Patent Application
20170049513
This invention relates generally to the advances in medical systems and procedures for prolonging and improving human life. The present invention relates generally to a system and method for applying energy, particularly radiofrequency electrical energy, to a living body. The present invention also relates generally to a system and method for apply energy for the purpose of tissue ablation, including the ablation of nervous tissue. The present invention also relates generally to a system and method for apply energy to a living body for the purpose of treating a medical disorder.
The theory behind and practice of RF heat ablation has been known for decades, and a wide range of suitable RF generators and electrodes exists. For example, equipment for causing heat lesions is available from Radionics, Inc., located in Burlington, Mass. A research paper by E. R. Cosman, et al., entitled “Theoretical Aspects of Radio Frequency Lesions in the Dorsal Root Entry Zone,” Neurosurgery, Vol. 15, No. 6, pp. 945-0950 (1984), describes various techniques associated with radio frequency lesions and is hereby incorporated by reference herein in its entirety. Also, research papers by S. N. Goldberg, et al., entitled “Tissue Ablation with Radio Frequency: Effect of Probe Size, Gauge, Duration, and Temperature on Lesion Volume,” Acad. Radiol., Vol. 2, pp. 399-404 (1995), and “Thermal Ablation Therapy for Focal Malignancy,” AJR, Vol. 174, pp. 323-331 (1999), described techniques and considerations relating to tissue ablation with radio frequency energy and are hereby incorporated by reference herein in its entirety.
Examples of high frequency generators and electrodes are given in the papers of entitled “Theoretical Aspects of Radiofrequency Lesions and the Dorsal Root Entry Zone,” by Cosman, E. R., et al., Neurosurg 15:945-950, 1984; and “Methods of Making Nervous System Lesions,” by Cosman, E. R. and Cosman, B. J. in Wilkins R. H., Rengachary S. S. (eds): Neurosurgery, New York, McGraw-Hill, Vol. III, pp. 2490-2498, 1984, and are hereby incorporated by reference herein in their entirety.
The Untied Stated Patent Application Publication entitled Method and Apparatus for Diagnosing and Treating Neural Dysfunction, by W. J. Rittman, Pub. No. US 2007/0032835 A1, Pub. Date: Feb. 8, 2007, describes an RF generator system comprising an RF generator with multiple active electrode output connections that enables the RF signal output the generator to be connected and delivered simultaneously to more than one electrode to deliver a therapeutic effect at each of the electrode positions at the same time. The RF generator's signal output is switched by switches and switch controllers so that the RF generator's output is applied to multiple needle-type treatment electrodes at the same time, and a reference electrode that does not have a specified treatment objective (such as a ground pad) is used as the path for return currents from the treatment electrodes. In another aspect, the switch and switch controller for one of the treatment electrodes performs independently from those of a second treatment electrode or from those of multiple individual treatment electrodes. This has one disadvantage that, because the same the signal output potential can be applied to more than one treatment electrode at the same time, the voltage of the generator's power supply and output electronics can be loaded down at the same time, causing sag or droop of the signal output voltage during application. Another disadvantage is that the electrical field from each of the treatment electrodes adds coherently in the bodily tissue, making it more difficult to separate their individual effects on the bodily tissue. Another disadvantage is that it makes it more difficult to control the RF signal output and to maintain the RF signal output so as to maintain the temperatures of the treatment electrodes at a set temperature chosen by the user. Another disadvantage is that no control objective, such as a target temperature value, is specified for the reference electrode. Another limitation is that inserted treatment electrodes are all connected via switches to the same output pole of the generator so that electric current does not flow between any two inserted treatment electrodes. Another limitation is that an indifferent reference electrode serves as the path for all return currents from all inserted electrodes. Another limitation is that the reference electrode is connected to one output pole of the generator for all steps in switching sequences produced by said system. Another limitation is that a switch is not specified for the reference electrode.
The use of radiofrequency (RF) generators and electrodes in neural tissue for the treatment of pain and functional disorders is well known. Included herein by reference, an as an example, the RFG-3C Plus RF Generator of Radionics, Inc., Burlington, Mass., and its associated electrodes are used in the treatment of the nervous system, and the treatment pain and functional disorders. The RFG-3C Plus generator has one electrode output jack for connection to a single active electrode, and it has one reference electrode jack for connection to a reference electrode. When the active electrode is inserted into the body, and the reference electrode is placed, typically on the patient's skin, then RF current form the RF generate flows through the patient's body between the two electrodes. The generator can be activated and its signal output can be applied between the electrodes. Typically, this is referred to as a monopolar configuration because the active electrode is of smaller area than the reference electrode, and so the concentration of RF current is highest near it and the action of the RF electric field, whether for heating or for pulsed RF field therapy is greater there. This usually referred to as a single electrode configuration since there is only one “active” electrode. Parameters that can be measured by the RFG-3C Plus RF generator include impedance, HF voltage, HF current, HF power, and electrode tip temperature. Parameters that may be set by the user include time of energy delivery, desired electrode temperature, stimulation frequencies and durations, and level of stimulation output. In general, electrode temperature is a parameter that may be controlled by the regulation of high frequency output power. Existing RF generators have interfaces that allow the selection of one or more of these treatment parameters, as well as various methods to display the parameters mentioned above.
In another example, the reference electrode can be inserted into the patient's body, and it can have an active area that is smaller and of comparable size to the active electrode. In that case, both electrodes become “active” in the sense that both of the electrodes have high temperature or electrical field effects on the tissues around them, so that they are both involved actively in the therapeutic effects the RF signal output. This can be referenced to as a single “bipolar configuration”.
A limitation for the monopolar and the bipolar configuration just described is that it limits the RF therapy to one or two electrode locations, respectively. In some situations it is desirable to treat more than one or two positions in the bodily tissue, and thus desirable to have more electrodes involved as the procedure goes on. For example, this can save time if there are multiple sites to be treated, as for example, multiple levels of the spinal medial branches to be treated for back pain.
The use of high frequency electrodes for heat ablation treatment of functional disease and in the destruction of tumors is well known. One example is the destruction of cancerous tumors of the kidney using radio frequency (RF) heat ablation. A paper by D. W. Gervais, et al., entitled “Radio Frequency Ablation of Renal Cell Carcinoma: Early Clinical Experience,” Radiology, Vol. 217, No. 2, pp. 665-672 (2000), describes using a rigid tissue perforating and penetrating electrode that has a sharpened tip to self-penetrate the skin and tissue of the patient. This paper is hereby incorporated by reference herein in its entirety.
Four patents have issued on PRF by Sluijter M. E., Rittman W. J., and Cosman E. R. They are “Method and Apparatus for Altering Neural Tissue Function,” U.S. Pat. No. 5,983,141, issued Nov. 9, 1999; “Method and System for Neural Tissue Modification,” U.S. Pat. No. 6,161,048, issued Dec. 12, 2000; “Modulated High Frequency Tissue Modification,” U.S. Pat. No. 6,246,912 B1, issued Jun. 12, 2001; and “Method and Apparatus for Altering Neural Tissue Function,” U.S. Pat. No. 6,259,952 B1, issued Jul. 10, 2001. These four patents are hereby incorporated by reference herein in their entirety.
United States patents by E. R. Cosman and W. J. Rittman, III, entitled “Cool-Tip Electrode Thermal Surgery System,” U.S. Pat. No. 6,506,189 B1, date of patent Jan. 14, 2003, and “Cluster Ablation Electrode System,” U.S. Pat. No. 6,530,922 B1, date of patent Mar. 11, 2003, described systems and method related to tissue ablation with radiofrequency energy and electrodes and are hereby incorporated by reference herein in their entirety.
In the prior art, the Cosman G4 Radiofrequency generator, in one mode of operation, switches radiofrequency electrical signal output among one, two, three, or four treatment electrodes such that a dispersive electrode carries all return currents from said treatment electrodes. This mode of operation can be referred as a “monopolar” mode. The energy delivered to each electrode can be adjusted to independently control one electrode-specific parameter for each electrode at the same time. In one sub-mode of operation, the said one electrode-specific parameter is the temperature measured at an electrode. In one sub-mode of operation, the said one electrode-specific parameter is the voltage applied between an electrode and the dispersive electrode. In one sub-mode of operation, the said one electrode-specific parameter is the output current flowing from an electrode. In one sub-mode of operation, the said one electrode-specific parameter is the power delivered to tissue due to signal output flowing from an electrode. One limitation of the prior art is that a reference electrode is used in addition to the four treatment electrodes. Another limitation is that the reference electrode is connected to signal output for all steps in all switching sequences whereby said treatment electrodes are connected to signal output.
In another mode of operation, the Cosman G4 Radiofrequency generator (Cosman Medical, Inc., Burlington, Mass.) connects radiofrequency electrical signal output to two treatment electrodes in a bipolar manner, without the use of a ground pad, such that each electrode serves as the path for return currents from the other electrode. In this bipolar configuration, said two treatment electrodes can be referred to a “bipolar pair”. Energizing two electrodes in a bipolar manner tends to focus the electrical current density and deposition of energy into the tissue between the two electrodes when said electrodes are close to each other. Energizing two electrodes in a bipolar manner can be used to create a “bipolar lesion” or “strip lesion”. Generation bipolar RF lesions is described in a paper by M. F. Ferrante, et al., entitled “Radiofrequency Sacroiliac Joint Denervation for Sacroiliac Syndrome”, Reg Anesth Pain Med 2001; 26(2):137-142, which is hereby incorporated by reference herein in its entirety. Generation bipolar RF lesions is described in a paper by C. A. Pino, et al., entitled “Morphologic Analysis of Bipolar Radiofrequency Lesions: Implications for Treatment of the Sacroiliac Joint”, Reg Anesth Pain Med 2005; 30(4):335-338, which is hereby incorporated by reference herein in its entirety. Generation bipolar RF lesions is also described in a paper by R. S. Burnham, et al., entitled “An Alternate Method of Radiofrequency Neurotomy of the Sacroiliac Joint: A Pilot Study of the Effect on Pain, Function, and Satisfaction”, Reg Anesth Pain Med 2007; 32(1):12-19, which is hereby incorporated by reference herein in its entirety. Generation bipolar RF lesions is also described in a paper by E. R. Cosman, Jr., et al., entitled “Bipolar Radiofrequency Lesion Geometry: Implications for Palisade Treatment of Sacroiliac Joint Pain”, Pain Practice 2010 (publication is currently pending), which is hereby incorporated by reference herein in its entirety. In the bipolar configurations described in the prior art, one parameter at a time is controlled independently by the energy delivered by the bipolar pair, and is hereby incorporated by reference herein in its entirety. In one sub-mode of operation, said one parameter is the maximum of the two temperatures measured at electrodes in a pair. In one sub-mode of operation, said one parameter is the RF voltage between the two electrodes in the pair. In one sub-mode of operation, said one parameter is the RF current flowing between the two electrodes in the pair. In one sub-mode of operation, said one parameter is the power delivered to tissue delivered by signal output delivered to the pair of electrodes. One limitation of the prior art is that the temperatures measured at each electrode in a bipolar pair are not controlled substantially independently. Another limitation of the prior art is that the temperature of one electrode in a bipolar pair can be substantially below a target set temperature for a substantial portion of the total treatment time; one example of a explanation for this phenomenon is that the electrical current flowing through one electrode in a bipolar pair is substantially the same as the electrical current flowing through the other electrode in a bipolar pair, because both electrodes in a bipolar pair serves as a path for return current for the other electrode. Another limitation is that the power delivered by one electrode in a pair is the same as the power delivered as the other electrode in said pair. Another limitation is the signal output for one electrode in the bipolar pair is not controlled independently of the other. Another limitation is that the voltage for one electrode is not controlled independently of the other. Another limitation is that the current for one electrode is not controlled independently of the other. Another limitation is that the power for one electrode is not controlled independently of the other.
In another mode of operation, four electrodes, labeled “E1”, “E2”, “E3”, and “E4”, are placed in tissue and connected to the Cosman G4 Radiofrequency generator. In this mode of operation, the generator produces a sequence of switch states, where the switch states can take one of three forms at any one time. In the first said form of switch states, E1 and E2 are connected to opposite poles of an RF power supply and E3 and E4 and disconnected from signal output. In the second said form of switch states, E3 and E4 are connected to opposite poles of an RF power supply and E1 and E2 are disconnected from signal output. In the third said form of switch states, all electrodes are disconnected from signal output. As such the generator produces energizes fixed, disjoint pairs of electrodes, E1-E2 and E3-E4, in sequence, where each pair is energized in a bipolar manner and where each electrode in a pair serves as the path for return currents for the other electrode in the pair, for the entire duration of the operational mode. The energy delivered to each pair is adjusted to independently control one pair-specific parameter for each pair of the other pair's pair-specific parameter. In one sub-mode of operation, said one pair-specific parameter is the maximum of the temperatures measured at each electrode in a pair. In one sub-mode of operation, said one pair-specific parameter is the voltage between the two electrodes in a pair. In one sub-mode of operation, said one pair-specific parameter is the current flowing between electrodes in a pair. In one sub-mode of operation, said one pair-specific parameter is the power delivered to tissue by a pair. One limitation of the prior art is that temperature is not independently controlled at all four electrodes at the same time. Another limitation of the prior art is that an electrode-specific parameter, such as the temperature measured at an electrode, is not controlled for each electrode at the same time in a manner that is substantially independent of the electrode-specific parameters associated with all other electrodes. Another limitation is that a parameter that is a function of the signal applied to one electrode over more than one switching step, is not independently controlled for each electrode. Another limitation is that the root-mean-square (RMS) voltage applied to one electrode over a duration containing more than one switching step, is not independently controlled for all electrodes. Another limitation is that the root-mean-square (RMS) current applied to one electrode over a duration containing more than one switching step, is not independently controlled for all electrodes. Another limitation is that the average power applied to one electrode over a duration containing more than one switching step, is not independently controlled for all electrodes. Another limitation of the prior art is that the temperature of one electrode in each bipolar pair may be substantially below a target set temperature for a substantial portion of the total treatment time; one example of a reason for why this can occur is that the electrical current flowing through one electrode in a bipolar pair is substantially the same as the electrical current flowing through the other electrode in a bipolar pair, because both electrodes in a bipolar pair serves as a path for return current for the other electrode. Another limitation is that at most two electrodes are connected to signal output in all steps of sequences by which electrodes are connected and disconnected from signal output.
In the prior art, the Cosman G4 radiofrequency generator can be switched between monopolar and bipolar modes operation by manual action of the user, said actions including changing controls in the user interface of the generator, and said actions including attaching electrodes and dispersive ground pads into external jacks of the generator. Such mode switching is not automated and requires a duration that is very long relative to the time in which a single set of switch states is held before it is changed in an automated manner during mode of automated multi-electrode control. A limitation of this prior art is that the Cosman G4 is not configured to automatically generate a sequence of connections between electrodes and system output poles that includes a step in which three or more electrodes are connected to system output poles at the same time, and in which a reference ground pad is not persistently connected to a reference output pole for the purpose of collecting return currents from other electrodes. Another limitation of this prior art is that the Cosman G4 is not configured to rapidly generate a sequence of connections between electrodes and system output poles that includes a step in which three or more electrodes are connected to system output poles at the same time, and in which a reference ground pad is not persistently connected to a reference output pole for the purpose of collecting return currents from other electrodes. Another limitation of the prior art is the temperature at each electrode is not controlled at the same while delivering electrical current between arbitrary connections of electrodes and ground pads to generator output poles. Another limitation of the prior art is an electrode-specific parameter, such as average power, at each electrode is not controlled at the same while delivering electrical current between arbitrary grouping of electrodes and the ground pad.
