Patent Publication Number: US-2023158319-A1

Title: System for treating unwanted tissue

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation of Patent Cooperation Treaty (PCT) application No. PCT/CA2021/050721 having an international filing date of 27 May 2021 and entitled SYSTEM FOR TREATING UNWANTED TISSUE, which in turn claims priority from, and for the purposes of the United States of America claims the benefit under 35 U.S.C. § 119 of, U.S. application No. 63/030,879 filed 27 May 2020 and entitled SYSTEM FOR TREATING UNWANTED TISSUE. All of the applications referred to in this paragraph are hereby incorporated herein by reference. 
    
    
     FIELD 
     The invention relates to medical devices and methods for treating unwanted tissues. The invention has example application in treating lung diseases such as chronic obstructive pulmonary disease (COPD), one example of which is emphysema. 
     BACKGROUND 
     There are a variety of medical conditions for which treatment can include destroying or affecting a non-desired tissue. Such treatments should ideally avoid harming normal tissues adjacent to the non-desired tissue. For example, some lung conditions can benefit from treatments that involve destroying or affecting diseased lung tissue. Some of these treatments involve heating the lung tissue. Background information on lung disease can be found in medical textbooks, such as “Pulmonary Pathophysiology” by Dr. John B. West, ISBN 0-683-08934-X. 
     Emphysema is a disease that damages the alveoli (air sacs) in a patient&#39;s lungs. 
     Emphysema can cause the alveoli in the patient&#39;s lungs to rupture. This alters the distribution of air spaces in the lungs and reduces the surface area of the lungs available to take up oxygen. The lung damage caused by emphysema can trap stale air in the lungs and/or reduce the flow of fresh, oxygen-rich air into the lungs. In a patient suffering from emphysema, diseased parts of the patient&#39;s lungs are not effectively ventilated through the bronchi and trachea, thus preventing the lungs from fully deflating and inflating. Air trapped inside the lungs can prevent the diaphragm from moving up and down naturally. This condition results in difficulty breathing and an overall reduced health and life quality. 
     Some prior art approaches to heating diseased tissue within the lung involve inserting an ablation device through the trachea and bronchi into the diseased area (for example, see Brannan et al. US 2016/0184013). This approach has various shortcomings: only a small part of the lung is accessible, precise mapping of the diseased area is required, and the ablation device must be accurately guided to a precise location. In addition, during treatment, collateral damage is caused to tissue located along the path of the device from the point of entry to the point of treatment. 
     Some prior references in the general field of the invention are:
         a) Lichtenstein et al., U.S. Pat. No. 8,444,635, which is hereby incorporated herein by reference, discloses a system that exposes undesired tissue to a scanning focused microwave beam.   b) Palti, U.S. Pat. No. 8,019,414 discloses combining chemotherapy treatment with low intensity, intermediate frequency alternating electric fields that are tuned to a particular type of target cell.   c) Armitage, U.S. Pat. No. 4,269,199 discloses a method for inducing local hyperthermia in treatment of a tumor by short wave diathermy. The method involves moving an induction coil over the portion of the body containing the tumor such that the axis of the coil constantly transects different portions of the tumor.   d) Turner, U.S. Pat. No. 4,798,215 discloses a combined hyperthermia treatment and non-invasive thermometry apparatus.   e) Leveen, U.S. Pat. No. 5,010,897 discloses an apparatus for the deep heating of cancers. The apparatus employs two single turn coaxial coils which rotate synchronously in planes which are parallel to each other with the central axis of each coil lying in exactly the same line which is perpendicular to the plane of the coil. The combined magnetic field of the rotating coils continuously heats a tumor.   f) Evans, U.S. Pat. No. 5,503,150 discloses an apparatus and method for noninvasively locating and heating a volume of tissue that includes the ability to detect temperature changes in the volume of tissue.   g) Kasevich, U.S. Pat. No. 6,181,970 discloses medical systems and instruments which utilize microwave energy to provide heat treatment and diagnostic imaging of tissue.   h) Barry et al., U.S. Pat. No. 8,585,645 discloses treating locations in a patient&#39;s lung using high temperature vapor delivered through the inner lumen of a catheter.   i) Turnquist et al., US2011/0054431 discloses devices and methods to non-invasively heat bodily tissues and fluid using emitted energy and non-invasively measure the resulting temperature changes in the target and surrounding fluid and tissue to detect and/or treat for various physical conditions, such as, for example, vesicoureteral reflux.   j) Lichtenstein et al. WO 2017/201625 describes methods and apparatus that can be used to heat tissues to treat emphysema with energy delivered through external electrodes or coils.   k) Vertikov et al., U.S. Pat. No. 8,467,858 describes devices and techniques for thermotherapy based on optical imaging.   l) Ruggera et al. CA1212424A describes a helical coil for diathermy apparatus driven by frequencies corresponding to integral multiples of one-half the basic wavelength, to achieve transverse uniform heating and enable shifting the heat focus volume along the coil axis from the normal centered location on the axis produced by full-wave excitation.       

     There is a general desire for systems that can automatically heat tissues in diseased areas. There is a general desire for systems which can heat tissues in diseased areas without having to locate the diseased areas precisely. There is a particular need for new practical methods and apparatus for heating all diseased parts of the lung without excessively heating healthy parts of the lung or surrounding healthy tissues. 
     SUMMARY 
     This invention has a number of aspects. These aspects include, without limitation:
         Apparatus useful for selectively heating tissues within a patient.   Control systems for tissue heating apparatus;   Methods for controlling apparatus for selectively heating tissues within a patient;   Methods for treating a patient which include the selective heating of tissues within the patient.   Uses of apparatus for treatment of COPD and other lung diseases.
