant
European Search Report EP 04778192.7 dated Jul. 1, 2009.Applicant
European Search Report EP 05002027.0 dated May 12, 2005.Applicant
European Search Report EP 05002769.7 dated Jun. 19, 2006.Applicant
European Search Report EP 05013463.4 dated Oct. 7, 2005.Applicant
European Search Report EP 05013895 dated Oct. 21, 2005.Applicant
European Search Report EP 05014156.3 dated Jan. 4, 2006.Applicant
European Search Report EP 05016399 dated Jan. 13, 2006.Applicant
European Search Report EP 05017281 dated Nov. 24, 2005.Applicant
European Search Report EP 05019130.3 dated Oct. 27, 2005.Applicant
European Search Report EP 05019882 dated Feb. 16, 2006.Applicant
European Search Report EP 05020665.5 dated Feb. 27, 2006.Applicant
European Search Report EP 05020666.3 dated Feb. 27, 2006.Applicant
European Search Report EP 05021025.1 dated Mar. 13, 2006.Applicant
European Search Report EP 05021197.8 dated Feb. 20, 2006.Applicant
European Search Report EP 05021777 dated Feb. 23, 2006.Applicant
European Search Report EP 05021779.3 dated Feb. 2, 2006.Applicant
European Search Report EP 05021780.1 dated Feb. 23, 2006.Applicant
European Search Report EP 05021935 dated Jan. 27, 2006.Applicant
European Search Report EP 05021936.9 dated Feb. 6, 2006.Applicant
European Search Report EP 05021937.7 dated Jan. 23, 2006.Applicant
European Search Report EP 05021939 dated Jan. 27, 2006.Applicant
European Search Report EP 05021944.3 dated Jan. 25, 2006.Applicant
European Search Report EP 05022350.2 dated Jan. 30, 2006.Applicant
European Search Report EP 05023017.6 dated Feb. 24, 2006.Applicant
European Search Report EP 05025423.4 dated Jan. 19, 2007.Applicant
European Search Report EP 05025424 dated Jan. 30, 2007.Applicant
European Search Report EP 05810523 dated Jan. 29, 2009.Applicant
European Search Report EP 06000708.5 dated May 15, 2006.Applicant
European Search Report EP 06002279.5 dated Mar. 30, 2006.Applicant
European Search Report EP 06005185.1 dated May 10, 2006.Applicant
European Search Report EP 06005540 dated Sep. 24, 2007.Applicant
European Search Report EP 06006717.0 dated Aug. 11, 2006.Applicant
European Search Report EP 06006961 dated Oct. 22, 2007.Applicant
European Search Report EP 06006963 dated Jul. 25, 2006.Applicant
European Search Report EP 06008779.8 dated Jul. 13, 2006.Applicant
European Search Report EP 06009435 dated Jul. 13, 2006.Applicant
European Search Report EP 06010499.9 dated Jan. 29, 2008.Applicant
European Search Report EP 06014461.5 dated Oct. 31, 2006.Applicant
European Search Report EP 06018206.0 dated Oct. 20, 2006.Applicant
European Search Report EP 06019768 dated Jan. 17, 2007.Applicant
European Search Report EP 06020574.7 dated Oct. 2, 2007.Applicant
European Search Report EP 06020583.8 dated Feb. 7, 2007.Applicant
European Search Report EP 06020584.6 dated Feb. 1, 2007.Applicant
European Search Report EP 06020756.0 dated Feb. 16, 2007.Applicant
European Search Report EP 06022028.2 dated Feb. 13, 2007.Applicant
European Search Report EP 06023756.7 dated Feb. 21, 2008.Applicant
European Search Report EP 06024122.1 dated Apr. 16, 2007.Applicant
European Search Report EP 06024123.9 dated Mar. 6, 2007.Applicant
European Search Report EP 06025700.3 dated Apr. 12, 2007.Applicant
European Search Report EP 07000885.9 dated May 15, 2007.Applicant
European Search Report EP 07001480.8 dated Apr. 19, 2007.Applicant
European Search Report EP 07001481.6 dated May 2, 2007.Applicant
European Search Report EP 07001485.7 dated May 23, 2007.Applicant
European Search Report EP 07001488.1 dated Jun. 5, 2007.Applicant
European Search Report EP 07001489.9 dated Dec. 20, 2007.Applicant
European Search Report EP 07001491 dated Jun. 6, 2007.Applicant
European Search Report EP 07001527.6 dated May 18, 2007.Applicant
European Search Report EP 07007783.9 dated Aug. 14, 2007.Applicant