In the prior art, the Neurotherm SimplicityIII probe (Neurotherm, Wilmington, Mass.) has three metallic elements which are integrated into a single elongated probe, such that each metallic element is electrically insulated from the other elements, and such that each metallic element can be connected to system power supplies independently. Each of these metallic elements constitutes a treatment electrode and can be referred to as “E1”, “E2”, and “E3”, respectively. When the Simplicity III probe is connected to the Neurotherm NT1100 radiofrequency generator and is placed in the sacroiliac region of a body, and a reference ground pad “GP” is attached to the NT 1100 and to the said body, a non-repeating automatic sequence is produced. In one step of the sequence, E1 and E2 are energized in a bipolar manner, with E3 and the ground pad disconnected, and maximum of the temperatures at E1 and E2 is controlled to produce a heat lesion. In another step of the sequence, E2 and E3 are energized in a bipolar manner, with E1 and the ground pad disconnected, and maximum of the temperatures at E2 and E3 is controlled to produce a heat lesion. In another step of the sequence, the ground pad carries return currents from the electrode E1, with electrodes E2 and E3 disconnected, and the temperature at E1 is controlled to produce a heat lesion. In another step of the sequence, the ground pad carries return currents from the electrode E2, with electrodes E2 and E3 disconnected, and the temperature at E2 is controlled to produce a heat lesion. In another step of the sequence, the ground pad carries return currents from the electrode E3, with electrodes E2 and E1 disconnected, and the temperature at E3 is controlled to produce a heat lesion. One limitation of the prior art is that the steps of this sequence typically have duration on the order of 1 to 1.5 minutes or greater. Another limitation of the prior art is that the steps of this sequence do not have duration that is small relative to the thermal dynamics of an electrode when they are placed in a living body. Another limitation of the prior art is the temperatures measured at each of the three treatment electrodes are not controlled independently of each other at the same time. Another limitation of the prior art is the temperature of one electrode in a bipolar pair may be substantially below a target set temperature for a substantial portion of the phase of the sequence in which that pair is energized; one example of a reason for this phenomenon is that the electrical current flowing through one electrode in a bipolar pair is substantially the same as the electrical current flowing through the other electrode in a bipolar pair, because both electrodes in a bipolar pair serves as a path for return current for the other electrode. Another limitation of the prior art is that at most two electrodes are connected to signal output at once during the entirety of the sequence. Another limitation of the prior art is that no electrode-to-ouput-pole configuration is repeated in another step. The Neurotherm NT1100 can be manually switched to another mode of operation, the “SimplicityII” mode, in which the automatic sequence only includes the E1-E2, E1-GP, and E2-GP steps. The Neurotherm NT1100 can be manually switched to another mode of operation in which one, two, or three treatment electrodes are placed in a living body and energized in a monopolar configuration such that a reference ground pad carries the return currents from all treatment electrodes. The Neurotherm NT1100 can be manually switched to another mode of operation in which two treatment electrodes can be energized in a bipolar configuration. The time to switch between the monopolar, bipolar, SimplicityII, SimplicityIII, and other output modes is longer than 5 seconds and in typical use is not performed in less than 10 seconds. A limitation of this prior art is that the Neurotherm NT1100 is not configured to automatically generate a sequence of connections between electrodes and system output poles that includes a step in which three or more electrodes are connected to system output poles at the same time, and in which a reference ground pad is not persistently connected to a reference output pole for the purpose of collecting return currents from other electrodes. Another limitation of this prior art is that the Neurotherm NT1100 is not configured to rapidly generate a sequence of connections between electrodes and system output poles that includes a step in which three or more electrodes are connected to system output poles at the same time, and in which a reference ground pad is not persistently connected to a reference output pole for the purpose of collecting return currents from other electrodes.
In the prior art, multiple, non-temperature-sensing electrodes are placed in porcine or human liver and energized by rapidly duty-cycling between pairs of said electrodes, in order to control the power delivered to each pair of electrodes, in order to reduce blood flow in a region of the liver to facilitate tissue resection or ablate tumors. This prior art is described in the following publications, which are hereby incorporated by reference herein in their entirety: a paper by D. Haemmerich, et al., entitled “A device for radiofrequency assisted hepatic resection”, Proceedings of the 26th Annual International Conference of the IEEE EMBS, Sept. 1-5, 2004: 2503-2506; a paper by I. dos Santos I, et al., entitled “A surgical device for radiofrequency ablation of large liver tumors”, Physiol. Meas. 2009; 29: N59-N70.; a paper by D. J. Schutt, et al., entitled “An electrode array that minimizes blood loss for radiofrequency assisted hepatic resection”, Med Eng Phys. 2008 May; 30(4): 454-459; and a paper by R. M. Striegel entitled “An Electrode Array for Limiting Blood Loss During Liver Resection: Optimization via Mathematical Modeling”, The Open Biomedical Engineering Journal 2010; 4:39-46. One limitation of the prior art is that rapid duty-cycling among multiple electrode is not configured for control of a measured temperature. One limitation of the prior art is that rapid duty-cycling among multiple electrode is not configured for control of a temperature at each electrode. Another limitation to the prior art is that rapid switching between electrode pairs is not configured to control a different parameter for each electrode, such as the average power delivered to a specific electrode over a duration longer than one step of the duty-cycling. Another limitation to the prior art is that rapid switching between electrode pairs is not configured to control a different parameter for each electrode, such as an aggregate measure of current delivered to a specific electrode over a duration longer than one step of the duty-cycling. Another limitation to the prior art is that rapid switching between electrode pairs is not configured to control a different parameter for each electrode, such as an aggregate measure of voltage delivered to a specific electrode over a duration longer than one step of the duty-cycling. Another limitation of the prior art is that rapid duty-cycling among multiple adjacent electrodes is not performed in the sacroiliac region, nor for ablating nervous tissue, nor for managing pain. Another limitation of the prior art is no more than two electrodes are energized in any step of the duty-cycle switching process. Another limitation is that the impedance between pairs of electrodes is not controlled. Another limitation is that voltage between pairs of electrodes is not controlled. Another limitation is that the current between pairs of electrodes is not controlled. Another limitation is the water content of tissue is not controlled. Another limitation is that the blood flow tissue is not controlled.
In a paper by A. Hacker, et al., “Technical characterization of a new bipolar and multipolar radiofrequency device for minimally invasive treatment of renal tumours”, BJU International 2006; 97: 822-828, two, four, or six electrodes are placed in the porcine or human kidney, and pairs of said electrodes are energized in a bipolar manner sequentially, where each pair is energized one after another for a specific period of 3 seconds, and where the output level applied to each pair is adjusted to control either a single impedance or a single resistance measured between the two output poles of a radiofrequency power supply which are sequentially to connected to exactly two electrodes at a time. One limitation of the prior art is that duty-cycling among multiple electrode is not configured for control of a measured temperature. Another limitation to the prior art is that rapid switching between electrode pairs is not configured to control independently an electrode-specific parameter for each electrode, such as the power delivered to a specific electrode. Another limitation to the prior art is that rapid switching between electrode pairs is not configured to control an impedance for each pairing of electrodes. Another limitation to the prior art is that rapid switching between electrode pairs is not configured to control an impedance for each electrode, where each the impedance for a given electrode is measured between said electrode and a reference structure, such as another electrode or set of electrodes connected to a reference potential. Another limitation of the prior art is the respective impedances between each pairing of electrodes are not controlled independently. Another limitation of the prior art is that rapid duty-cycling among multiple adjacent electrodes is not performed in the sacroiliac region, nor for ablating nervous tissue, nor for managing pain. Another limitation of the prior art is no more than two electrodes are energized in every step in the duty-cycle switching process. Another limitation is that the duration of connection to each pair of electrodes is a fixed duration. Another limitation is that the output level is adjusted to control only one parameter at a time.
The present invention overcomes the stated and other limitations of the prior art.
In one exemplary embodiment, the present invention is directed towards systems and methods for ablating tissue in the living body, including use of multiple probes comprising high frequency electrodes and temperature-sensing probes.
In another example of the present invention, a system for ablating tissue includes more than two electrodes that are inserted into a patient's tissue and includes an RF generator that can apply output signal from the generator and a control system that can monitor the temperature of the electrode, adjust the amplitude, distribution, and timing of the of the output signal in a bipolar manner across at least two subgroups of electrodes at a given time so as to achieve a uniform temperature distribution on the inserted electrodes.
In another example of the present invention, a system for ablating tissue includes more than two electrodes that are inserted into a patient's tissue and includes an RF generator that can apply output signal from the generator and a control system that can monitor the temperature of the electrode, adjust the amplitude, distribution, and timing of the of the output signal in a bipolar manner across at least two subgroups of electrodes at a given time so as to achieve a desired temperature distribution on the inserted electrodes.
In another example of the present invention, a system for ablating tissue using a multiplexing system so that the output of a high frequency generator can be applied in a bipolar configuration across a first subgroup of n electrodes and a second subgroup of m electrodes that are subgroups of a total of N electrodes inserted into a patient's body, where N is an integer greater than two. A control system can vary the amplitude, time duration, and the distribution of n and m so that the respective temperatures of the N electrodes can each be held at a desired temperature.
In another example of the present invention, a system and method includes at least three electrodes inserted into a patient's body and a high frequency generator that can be connected to the electrode through a switching and control system so that the output signal of the generator can be connected to subgroups of the electrodes in a distributions of time and of electrode combinations to achieve a constant temperature on the electrodes.
In another example of the present invention, a system and method can include in addition to at least two electrodes inserted into the patient's body, a ground electrode or reference electrode in contact with the patient's skin or other anatomy remote of the treatment location, that can also be introduced into the switching and control system so that the reference electrode can be used at controlled times and durations as one of a bipolar pair involving the reference electrode as one of the pairs and one or more of the inserted electrode as the other pair of the bipolar configuration. In one more specific example, said system and method can be used to control the temperature measured at each of the said at least two electrodes inserted into the patient's body. In another more specific example, said system and method can be used to control the power delivered to each of the said at least two electrodes.
In another example of the present invention, a system and method for applying electrical output signals to tissue can include at least three electrodes that are placed in or on a patient's body, and includes a control system that can produce a sequence of operational states of an electrical signal generator; where said electrical signal generator includes at least two output poles capable for producing different electrical potentials; where a step of said sequence of operational states can be configured to connect each of at least two disjoint subsets of electrodes to a different output pole of the electrical signal generator; where in at least one step of said sequence, the total number of inserted electrodes connected to any output pole is at least three; where there is no designated reference electrode that carries substantial return current from other electrodes during every step of the said sequence of operational states; where electrical signal applied to each output pole and/or the duration of a step and/or the assignment of electrodes to poles can be adjusted by the controller during and/or between each step of said sequence of operational states. In one more specific example, the said controller can produce said sequence of operational states in a fully automated manner. In one more specific example, the said controller can produce said sequence of operational states in a rapid manner. In one more specific example, the said controlled can produce said sequence of operational states, where each step of said sequence has a duration of less than one minute. In one more specific example, the said controller can produce said sequence of operational states, where each step of said sequence has a duration of less than five seconds. In one more specific example, the said controlled can produce said sequence of operational states, where each step of said sequence has a duration of less than one second. In one more specific example, the said controlled can produce said sequence of operational states, where each step of said sequence has a duration of less than 250 milliseconds. In one more specific example, the said controlled can produce said sequence of operational states, where each step of said sequence has a duration of less than 100 milliseconds. In one more specific example, the sequence can be configured to use electrical signal output to control other parameters at the same time, substantially independently of each other, where the number of other parameters is at equal to the total number of electrodes connected to the system. In another more specific example, the sequence can be configured to control the temperature of tissue near each electrode at the same time. In another more specific example, the sequence can be configured to control simultaneously the average power delivered to each electrode over a window of time that contains more than one step in the sequence.
In another example of the present invention, a system and method can deliver electrical signal output sequentially to subsets of at least three electrodes placed in bodily tissue for the purpose controlling a parameter for each of said at least three electrodes, where control of all parameters is achieved at the same time, and where each parameter is controlled substantially independently of all other parameters. One advantage of this aspect of the present invention that a substantially independent parameter can be controlled for each of said at least three electrodes at the same time without the use of an additional electrode.
In another example of the present invention, a system and method can deliver electrical signal output sequentially to subsets of at least three electrodes placed in bodily tissue for the purpose of controlling multiple parameters, where the number of said multiple parameters is at least the number of said at least three electrodes, where control of all parameters is achieved at the same time, and where each parameter is controlled substantially independently of all other parameters. One advantage of this aspect of the present invention is that more independent parameters can be controlled than the number of electrodes.
In another example of the present invention, a system and method can switch electrical energy among at least two electrodes placed in tissue of a body and at least one additional electrode placed in contact with the said body for the purpose controlling a parameter for each of said at least two electrodes, where control of all parameters is achieved at the same time, and where each parameter is controlled substantially independently of all other parameters. One advantage of this aspect of the present invention is that a substantially independent parameter can be controlled for each of said at least two electrodes at the same time by delivery of electrical energy, where said electrical energy is delivered only to the said two electrodes for some duration of the time into which electrical energy is delivered. Another advantage of this aspect of the present invention that delivery of electrical energy can be focused in a tissue region between the said at least two electrodes, while at the same time independently and simultaneously controlling a parameter for each of said two electrodes.
In another example of the present invention, a system and method can switch electrical energy among at least two electrodes placed in tissue of a body and at least one additional electrode placed in contact with the said body for the purpose controlling multiple parameters, where the number of said multiple parameters is at least the number of said at least two electrodes, where control of all parameters is achieved at the same time, and where each parameter is controlled substantially independently of all other parameters. One advantage of this aspect of the present invention is that more independent parameters can be controlled than the number of the said at least two electrodes. Another advantage is that the operating conditions under which control of all said parameters are achievable can be expanded relative to the case where the said at least one additional electrodes are not used.
In another example of the present invention, a system and method can switch electrical energy among at least three electrodes inserted into bodily tissue where for at least one step of a switching sequence more than two electrodes are connected to generator signal output at the same time. In one more specific example, at least two of the said at least three electrodes can be integrated into different physical structures. In one more specific example, all said at least three electrodes can be integrated in the same physical structure. One advantage of this aspect of the present invention is additional patterns of electrical energy delivery are possible when more than two inserted electrodes are energized for some duration of an overall energy-delivery period, than are possible if at most two electrodes are energized at any time during an overall energy-delivery period.
Advantages of the system and method of the present invention include the ability to heat multiple electrodes in the same clinical intervention using multiple and multiplexed bipolar configurations so that uniform temperature can be achieved on the electrodes.
In another aspect, an advantage of the system and method of the present invention is that multiple electrodes can be placed and heated in a simultaneous, or nearly simultaneous, process while avoiding the differences of impedance characteristics that would cause non-uniform heating in the case of standard bipolar RF application wherein difference in tissue impedance would cause runaway heating on one electrode of a bipolar pair.