 
An example and non-limiting application of methods and apparatus as described herein is treatment of diseased lung tissues, for example, lung tissues affected by emphysema or other forms of COPD. Some embodiments provide methods and/or apparatus that are particularly adapted for selectively heating lung tissues to treat COPD and/or other diseases of the lungs.
       

     One aspect of the invention provides an apparatus for treating emphysema or COPD by selectively heating diseased lung tissue in a patient to a treatment temperature sufficient to cause a therapeutic effect in the diseased lung tissue, the apparatus comprising: at least one signal applicator comprising an electrical conductor dimensioned to extend circumferentially around or nearly around the torso of the patient; a power source connected to deliver a radiofrequency (RF) signal to the at least one applicator, the power source comprising an impedance matching network operative to match an output impedance of the power source to an input impedance of the signal applicator; a controller operatively associated with the power source and configured to control the power source to apply the RF signal to the applicator; the applicator, when energized by the RF signal, operative to couple an electromagnetic energy signal into tissues of the patient, such that the tissues of the patient are heated by the electromagnetic energy signal and the diseased tissue is selectively heated to higher temperatures than healthy tissues due to relatively lower blood circulation to the diseased tissue. 
     In some embodiments the power source has a maximum RF signal output power of at least 500 watts. In some embodiments the RF signal creates a localized axial electric or magnetic field within lungs of the patient. This localized field may serve as a primary source of (dielectric) heating of the tissues of the patient. 
     In some embodiments, the temperature monitor is operative to monitor a temperature at one or more locations within the tissue of the patient wherein the controller is connected to receive a temperature signal from the temperature monitor indicating a temperature at the one or more locations, and the controller is configured to apply feedback control to the power source to regulate the electromagnetic energy signal delivered into the patient based at least in part on the temperature signal. 
     In some embodiments, the temperature monitor is a non-invasive temperature monitor. 
     In some embodiments, the temperature monitor comprises a magnetic resonance imaging (MRI) imaging system and a processor configured to process a MRI signal provided by the MRI imaging system to determine the temperature corresponding to each of the one or more locations. 
     In some embodiments, the temperature monitor comprises an ultrasound imaging (US) system and a processor configured to process an ultrasound signal provided by the US imaging system to determine the temperature corresponding to each of the one or more locations. 
     In some embodiments, the controller is configured to control one or more parameters of the RF signal until the temperature at the location is at least equal to the treatment temperature. 
     In some embodiments, the controller comprises a thermal model of at least a portion of the patient, the thermal model correlating temperatures at the one or more locations to a temperature of a location of interest and the controller is configured to apply the thermal model using the temperature signal as an input and to regulate the heating energy based at least in part on an output of the thermal model. 
     In some embodiments, the thermal model comprises one or more of: electrical and thermal properties of different tissue types in the patient, distributions of the different tissue types in the patient, geometry of the one or more electromagnetic energy applicators, resulting expected electromagnetic field distributions, and perfusion rates in the patient. 
     In some embodiments, the at least one signal applicator comprises a coil. 
     In some embodiments, the coil comprises in the range of 5 to 100 turns. 
     In some embodiments, the coil comprises in the range of 10 to 60 turns. 
     In some embodiments, turns of the coil are uniformly spaced apart along the longitudinal axis of the coil by a pitch distance. 
     In some embodiments, turns of the coil are non-uniformly spaced apart along the longitudinal axis of the coil. 
     In some embodiments, a cross section of the coil is not circular. 
     In some embodiments, a spacing between turns of the coil along the longitudinal axis of the coil is adjustable. 
     In some embodiments, the cross section of the coil is adjustable along the longitudinal axis of the coil. 
     In some embodiments, the coil has a length of at least 70 centimeters. 
     In some embodiments, the coil has a length of at least 1 meter. 
     In some embodiments, the coil has an inside diameter of at least 30 cm. 
     In some embodiments, the length of the coil is greater than or equal to the width of the coil. 
     In some embodiments, the length of the coil is greater than or equal to four times the width of the coil. 
     In some embodiments, the coil comprises multi-layer windings. 
     In some embodiments, the coil is configured to open as a clamshell to admit the patient. 
     In some embodiments, the apparatus comprises a patient support configured to support the patient in a lying position, the patient support comprising a head support wherein the head support is outside of the coil. 
     In some embodiments, the RF signal has a frequency in the range of about 5 kHz to about 100 MHz. 
     In some embodiments, the RF signal has a frequency in the range of about 500 kHz to about 10 MHz. 
     In some embodiments, the controller is configured to set a frequency of the RF signal such that an electric field maximum of the electromagnetic energy signal is at a desired location relative to the at least one applicator. 
     In some embodiments, the controller is configured to set the frequency of the RF signal to create a standing wave in the at least one applicator. 
     In some embodiments, the controller is configured to set the frequency of the RF signal to create a standing wave in the at least one applicator, the standing wave having an electric field maximum in a desired location (e.g. in the patient&#39;s lung at or near a location of a volume of diseased tissue). 
     In some embodiments, the controller is configured to set the frequency of the RF signal to be at or near a resonant frequency of the applicator and the patient. 
     In some embodiments, the controller is configured to set the frequency of the RF signal to or near to an integer multiple of a resonant frequency of the applicator when the patient is present. 
     In some embodiments, the RF signal has a power in the range of about 500 watts to about 5 kilowatts. 
     In some embodiments, the controller is configured to apply time domain modulation to the RF signal. 
     In some embodiments, the controller is configured to control the power source to generate the RF signal as a pulsed signal and to control widths of pulses in the pulsed signal. 
