Abstract:
To treat and diagnose tissue, a radiating antenna system is positioned within the tissue to radiate electromagnetic energy into a portion of the tissue desired to be heated, and a plurality of antenna elements are positioned for receiving and/or reflecting the radiated electromagnetic energy from the radiating antenna system. In certain applications, one or more of the antennas has an interior volume for receiving a heat exchange fluid to change the temperature of the tissue proximal to the receiving element.

Description:
BACKGROUND OF THE INVENTION 
     The present invention relates to microwave devices used in medical hyperthermia and thermotherapy (referred to collectively herein as “heat therapies”) and diagnostics, and to methods of using such devices. 
     Localized heat therapies, i.e., hyperthermia (heating to temperatures below 45° C.) and thermotherapy (heating to temperatures above 45° C.), have been intensively investigated for the last two decades for many disease processes. 
     However, methods of delivering heat including warm fluid, focused ultrasound, radio frequency, and microwave approaches have been applied to abnormal tissue with only limited success. Because microwave energy can be applied with limited invasiveness, this approach is one that is currently being proposed. 
     For heat therapy to be applied safely, it is very important that the applied heat be confined to a target area alone, to avoid damaging nearby healthy tissue or organs. 
     Some devices for heat therapy have utilized microwave heating, for example, those disclosed in U.S. Pat. Nos. 4,700,716 and 4,776,086, the disclosures of which are incorporated herein by reference. Microwave energy elevates temperature by increasing the molecular motion within cell structures. As the frequency decreases, tissue penetration increases. Small diameter microwave antenna and other probes have been inserted into the body through normal body passages or, on occasion, directly into diseased tissue, using hollow plastic catheters. 
     SUMMARY OF THE INVENTION 
     The invention features a medical treatment system which utilizes microwave energy to provide heat treatment and diagnostic imaging of an arbitrarily shaped tissue mass. The term “microwave”, as used herein, refers to electromagnetic energy in the microwave frequency spectrum of about 300 MHZ to about 300 GHz. 
     In one aspect of the invention, a medical treatment system for treatment of tissue includes a radiating antenna system, positioned to radiate electromagnetic energy through the tissue, and receiving elements, each configured to be positioned within or on the periphery of the tissue to receive at least a portion of the radiated electromagnetic energy from the radiating antenna system to the tissue. Each receiving element has an interior volume for receiving a heat exchange fluid to change the temperature of the tissue proximal to the receiving element. 
     In another aspect of the invention, a medical treatment system for treatment of tissue includes a radiating element system, positioned to radiate electromagnetic energy through the tissue, and reflecting elements, each configured to be positioned within or on the periphery of the tissue to reflect at least a portion of the radiated electromagnetic energy from the radiating antenna system to the tissue. 
     The inventions have numerous advantages. The radiated energy from the radiating antenna system is used to heat a desired area of tissue and the receiving elements are positioned to operate as “heat pipes”, which act as a source or sink for the heated tissue. In addition, the individual receiving elements receive the radiated energy and provide signals which together provide an image and a property map of the area of tissue defined by the positioning of the elements. Thus, the receiving elements improve control of the temperature of the volume of the tissue mass being radiated by the radiating antenna system. With this arrangement a safer, more efficacious delivery of microwave energy is provided. It is important to recognize that although the receiving elements serve as “heat pipes”, in operation, they can provide both heating as well as cooling, depending on whether the fluid (e.g., liquid or gas) flowing through the heat pipe structure is hot or cold. 
     Embodiments of these aspects of the invention may include one or more of the following features. 
     At least one of the reflecting elements can include an interior volume for receiving a heat exchange fluid to change the temperature of the tissue proximal to the reflecting element. 
     One (or more) of the receiving and/or reflecting elements has a conduit for conveying the heat exchange fluid from a heat exchanger to a distal end of the receiving element. The receiving and/or reflecting element also has a transmission line extending from the distal end to a proximal end of the receiving and/or reflecting element. The conduit extends through the transmission line and forms a hollow center conductor of the transmission line. The transmission line also has an outer shield which is coaxial with respect to the conduit. The interior volume of the receiving and/or reflecting element and the conduit are sized to cause capillary action of fluid flowing between the internal volume and the conduit. The heat exchanger can include a condenser and the heat exchange fluid can be a coolant. 
     One or more of the receiving and/or reflecting elements has a temperature detector for sensing the temperature at a location proximate to that receiving element. In response to the sensed temperature, the detector provides signals for controlling the amount of fluid delivered to the interior volume of the receiving and/or reflecting element by the heat exchanger. 
     A measurement analyzer, connected to one (or more) of the receiving and/or reflecting elements, measures electrical characteristics associated with the receiving and/or reflecting element. These electrical characteristics include amplitude and phase voltage characteristics. The electrical characteristics can also be magnitude and phase of S 12  scattering parameter between the radiating antenna system and the receiving and/or reflecting element. A processor processes the measured electrical characteristic to generate an image of the tissue, and a display then displays the generated image. 
     One (or more) of the receiving and/or reflecting elements and the antenna system can be configured to deliver a material to the tissue. The material can be a chemotherapeutic agent, a heat sensitizer, or a cyropreservative. 
     At least one of the receiving elements includes a reflecting structure for reflecting the radiated electromagnetic energy from the radiating antenna system in a desired direction, thereby increasing the uniformity of the radiation applied to the targeted tissue. 
     The radiating antenna system has a plurality of antennas in the form of a collinear array. The radiating antenna system is configured to be received within the tissue to be treated. 
     A cannula is provided to receive the radiating antenna system within its inner lumen. The radiating antenna system includes antennas, each in the form of a collinear array. 
     The electromagnetic energy is radiated at a frequency in a range between 0.3 and 10 GHz, and at a power level in a range between about 100 mwatts and 150 watts. 
     In another aspect of the invention, a method of treating tissue is provided where a radiating antenna system is positioned within the tissue to radiate electromagnetic energy into a portion of the tissue desired to be heated, and receiving elements are positioned for receiving the radiated electromagnetic energy from the radiating antenna system with each receiving element positioned so that the path of received energy is through the portion of the tissue desired to be heated. 
     In still another aspect of the invention, a method of treating tissue is provided where a radiating antenna system is positioned within the tissue to radiate electromagnetic energy into a portion of the tissue desired to be heated, and reflecting elements are positioned for reflecting the radiated electromagnetic energy from the radiating antenna system toward the tissue to be treated. 
     With respect to these methods of treating tissue, the receiving and/or reflecting elements can be substantially positioned around a periphery of the portion of the tissue desired to be heated. The temperature proximate to at least one of the receiving and/or reflecting elements is sensed and, in response to the sensed temperature, the amount of fluid delivered to an interior volume of the receiving and/or reflecting elements is controlled. 
     Other features and advantages of the invention will be apparent from the drawings, the following Detailed Description, and the claims. 
    