Another advantage is that use of varied numbers of subsets of the electrodes in the bipolar pairs enables control of the balance in thermal heating around several electrodes at the same time. This has an advantage, for example, in the application of pain therapy of the sacroiliac (SI) joint where it is an advantage to be able to simultaneously heat several electrodes in one procedure process. This can save time for the clinical and provide a more complete and uniform thermal lesion to be made over a large area of innervations as in the SI joint.
Another advantage is that multiple bipolar electrodes heating can produce a more complete and greater heating between the electrodes than multiple monopolar heating for comparable electrode spacing.
The invention can be used in numerous organs in the body, including the brain, spine, liver, lung, bone, kidney, abdominal structures, etc., and for the treatment of cancerous tumors, functional disorders, pain, tissue modifications, bone and cartilage fusions, and in cardiac ablation.
The detail of one or more embodiments of the invention are set forth in the accompanying drawings and description below. Other features, objects and advantages of the invention will be apparent from the description and drawings and from the claims.
In the drawings that constitute a part of the specification, embodiments exhibited various forms and features hereof are set forth, specifically:
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In one example, a desired high frequency voltage amplitude V(RF) can be produced by generator 2011 and the signal outputs at the output jacks + and − will be voltage +V and −V, and this voltage will oscillate at the frequency of the high frequency generator 2011. This oscillating signal output can then be connected to the exposed conductive tips of the bipolar pairs of electrodes via the switches at any given time and in a sequence that is controlled by unit 2027. In one example, the Voltage amplitude V can be controlled by a manual control 2037 unit 2011. In another example, it can be controlled by the control unit 2027, the control signal being fed back into the generator 2011 by the connection 2027. During the process of tissue heating, the voltage V can be adjusted so that a desired temperature is reached on all the electrodes.
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The duration, number, combinations of multiplexing pairs and temperature objectives for each interval, the level incremental changes in the signal output level applied to the electrodes during each interval, and the ultimate end point temperature distribution on the electrodes for the desires clinical objectives can be determined and adjusted by the controller 2027 based on the measured temperatures at each point in time during the heating process, the degree and rapidity of the temperature rise at each interval, the electrodes' impedances and temperature imbalances at each point in time, and the controller's control algorithm that utilizes this information to determine the successive switching combinations on the multiplexing process.
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The time intervals can have a range of values according to clinical objectives and the controller algorithm. In one example, the intervals, such as Dt1 through Dt5 in
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Another advantage of the multiplexed bipolar system and method herein is that if one electrode of the pair of the bipolar electrodes configuration does not heat up compared to the other electrode of the bipolar pair, then by switching in another multiplexed electrode bipolar configuration, as illustrated by the exemplary embodiment s of the
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In one example, generator 625 can be an electrosurgical generator. In one example, generator 625 can be a radiofrequency generator. In one example, generator 625 can be a high-frequency generator. In one example, generator 625 can generator electrical output signals.
Each electrode, such as 641, 642, 643, or 644, can have an active region, for example, an exposed conductive tip, through which electrical output of the electrosurgical system 625 can be applied, and can have other regions which are composed of an electrical insulator. Said at least three electrodes 641, 642, 643, 644 can be placed in a living body 630, such as the human body. Said at least three electrodes 641, 642, 643, 644 can be placed in a living body 630 percutaneously. For example, electrode 641 is shown passing through the surface of the skin 635. Said at least three electrodes 641, 642, 643, 644 can also be placed in a living body 630 during an open surgical procedure, a laproscopic surgical procedure, or an endoscopic surgical procedure.
For example, each of electrodes 641, 642, and 644 can have an elongated shaft with an active conductive tip at its distal end, with the remaining proximal aspect of the shaft being non-active. An active zone can be constructed from an electrical conductor, such as a metal, which is in electrical communication with the electrical output of the generator 625 via wires shrouded in the insulated, non-active portions of the electrode probe and cable system.
Each electrode, such as 641, 642, 643, or 644, can have an active region through which electrical output of the electrosurgical system 625 can be applied, and can have other regions which are composed of an electrical insulator. For example, each of electrodes 641, 642, 643, and 644 can have an elongated shaft with an active region at its distal end, with the remaining proximal aspect of the shaft being non-active. An active zone can be constructed from an electrical conductor, such as a metal, which is in electrical communication with the electrical output of the generator 625 via wires shrouded in the insulated, non-active portions of the electrode probe and cable system.
The electrical output of the generator 625 can have a physical effect in a region of influence near an electrode's active zone. Electrodes 641, 642 and 644 have regions of influence 651, 652, and 654, respectively, in the tissue of living body 630. Ellipsis 643 can represent a non-negative integral number of electrodes, where each electrode has an active zone and an associated region of influence. The physical effect in an electrode's region of influence can be a change in temperature, change in electrical resistance, change in electrical impedance, protein denaturation, coagulation, tissue desiccation, tissue ablation, lesion generation, tumor ablation, destruction of nervous tissue, stimulation of nervous tissue, modification of nerves, exposure of tissue to electrical phenomena, integrated exposure of tissue to electromagnetic fields, exposure of tissue to an electric field, exposure of tissue to a current density field, frictional heating, tissue heating, ohmic power loss, and other physical effects that should be familiar to one skilled in the art. The regions of influence of different electrodes can overlap or can be physically disjoint. The extent of the region of influence for a given electrode can be influenced by another electrode. The region of influence of two electrodes can be between those electrodes, such as when two electrodes are connected to signal output of the generator 625 in a bipolar manner.
The placement of treatment electrodes 641, 642, 643, 644 can be configured so that their regions of influence are near to, next to, adjacent to, inside, or enveloping a target structure, in whole or in part. A target structure can be a nerve; nervous tissue; a set of nerves; a tumor; an organ; a tissue structure; an anatomical structure; a membrane; a blood vessel; a set of blood vessels; tissue surrounding a tumor; tissue adjacent to a tumor; tissue carrying blood supply for a tumor; a region of the liver; a region of the heart; a region of the kidney; a region of the brain; a region of the lung; a region of the pancreas; a region of the prostate grand; a region of the breast; tissue in the sacroiliac region; innervations of the sacroiliac joint; the medial branch nerves; innervations of a facet joint; medical branch nerves in the lumbar, thoracic, or cervical region of the spine; intraarticular nerves; a joint; and the interior of a joint.
It is understood that said electrodes, cables, and jacks can be integrated into one or more physical structure. For example, a single electrode connection jack can connect to a branching cable which can connect to multiple individual electrodes. For example an electrode connection jack can refer to one or more pins in a larger connection structure. For example, multiple electrodes can be integrated into a single physical structure. For example, multiple active zones can be integrated in a single physical structure such that each zone is substantially electrically isolated from the other active zones, and such that said active zone are connected to the electrosurgical generator 625 in a manner that they each act as an individual electrode 641, 642, 643, 644. Each electrode, such as 641, can take a variety of forms which should be familiar to one skilled in the arts of electrosurgery, tissue ablation, neural tissue ablation, or tumor ablation. For example, each electrode, such as 641, 642, 643, or 644, can be a combination of a cannula and electrode used for radiofrequency tissue ablation, such as the Cosman CC cannula and Cosman CSK-TC electrode, respectively. For example, each electrode can be an internally-cooled radiofrequency electrode, such as the ValleyLab CoolTip electrode.
The electrical output of the electrosurgical system 625 can be electrical current, electrical voltage, electoral potential, electrical energy, electrical power, a reference signal, a reference potential, a radiofrequency signal, a stimulation signal, a pulsed radiofrequency signal, radiofrequency current, radiofrequency voltage, a signal whose carrier signal is in the range 300 kHz to 1000 kHz, a signal whose carrier signal is 480 kHz, a 50 kHz signal, a signal configured for impedance monitoring, an oscillating signal, a signal configured to ablate tissue, a signal configured to coagulate blood, a signal configured to stimulate nerve tissue, or other types of outputs which should be familiar to one skilled in the art of electrosurgery, tumor ablation, radiofrequency lesioning, and radiofrequency pain management. The electrical output of the electrosurgical system can be the superposition of multiple signal types, such as the aforementioned types.
Electrodes 641, 642, 643, or 644 can be connected and disconnected from the output of the electrosurgical system 625 by means of switches integrated into the electrosurgical system 625, integrated into the cable system 661, 662, 663, 664, or otherwise connected to both the electrosurgical system and the electrodes. The switching system can be manually controlled, automatically controlled, or both. The switches can connect each electrode 641, 642, 643, or 644 to multiple different system electrical potentials, either at the same time, or at different times. The switches can connect each electrode 641, 642, 643, or 644 to multiple different output types, either at the same time, or at different times. For example, switches can be configured such that, by changing the state of the switches, each electrode can be connected to a reference potential, connected to a radiofrequency signal, or disconnected from system potentials. An electrode that is disconnected from direct connection to system power supplies by its switches can be referred to a “floating” or “electrically passive”. The electrical state of a floating electrode can be influenced by the electrosurgical system via output delivered to other electrodes, but a floating electrode does not draw or emit a substantial amount of electrical current from system power supplies through its cable system. Switches can be configured such that pairs of electrodes can be energized in a bipolar manner, where each electrode in a pair serves as the path for return currents from the other electrode in the pair. Switches can be configured such that groups of electrodes are connected to various system potentials at the same time. Switches can be changed over time such that at any time only one pair of electrodes is connected to electrical signal output in a bipolar manner, with all other electrodes floating. Switches can be changed over time such that groups of electrodes are energized in sequence, such that when electrodes in a group are connected to system potentials, electrodes not in that group are floating. Switch positions can be changed at a rate sufficient to achieve system control objectives. In one example, switch positions can be changed after durations of at most 1 millisecond. In one example, switch positions can be changed after durations of at most 2 milliseconds. In one example, switch positions can be changed after durations of at most 5 milliseconds. In one example, switch positions can be changed after durations of at most 10 milliseconds. In one example, switch positions can be changed after durations of at most 50 milliseconds. In one example, switch positions can be changed after durations of at most 100 milliseconds. In one example, switch positions can be changed after durations of at most 500 milliseconds. In one example, switch positions can be changed after durations of at most 1 second. In one example, switch positions can be changed after durations of at most 2 seconds. In one example, switch positions can be changed after durations of at most 3 seconds. In one example, switch positions can be changed after durations of at most 5 seconds. In one example, switch positions can be changed after durations of at most 10 seconds. In one example, switch positions can be changed after durations of at most 15 seconds. In one example, switch positions can be changed after durations of at most 30 seconds. In one example, switch positions can be changed after durations that are configured to achieve a control objective. In one example, switch positions can be changed after durations that are configured to achieve a clinical objective. One advantage of selecting the a particular maximum duration in which switch positions are changed is that the said duration can be configured to physical dynamics of a parameter under control.
Electrodes 641, 642, 643, or 644 can also be connected and disconnected from the output of the electrosurgical system 625 by means of enabling and disabling power supplies associated with the electrosurgical system 625. For example, an electrode can be connected to only one power supply, and that electrode can be put into an electrically passive “floating” state by disabling its sole dedicated power supply.
The electrosurgical generator 625 can have a measurement system. The measurement system can monitor the state of the three or more electrodes 641, 642, 643, and 644, and can measure time. The measurement system can monitor the electrical output delivered to each electrode, such as the Voltage, Current, or Power delivered to an electrode. The measurement system can measure over time tissue properties related to the electrical output of the generator, such as the tissue resistance and tissue impedance. The measurement system can monitor signals from sensors integrated into any electrode. For example, each electrode can include a temperature sensor. For example, each electrode can include sensors configured to monitor its active zone or its region of influence in the tissue. For example, each electrode can include a temperature sensor in the active zone configured such that the temperature sensor's readings are indicative of the tissue temperature in that active zone's region of influence in the tissue. The measurement system can associate each measurement it collects with a time stamp. The measurement system can compute functions of some measurements to produce other measurements. A measurement can be referred to as a “parameter”. A measurement can be an estimate of a quantity based on other measured values. For example, the measurement system can divide a Voltage measurement V by a Current measurement I, to yield an Impedance measurement Z=V/I. For example, the measurement system can integrate or average functions of measurements over time. For example, the measurement system can measure the average power delivered to a particular electrode over a period of time. The measurement system can also monitor quantities that are not specific to only one electrode. For example, the measurement system can monitor the electrical potential between two electrodes. For example, the measurement system can monitor the total power delivered to a group of electrodes that are connected to system output potentials at the same time. Examples of an electrode-specific measurement, a function of electrode-specific measurements, an electrode-specific parameter, or an estimate of an electrode-specific quantity which an electrosurgical system 625 can control include, but are not limited to, a parameter that is influenced by the application of signal output to an electrode, the Voltage or RMS Voltage applied to an electrode, the Voltage amplitude of an radiofrequency signal applied to an electrode, the Current or RMS Current applied to an electrode, the Current amplitude of a radiofrequency signal applied to an electrode, the Power or average Power applied to an electrode, the energy applied to an electrode, the energy applied to an electrode over a period of time, the ohmic power loss in tissue to which an electrode is delivering energy, the Impedance measured at an electrode, the resistance measured at an electrode, the Impedance magnitude measured at an electrode, the Impedance phase measured at an electrode, the Temperature measured at or near an electrode, the electric field exposure of tissue near an electrode, the current density exposure of tissue near an electrode, the power-density exposure of a tissue near an electrode, and the average exposure of tissue near an electrode to electromagnetic phenomena.
The electrosurgical generator 625 can have alphanumerical displays 691, 692, 693, and 694 that display one or more measured values for each electrode 641, 642, 643, and 644, respectively, where ellipsis 693 represents a non-negative, integral number of displays that correspond respectively to the non-negative, integral number of electrodes represented by ellipsis 643. Each electrode display 691, 692, 693, and 694 can display a timer value. The electrosurgical generator 625 can have graphical displays 681, 682, 683, and 684 that graph over time one or more measured values for each electrode 641, 642, 643, and 644, respectively, where ellipsis 683 represents a non-negative, integral number of displays that correspond respectively to the non-negative, integral number of electrodes represented by ellipsis 643. Said graphical displays can be dynamic plots which are updated regularly to show ongoing changes.