     In some embodiments, the one or more signal applicators comprises two signal applicators connected to the power source and operative to deliver the electromagnetic energy signal into tissues of the patient. 
     In some embodiments, the two signal applicators comprise a first signal applicator positioned cranially from a volume to be treated and a second signal applicator positioned caudally from the volume to be treated. 
     In some embodiments, each of the two signal applicators is shaped to wrap or partially wrap around a circumference of the torso of the patient. 
     In some embodiments, the signal applicators are adjustable to conform to contours of the treated patient. 
     In some embodiments, the apparatus comprises cooling means for cooling the patient. 
     In some embodiments, the cooling means comprises a source of a cooled fluid arranged to bring the cooled fluid into thermal contact with an area of skin of the patient. 
     In some embodiments, the cooling means comprises a patient support comprising passages connected to carry the cooled fluid that are in thermal contact with a surface for supporting the patient. 
     In some embodiments, the cooling means is configured to cool the chest and back of the patient. 
     In some embodiments, the cooling means is configured to cool the groin of the patient. 
     In some embodiments, the cooling means comprises a source of chilled air. 
     In some embodiments, the apparatus is used in the treatment of emphysema or COPD. 
     One aspect of the invention provides a method for treating emphysema or COPD by selectively heating diseased lung tissue in a patient to a treatment temperature sufficient to cause a therapeutic effect in the diseased lung tissue, the method comprising: providing at least one signal applicator comprising an electrical conductor extending circumferentially around or nearly around the torso of the patient; delivering a radiofrequency (RF) signal to the at least one applicator and allowing the RF signal to be absorbed in both healthier and diseased tissues of the patient&#39;s lungs, thereby heating the tissues of the patient&#39;s lungs, whereby the heating raises the diseased tissues to temperatures exceeding a treatment threshold temperature while temperatures of the healthier tissues are kept below a safe threshold temperature lower than the treatment threshold temperature by blood circulation through the healthier tissues; keeping the temperatures of the diseased tissues above the treatment threshold temperature for a cumulative time sufficient to provide a therapeutic effect. 
     In some embodiments, the RF signal has an output power of at least 500 watts. 
     In some embodiments, the therapeutic effect is ablation of the diseased tissues. 
     In some embodiments, the therapeutic effect is necrosis of the diseased tissues. 
     In some embodiments, the therapeutic effect is induced inflammation of the diseased tissues. 
     In some embodiments, the RF signal creates a localized axially extending alternating electric or magnetic field within lungs of the patient. 
     In some embodiments, the at least one applicator comprises a coil and the patient&#39;s lungs are within the coil. 
     In some embodiments, the RF signal creates alternating magnetic fields extending substantially parallel to an inferior superior direction of the patient. 
     In some embodiments, the method comprises a strength of the alternating magnetic fields that is substantially uniform within the coil. 
     In some embodiments, the at least one applicator comprises a pair of electrically conductive members spaced apart along the torso of the patient. 
     In some embodiments, the RF signal creates localized alternating electric fields extending in an axial direction substantially parallel to an inferior superior direction of the patient. 
     In some embodiments the method comprises monitoring a temperature of a tissue within the patent and controlling the RF signal based on the monitored temperature. For example, controlling the RF signal may comprise one or more of setting a frequency of the RF signal, and setting an amplitude or power of the RF signal. In some embodiments the method comprising setting the frequency of the RF signal to create an electromagnetic standing wave in the patient (e.g. in the lungs of the patient). 
     Further aspects and example embodiments are illustrated in the accompanying drawings and/or described in the following description. 
     The present invention has aspects that are expressed as methods and aspects that are expressed as apparatus. Where apparatus is described herein, all the described features of the apparatus and the use of such apparatus is intended to also describe corresponding methods and where methods are described herein it is intended that the disclosure of such methods also provides apparatus configured to implement such methods. 
     It is emphasized that the invention relates to all combinations of the above features, even if these are recited in different claims. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The accompanying drawings illustrate non-limiting example embodiments of the invention. 
         FIG.  1    illustrates apparatus according to an example embodiment. 
         FIG.  1 A  is a schematic graph illustrating differential heating of diseased and healthy tissues. 
         FIG.  1 B  is a block diagram showing an example control system for apparatus as described herein. 
         FIG.  1 C  is a schematic cross section of a coil illustrating one way to adjust a cross sectional shape of the coil. 
         FIG.  2    is a side elevation of apparatus according to an example embodiment which includes a multi-layer coil. 
         FIG.  3    is a side elevation of another example apparatus which includes a pair of spaced apart applicators that extend circumferentially or partially circumferentially around a patient. 
     
    
    
     DETAILED DESCRIPTION 
     Throughout the following description, specific details are set forth in order to provide a more thorough understanding of the invention. However, the invention may be practiced without these particulars. In other instances, well known elements have not been shown or described in detail to avoid unnecessarily obscuring the invention. Accordingly, the specification and drawings are to be regarded in an illustrative, rather than a restrictive sense. 
       FIG.  1    illustrates apparatus  10  according to an example embodiment. A patient P has a volume V of tissue which it is desired to treat by heating. Volume V may, for example, comprise alveoli in the patient&#39;s lung L which are impacted by emphysema. 