European Search Report EP 07008207.8 dated Sep. 13, 2007.Applicant
European Search Report EP 07009026.1 dated Oct. 8, 2007.Applicant
European Search Report EP 07009028 dated Jul. 16, 2007.Applicant
European Search Report EP 07009029.5 dated Jul. 20, 2007.Applicant
European Search Report EP 07009321.6 dated Aug. 28, 2007.Applicant
European Search Report EP 07009322.4 dated Jan. 14, 2008.Applicant
European Search Report EP 07010672.9 dated Oct. 16, 2007.Applicant
European Search Report EP 07010673.7 dated Oct. 5, 2007.Applicant
European Search Report EP 07013779.9 dated Oct. 26, 2007.Applicant
European Search Report EP 07015191.5 dated Jan. 23, 2007.Applicant
European Search Report EP 07015601.3 dated Jan. 4, 2007.Applicant
European Search Report EP 07015602.1 dated Dec. 20, 2007.Applicant
European Search Report EP 07018375.1 dated Jan. 8, 2008.Applicant
European Search Report EP 07018821 dated Jan. 14, 2008.Applicant
European Search Report EP 07019173.9 dated Feb. 12, 2008.Applicant
European Search Report EP 07019174.7 dated Jan. 29, 2008.Applicant
European Search Report EP 07019178.8 dated Feb. 12, 2008.Applicant
European Search Report EP 07020283.3 dated Feb. 5, 2008.Applicant
European Search Report EP 07253835.8 dated Dec. 20, 2007.Applicant
European Search Report EP 08001019 dated Sep. 23, 2008.Applicant
European Search Report EP 08004975 dated Jul. 24, 2008.Applicant
European Search Report EP 08006731.7 dated Jul. 29, 2008.Applicant
European Search Report EP 08006733 dated Jul. 7, 2008.Applicant
European Search Report EP 08006734.1 dated Aug. 18, 2008.Applicant
European Search Report EP 08006735.8 dated Jan. 8, 2009.Applicant
European Search Report EP 08011282 dated Aug. 14, 2009.Applicant
European Search Report EP 08011705 dated Aug. 20, 2009.Applicant
European Search Report EP 08012829.1 dated Oct. 29, 2008.Applicant
European Search Report EP 08015842 dated Dec. 5, 2008.Applicant
European Search Report EP 08019920.1 dated Mar. 27, 2009.Applicant
European Search Report EP 08169973.8 dated Apr. 6, 2009.Applicant
European Search Report EP 09156861.8 dated Aug. 4, 2009.Applicant
European Search Report EP 09161502.1 dated Sep. 2, 2009.Applicant
European Search Report EP 09166708 dated Oct. 15, 2009.Applicant
International Search Report PCT/US98/18640 dated Jan. 29, 1998.Applicant
International Search Report PCT/US98/23950 dated Jan. 14, 1998.Applicant
International Search Report PCT/US99/24869 dated Feb. 11, 2000.Applicant
International Search Report PCT/US01/11218 dated Aug. 14, 2001.Applicant
International Search Report PCT/US01/11224 dated Nov. 13, 2001.Applicant
International Search Report PCT/US01/11340 dated Aug. 16, 2001.Applicant
International Search Report PCT/US01/11420 dated Oct. 16, 2001.Applicant
International Search Report PCT/US02/01890 dated Jul. 25, 2002.Applicant
International Search Report PCT/US02/11100 dated Jul. 16, 2002.Applicant
International Search Report PCT/US03/09483 dated Aug. 13, 2003.Applicant
International Search Report PCT/US03/22900 dated Dec. 2, 2003.Applicant
International Search Report PCT/US03/37110 dated Jul. 25, 2005.Applicant
International Search Report PCT/US03/37111 dated Jul. 28, 2004.Applicant
International Search Report PCT/US03/37310 dated Aug. 13, 2004.Applicant
International Search Report PCT/US04/04685 dated Aug. 27, 2004.Applicant
International Search Report PCT/US04/13273 dated Dec. 15, 2004.Applicant
International Search Report PCT/US04/15311 dated Jan. 12, 2004.Applicant
International Search Report PCT/US05/36168 dated Aug. 28, 2006.Applicant
International Search Report PCT/US08/052460 dated Apr. 24, 2008.Applicant
International Search Report PCT/US09/31658 dated Mar. 11, 2009.Applicant
European Search Report EP 10 01 4081 dated Mar. 4, 2011.Applicant
European Search Report; Application No. EP 10 01 4080 dated Mar. 4, 2011.Applicant

Abstract