The electrosurgical generator 625 can have a control system. The control system can use measurements from the three or more electrode 641, 642, 643, and 644 to adjust the output delivered to each electrode for the purpose of achieving a control objective for each electrode. In one example, the control objective for each electrode is unique. In another example, the control objective for each electrode is substantially independent of the control objectives associated with other electrodes. In another example, the number of control objectives can exceed the number of electrodes. A control objective can be that of changing the value of a measurement, or a function of a measurement or measurements, from its idle value. A control objective can be that of holding the value of a measurement near a target value, within a target range, within a range of a target value, or within a range of a time-varying target value. A control objective can be configured to achieve, approach, or control a physical effect, such as the aforementioned physical effects in the region of influence of an electrode. A control objective can be the control of an electrode-specific measurement, an electrode-specific parameter, or an estimated electrode-specific quantity. For example, a control objective can be that of holding a temperature measured at an electrode at a set value. In one example, a control objective can be that of holding the temperature measured at an electrode within 0.5° C. of a desired value. In one example, a control objective can be that of holding the temperature measured at an electrode within 1° C. of a desired value. In one example, a control objective can be that of holding the temperature measured at an electrode within 2° C. of a desired value. In one example, a control objective can be that of holding the temperature measured at an electrode within 5° C. of a desired value. In one example, a control objective can be that of holding the temperature measured at an electrode within 10° C. of a desired value. In one example, a control objective can be that of holding the temperature measured at an electrode within 20° C. of a desired value. In one example, a control objective can be that of holding the temperature measured at an electrode within a desired range of temperature values that is configured to achieve a clinical objective such as achieving cell death. One advantage of selecting a small range around a set value is that a more predictable lesion can be formed. One advantage of selecting a larger range around a set value is that a controller is less constrained in achieving its objectives. For example, an electrode-specific control objective can be that of holding the temperature measured at an electrode below a value, such as 42° C., or such as 45° C. For example, a control objective can be that of holding the temperature measured at an electrode above a value, such as 42° C., 45° C., 50° C., 60° C., 70° C., 80° C., 90° C., 95° C., 100° C., or a value configured to achieve a clinical objective. For example, a control objective can be that of delivering an amount of electrical power to an electrode. For example, a control objective can be that of delivering an amount of electrical current to an electrode. For example, a control objective can be that of delivering an amount of electrical voltage to an electrode. For example, a control objective can be that of delivering an average power to an electrode over a time period, such as a time period less than 100 millisecond, a time period less than 1 second, a time period less than 15 seconds, a time period less than 30 seconds, a time period less than 1 minute, a time period dependent on measured values, a time period terminated by a measured rise a measured impedance, a time period terminated by a change in a measured electrical current, the a time period terminated by a measured rise in temperature. For example, a control objective can be that of holding the impedance between a specific electrode and reference structures at, near, or below a set value; an example of said reference structure can be one or more other electrodes. For example, a control objective can be that of preventing a rise in the impedance between an electrode and reference structures, where said impedance rise is indicative of a change in the temperature of tissue near the said electrode. For example, a control objective can be that of preventing a rise in the impedance between an electrode and reference structures, where said impedance rise is indicative of tissue boiling or beginning to boil near said electrode.
In one example, a parameter can be said to be “under control” or “controlled” if it induced to fall within a target range of values. In one example, said target range can vary over time. In another example, said target range can be fixed. In one example, a parameter that has been induced into a target range by delivery of electrical energy by one or more electrodes, can remain in said target range for a period of time after the cession of all energy delivery that substantially affects said parameter. In one example, the temperature of an electrode placed in tissue can stay within a target temperature range a period of time after energy delivered through that electrode has ceased due the thermal dynamics of the said electrode and tissue, even if energy delivered through other electrodes during said period of time does not substantially influence the temperature of the first said electrode. In one example, the power delivered to an electrode in bursts of energy can fluctuate, but still achieve an average power value that falls within a target range over a specified moving-average time window; in this example, the power can be said to be controlled. In one example, the average power delivered to an electrode in bursts of energy can fluctuate, but still fall within a target range over a moving time window; in this example, the power can be said to be under control. In one example, for an electrode whose temperature is elevated into a target range by bursts of electrical energy delivered to said electrode, the said temperature does not fall out of said target range between bursts of energy, if the rate of energy bursts rapid relative to the physical dynamics of said temperature; in this example, said temperature can be said to be controlled. In one example, for the tissue near an electrode whose impedance has a value induced into a target range by bursts of electrical energy delivered to said electrode, the said impedance does not leave that target range between bursts of energy, when the rate of energy bursts rapid relative to the physical dynamics of said temperature; in this example, said impedance can be said to be controlled.
The electrosurgical generator 625 can have control panels 701, 702, 703, and 704 by means of which a human operator can adjust the control objective and output parameters for each electrode 641, 642, 643, and 644, respectively, where ellipsis 703 represents a non-negative, integral number of controls that correspond respectively to a non-negative, integral number of electrodes represented by ellipsis 643. Each control panel can consist of one or more controls. For example, a control can be a lesion time, a set value for a measurement or a function of measurements, a target value for a measurement or function of measurements, a target range for a measurement or function of measurements, or a limit on the output level. A control panel can include a control knob, buttons, elements of graphical user interface, or items displayed on a touch screen. The control panels 701, 702, 703, and 704 can also be configured such that one or more specific control applies to more than one electrode, or to all electrodes. For example, all the controls in a single control panel can apply either to all electrodes, or only to all electrodes selected as active on the control panel. The electrosurgical generator 625 can have alphanumerical displays 691, 692, 693, and 694 which show the control settings for each electrode 641, 642, 643, and 644, respectively, where ellipsis 693 represents a non-negative, integral number of controls that correspond respectively to a non-negative, integral number of electrodes represented by ellipsis 643. The electro surgical generator 625 can have graphical displays 681, 682, 683, and 684 which graph measurements over time relative to control targets for those measurements, for each electrode 641, 642, 643, and 644, respectively, where ellipsis 683 represents a non-negative, integral number of controls that correspond respectively to a non-negative, integral number of electrodes represented by ellipsis 643. In
The control system for an electrosurgical system can employ one or more of a number of types of stopping criteria to determine when to stop delivering generator output to an electrode. For example, the control system can discontinue delivering output to an electrode if a parameter exceeds a maximum value, or if a parameter falls below a minimum value. Examples of said parameters that can be employed for the purpose of a stopping criteria include, but are not limited to, a duration of time for which an electrode is energized, the duration of time elapsed since an electrode was initially connected to a system output signal, the number of bursts of generator output delivered to an electrode, the number of burst of radiofrequency energy applied to an electrode, the time-integral of an electromagnetic quantity applied to an electrode, the time-integrated Voltage applied to an electrode, the time-integrated Current applied to an electrode, the time-integrated Power applied to an electrode, the time-integral of the electric-field applied to tissue near an electrode, the time-integral of the current-density field applied to tissue near an electrode, the time-integral of the power-density field applied to an electrode.
The control system of the electrosurgical generator 625 can operate such that it intermittently determines an output signal, such as an output level, and switch positions which are configured to achieve electrode-specific control objectives associated with each of the three or more electrodes 641, 642, 643, and 644. The system settings or sequence of system settings determined by the control system can be effected by the system power supplies and switching system until the next determination by the control system. The time interval between said determinations by the control system can be referred to as the “control period”, “control update period”, or “control update time”. A said determination of system output and switches by the control system can be referred to as a “control update”. For each electrode, the control system can use the history of a measurement and the current control objective, such as a target value, to determine an output signal or output level for the upcoming control period. An example of an output level is the average power delivered to an electrode over the upcoming control period. Another example of an output level is the voltage amplitude, current amplitude, squared voltage amplitude, squared current amplitude, or average power of a radiofrequency signal delivered to an electrode. An example of a parameter that can be subject to a control objective is the temperature measured by an electrode. Another example of a measurement and a parameter subject to a control objective is the impedance measured at an electrode with respect to reference structures. The control system can produce a control update for each electrode by means of algorithms or methods such as a proportional controller, a proportional-integral (PI) controller, a proportional-integral-derivative (PID) controller, or another control algorithm which should be familiar to one skilled in the art. The control system can implement that control update for each electrode by energizing groups of electrodes in sequence, such that during the “on-time” in which an electrode group is connected to an electrical output signal, the switching system connects system power supplies to electrodes that are included in the current group, and the switching system disconnects from system power supplies all electrodes that are not included in the current group. The controller can assign different electrical potentials to each electrode in a group. The term “duty-cycle period” can refer to the period of time over which the energy is delivered to electrode groups sequentially. A given electrode can be assigned to one or more electrode groups. The controller can restrict the electrode groups to pairs, so that during each pair's on-time the constituent electrodes are connected to system power supply output in a bipolar configuration. The controller can assign one of two electrical potentials to each electrode in a group, for all groups during a control period. The controller can assign electrical potentials to each electrode in a group such that the potential difference between any two electrodes in that group is either zero or a non-zero value, for all groups during a control period. The controller can predict the output level, such as the electrical current, for each electrode in an electrode group while that group is connected to a generator output signal; said predictions can be made using, for example, past measurements, exploratory measurements, and system identification techniques. The timing of cycling among electrode groups and the output signals applied to each electrode in each electrode group can be determined by the control system such that over the duty-cycle period, each electrode is delivered an output signal which is equivalent to that specified by that electrode's control update for the purpose of achieving an electrode-specific control objective for that electrode. For example, for the purpose of controlling an electrode's temperature or impedance, an average output level can be delivered to that electrode over a period time by applying output to that electrode intermittently over the said period of time. The said determination of timing of cycling among groups and the assignment of output signals to electrodes in each group can be made by the controller by solving a system of equations. For three or more treatment electrodes, the controller can assign output signals and an on-time for each group by solving a system of equations. For example, said system of equations can state that, for each electrode, the total exposure to the output signal for that electrode is the sum of products of the output level and the on-time for each electrode group in which that electrode is included. The duration of the duty-cycle period and the duration of the control period can each be determined by the controller as part of each overall control update, or can each be pre-selected as part of the controller's design. The duration and of the duty-cycle period and the duration of the control period can each be configured such that each electrode's electrode-specific control objective can be targeted or achieved even if the specified output level is not delivered to each electrode in a continuous time segment of the said upcoming period of time. The duration and of the duty-cycle period and the duration of the control period can each be configured such that each electrode's electrode-specific control objective can be targeted or achieved even if the output is delivered to electrodes by duty-cycling among electrode groups during the said duty-cycle period.
In one example, the electrosurgical system 625 can individually control the temperature measured by each of three or more electrode electrodes 641, 642, 643, and 644 placed in the human body by energizing electrode groups in sequence such that the generator output delivered to each electrode in the course of switching among electrode groups is configured to control that electrode's measured temperature, without the use of an additional electrode, such as a ground pad. In one example, the electrosurgical system 625 can individually control the tissue impedance in the region of influence of each of three or more electrode electrodes 641, 642, 643, and 644 placed in the human body by energizing electrode groups in sequence such that the generator output delivered to each electrode in the course of switching among electrode groups is configured to control the impedance measured by that electrode, without the use of an additional electrode, such as a ground pad. In one example, the electrosurgical system 625 can individually control the average power delivered to each of three or more electrode electrodes 641, 642, 643, and 644 placed in the human body by energizing electrode groups in sequence such that the generator output delivered to each electrode in the course of switching among electrode groups is configured to control the average power delivered to that electrode, without the use of an additional electrode, such as a ground pad. In one example, the electrosurgical system 625 can achieve an electrode-specific control objective for each of three or more electrode electrodes 641, 642, 643, and 644 placed in the human body by energizing electrode groups in sequence such that the generator output delivered to each electrode in the course of switching among electrode groups is configured to control parameters subject to that electrode-specific control objective, without the use of an additional electrode, such as a ground pad.
It is understood that controls 701, 702, 703, 704 can be used to manually disable one or more of the electrodes 641, 642, 643, 644 plugged into the electrode jacks 671, 672, 673, 674, respectively, while three or more other of the electrodes are connected to electrical signal output. Said disabling of an electrode can be performed by opening the switches which connect that electrode to system power supplies, or by disabling the power supplies that are dedicated to that electrode.
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It is understood that the switching system 605 can be omitted and that each one of the electrodes 600 can be individually energized and de-energized by enabling and disabling power supplies 610. For example, an individual power supply component of 610 can be dedicated to one and only one of the electrodes 600, so that disabling the said power supply component puts its dedicated electrode into an electrically-passive state, and so that enabling the said power supply component and setting its output potential puts sets the output potential for its dedicated electrode.
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Referring now to
It is understood that error-checking steps can be included in any part of the algorithm provided in
In accordance with one example of the present invention, a control update step 1160 is provided. Integer N can refer to a number of treatment electrodes greater than or equal to three, N≧3. Integer i can index said electrodes by taking values i=1, . . . , N. Integer M can refer to a number of electrode groups. Integer j can index said electrodes by taking values j=1, . . . , M. Each electrode group, indexed by j=1, . . . , M, can be represented by mathematical object Cj, for j=1, . . . , M respectively. For a given value of j, Cj is a collection of electrode indices. For example, if an electrode group with index j=3 contains electrodes indexed i=2, i=4, and i=7, this group can be denoted C3, and its contents can be denoted (2,4,7). The contents of the same example electrode group C3 can also be denoted (2,7,4), (4,2,7), (4,7,2), (7,2,4), or (7,4,2). An indicator variable Hij can be defined for all indices i=1, . . . , N and j=1, . . . , M. For a given value of i and j, indicator variable Hij takes value one (1) if the electrode indexed i is contained in the group indexed j, and otherwise takes value zero (0). For example, given the example electrode group C3 containing electrodes indexed i=2, i=4, and i=7, indicator variables take the following values H13=0, H23=1, H33=0, H43=1, H53=0, H63=0, H73=1. For each of the electrodes with respective indices i=1, . . . N, the value Ui can denote an output level which is configured to achieve an control objective for electrode i by means of delivering output of level value Ui to electrode i over the upcoming duty-cycle period of time duration td. Each value Ui can be determined by a control algorithm. For example, each Ui can be determined by an algorithm configured to control of the Temperature Ti measured as electrode i, by means of adjusting the output level delivered to electrode i. In one example, an output level value Ui can be a scalar variable representing an average power output; an average radiofrequency voltage amplitude; an average radiofrequency current amplitude; an average voltage; an average electrical current; an average of a function of a voltage, a current, or both; a radiofrequency voltage amplitude; a radiofrequency current amplitude; a radiofrequency power; the square of the value of a radiofrequency voltage amplitude; a voltage; a current; a power; a parameter of an electrical signal output; or a time-averaged parameter of an electrical signal output. In another example, an output level value Ui can be a vector-value parameterizing a waveform or can be a representation of a waveform over the upcoming duty-cycle period td. For each electrode group, indexed j=1, . . . , M respectively, the value tj can denote the amount of time that electrode group j is energized during the upcoming duty-cycle period. Each value tj can have the property tj≧0. The sum of the on-times t1, . . . , tM over all groups can be restricted to be less than or equal to the duty-cycle period td. An output level variable Vij can be defined for all indices i=1, . . . , N and j=1, . . . , M. For a given value of i and j, the variable Vij can denote an output level which is delivered to electrode i when electrode group j is energized during the upcoming duty-cycle period. Each variable Vij can be scalar-valued or vector-valued, can represent the same types of output levels and waveforms that each Ui can represent. In one example, each Vij and Ui represent the same physical quantity, such as power, for all indices i=1, . . . , N and j=1, . . . , M.