     Volume V may have relatively lower blood circulation as compared to healthier tissues in other parts of lung L such that delivery of energy at a given power density to the tissues in volume V (i.e. the energy is delivered to the tissues in volume V at a given rate which may for example be measured in watts per unit of volume in volume V which may for example be measured in cm 3 ) results in a higher temperature rise than would occur if energy at the same power density were delivered to healthier tissues in other parts of lung L. The higher temperature rise in volume V may be attributed at least in significant part to reduced blood circulation in volume V as compared to blood circulation in the healthier tissues. The circulating blood acts as a coolant which removes energy from healthier tissues at a higher rate than from volume V. This effect may be applied to heat the tissue of volume V to a temperature high enough to achieve a desired result (e.g. destruction of tissue in volume V such as tissue ablation, tissue necrosis or inducing inflammation of tissue in volume V) while the temperature in surrounding healthier tissues may remain below a safe threshold temperature such that the healthier surrounding tissues are not harmed. 
     For example, if one can cause each volume of the tissue of a portion of lung L that includes one or more volumes V of diseased tissue to dissipate the same amount of power per unit volume then one can choose a power level such that the one or more volumes of diseased tissue within lung L that have poor blood circulation will be heated to a temperature that is at least at a treatment temperature threshold while temperatures of volumes of healthier tissues within lung L that have better blood circulation remain below a safe temperature threshold. 
       FIG.  1 A  is a schematic graph illustrating the principle described above. Initially, the temperature T V  in a volume V of diseased tissue and the temperature T H  in a volume of healthy tissue are both equal to body temperature T B . At time t=0 energy having a selected power density is applied to volume V and to the volume of healthy tissue. This causes temperatures T V  and T H  to rise. As this occurs, temperature T V  tends to be higher than temperature T H  because of the poor blood circulation in volume V. The power density of the applied energy and the time for which the applied energy is delivered to patient P are selected so that the temperature of healthy tissue does not exceed a safe threshold temperature T 1  while the temperature in volume V reaches at least a treatment temperature threshold T 2 . 
     Apparatus  10  delivers energy to tissues in a patient by way of a signal applicator which, in apparatus  10  has the form of a coil  20  that extends around a portion of the body of patient P that includes diseased tissue to be heated. 
     Coil  20  is driven by a power source  25  to generate electromagnetic fields that deliver energy into the tissues of patient P. In apparatus  10 , power source  25  has output terminals  26 A and  26 B that are connected to apply a signal to corresponding terminals of coil  20  by signal conductors  27 A and  27 B. In some embodiments power source  25  is connected to coil  20  at ends of coil  20  (e.g. at terminals  28 A and  28 B). In some embodiments, power source  25  is connected to coil  20  at terminals located away from ends of coil  20  (e.g. at terminals  28 C and  28 D). 
     A controller  24  controls power source  25  to deliver energy to the tissues of patient P to yield a desired treatment outcome. In some embodiments controller  24  is connected to receive feedback from a temperature monitor  23  that monitors temperatures at one or more points  23 A in and/or near volume V. 
     Controller  24  may be configured to adjust the signal delivered to coil  20  to yield a desired temperature distribution in tissues of patient P. For example, it may be desired to heat volumes of diseased tissue to a temperature of at least the treatment temperature threshold T 2  for a desired time period while maintaining temperatures of healthier tissues below the safe temperature threshold T 1 . 
     Controller  24  may comprise a feedback controller that has one or more inputs. The one or more inputs may include temperature measurements of tissues of patient P. Apparatus  10  includes temperature monitor  23  which acquires temperature measurements. The temperature measurements may be made with one or more temperature sensors of any suitable type(s). 
     Coil  20  has a number of windings  20 A. In a typical, non-limiting, embodiment the number of windings is in the range of 5 to 100. In some embodiments, coil  20  has in the range of 10 to 60 windings  20 A. It is not necessary that coil  20  has an integer number of windings. 
     Windings  20 A may, for example, comprise electrically conductive wires, tubes, bars etc. Windings  20 A may have cross sections: such as round, elliptical, or others. The cross sections may vary along the length of coil  20 . In some embodiments windings  20 A have a tubular construction. 
     Coil  20  is arranged to receive at least a part of the body of patient P that includes volume V. For example, where volume V is in the lungs, coil  20  may be dimensioned to receive the torso of patient P such that volume V lies inside of coil  20 . For example, where patient P is an adult and coil  20  receives the torso of patient P as illustrated in  FIG.  1    then coil  20  may, for example, have a diameter D 20  of about 30 to 90 cm (for some larger patients, diameters toward the high end of this range or even higher may be required). Windings  20 A may be wound tightly around patient P or may be dimensioned so that there is a gap between windings  20 A and patient P. Where patient P is a child or other small person coil  20  may have a diameter that is smaller but large enough to extend around the torso of patient P. 
       FIG.  1 B  is a block diagram that illustrates a control system that may be applied in apparatus  10  or other apparatus as described herein. In this example, power source  25  comprises a signal generator  25 A that delivers an output signal  22 - 1  to an amplifier  25 B. Signal generator  25 A is operable to generate a signal which is amplified by amplifier  25 B to yield an amplified signal  22 - 2 . Amplified signal  22 - 2  is applied to drive coil  20 . 
     Amplified signal  22 - 2  may, for example comprise a sinusoidal signal with a frequency in the range of about 5 kHz to about 100 MHz. In some embodiments, signal  22 - 2  has a frequency in the range of about 500 kHz to about 10 MHz. In some embodiments amplified signal  22 - 2  has a power in the range of about 500 watts to 5 kilowatts. 
     In the embodiment of  FIG.  1 B , power source  25  includes an impedance matching network  25 C. Impedance matching network  25 C is connected between the output of amplifier  25 B and coil  20  and is adjustable to provide optimal power delivery to patient P. As is known to those of skill in the art of RF systems, a matching network comprises a combination of circuit elements such as capacitors, resistors and/or inductors which may be connected in various topologies to match an output impedance of amplifier  25 B to an input impedance of the system comprising coil  20  and patient P. The input impedance of coil  20  and patient P depends on characteristics of coil  20  and patient P as well as characteristics of the channel that delivers the RF energy of signal  22 - 2  to coil  20 . Matching network  25 C is adjustable to maximize power delivery to patient P and minimize power reflected back to amplifier  25 B. 
     In the embodiment illustrated in  FIG.  1 B , a reflection detector  25 D is provided to measure RF power reflected from coil  20  and patient P. Reflection detector  25 D may, for example, comprise a circulator configured to direct RF power reflected from coil  20  to an output port at which an RF power meter of any suitable kind is provided to measure the reflected power. Matching network  25 C may be tuned to minimize the reflected power detected by reflection detector  25 D for a particular patient P and coil  20 . 
     Signal  22 - 2  causes an alternating electrical current to flow in windings  20 A of coil  20 . This current causes an alternating magnetic field inside coil  20 . The alternating magnetic field results in an alternating electric field and induces electrical eddy currents in electrically conductive materials (e.g. the tissues of patient P) that are located within the coil  20 . The combination of coil  20  and the signal provided by power source  25  may be selected such that an electric field maximum is in a plane perpendicular to the axis of coil  20  and positioned at a desired location (e.g. at the location of a treatment volume V). 
     In the illustrated embodiment, coil  20  has the form of a solenoid and magnetic fields within coil  20  that result from the flow of electrical current in windings  20 A are directed generally parallel to a longitudinal axis of coil  20 . In the illustrated embodiment, coil  20  is oriented so that the magnetic field lines extend in a superior/inferior direction (i.e. parallel to a longitudinal centerline of the patient&#39;s body). Advantageously the strength of the magnetic field is generally uniform in a cross section through coil  20  taken perpendicular to the longitudinal axis of coil  20 . 
       FIG.  1 B  shows outputs and inputs of an example controller  24 . Some embodiments may include all of these outputs and inputs. Other embodiments may lack some of these inputs and outputs. The same hardware optionally provides two or more or all different inputs and/or outputs of controller  24 . Control signals and/or data signals may comprise analog or digital signals in any suitable format. 
     Controller  24  obtains patient data  30  as input  30 - 1 . Patient data  30  may comprise one or more of:
         prescribed characteristic(s) of amplifier output signal  22 - 2  such as one or more of: power or power density to be delivered to a particular patient P, frequency or frequency spectrum for signal  22 - 2  etc.;   a prescribed sequence for delivering power to a particular patient P;   treatment temperature(s) and/or temperature thresholds;   location(s) of one or more volumes V containing diseased tissue to be treated;   physical characteristics of a particular patient P (e.g. height, weight, body fat content, girth, pulmonary circulation measures, lung volume, pretreatment imaging data (e.g. from a MRI, CT scan etc.) from which dimensions and.or tissue characteristics of the patient P may be determined); etc.
 
Input  30 - 1  may for example receive input from one or more of a graphical user interface, discrete controls, wired or wireless data interface, data store, data server, etc.
       

     Depending on the nature of patient data  30  and the capabilities of controller  24 , controller  24  may: directly receive specified characteristics for signal  22 - 2  or derive characteristics for signal  22 - 2  based on information about patient P (e.g. information of one or more of the types described above). Also depending on the nature of patient data  30  and the capabilities of controller  24 , controller  24  may: receive and apply specific parameters for controlling power source  25  in patient data  30 ; apply built in control parameters; or derive control parameters by processing patient data  30 . 
     Controller  24  may receive input signals  31  at an input  31 - 1  that indicate one or both of RF power reflected from coil  20  and RF power being delivered to coil  20 . Controller  24  may output signals  33  at an output  33 - 1  connected to matching network  25 C. Controller  24  may be configured to adjust matching network  25 C by signals  33  to minimize reflected RF power from coil  20 /patient P. This adjustment may be performed once prior to treatment and/or automatically on a continuing or periodic basis. 
     If signals  31  include a measured power level of signal  22 - 2 , controller  24  may use the measured power level of signals  22 - 2  as feedback for controlling signals  22 - 2 . 
     Controller  24  may receive signals  32  at input  32 - 1  from temperature monitor  23 . Controller  24  may be configured based on signals  32  to control the power of signal  22 - 2 , control modulation of signal  22 - 2  and/or stop a treatment if a measured temperature crosses a high temperature threshold. 
       FIG.  1 B  shows output  34 - 1  which delivers control signals  34  to control signal generator  25 A. Signals  34  may, for example, control one or more of: frequency of signal  22 - 1 , frequency spectrum of signal  22 - 1 , pulsing of signal  22 - 1 , and amplitude of signal  22 - 1 . 
       FIG.  1 B  shows output  35 - 1  which delivers control signals  35  to control amplifier  25 B. Control signals  35  may, for example, control gain of amplifier  25 B. 
     Controller  24  may adjust the power being delivered to tissues of patient P (e.g. by signals  34  and/or  35 ) in response to temperature measurements (e.g. in signals  32 ). For example, controller  24  may control power source  25  to one or more of:
         adjust the power level of signal  22 - 2 ; e.g. to match the cooling effect of the perfusion in the healthy tissue such that it does not overheat while the diseased tissue is heated to a required temperature;   perform time domain modulation of signal  22 - 2  e.g. to allow intermittent power delivery that enables the perfusion in the healthy areas to cool down the tissue below a required temperature while allowing the diseased tissue to remain at a required temperature;   adjust a frequency of signal  22 - 1  e.g. to be at a resonant frequency as described below.       