Variables Vij, Hij and tj for all i=1, . . . , N and j=1, . . . , M can be determined by solving a system of equations configured to describe the equivalence of electrode-independent output waveforms parameterized by U1, . . . UN and group-duty-cycled output waveforms parameterized by Vi1, . . . , ViM, t1, . . . tM, Hi1, . . . , HiM over the upcoming time period td, for the purpose of achieving a control objective for each electrode i=1, . . . , N. For example, if a control algorithm employs the time-averaged output level applied to each electrode over the upcoming duty-cycle period for the purpose of achieving an control objective for each electrode, then said equations can equate the time-averaged output level due to the output waveforms parameterized by U1, . . . , UN over the upcoming time period td, to the time-averaged output level due to the output waveforms parameterized by Vi1, . . . , ViM, t1, . . . tM, Hi1, . . . , HiM over the upcoming time period td. The said system of equations can also include equations that describe any mutual constraint on values V1j, . . . , VNj for a each electrode group j, given the assignment of electrodes to groups as indicated by H1j, . . . , HNj. Said mutual constraint can be determined by the electrodes' interaction through the tissue and by the design of the electrode surgical generator. An example of such a mutual constraint include the law of electrical current conservation. Said mutual constraint can be determined by physical relations among the electrodes and the electrosurgical generator applicable when an electrode group j is energized during the upcoming duty-cycle period. A controller can determine said system of equations either by means of known physical relations among the electrodes and the electrosurgical generator, or by means of information about the physical relations among the electrodes and the electrosurgical generator that is collected in the source of energizing said electrodes. For example, said physical relations among the electrodes and the electrosurgical generator can be determined or estimated by means of measurements collected from said electrodes and system identification methods.
Said system of equations can be solved by algebraic or numerical methods. Said system of equations can be solved exactly or approximately. When said system of equations has no solution Vi1, . . . , ViM, t1, . . . tM, Hi1, . . . , HiM the controller can go into an error mode; or, the controller can select values for variables Vi1, . . . , ViM, t1, . . . tM, Hi1, . . . , HiM that produce suboptimal control results that are do not exceed other bounds. For example, the said system of equations can have no solution for which tj≧0 for all j=1, . . . , M. For example, if the control objective for each electrode is to raise its temperature to a set value, Vi1, . . . , ViM, t1, . . . tM, Hi1, . . . , HiM can be selected such that the temperature of some or all electrodes are raised, but not above their set temperature values.
The values determined by the said system of equations Vi1, . . . , ViM, t1, . . . tM, Hi1, . . . , HiM, or other equation in the case where said system has no solution, can be used to determine behavior of the electrosurgical generator in the upcoming duty-cycle loop 1170. The values determined by the above system of equations Vi1, . . . , ViM, t1, . . . tM, Hi1, . . . , HiM can determine which electrodes are assigned to which electrode groups, how long each electrode group is energized, and the output applied to each electrode during the time when each electrode group is energized during the upcoming duty-cycle period.
In one example, the said system of equations can be written as shown below, using functions F1, . . . , FN, f1, . . . , fN, G1, . . . , GM, each of which can be scalar-valued or vector-valued.
F
i(Vi1, . . . ,ViM,t1, . . . tM,Hi1, . . . ,HiM)=fi(Ui,td), for i=1, . . . ,N (1)
G
j(V1j, . . . ,VNj,H1j, . . . ,HNj)=0, for j=1, . . . ,M (2)
The above equations (2) involving G1, . . . , GM, are one example of the form of equations can be configured to describe mutual constraints among the output waveforms applied to electrodes in each electrode group while that electrode group is energized. A controller can determine functions F1, . . . , FN, f1, . . . , fN, G1, . . . , GM either by means of known physical relations among the electrodes and the electrosurgical generator, or by means of information about the physical relations among the electrodes and the electrosurgical generator that is collected in the source of energizing said electrodes. Given values for F1, . . . , FN, f1, . . . , fN, G1, . . . , GM, U1, . . . , UN, and td, above example of a system of equations can be solved for Vi1, . . . , ViM, t1, . . . tM, Hi1, . . . , HiM.
In one example of an electrosurgical system in accordance with the present invention, all electrode groups restricted to contains two and only two electrodes. A control update step 1160 can operate in accordance with bipolar restriction. Such an electrode group can be referred to as an “electrode pair group”, a “pair group”, an “electrode pair”, or a “pair”. One advantage of the said restriction is that two electrodes are energized in a bipolar manner, with all other electrodes floating. Another advantage of the said restriction is that when an electrode pair group is energized, each electrode can serve as the path for return currents for the other electrode. Another advantage of the said restriction is that when an electrode pair group is energized, each electrode can serve as reference electrode for the other electrode. Another advantage the said restriction is that the same relative electrical voltage can be applied to both electrodes of a group when that group is energized. Another advantage of the said restriction is that the same electrical current flows through both electrodes of a group when that group is energized. Another advantage of the said restriction is that the same electrical power loss can be ascribed to both electrodes of a group when that group is energized. For example, with the said bipolar restriction, if the total number of electrodes is N=3, there are three possible electrode groups (1,2), (2,3), and (3,1). For example, with the said bipolar restriction, if the total number of electrodes is N=4, there are six possible electrode groups (1,2), (2,3), (3,4), (4,1), (1,3), (2,4). For example, with the said bipolar restriction, if the total number of electrodes is an integer greater than or equal to three N≧3, the number of possible electrode groups is (N*(N−1)/2). With the said bipolar restriction, a control update step 1160 can use the same variable Vj can parameterize the output for both electrodes in the electrode group with index j. With the said bipolar restriction, if Hij=1, then the restriction Vij=Vj can be applied; this can be considered a specialization of equation (2). For example, a possibly time-varying electrical potential difference between the two electrodes in each electrode group j=1, . . . , M can be regulated to establish the output level Vj.
In a more specific example of the said bipolar restriction, the controller can be configured to determine a time-average output level Ui to achieve a control-objective for each electrode i. In this more specific example of the bipolar restriction with a time-average controller output, the output level for each electrode pair group j=1, . . . , M can be determined by a parameter Vj for the time-average output level when that group j is energized, with all non-group electrodes floating. In this more specific example, for the upcoming duty-cycle period, the controller can determine electrode pair assignments Hij for i=1, . . . , N and j=1, . . . , M, electrode pair output parameters Vj for j=1, . . . , M, and electrode pair on-times tj by equating, for each electrode i, the time-average output level Ui over duty-cycle period td is equated to the time-average output level delivered to electrode i by duty-cycling using the parameters Hi1, . . . , HiM, V1, . . . , VM, t1, . . . , tM. The said equating can be performed by the following equations (3).
V
1
×t
1
×H
i1
+ . . . +V
M
×t
M
×H
iM
=U
i
×t
d, for i=1, . . . ,N (3)
In another example of an electrosurgical system in accordance with the present invention, a control update step 1160 can use a single variable V to parameterize the output assigned to each electrode group. With this single-output-level restriction, if Hij=1, then the restriction Vij=V can be applied for i=1, . . . , N and j=1, . . . , M. An advantage of the single-output-level restriction is that the electrosurgical system can contain only one power supply.
In another example of an electrosurgical system in accordance with the present invention, the said bipolar restriction, the said time-average controller output, and the said single-output-level restriction can all be applied the same system at the same time. A control update step 1160 can operate in accordance with all these specializations. An advantage of a system with all these specializations is that the system can have some or all the advantages of each of these specializations. In a system with all of the said specializations, for the upcoming duty-cycle period, the controller can determine electrode pair assignments Hij for i=1, . . . , N and j=1, . . . , M, the output parameter V, and electrode pair on-times tj by equating, for each electrode i, the time-average output level Ui over duty-cycle period td is equated to the time-average output level delivered to electrode i by duty-cycling using the parameters Hi1, . . . , HiM, V, t1, . . . , tM. The said equating can be performed by the following equations (4).
V×(t1×Hi1+ . . . +tM×HiM)=Ui×td, for i=1, . . . ,N (4)
An advantage of the N equations (4) is that, given an output level V and group assignments Hi1 for i=1, . . . , N and j=1, . . . , M, the equations are linear in the group on-times t1, . . . , tM. An advantage of equations (4) is that if the number of distinct groups M is greater than or equal to the number of electrodes N, the equations (4) can have a valid solution. An output level V and group assignments Hij for i=1, . . . , N and j=1, . . . , M can be selected by a control algorithm on the basis that equations (4) have a valid solution for the on-times t1, . . . , tM such that t1≧0, . . . , and tM≧0.
In a more specific example of equations (4), the number of electrodes is N=3 and equations (4) can be written as equations (5). For this example, group 1 contains electrodes 1 and 3; group 2 contains electrodes 1 and 2; and group 3 contains electrodes 2 and 3; however, it is understood that the ordering of the electrode and group indices can change without affecting the essential form of the control update step.
V×(t1+t2)=U1×td
V×(t2+t3)=U2×td
V×(t3+t1)=U3×td (5)
In a more specific example of equations (4), the number of electrodes is N=4 and equations (4) can be written as equations (6). For this example, without loss of generality, group 1 contains electrodes 1 and 2; group 2 contains electrodes 2 and 3; group 3 contains electrodes 3 and 4; group 4 contains electrodes 4 and 1; group 5 contains electrodes 2 and 4; and group 6 contains electrodes 3 and 1; however, it is understood that the ordering of the electrode and group indices can change without affecting the essential form of the control update step. Equation (6) can have more than one solution for a given value of V.
V×(t1+t4+t6)=U1×td
V×(t1+t2+t5)=U2×td
V×(t3+t2+t6)=U3×td
V×(t3+t4+t5)=U4×td (6)
In another example of an electrosurgical system in accordance with the present invention, each electrode group is restricted such all electrodes in the group but one are set to a reference potential, and an output waveform is delivered to the said remaining one electrode in the group. A control update step 1160 can operate in accordance with this single-non-reference-electrode-per-group restriction. For example, each electrode group can contain all electrodes of which exactly one electrode is at connected to a non-reference potential while that group is energized, and all other electrodes are connected to the same reference potential while that group is energized. For example, the reference potential can either be a constant voltage or a time-varying voltage. For example, the non-reference potential applied to only one electrode in each group can either be a constant voltage or a time-varying voltage. The number of electrode groups can be equal to the total number of electrodes. Each electrode can assigned as the non-reference electrode in at least one electrode group. A controller can be configured to omit an electrode group from a duty-cycle period for the purpose of achieving an electrode-specific control objective on the non-reference electrode in that group. For an electrode group with a given non-reference electrode, a controller can include other electrode in that group so that the amount of electrical current flowing through each non-reference electrode in that group is at a level low enough that it does not substantially affect the parameter which is the subject of the electrode-specific control objective of each non-reference electrode. An advantage of the said single-non-reference-electrode-per-group restriction is that while a group is energized, the return current from the one non-reference electrode is divided among all other electrodes in that group. An advantage of the said single-non-reference-electrode-per-group restriction is that while an electrode group is energized, it can be that only the non-reference electrode carries enough electrical current to substantially affect the electrode-specific parameter which is the subject of its control objective.
In a system with the said single-non-reference-electrode-per-group restriction, a control update step 1160 can have a single variable Vj which parameterizes the output level of the one non-reference electrode in each group j=1, . . . , M, and indicator variables Aij can be assigned value one (1) when electrode i is the one non-reference electrode in group j, and Aij can be assigned value zero (0) otherwise. The the upcoming duty-cycle the controller can determine electrode group assignments Hij for i=1, . . . , N and j=1, . . . , M, the output parameters Vj, and electrode pair on-times tj by equating, for each electrode i, the time-average output level Ui over duty-cycle period td is equated to the time-average output level delivered to electrode i by duty-cycling using the parameters Hi1, . . . , HiM, Ai1, . . . , AM, V1, . . . , VM, t1, . . . , tM. The said equating can be performed by the following equations (7).
V
1
×t
1
×A
i1
+ . . . +V
M
×t
M
×A
iM
=U
i
×t
d, for i=1, . . . ,N (7)
In one example of a control update step 1160 with the said single-non-reference-electrode-per-group restriction, each electrode is assigned to exactly one group, so that the number of electrodes N is equal to the number of groups M. In this case, equations (7) can be written as equations (8).
V
i
×t
i
=U
i
×t
d, for i=1, . . . ,N (8)
In another example of a control update step 1160 with the said single-non-reference-electrode-per-group restriction, each electrode is assigned to exactly one group, so that the number of electrodes N is equal to the number of groups M, and a single variable V parameterizes the output level of the one non-reference electrode for all electrode groups; that is Vj=V for all j=1, . . . , M. In this example, equations (7) can be written as equations (9):
V×t
i
=U
i
×t
d, for i=1, . . . ,N (9)
In another example of an electrosurgical system in accordance with the present invention, zero or more electrode groups can be configured in accordance with the said bipolar restriction, zero or more other electrode groups can be configured with the said unique-electrode restriction, and zero or more other electrode groups can be unrestricted. Such an example system can also be configured in accordance with the said single-output-level restriction. Combining some or all of said restrictions into a single controller can have the advantage of expanding the conditions under which the controller can achieve electrode-specific control objectives on all electrodes.
Referring now to
In another example, the number of control objectives P can be greater than the number of electrodes N. In this example, integer k can index said control objective parameters Uk and take values k=1, . . . , P. The control objectives are parameterized by U1, . . . , UP. In this example, Equations (10) and (11) are analogous to equations (1) and (2). In equations (10), the functions Fk for k=1, . . . , P can model a physical relationship between each of the said N electrodes, indexed and the control objectives Uk for k=1, . . . , P. Said functions Fk for k=1, . . . , P can be determined by system identification methods. In equations (10), V denotes the combination of all values Vij for i=1, . . . , N and j=1, . . . , M, and H denotes the combination of all values Hij for i=1, . . . , N and j=1, . . . , M. In one example, equations (10) and (11) can have a solution if P≧M.
F
k(V,t1, . . . tM,H)=fk(Uk,td), for k=1, . . . ,P (10)
G
j(V1j, . . . ,VNj,H1j, . . . ,HNj)=0, for j=1, . . . ,M (11)
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The controller 3015 is connected to the power supply 3000, switches 3005, measurement system 3010. The controller can coordinate the actions of the power supply 3000, switches 3005, measurement system 3010. For example, the controller can implement feedback control of the power supply 3000 and switches 3005 based on measurements T1, T2, T3 from the measurement system 3015.
Power supply 3000 consists of voltage supplies Vs0, Vs1, Vs2, Vs3, referenced to a common reference potential 3002. The controller 3015 can control each of the voltage supplies independently. In one example, each voltage supply can produce a different output signal. In one example, the voltage supplies Vs0, Vs1, Vs2, Vs3 can produce radiofrequency signals. In one example, a two-pole system can be produced by setting voltage supplies Vs0, Vs1, Vs2, Vs3 such that each supply produces one of two output signals. For example, in one specific example of a two-pole system, a sequence of power supply settings can include a step in which Vs0=Vs3=V+ and Vs1=Vs2=V−, and another step in which Vs1=Vs3=V+ and Vs0=Vs2=V−, such that V+ and V− can be set individually by the controller. In one example, a three-pole system can be produced by setting voltage supplies Vs0, Vs1, Vs2, Vs3 such that each supply produces one of three output signals. For example, in one specific example of a three-pole system, a sequence of power supply settings can include a step in which Vs0=V+, Vs1=V−, and Vs2=Vs3=V*; and a step in which Vs1=V+, Vs2=V−, and Vs3=Vs0=V*; where V+, V−, and V* can be set individually by the controller. In one example, a four-pole system can be produced by independently assigning output signals to each of Vs0, Vs1, Vs2, Vs3.