     In some embodiments controller  24  comprises a thermal model of at least a portion of the treated patient. The thermal model correlates temperature(s) at one or more locations within the treated patient P for which temperature measurements are available to temperature(s) of one or more locations of interest for which temperature measurements may not be available. Controller  24  may be configured to apply the thermal model using the measured temperature(s) as an input of the thermal model and to regulate signal  22 - 2  based at least in part on an output of the thermal model. 
     The thermal model may, for example include one or more of: electrical and thermal properties of different tissue types in the treated patient P, distributions of the different tissue types in the treated patient P, geometry of coil  20  and resulting expected field distributions, and perfusion rates in the treated patient P. 
     In some embodiments controller  24  is configured to deliver power to patient P in power-on intervals spaced apart by periods in which no or reduced RF poser is delivered to patient P. For example, controller  24  may cause signal  22 - 2  to be applied for power-on intervals having lengths in the range of a few seconds to a few minutes separated by rests in the range of a few seconds to a few minutes. Controller  24  may be configured to control durations of the power-on intervals and/or the rests. 
     In some embodiments controller  24  may be configured to discontinue a treatment when a completion criterion is satisfied (such as a certain number of power-on intervals being completed, a certain temperature being achieved in diseased tissues of patient P, a certain function of temperature being achieved in diseased tissues of patient P—e.g. a time for which the temperature exceeded a threshold or the like). 
     In some embodiments the frequency of signal  22 - 1  (and  22 - 2 ) is selected to create a standing wave in coil  20 . The selection of frequency typically depends on the characteristics of coil  20  (e.g. geometry, number of windings W) as well as the impedance of the patient P. In some embodiments the standing wave has a single electric field maximum. Coil  20  may be positioned relative to patient P to place the electric field maximum at or near diseased tissue to be treated in patient P. 
     In some embodiments the frequency of signal  22 - 2  is adjusted to be at or almost at the resonant frequency of coil  20  (including patient P). In some embodiments the frequency of the signal is adjusted to be at or almost at an integer multiple of the resonant frequency of coil  20  including patient P. The selection of frequency typically depends on the characteristics of the coil (e.g. geometry, number of windings  20 A) and the impedance of the patient P. The frequency can be calculated in advance using these parameters (e.g. by controller  24  or in a computation external to controller  24 ) and later fine-tuned by measuring the electrical field in coil  20  using a field meter. 
     The power of signal  22 - 2  applied to drive coil  20  may be selected (e.g. by controlling a gain of amplifier  25 B and/or adjusting an amplitude of signal  22 - 1 ) to deliver a prescribed amount of heating to the tissues of patient P. The power of the signal  22 - 2  applied to coil  20  may, for example, be selected based on factors such as one or more of:
         the weight of patient P;   an estimate of a weight of a part of patient P (e.g. lungs of patient P);   the height and/or girth of patient P;   RF absorption of the tissues of patient P within coil  20  (which depends mostly on the percentage of fat in the body of patient P);   the RF coupling between coil  20  and tissues of patient P (which depends on the frequency of the signals as well as the dimensions and geometry of coil  20 ); and   a measure of the pulmonary circulation of patient P.       

     In some embodiments temperature monitor  23  is of a type operable to perform non-invasive temperature sensing. For example, tissue temperatures may be measured by processing ultrasound signals or magnetic resonance imaging (MRI) signals. 
     In some embodiments the temperature measurements are performed using non-contact temperature sensing systems (e.g. processing MRI data). In some such embodiments, coil  20  is located inside the MRI system. Controller  24  may be configured to interrupt delivering signal  22 - 2  to coil  20  to permit temperature measurements to be made. 
     In some embodiments the temperature measurements are performed using an invasive temperature sensor that is placed in patient P (e.g. through a needle or catheter). 
     In some embodiments apparatus as described herein is combined with an imaging system (for example an ultrasound imaging system or MRI system). The imaging system may be used for temperature monitoring and/or for imaging patient P. 
     Where apparatus  10  is applied to treat diseased tissues in lungs of patient P, coil  20  preferably has a length sufficient that at least the lungs L of patient P are received within coil  20 . It is generally desirable that the head of patient P is shielded from radiofrequency radiation and/or outside of coil  20 . 
       FIG.  1    depicts a non-limiting example embodiment in which the length L 20  of coil  20  is close to the height of patient P. In  FIG.  1   , the windings of coil  20  extend around the body of patient P and Volume V includes the lungs L. 
     Other configurations are also possible. For example coil  20  may have a shorter length so that coil  20  receives the torso of patient P inside coil  20 . Length L 20  may be selected based on the properties of patient P. 
     Coil  20  may be circular in cross section but this is not mandatory. In some embodiments coil  20  is flattened. For example, coil  20  may have an oval or elliptical cross sectional shape. 
     In some embodiments a cross sectional shape of coil  20  is adjustable. For example, the material of coil  20  may be elastically deformable so that coil  20  may be deformed into a configuration such that the bore of coil  20  is expanded and the height of coil  20  is reduced. This may be done, for example by spreading coil  20 .  FIG.  1 C  schematically shows, spreading coil  20  by separating electrically non-conductive bars  29 . 
     In some embodiments a cross sectional shape of coil  20  is independently adjustable along the longitudinal axis of coil  20 . Such adjustment can be made depending on the properties of the patient. Adjustment of the cross-sectional shape of coil  20  may be achieved by making the turns of coil  20  of a flexible conductive material (e.g. flexible wires, flexible bars) and deforming the coil by displacing the turns of coil  20  to take on a desired shape. 