It is understood that, in one example, the number of electrodes can be any number N that is at least two when a reference ground pad GP is used. In this case, the electrodes E1, . . . , EN, where N≧2, can be respectively associated with measurement elements, switches and voltage supplies is a manner that is analogous to that shown from electrodes E1, E2, E3; measurement elements T1, T2, T3; switches S1, S2, S3; voltage supplies Vs1, Vs2, Vs3, as shown in
Referring now to
In the first step of the sequence, during time period ta1, the ground pad GP is not connected to any output pole, electrode E1 is connected to output pole +, and electrode E2 is connected to output pole −. In the next step, during time period ta2, the ground pad GP is connected to output pole −, electrode E1 is connected to output pole +, and electrode E2 is not connected to any output pole. In the next step, during time period ta3, the ground pad GP is connected to output pole −, electrode E1 is not connected to any output pole, and electrode E2 is connected to output pole +. In the next step, during time period ta4, the ground pad GP is connected to output pole −, electrode E1 is connected to output pole +, and electrode E2 is connected to output pole −. In the next step, during time period ta5, the ground pad GP is not connected to any output pole, electrode E1 is connected to output pole +, and electrode E2 is connected to output pole −. This configuration of connections is a repetition of the configuration of the first step ta1. In the next step, during time period ta6, the ground pad GP is connected to output pole +, electrode E1 is connected to output pole −, and electrode E2 is connected to output pole −. In the next step, during time period ta7, the ground pad GP is connected to output pole +, electrode E1 is connected to output pole −, and electrode E2 is not connected to any output pole. In the next step, during time period ta8, the ground pad GP is connected to output pole +, electrode E1 is connected to output pole +, and electrode E2 is connected to output pole −. In the next step, during time period ta9, the ground pad GP is connected to output pole +, electrode E1 is connected to output pole −, and electrode E2 is connected to output pole −. This configuration of connections is a repetition of the configuration in time period ta6.
One advantage of the sequence presented in
In one example of the system presented in
In another example, the sequence shown in
The example shown in
Referring now to
In the first step of the sequence, during time period tb1, electrode E1 is not connected to any output pole, electrode E2 is connected to output pole +, and electrode E3 is connected to output pole −. In the next step, during time period tb2, electrode E1 is connected to output pole +, electrode E2 is not connected to any output pole, and electrode E3 is connected to output pole −. In the next step, during time period tb3, electrode E1 is connected to output pole +, electrode E2 is connected to output pole −, and electrode E3 is not connected to any output pole. In the next step, during time period tb4, electrode E1 is connected to output pole −, electrode E2 is connected to output pole −, and electrode E3 is connected to output pole +. In the next step, during time period tb5, electrode E1 is connected to output pole −, electrode E2 is connected to output pole +, and electrode E3 is connected to output pole −. In the next step, during time period tb6, electrode E1 is connected to output pole +, electrode E2 is not connected to any output pole, and electrode E3 is connected to output pole −. In the next step, during time period tb7, electrode E1 is connected to output pole +, electrode E2 is connected to output pole −, and electrode E3 is not connected to any output pole. This is is the same connection configuration as that in time period tb3. In the next step, during time period tb8, electrode E1 is connected to output pole +, electrode E2 is connected to output pole +, and electrode E3 is connected to output pole −. In the next step, during time period tb9, electrode E1 is connected to output pole +, electrode E2 is connected to output pole −, and electrode E3 is connected to output pole −. In the next step, during time period tb10, electrode E1 is not connected to any output pole, electrode E2 is connected to output pole −, and electrode E3 is connected to output pole +.
One advantage of the sequence presented in
In one example of the system presented in
In another example, the sequence shown in
The example shown in
Referring now to
In the first step of the sequence, during time period tc1, electrode E1 is connected to output pole *, electrode E2 is connected to output pole +, and electrode E3 is connected to output pole −. In the next step, during time period tc2, electrode E1 is connected to output pole −, electrode E2 is connected to output pole *, and electrode E3 is not connected to any output pole. In the next step, during time period tc3, electrode E1 is connected to output pole −, electrode E2 is not connected to any output pole, and electrode E3 is connected to output pole +. In the next step, during time period tc4, electrode E1 is connected to output pole −, electrode E2 is connected to output pole *, and electrode E3 is connected to output pole −. In the next step, during time period tc5, electrode E1 is not connected to any output pole, electrode E2 is connected to output pole +, and electrode E3 is connected to output pole *. In the next step, during time period tc6, electrode E1 is connected to output pole +, electrode E2 is not connected to any output pole, and electrode E3 is connected to output pole *. In the next step, during time period tc7, electrode E1 is connected to output pole +, electrode E2 is connected to output pole −, and electrode E3 is not connected to any output pole. In the next step, during time period tc8, electrode E1 is connected to output pole +, electrode E2 is connected to output pole *, and electrode E3 is connected to output pole −. In the next step, during time period tc9, electrode E1 is connected to output pole +, electrode E2 is connected to output pole *, and electrode E3 is connected to output pole *.
One advantage of the sequence presented in
In one example of the system presented in
In another example, the sequence shown in
The example shown in
Referring now to
Before the first step of the sequence, before time period td1, the measurements T1 and T2 are at their initial values. In the first step of the sequence, during time period td1, the ground pad GP is not connected to any output pole, electrode E1 is connected to output pole +, and electrode E2 is connected to output pole −. The output signal level Vd is increased to provide electrical energy configured to increase the measurements T1 and T2 toward their respective target ranges. Then, the output signal level Vd is decreased to prevent measurement T2 from exceeding the upper limit of its target range. During time period td1, the measurement T2 increases and achieves values within its target range, whereas the measurement T1 increases toward its target range, but T1 still remains outside its target range. In the next step, during time period td2, the ground pad GP is connected to output pole −, electrode E1 is connected to output pole +, electrode E2 is not connected to any output pole, and the output level Vd is decreased. This step is configured to deliver electrical energy to electrode E1 for the purpose of increasing the measurement T1 to within its target range, while limiting energy delivery to electrode E2 that might cause measurement T2 to rise above the upper bound of its target range. During time period td2, the measurement T2 decreases slightly but stays within its target range; and the measurement T1 increases to within its target range. In the next step, during time period td3, the ground pad GP is not connected to any output pole, electrode E1 is connected to output pole +, and electrode E2 is connected to output pole −. The output signal level Vd is decreased slightly to maintain measurements T1 and T2 within their respective target ranges. An advantage of this step is that electrical current is directed in the space between electrodes E1 and E2, rather than in the direction of the ground pad GP. In the next step, during time period td4, the ground pad GP is not connected to any output pole, electrode E1 is connected to output pole +, and electrode E2 is connected to output pole −. This repeats the connections of time period td3. The output signal level Vd is increased slightly to moderate a decline in the measurement T1, while still maintaining measurements T1 and T2 within their respective target ranges. During time period td4, measurement T2 approaches the upper bound of its target range, and measurement T1 approaches the lower bound of its target range. In the next step, during time period td5, the ground pad GP is connected to output pole −, electrode E1 is connected to output pole +, electrode E2 is not connected to any output pole, and the output level Vd is maintained at a constant value. The connections and output level Vd in this step are configured to increase the value of T1 away from the lower bound of its target range and toward the center of its target range. The connections in this step are also configured to reduce the value of T2 away from the upper bound of its target range and toward the center of its target range. Near the end of time period td5 and the beginning of time period td6, the target range for measurement T2 is shifted to subsume higher values, as indicated by the dotted lines 3102 and 3112. At the beginning of time period td6, the measurement T1 is within its target range, and measurement T2 is below its target range. In the next step, during time period td6, the ground pad GP is connected to output pole −, electrode E2 is connected to output pole +, electrode E1 is not connected to any output pole, and the output level Vd is increased to apply more energy to electrode E1 and to increase measurement T1 toward its target range. By the beginning of time period td7, the measurement T1 is approaching the lower bound of its target range, and measurement T2 remains below the lower bound of its target range. In the next step, during time period td7, the ground pad GP is not connected to any output pole, electrode E1 is connected to output pole −, electrode E2 is not connected to output pole +, and the output level Vd is decreased to moderate delivery of energy to electrodes E1 and E2, and thus, to hold measurement T1 within its target range, and to increase measurement T2 to within its target range. By the end of time period td7, the measurement T1 is approaching the upper bound of its target range. In the next step, during time period td8, the ground pad GP is connected to output pole −, electrode E2 is connected to output pole +, electrode E1 is not connected to any output pole, and the output level Vd is held constant to hold measurement T2 within its target range. Since electrode E1 is disconnected from all output poles, measurement T1 toward the lower bound of its target range. In the next step, during time period td9, the ground pad GP is not connected to any output pole, electrode E1 is connected to output pole −, electrode E2 is connected to output pole +, and the output level Vd is held constant to hold measurements T1 and T2 within their respective target ranges.
One advantage of the sequence presented in
In one example of the system presented in
In another example, the duration of each step in the sequence can be variable. In another example, the duration of each step in the sequence can be adjusted for the purpose of bringing measurements to within their respective target ranges. In another example, the duration of each step in the sequence can be adjusted for the purpose of controlling the average electrical output to an electrode over a time window greater than one step in the sequence. In another example, the duration of each step in the sequence can be adjusted for the purpose of controlling the average electrical output to a group of electrodes over a time window greater than one step in the sequence. In another example, the duration of each step in the sequence can be different for each step. In another example, the duration of each step in the sequence can have the same value as the duration of all other steps in the sequence.
In another example, the sequence shown in
The example shown in
In another example, the number of electrodes E1, . . . , EN and the number of measurements T1, . . . , TN are both a number N that is at least two, and the sequence contains at least one step in which the ground pad GP is disconnected from all electrical output poles and at least two electrodes are connected to opposite electrical output poles. For example, the number of electrodes and number of measurements can both be N=3. For example, the number of electrodes and number of measurements can both be N=4. For example, the number of electrodes and number of measurements can both be N=5. For example, the number of electrodes and number of measurements can both be N=6. For example, the number of electrodes and number of measurements can both be a number greater than six.
In another example, the number of electrical output poles can be a number that is at least two. For example, the number of electrical output poles can be three. For example, the number of electrical output poles can be four. For example, the number of electrical output poles can be five. For example, the number of electrical output poles can be six. For example, the number of electrical output poles can be greater than six. For example, the number of electrical output poles can be equal to the number of electrodes. It is understood that for examples where the number of output poles is greater than two, there can be more than output electrical output signal parameter Vd.
In another example, the electrical output signal parameter Vd can have a fixed value throughout all steps of the sequence. In another example, the electrical output signal parameter Vd can be varied during the sequence. In another example, the electrical output signal parameter Vd can be a voltage. In another example, the electrical output signal parameter Vd can be a current. In another example, the electrical output signal parameter Vd can be a power. In another example, the electrical output signal parameter Vd can be the amplitude of a radiofrequency signal.
It is understood that some measurements increase with the application of electrical energy, and that other measurements decrease with the application of electrical energy. It is understood that some measurements, such as an impedance, have a non-linear relationship between the applied energy and the direction of change. It is understood that a measurement that decreases with the application of energy can be converted into a measurement that increase with the application of energy by inverting the sign of the first said measurement. It is understood that a measurement that has a non-linear or time-varying relationship to the application energy can be converted into a measurement that increase with the application of energy by applying a properly configured mathematical function to the first said measurement.
In one example, the measurements T1 and T2 include a temperature. In another example, the measurements T1 and T2 are the temperatures of the electrodes E1 and E2, respectively. In another example, the measurements T1 and T2 are associated with electrodes E1 and E2, respectively. In another example, the measurements T1 and T2 include a measurement from a remote temperature probe. In another example, the measurements T1 and T2 include an impedance. In another example, the measurements T1 and T2 are a function of impedances associated with electrodes E1 and E2, respectively. In another example, the measurement T1 is the impedance between the electrode E1 and the ground pad GP. In another example, the measurement T2 is the impedance between the electrode E2 and the ground pad GP. In another example, the measurements T1 and T2 include a function of an electrical parameter over a duration of time that includes at least two steps of the sequence. In another example, the measurements T1 and T2 include a function of an electrical parameter over a duration of time that is configured to match the rate of a physical process within the tissue into which electrodes E1 and/or E2 are situated. For example, the time duration can be 100 milliseconds. For example, the time duration can be 200 milliseconds. For example, the time duration can be 300 milliseconds. For example, the time duration can be 500 milliseconds. For example, the time duration can be 1000 milliseconds. For example, the time duration can be a value less than 100 millisecond. For example, the time duration can be a value greater than 1000 milliseconds. In another example, the measurements T1 and T2 include the time-average of an electrical parameter over at least two steps of the sequence. In another example, the measurements T1 and T2 include the time-average of a power over at least two steps of the sequence. In another example, the measurements T1 and T2 include the time-average of a current over at least two steps of the sequence. In another example, the measurements T1 and T2 include the time-average of a voltage over at least two steps of the sequence. In another example, the measurement T1 is a function of the electrical output delivered to electrode E1 over a time period that includes at least two steps in the sequence. In another example, the measurement T1 is the average power delivered to electrode 1 over a number of steps in the sequence, where that number is at least two. In another example, the measurement T1 is the average current delivered to electrode 1 over a number of steps in the sequence, where that number is at least two. In another example, the measurement T1 is the average voltage delivered to electrode 1 over a number of steps in the sequence, where that number is at least two. In another example, the measurement T1 is the average power delivered to electrode 1 over one period of a periodic sequence of steps, where each period includes at least two steps. In another example, the measurement T2 is a function of the electrical output delivered to electrode E2 over a time period that includes at least two steps in the sequence. In another example, the measurement T2 is the average power delivered to electrode 2 over a number of steps in the sequence, where that number is at least two. In another example, the measurement T2 is the average current delivered to electrode 2 over a number of steps in the sequence, where that number is at least two. In another example, the measurement T2 is the average voltage delivered to electrode 2 over a number of steps in the sequence, where that number is at least two. In another example, the measurement T2 is the average power delivered to electrode 2 over one period of a periodic sequence of steps, where each period includes at least two steps.
In another example, the upper and lower bounds of target ranges for each measurement, i.e. 3101 and 3111 for measurement T1, and 3102 and 3112 for measurement T2, can vary arbitrarily over the course of the sequence. For example, either the upper and lower bounds of the target range for a measurement can both move upward or both move downward at any time during a sequence. For example, the upper and lower bound of the target range for a measurement can change independently of the other bound. For example, the target range can become more narrow or become wider during a sequence.
Referring now to
Before the first step of the sequence, before time period te1, the measurements T1, T2, and T3 are at their initial values. In the first step of the sequence, during time period te1, electrode E1 is not connected to any output pole, electrode E2 is connected to output pole +, and electrode E3 is connected to output pole −. At first, the output signal level Ve is increased to provide electrical energy to electrodes E2 and E3 for the purpose of increasing the measurements T2 and T3 toward their respective target ranges. Then, the output signal level Ve is held at a constant value to prevent measurement T3 from exceeding the upper limit of its target range. During time period te1, the measurement T3 increases and achieves values within its target range, whereas the measurement T2 increases toward its target range, but T2 still remains below its target range. In the next step of the sequence, during time period te2, electrode E1 is connected to output pole −, electrode E2 is connected to output pole +, electrode E3 is not connected to any output pole, so that energy is applied to electrode E1 and E2 for the purpose of bringing measurements T1 and T2 to values within their respective target ranges. Over the time period te2, T1 increases to a value within its target range, T2 increases above the center of its target range, and T3 falls below the center of its target range. The output level Ve is decreased slightly over duration te2 to maintain measurements T1 and T2 near the center of their respective target ranges. In the next step of the sequence, during time period te3, electrode E1 is not connected to any output pole, electrode E2 is connected to output pole +, electrode E3 is connected to output pole −. The output level Ve is decreased to moderate the power delivered to electrodes E2 since measurement T2 is above the center of its target range. During time period te3, measurements T2 and T3 remain in their target ranges, and T1 declines toward the lower bound of its target range since no substantial energy is being delivered to E1. In the next step of the sequence, during time period te4, electrode E1 is connected to output pole +, electrode E2 is not connected to any output pole, electrode E3 is connected to output pole −, and the output level Ve is increased slightly to apply energy to electrodes E1 and E3. During time period te4, the measurement T1 is roughly level, the measurement T2 declines, and the measurement T3 increases toward the upper bound of its target range. In the next step of the sequence, during time period te5, electrode E1 is connected to output pole −, electrode E2 is connected to output pole +, electrode E3 is not connected to any output pole, and the output level Ve is substantially constant to apply a constant rate of energy to electrodes E1 and E2. During time period te5, measurement T1 increases toward the center of its target range, measurement T2 decreases, and measurement T3 decreases. Near the end of time period te5, the target ranges for T2 and T3 both increase to cover a higher range of measurement values. At the beginning of time period te6, the measurements T2 and T3 are below their target ranges. In the next step of the sequence, during time period te6, electrode E1 is not connected to any output pole, electrode E2 is connected to output pole +, electrode E3 is connected to output pole −, and the output level Ve is increased and then decreased to raise the measurements T2 and T3 to within their respective target ranges, while reducing the degree to which T2 and T3 overshoot the central values of their respective target ranges. During time period te6, the measurement T1 declines since energy is not being delivered to electrode E1. In the next step of the sequence, during time period te7, electrode E1 is connected to output pole +, electrode E2 is not connected to any output pole, electrode E3 is connected to output pole − to apply energy to electrodes E1 and E3. Over time period te7, the measurement T1 increases above the central region of its target range, so the output level Ve is decreased slightly to reduce the degree to which T1 overshoots said central region. This reduction in output level causes T3 to decline below the central region of its target range. Since electrical energy is not applied to electrode E2, measurement T2 declines below the central region of its target range. To counteract the decline in measurement T2 and T3, the next step of the control sequence is initiated. In the next step of the sequence, during time period te8, electrode E1 is not connected to any output pole, electrode E2 is connected to output pole +, electrode E3 is connected to output pole − to deliver energy to electrodes E2 and E3 and, thus, to counteract the decline in measurement T2 and T3. The output level Ve is increased to increase the energy delivered to electrode E2 as compared with the last step of the sequence. During time period te8, the measurements T2 and T3 are held at substantially constant values within their target ranges, and T1 decreases within its target range. In the next step of the sequence, during time period te9, electrode E1 is connected to output pole +, electrode E2 is connected to output pole −, electrode E3 is not connected to any output pole, and the output level Ve is substantially constant to apply a constant rate of energy to electrodes E1 and E2. During time period te9, the measurement T1 increases toward the upper bound of its target range, the measurement T2 has a roughly constant value within its target range, and the measurement T3 has a roughly constant value within its target range.
One advantage of the sequence presented in
In one example of the system presented in
In another example, the duration of each step in the sequence can be variable. In another example, the duration of each step in the sequence can be adjusted for the purpose of bringing measurements to within their respective target ranges. In another example, the duration of each step in the sequence can be adjusted for the purpose of controlling the average electrical output to an electrode over a time window greater than one step in the sequence. In another example, the duration of each step in the sequence can be adjusted for the purpose of controlling the average electrical output to a group of electrodes over a time window greater than one step in the sequence. In another example, the duration of each step in the sequence can be different for each step. In another example, the duration of each step in the sequence can have the same value as the duration of all other steps in the sequence.
In another example, the sequence shown in
The example shown in
In another example, the number of electrodes E1, . . . , EN and the number of measurements T1, . . . , TN are both a number N that is at least N=3. For example, the number of electrodes and number of measurements can both be N=3. For example, the number of electrodes and number of measurements can both be N=4. For example, the number of electrodes and number of measurements can both be N=5. For example, the number of electrodes and number of measurements can both be N=6. For example, the number of electrodes and number of measurements can both be a number greater than six.
In another example, the number of electrical output poles can be a number that is at least two. For example, the number of electrical output poles can be three. For example, the number of electrical output poles can be four. For example, the number of electrical output poles can be five. For example, the number of electrical output poles can be six. For example, the number of electrical output poles can be greater than six. For example, the number of electrical output poles can be equal to the number of electrodes. It is understood that for examples where the number of output poles is greater than two, there can be more than output electrical output signal parameter Ve.
In another example, the electrical output signal parameter Ve can have a fixed value throughout all steps of the sequence. In another example, the electrical output signal parameter Ve can be varied during the sequence. In another example, the electrical output signal parameter Ve can be a voltage. In another example, the electrical output signal parameter Ve can be a current. In another example, the electrical output signal parameter Ve can be a power. In another example, the electrical output signal parameter Ve can be the amplitude of a radiofrequency signal.
It is understood that some measurements increase with the application of electrical energy, and that other measurements decrease with the application of electrical energy. It is understood that some measurements, such as an impedance, have a non-linear relationship between the applied energy and the direction of change. It is understood that a measurement that decreases with the application of energy can be converted into a measurement that increase with the application of energy by inverting the sign of the first said measurement. It is understood that a measurement that has a non-linear or time-varying relationship to the application energy can be converted into a measurement that increase with the application of energy by applying a properly configured mathematical function to the first said measurement.
In one example, the measurements T1, T2, and T3 include a temperature. In another example, the measurements T1, T2, and T3 are the temperatures of the electrodes E1, E2, and E3, respectively. In another example, the measurements T1, T2, and T3 are associated with electrodes E1, E2, and E3, respectively. In another example, the measurements T1, T2, and T3 include a measurement from a remote temperature probe. In another example, the measurements T1, T2, and T3 include an impedance. In another example, the measurements T1, T2, and T3 are a function of impedances associated with electrodes E1, E2, and E3, respectively. In another example, the measurement T1 is the impedance to current flow from electrode E1 to both electrodes E2 and E3. In another example, the measurement T2 is the impedance to current flow from electrode E2 to both electrodes E1 and E3. In another example, the measurement T3 is the impedance to current flow from electrode E3 to both electrodes E2 and E1. In another example, the measurement T1 is the impedance measured when electrode E1 is connected to one output pole and all other electrodes are connected to a different output pole. In another example, the measurement T2 is the impedance measured when electrode E2 is connected to one output pole and all other electrodes are connected to a different output pole. In another example, the measurement T3 is the impedance measured when electrode E3 is connected to one output pole and all other electrodes are connected to a different output pole. In another example, the measurements T1, T2, and T3 include a function of an electrical parameter over a duration of time that includes at least two steps of the sequence. In another example, the measurements T1, T2, and T3 include a function of an electrical parameter over a duration of time that is configured to match the rate of a physical process within the tissue into which electrodes E1, E2, and/or E3 are situated. For example, the time duration can be 100 milliseconds. For example, the time duration can be 200 milliseconds. For example, the time duration can be 300 milliseconds. For example, the time duration can be 500 milliseconds. For example, the time duration can be 1000 milliseconds. For example, the time duration can be a value less than 100 millisecond. For example, the time duration can be a value greater than 1000 milliseconds. In another example, the measurements T1, T2, and T3 include the time-average of a parameter that characterizes the electrical signal applied to output poles over a duration of time that is greater than the duration of one step in the sequence. In another example, the measurements T1, T2, and T3 include the time-average of the power delivered to one or more electrodes over at least two steps of the sequence. In another example, the measurements T1, T2, and T3 include the time-average of the current delivered to one or more electrodes over at least two steps of the sequence. In another example, the measurements T1, T2, and T3 include the RMS current delivered to one or more electrodes over at least two steps of the sequence. In another example, the measurements T1, T2, and T3 include the time-average of the voltage applied to an electrode over at least two steps of the sequence. In another example, the measurements T1, T2, and T3 include the RMS voltage delivered to one or more electrodes over at least two steps of the sequence.
In another example, the upper and lower bounds of target ranges for each measurement (i.e. 3321 and 3331 for measurement T1, 3322 and 3332 for measurement T2, and 3323 and 3333 for measurement T3) can vary arbitrarily over the course of the sequence. For example, either the upper and lower bounds of the target range for a measurement can both move upward or both move downward at any time during a sequence. For example, the upper and lower bound of the target range for a measurement can change independently of the other bound. For example, the target range can become more narrow or become wider during a sequence.
Referring now to
Measurement T1 is plotted during steps of the sequence as line 3431 over time-axis 3401. The lower bound of the target range for measurement T1 is plotted during the steps of the sequence as dotted line 3411 over time-axis 3401. The upper bound of the target range for measurement T1 is plotted during the steps of the sequence as dotted line 3421 over time-axis 3401. Measurement T2 is plotted during steps of the sequence as line 3432 over time-axis 3402. The lower bound of the target range for measurement T2 is plotted during the steps of the sequence as dotted line 3412 over time-axis 3402. The upper bound of the target range for measurement T2 is plotted during the steps of the sequence as dotted line 3422 over time-axis 3402. Measurement T3 is plotted during steps of the sequence as line 3433 over time-axis 3403. The lower bound of the target range for measurement T3 is plotted during the steps of the sequence as dotted line 3413 over time-axis 3403. The upper bound of the target range for measurement T3 is plotted during the steps of the sequence as dotted line 3423 over time-axis 3403. Measurement T4 is plotted during steps of the sequence as line 3434 over time-axis 3404. The lower bound of the target range for measurement T4 is plotted during the steps of the sequence as dotted line 3414 over time-axis 3404. The upper bound of the target range for measurement T4 is plotted during the steps of the sequence as dotted line 3424 over time-axis 3404. Measurement T5 is plotted during steps of the sequence as line 3435 over time-axis 3405. The lower bound of the target range for measurement T5 is plotted during the steps of the sequence as dotted line 3415 over time-axis 3405. The upper bound of the target range for measurement T5 is plotted during the steps of the sequence as dotted line 3425 over time-axis 3405. Measurement T6 is plotted during steps of the sequence as line 3436 over time-axis 3406. The lower bound of the target range for measurement T6 is plotted during the steps of the sequence as dotted line 3416 over time-axis 3406. The upper bound of the target range for measurement T6 is plotted during the steps of the sequence as dotted line 3426 over time-axis 3406.
In one more specific example, the sequence can be produced by the system shown in
In the example sequence shown in
In the first step of the sequence, during time period tf1, electrode E1 is connected to output pole +, electrode E2 is connected to output pole −, and electrodes E3 and E4 are not connected to any output pole. During time period tf1, the measurement T1 decreases and achieves values within its target range; measurements T2, T4, T5, and T6 decrease slightly toward their respective target ranges; and measurement T3 is substantially unchanged.
In the next step of the sequence, during time period tf2, electrode E3 is connected to output pole +, electrode E2 is connected to output pole −, and electrodes E1 and E4 are not connected to any output pole. During time period tf2, the measurement T2 decreases and achieves values within its target range; measurements T1, T3, T5, and T6 decrease, with T1 staying within its target range; and measurement T4 increases slightly toward its initial value.
In the next step of the sequence, during time period tf3, electrode E3 is connected to output pole +, electrode E4 is connected to output pole −, and electrodes E1 and E2 are not connected to any output pole. During time period tf3, the measurement T3 decreases and achieves values within its target range; measurements T2, T4, T5, and T6 decrease, with T2 remaining in its target range; and measurement T1 increases slightly but stays within its target range.
In the next step of the sequence, during time period tf4, electrode E1 is connected to output pole +, electrode E4 is connected to output pole −, and electrodes E2 and E3 are not connected to any output pole. During time period tf4, the measurements T4 and T6 decrease and achieve values within their respective target ranges; measurements T1, T3, and T5 decrease slightly, with T1 and T3 remaining in their respective target ranges; and measurement T2 increases but stays within its target range.
In the next step of the sequence, during time period tf5, electrode E1 is connected to output pole +, electrode E3 is connected to output pole −, and electrodes E2 and E4 are not connected to any output pole. During time period tf5, the measurement T5 decreases and achieves values within its target range; measurements T1, T2, T3, and T4 decrease slightly and stay within their respective target ranges; and measurement T6 increases towards its initial value outside its target range.
In the next step of the sequence, during time period tf6, electrode E2 is connected to output pole +, electrode E4 is connected to output pole −, and electrodes E1 and E3 are not connected to any output pole. During time period tf6, the measurement T6 decreases and achieves values within its target range; measurements T1 and T2 are substantially unchanged within their respective target ranges; T3 and T4 decrease slightly, with T4 approaching the lower limit of its target range; and measurement T5 increases toward the upper limit of its target range.
In the next step of the sequence, during time period tf7, electrode E1 is connected to output pole +, electrode E3 is connected to output pole −, and electrodes E2 and E4 are not connected to any output pole. During time period tf7, the measurement T5 decreases from the upper limit of its target range to a more central values within its target range; measurements T1, T2, T3, and T6 are maintained at values near the centers of their respective target ranges; and measurement T4 increases toward the upper limit of its target range.
In the next step of the sequence, during time period tf8, electrode E1 is connected to output pole +, electrode E4 is connected to output pole −, and electrodes E2 and E3 are not connected to any output pole. During time period tf8, the measurement T4 decreases from the upper limit of its target range toward the bottom of its target range; measurements T3, T5, and T6 are maintained at values within their respective target ranges; measurement T1 decreases to near the bottom limit of its target range; and measurement T2 increases toward the upper limit of its target range.
In the next step of the sequence, during time period tf9, electrode E3 is connected to output pole +, electrode E2 is connected to output pole −, and electrodes E1 and E4 are not connected to any output pole. During time period tf9, the measurement T2 decreases from the upper limit of its target range toward the bottom of its target range; measurements T3, T5, and T6 are maintained at values within their respective target ranges; and measurements T1 and T4 increases toward the upper limits of their respective target ranges.
One advantage of the sequence presented in
In one example of the system presented in
In one example, the total duration of the switching sequence can up to 10 seconds. In another example, the total duration of the switching sequence can up to 30 seconds. In another example, the total duration of the switching sequence can up to 60 seconds. In another example, the total duration of the switching sequence can up to 90 seconds. In another example, the total duration of the switching sequence can up to 120 seconds. In another example, the total duration of the switching sequence can up to 150 seconds. In another example, the total duration of the switching sequence can up to 180 seconds. In another example, the total duration of the switching sequence can up to 600 seconds. In another example, the total duration of the switching sequence can up to 1800 seconds. In another example, the total duration of the switching sequence can be greater than 1800 seconds.
In another example, the sequence shown in
The example shown in
In another example, the number of electrodes E1, . . . , EN is a number N that is at least 3, and the number of measurements T1, . . . , TP is a number P that is great than or equal to the number N. For example, the number of electrodes and number of measurements can both be N=P=3. For example, the number of electrodes and number of measurements can both be N=4. For example, the number of electrodes can be N=4, and the number of measurements can be P=6. For example, the number of electrodes and number of measurements can both be N=P=5. For example, the number of electrodes can be N=5, and the number of measurements can be P=10. For example, the number of electrodes and number of measurements can both be N=P=6. For example, the number of electrodes can be N=6, and the number of measurements can be P=15. For example, the number of electrodes and number of measurements can both be a number greater than six. For example, the number of electrodes can be a number greater than six, and the number of measurements can be a number than that number of electrodes.