     In some embodiments the geometry of coil  20  is varied along the length of coil  20 . For example, the turns of coil  20  may be made tighter (smaller pitch distance PD between adjacent turns). For example, it may be beneficial to wind coil  20  more tightly (smaller PD) around certain areas for best results. In some embodiments, end portions of coil  20  are wound more tightly than an intermediate portion of coil  20  between the end portions. 
     Windings  20 A are spaced apart along length L 20 . Windings  20 A may be uniformly or non-uniformly spaced apart from one another (i.e pitch distance PD may be uniform or non-uniform). 
     In some embodiments the spacing between windings  20 A along the longitudinal axis of coil  20  is adjustable. In such embodiments the spacing between windings  20 A may be adjusted depending on the properties of the patient. This could be accomplished, for example, by using flexible elements, such as a coaxial network cable or other flexible wire as windings of coil  20  and supporting the windings on an adjustable frame made of material that does not absorb radiofrequency (RF) radiation. 
     In some embodiments the diameter of coil  20  varies along the length of coil  20 . 
     In some embodiments coil  20  has multi-layer windings as shown, for example in  FIG.  2     
     The technology described herein may be varied. For example, instead of a single coil  20 , apparatus as described herein may include two or more applicators that cooperate to deliver energy into the tissues of patient P. For example,  FIG.  3    shows example apparatus  40  which is like apparatus  10  except that it includes two spaced apart applicators A 1  and A 2 . Each of Applicators A 1  and A 2  is configured to wrap or partially wrap around the circumference of the torso of patient P. Applicators A 1  and A 2  may be ring shaped. Applicators A 1  and A 2  may, for example, have circular, elliptical or obround cross sections. 
     In some embodiments applicators A 1  and A 2  extend completely (360 degrees) around the torso of patient P. In some embodiments, one or both of applicators A 1  and/or A 2  extend through an angle of at least 180 degrees or at least 230 degrees or at least 250 degrees or at least 270 degrees or at least 300 degrees or at least 330 degrees relative to a point that is centered side to side and up and down inside the applicator in a plane of the applicator. In some embodiments applicators A 1  and A 2  extend circumferentially nearly around a patient P. In this disclosure. “nearly around” when applied to an applicator means that the applicator extends through an angle in the range of 180 degrees to 360 degrees relative to a point that is centered side to side and up and down inside the applicator in a plane of the applicator. 
     For example, applicators A 1  and A 2  may be made of thin electrically conductive sheets (e.g. copper foil) formed to extend around the body of patient P. 
     When an output signal  22 - 2  of a power source  25  is delivered to applicators A 1  and A 2 , varying electric fields between applicators A 1  and A 2  cause energy to be delivered to and dissipated in tissues of patient P. 
     In apparatus  40 , one or both of applicators A 1  and A 2  overlaps with a volume V within which there is tissue to be treated. In another example embodiment, applicators A 1  and A 2  are positioned symmetrically relative to a volume V that includes tissues to be treated. For example, applicator A 1  may be positioned cranially relative to a treatment volume V and applicator A 2  may be positioned caudally relative to treatment volume V. 
     In another example embodiment, applicators A 1  and/or A 2  are configured to form unclosed sections of a ring. The applicators may be connected to terminals of a power source  25 . For example, one of the applicators may be grounded and the other applicator may be connected to a terminal of a power source  25  that carries a signal  22 - 1  (e.g. a varying voltage signal). 
     The technology described herein may be further varied. For example, Apparatus  10  and Apparatus  40  may be positioned vertically rather than horizontally such that patient P stands or sits inside coil  20  or inside applicators A 1  and A 2 . This saves the need for a table for patient P to lie on and may have further advantages. 
     Further variations of the disclosed technology are also possible. For example, a coil  20  and/or applicators A 1 , A 2  may be configured to open like a clamshell to receive a patient P. Windings of a coil  20  or applicators A 1 , A 2  may be split along an opening line of the clamshell and may make electrical contact when the clamshell is closed. 
     In some embodiments a coil  20  is wound around patient P as patient P lies on a table, sits or stands. 
     In some embodiments shielding is provided to shield certain parts of the patient from RF radiation. Shielding may for example be provided by shields made of meshes, grids or continuous sheets of electrically conductive material. The shields are optionally transparent to allow viewing the shielded parts. 
     In some embodiments the entire apparatus including patient P is contained within a shielding structure such as a Faraday cage or any other enclosure made of conductive material. Such a structure may prevent radiofrequency radiation from the apparatus from interfering with other systems. A shielding structure may be continuous or made of a wire mesh. In some embodiments suitable RF shielding is embedded into or supported on walls of a room in which the apparatus is located. 
     Some embodiments comprise means for locally cooling the skin of patient P (e.g. by a flow of air, water or another liquid either directly in contact with the skin or through a bladder placed in contact with the area(s) to be cooled). Such cooling may help to protect the skin and surface tissues of patient P from being overheated, improve comfort for patient P and/or help to remove heat from the blood of patient P. 
     In some embodiments cooling is provided to areas of patient P where there is significant blood circulation close to the skin (e.g. in the area of the groin).  FIG.  2    shows a fan  33  arranged to deliver a stream of cooled air to patient P. In some embodiments patient P is supported on a cooled support (e.g. a table or mat that includes passages which carry a cooled gas or liquid or a mesh through which a cooled gas may be delivered to remove heat from the skin of patient P). 
     Signals as described herein may be delivered from their sources to their destinations in any suitable manner. For example, control signals may be carried by electrical conductors, optical conductors, wireless communication technology or the like. Power signals such as output signal  22 - 2  of a power source  25  may be delivered to a destination by suitable electrical conductors such as coaxial cables, wires, waveguides, inductive or capacitive couplings, free space transmission etc. 