In another example, the number of electrical output poles can be a number that is at least two. For example, the number of electrical output poles can be three. For example, the number of electrical output poles can be four. For example, the number of electrical output poles can be five. For example, the number of electrical output poles can be six. For example, the number of electrical output poles can be greater than six. For example, the number of electrical output poles can be equal to the number of electrodes. It is understood that for examples where the number of output poles is greater than two, there can be more than output electrical output signal parameter Vf.
In another example, the electrical output signal parameter Vf can have a fixed value throughout all steps of the sequence. In another example, the electrical output signal parameter Vf can be varied during the sequence. In another example, the electrical output signal parameter Vf can be a voltage. In another example, the electrical output signal parameter Vf can be a current. In another example, the electrical output signal parameter Vf can be a power. In another example, the electrical output signal parameter Vf can be the amplitude of a radiofrequency signal.
It is understood that some measurements increase with the application of electrical energy, and that other measurements decrease with the application of electrical energy. It is understood that some measurements, such as an impedance, have a non-linear relationship between the applied energy and the direction of change. For example, the impedance measured between an electrode and another structure can decrease as the application of energy increases the temperature of the tissue in which the electrode is placed, while that temperature is substantially below boiling; however, the said impedance can then increase with the application of energy if the temperature of said tissue exceeds boiling. It is understood that a measurement that decreases with the application of energy can be converted into a measurement that increases with the application of energy by inverting the sign of the first said measurement. It is understood that a measurement that has a non-linear or time-varying relationship to the application energy can be converted into a measurement that increase with the application of energy by applying a properly configured mathematical function to the first said measurement.
In one example, the measurements T1, T2, T3, T4, T5, and T6 include a temperature. In another example, the measurements T1, T2, T3, T4, T5, and T6 include a measurement from a remote temperature probe. In another example, the measurements T1, T2, T3, T4 are the temperatures of the electrodes E1, E2, E3, and E4, respectively, and T5 and T6 are temperatures of remote temperature probes. In another example, the measurements T1, T2, T3, T4, T5, and T6 are measurements from temperature probes place between each pair of electrodes E1, E2, E3, and E4. In another example, the measurements T1, T2, T3 and T4 are associated with electrodes E1, E2, E3 and E4, respectively. In another example, the measurements T1, T2, T3, T4, T5, and T6 include an impedance. In another example, the measurements T1, T2, T3, T4, T5, and T6 are a function of impedances associated with electrodes E1, E2, E3 and E4, respectively. In another example, the measurements T1, T2, T3, T4, T5, and T6 are the impedance to current flow between each pair of electrodes E1, E2, E3, and E4. In another example, each measurement T1, T2, T3, T4, T5, and T6 is the impedance to current flow from one electrode to at least one other electrode. In another example, the measurements T1, T2, T3, T4, T5, and T6 include the impedance measured when one electrode is attached to one output pole, and all other electrodes are connected to a different output pole. In another example, the measurements T1, T2, T3, T4, T5, and T6 include a function of an electrical parameter over a duration of time that includes at least two steps of the sequence. In another example, the measurements T1, T2, T3, T4, T5, and T6 include a function of an electrical parameter over a duration of time that is configured to match the rate of a physical process within the tissue into which electrodes E1, E2, E3 and/or E4 are situated. For example, the time duration can be 100 milliseconds. For example, the time duration can be 200 milliseconds. For example, the time duration can be 300 milliseconds. For example, the time duration can be 500 milliseconds. For example, the time duration can be 1000 milliseconds. For example, the time duration can be a value less than 100 millisecond. For example, the time duration can be a value greater than 1000 milliseconds. In another example, the measurements T1, T2, T3, T4, T5, and T6 include the time-average of a parameter that characterizes the electrical signal applied to output poles over a duration of time that is greater than the duration of one step in the sequence. In another example, the measurements T1, T2, T3, T4, T5, and T6 include the time-average of the power delivered to one or more electrodes over at least two steps of the sequence. In another example, the measurements T1, T2, T3, T4, T5, and T6 include the time-average of the current delivered to one or more electrodes over at least two steps of the sequence. In another example, the measurements T1, T2, T3, T4, T5, and T6 include the RMS current delivered to one or more electrodes over at least two steps of the sequence. In another example, the measurements T1, T2, T3, T4, T5, and T6 include the time-average of the voltage applied to an electrode over at least two steps of the sequence. In another example, the measurements T1, T2, T3, T4, T5, and T6 include the RMS voltage delivered to one or more electrodes over at least two steps of the sequence.
In another example, the upper and lower bounds of target ranges for each measurement (i.e. 3421 and 3431 for measurement T1, 3422 and 3432 for measurement T2, 3423 and 3433 for measurement T3, 3424 and 3434 for measurement T4, 3425 and 3435 for measurement T5, and 3426 and 3436 for measurement T6) can vary arbitrarily over the course of the sequence. For example, either the upper and lower bounds of the target range for a measurement can both move upward or both move downward at any time during a sequence. For example, the upper and lower bound of the target range for a measurement can change independently of the other bound. For example, the target range can become more narrow or become wider during a sequence.
Referring now to
Referring to the example sequences provided in
Referring to the example sequences provided in
Referring to the example sequences provided in
For example, for a measurement that is an impedance, the target value can be a value configured to indicate a temperature that is near 100° C. For example, for a measurement of impedance, the target value can be a value configured to indicate a temperature that is below 100° C. For example, for a measurement of impedance, the target value can be a value configured to indicate that tissue near an electrode is not boiling. For example, for a measurement of impedance, the target value can be 10 Ohms. For example, for a measurement of impedance, the target value can be 10 Ohms. For example, for a measurement of impedance, the target value can be 10 Ohms. For example, for a measurement of impedance, the target value can be 20 Ohms. For example, for a measurement of impedance, the target value can be 30 Ohms. For example, for a measurement of impedance, the target value can be 40 Ohms. For example, for a measurement of impedance, the target value can be 50 Ohms. For example, for a measurement of impedance, the target value can be 60 Ohms. For example, for a measurement of impedance, the target value can be 70 Ohms. For example, for a measurement of impedance, the target value can be 80 Ohms. For example, for a measurement of impedance, the target value can be 90 Ohms. For example, for a measurement of impedance, the target value can be 100 Ohms. For example, for a measurement of impedance, the target value can be 150 Ohms. For example, for a measurement of impedance, the target value can be 200 Ohms. For example, for a measurement of impedance, the target value can be 500 Ohms. For example, for a measurement of impedance, the target value can be 1000 Ohms. For example, for a measurement of impedance, the target value can be a value less than 10 Ohms. For example, for a measurement of impedance, the target value can be a value greater than 1000 Ohms. For example, for a measurement of impedance, the target range can be +/−10 Ohms of a target value. For example, for a measurement of impedance, the target range can be +/−20 Ohms of a target value. For example, for a measurement of impedance, the target range can be +/−30 Ohms of a target value. For example, for a measurement of impedance, the target range can be +/−50 Ohms of a target value. For example, for a measurement of impedance, the target range can be +/−100 Ohms of a target value. For example, for a measurement that is an impedance, the target range can contain values that are less than 10 Ohms of a target value. For example, for a measurement that is an impedance, the target range can contain values that are greater than 100 Ohms of a target value. For example, for a measurement that is an impedance, the target range can contain values that indicate the tissue near an electrodes is not boiling.
For example, for a measurement of power, the target power can be a value less than 50 Watts. For example, for a measurement of power, the target power can be a value greater than 50 Watts. For example, for a measurement of power, the target power can be 1 Watts. For example, for a measurement of power, the target power can be 5 Watts. For example, for a measurement of power, the target power can be 10 Watts. For example, for a measurement of power, the target power can be 20 Watts. For example, for a measurement of power, the target power can be 25 Watts. For example, for a measurement of power, the target power can be 50 Watts. For example, for a measurement of power, the target power can be 100 Watts. For example, for a measurement of power, the target power can be 200 Watts. For example, for a measurement of power, the target range can be +/−1 Watts of a target value. For example, for a measurement of power, the target range can be +/−2 Watts of a target value. For example, for a measurement of power, the target range can be +/−5 Watts of a target value. For example, for a measurement of power, the target range can be +/−10 Watts of a target value. For example, for a measurement of power, the target range can be +/−20 Watts of a target value. For example, for a measurement of power, the target range can contain values that are less than 1 W different from a target value. For example, for a measurement of power, the target range can contain values that are greater than 20 W different from a target value.
For example, for a measurement of voltage, the target voltage can be a value less than 100 Volts. For example, for a measurement of voltage, the target voltage can be a value greater than 100 Volts. For example, for a measurement of voltage, the target voltage can be 1 Volts. For example, for a measurement of voltage, the target voltage can be 5 Volts. For example, for a measurement of voltage, the target voltage can be 10 Volts. For example, for a measurement of voltage, the target voltage can be 15 Volts. For example, for a measurement of voltage, the target voltage can be 20 Volts. For example, for a measurement of voltage, the target voltage can be 25 Volts. For example, for a measurement of voltage, the target voltage can be 30 Volts. For example, for a measurement of voltage, the target voltage can be 50 Volts. For example, for a measurement of voltage, the target voltage can be 100 Volts. For example, for a measurement of voltage, the target voltage can be 200 Volts. For example, for a measurement of voltage, the target range can be +/−1 Volts of a target value. For example, for a measurement of voltage, the target range can be +/−2 Volts of a target value. For example, for a measurement of voltage, the target range can be +/−5 Volts of a target value. For example, for a measurement of voltage, the target range can be +/−10 Volts of a target value. For example, for a measurement of voltage, the target range can be +/−20 Volts of a target value. For example, for a measurement of voltage, the target range can be +/−25 Volts of a target value. For example, for a measurement of voltage, the target range can be +/−50 Volts of a target value. For example, for a measurement of voltage, the target range can contain values that are less than 1 V different from a target value. For example, for a measurement of voltage, the target range can contain values that are greater than 50 V different from a target value.
For example, for a measurement of current, the target current can be a value less than 1000 Milliamps. For example, for a measurement of current, the target current can be a value greater than 1000 Milliamps. For example, for a measurement of current, the target current can be 1 Milliamps. For example, for a measurement of current, the target current can be 5 Milliamps. For example, for a measurement of current, the target current can be 10 Milliamps. For example, for a measurement of current, the target current can be 50 Milliamps. For example, for a measurement of current, the target current can be 100 Milliamps. For example, for a measurement of current, the target current can be 200 Milliamps. For example, for a measurement of current, the target current can be 250 Milliamps. For example, for a measurement of current, the target current can be 500 Milliamps. For example, for a measurement of current, the target current can be 1000 Milliamps. For example, for a measurement of current, the target current can be 2000 Milliamps. For example, for a measurement of current, the target range can be +/−1 Milliamps of a target value. For example, for a measurement of current, the target range can be +/−2 Milliamps of a target value. For example, for a measurement of current, the target range can be +/−5 Milliamps of a target value. For example, for a measurement of current, the target range can be +/−10 Milliamps of a target value. For example, for a measurement of current, the target range can be +/−20 Milliamps of a target value. For example, for a measurement of current, the target range can be +/−25 Milliamps of a target value. For example, for a measurement of current, the target range can be +/−50 Milliamps of a target value. For example, for a measurement of current, the target range can be +/−100 Milliamps of a target value. For example, for a measurement of current, the target range can be +/−200 Milliamps of a target value. For example, for a measurement of current, the target range can be +/−500 Milliamps of a target value. For example, for a measurement of current, the target range can contain values that are less than 1 Milliamps different from a target value. For example, for a measurement of current, the target range can contain values that are greater than 2000 mA different from a target value.
For example, for a measure of any type, the target value can be suited to a clinical objective. For example, for a measure of any type, the range of target values can be suited to a clinical objective. For example, for a measure of any type, the size of the target range can be different for different target values. For example, for a measure of any type, the target range can be specified relative to the target value. For example, for a measure of any type, the target range can be a specified as a percentage of the target value. For example, for a measurement of any type, the target range can be +/−1% of a target value. For example, for a measurement of any type, the target range can be +/−2% of a target value. For example, for a measurement of any type, the target range can be +/−5% of a target value. For example, for a measurement of any type, the target range can be +/−10% of a target value. For example, for a measurement of any type, the target range can be +/−15% of a target value. For example, for a measurement of any type, the target range can be +/−20% of a target value. For example, for a measurement of any type, the target range can be +/−25% of a target value. For example, for a measurement of any type, the target range can be +/−30% of a target value. For example, for a measurement of any type, the target range can be greater than +/−30% of a target value.
Referring now to
The controller 4015 is connected to the power supply 4000, switches 4005, and measurement system 4010. The controller can coordinate the actions of the power supply 4000, switches 4005, and measurement system 4010. For example, the controller can implement feedback control of the power supply 4000 and switches 4005 based on measurements T1, T2, T3 from the measurement system 4015.
Power supply 4000 consists of voltage supplies Vt0, Vt1, Vt2a, Vt2b, Vt3, referenced to a common reference potential 4002. The controller 4015 can control each of the voltage supplies independently. In one example, each voltage supply can produce a different output signal. In one example, the voltage supplies Vt0, Vt1, Vt2a, Vt2b, Vt3 can produce radiofrequency signals. In one example, a two-pole system can be produced by setting voltage supplies Vt0, Vt1, Vt2a, Vt2b, Vt3 such that each supply produces one of two output signals. For example, in one specific example of a two-pole system, a sequence of power supply settings can include a step in which Vt0=Vt3=V+ and Vt1=Vt2a=Vt2b=V−, and another step in which Vt1=Vt3=V+ and Vt0=Vt2a=Vt2b=V−, such that V+ and V− can be set individually by the controller. In one example, a three-pole system can be produced by setting voltage supplies Vt0, Vt1, Vt2a, Vt2b, Vt3 such that each supply produces one of three output signals. For example, in one specific example of a three-pole system, a sequence of power supply settings can include a step in which Vt0=V+, Vt1=V−, and Vt2a=Vt2b=Vt3=V*; and a step in which Vt1=V+, Vt2a=Vt2b=V−, and Vt3=Vt0=V*; where V+, V−, and V* can be set individually by the controller. In one example, a four-pole system can be produced by assigning output signals to each of Vt0, Vt1, Vt2a=Vt2b, Vt3.
In one example, it is understood that the system presented in
In another example, the system in
It is understood that, in another example, more than two electrodes can be configured as are electrodes E2a and E2b shown in
In another aspect, the examples of
A number of embodiments of the invention have been described. Nevertheless, it will be understood that various modifications may be made without departing from the spirit and scope of the invention. Accordingly, other embodiments are within the scope of the following claims:
This application claims the benefit of prior U.S. Provisional Application No. 61/258,971, filed on Nov. 6, 2009, which is incorporated by reference in its entirety.
| Number | Date | Country | |
|---|---|---|---|
| 61258971 | Nov 2009 | US |