     A controller  24  may be implemented by way of any suitable technology including specifically designed hardware, configurable hardware, programmable data processors configured by the provision of software (which may optionally comprise “firmware”) capable of executing on the data processors, special purpose computers or data processors that are specifically programmed, configured, or constructed to perform one or more steps in a method as explained in detail herein and/or combinations of two or more of these. Examples of specifically designed hardware are: logic circuits, application-specific integrated circuits (“ASICs”), large scale integrated circuits (“LSIs”), very large scale integrated circuits (“VLSIs”), and the like. Examples of configurable hardware are: one or more programmable logic devices such as programmable array logic (“PALs”), programmable logic arrays (“PLAs”), field programmable gate arrays (“FPGAs”) and configurable neural networks such as convolutional neural networks (“CNNs”). Examples of programmable data processors are: microprocessors, digital signal processors (“DSPs”), embedded processors, graphics processors, math co-processors, general purpose computers, server computers, cloud computers, mainframe computers, computer workstations, and the like. For example, one or more data processors in a controller  24  may implement methods as described herein by executing software instructions in a program memory accessible to the processors. 
     INTERPRETATION OF TERMS 
     Unless the context clearly requires otherwise, throughout the description and the claims:
         “comprise”, “comprising”, and the like are to be construed in an inclusive sense, as opposed to an exclusive or exhaustive sense; that is to say, in the sense of “including, but not limited to”;   “connected”, “coupled”, or any variant thereof, means any connection or coupling, either direct or indirect, between two or more elements; the coupling or connection between the elements can be physical, logical, or a combination thereof;   “herein”, “above”, “below”, and words of similar import, when used to describe this specification, shall refer to this specification as a whole, and not to any particular portions of this specification;   “or”, in reference to a list of two or more items, covers all of the following interpretations of the word: any of the items in the list, all of the items in the list, and any combination of the items in the list;   the singular forms “a”, “an”, and “the” also include the meaning of any appropriate plural forms.       

     Words that indicate directions such as “vertical”, “transverse”, “horizontal”, “upward”, “downward”, “forward”, “backward”, “inward”, “outward”, “left”, “right”, “front”, “back”, “top”, “bottom”, “below”, “above”, “under”, and the like, used in this description and any accompanying claims (where present), depend on the specific orientation of the apparatus described and illustrated. The subject matter described herein may assume various alternative orientations. Accordingly, these directional terms are not strictly defined and should not be interpreted narrowly. 
     Some aspects of the invention may also be provided in the form of a program product. The program product may comprise any non-transitory medium which carries a set of computer-readable instructions which, when executed by a data processor, cause the data processor to execute a method of the invention. For example, a program product may store computer executable instructions that, when executed by one or more processors cause the execution of one or more control methods performed by controller  24 . Program products according to the invention may be in any of a wide variety of forms. The program product may comprise, for example, non-transitory media such as magnetic data storage media including floppy diskettes, hard disk drives, optical data storage media including CD ROMs, DVDs, electronic data storage media including ROMs, flash RAM, EPROMs, hardwired or preprogrammed chips (e.g., EEPROM semiconductor chips), nanotechnology memory, or the like. The computer-readable signals on the program product may optionally be compressed or encrypted. 
     Where a component (e.g. a coil, applicator, amplifier, matching network, power source, controller, table, assembly, device, circuit, etc.) is referred to above, unless otherwise indicated, reference to that component (including a reference to a “means”) should be interpreted as including as equivalents of that component any component which performs the function of the described component (i.e., that is functionally equivalent), including components which are not structurally equivalent to the disclosed structure which performs the function in the illustrated exemplary embodiments of the invention. 
     Specific examples of systems, methods and apparatus have been described herein for purposes of illustration. These are only examples. The technology provided herein can be applied to systems other than the example systems described above. Many alterations, modifications, additions, omissions, and permutations are possible within the practice of this invention. This invention includes variations on described embodiments that would be apparent to the skilled addressee, including variations obtained by: replacing features, elements and/or acts with equivalent features, elements and/or acts; mixing and matching of features, elements and/or acts from different embodiments; combining features, elements and/or acts from embodiments as described herein with features, elements and/or acts of other technology; and/or omitting combining features, elements and/or acts from described embodiments. 
     For example, while various methods are presented as proceeding in a given sequence, alternative examples may proceed in a different sequence or perform routines having steps, or employ systems having blocks, in a different order. Steps, acts, processes or blocks may be deleted, moved, added, subdivided, combined, and/or modified to provide alternative or subcombinations. Described processes or blocks may be implemented in a variety of different ways. Also, when processes or blocks are at times shown as being performed in series, certain processes or blocks may instead be performed in parallel, or may be performed at different times. 
     Various features are described herein as being present in “some embodiments”. Such features are not mandatory and may not be present in all embodiments. Embodiments of the invention may include zero, any one or any combination of two or more of such features. All possible combinations of such features are contemplated by this disclosure even where such features are shown in different drawings and/or described in different sections or paragraphs. This is limited only to the extent that certain ones of such features are incompatible with other ones of such features in the sense that it would be impossible for a person of ordinary skill in the art to construct a practical embodiment that combines such incompatible features. Consequently, the description that “some embodiments” possess feature A and “some embodiments” possess feature B should be interpreted as an express indication that the inventors also contemplate embodiments which combine features A and B (unless the description states otherwise or features A and B are fundamentally incompatible). 
     It is therefore intended that the following appended claims and claims hereafter introduced are interpreted to include all such modifications, permutations, additions, omissions, and sub-combinations as may reasonably be inferred. The scope of the claims should not be limited by the preferred embodiments set forth in the examples, but should be given the broadest interpretation consistent with the description as a whole.