    
     BRIEFED DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a schematic diagram of one embodiment of a tissue treatment and diagnosis system, showing three receiving microwave probes and one radiating microwave probe. 
     FIG. 2 is a diagrammatic view of the positions of the receiving microwave probes and the radiating microwave probe relative to a tissue mass under treatment. 
     FIG. 3 is a cross-sectional side view of a receiving antenna of one of the receiving microwave probes. 
     FIG. 4 is a schematic diagram showing the circuitry of a diagnosis and treatment station of tissue treatment and diagnosis system of FIG.  1 . 
     FIGS. 5A-5C are diagrammatic views of exemplary positions of the receiving probes and the radiating probe relative to different tissue masses under treatment. 
    
    
     DETAILED DESCRIPTION 
     Referring to FIG. 1, microwave treatment and diagnosis system  1  includes at least one radiating microwave probe  10 , at least two receiving microwave probes  12 , a diagnosis and treatment station  14 , and a monitor  14 ′. Receiving microwave probes  12  are configured and operated to act as “heat pipes.” Hence, each one of receiving microwave probes  12  serves as a source or sink for thermal energy at the interface of that receiving microwave probe  12  and the adjacent tissue, resulting in a greater control of temperature at the interface. It is important to note that although receiving microwave probes  12  are said to act as heat pipes, receiving microwave probes  12  can cool as well as heat a targeted tissue. This allows for further control of temperature at the interface. 
     Referring to FIG. 2, diagnosis and treatment station  1  allows diagnosing and applying heat therapy to a tissue mass  11  of arbitrary shape (here, a tumor in a patient&#39;s kidney  13 ). In particular, radiating microwave probe  10  and receiving microwave probes  12  are inserted into kidney  13  and positioned relative to one another so that electromagnetic energy travels through tissue mass  11  from radiating microwave probe  10  to receiving microwave probes  12 . Therefore, as radiating microwave probe  10  radiates microwave electromagnetic energy, tissue mass  11  is heated. As can be seen in FIG. 2, radiating microwave probe  10  and receiving microwave probes  12  each extend to radiating probe contacts  10   a  and receiving probe contacts  12   a , which, in use, are attached to the skin. Lead wires  15  connect probe contacts  10   a ,  12   a  to diagnosis and treatment station  14 . 
     Receiving microwave probes  12  perform multiple functions. Because of their heat pipe structure, receiving microwave probes  12 , under control of diagnosis and treatment station  14 , act as heat sinks at the boundary of tissue mass  11 . Hence, depending on their number and positioning relative to tissue mass  11 , receiving microwave probes  12  can substantially limit heating to tissue mass  11 . In effect, based on their positioning within the tissue, receiving microwave probes  12  can be used to define any arbitrary area within the tissue, and limit heat therapy substantially to that arbitrary area. 
     In addition, receiving microwave probes  12  act as antennas receiving radiated electromagnetic energy. Characteristics of the electromagnetic energy received at receiving microwave probes  12  depend on characteristics of tissue mass  11 . Hence, for diagnosis, the characteristics of the received electromagnetic energy are measured by diagnosis and treatment station  14 . Based on that measurement, diagnosis and treatment station  14  determines the characteristics of tissue mass  11  and can also generate an image of the tissue mass  11 . 
     We will now describe in detail an embodiment of microwave treatment and diagnosis system  1 . Referring to FIG. 1, each one of receiving microwave probes  12  includes a receiving antenna  20  deployed within a cannula  22 . (The term “cannula” is intended to include all cannula-like structures, whether rigid or flexible, including catheters.) Receiving antenna  20  is configured not only to receive the microwave energy radiated by radiating microwave probe  10 . Cannula  22  is constructed to be inserted into a portion of the body, typically through a body opening or passage, a small incision, or by using an internal stylet, as will be described in detail below. Receiving microwave probes  12  are preferably sized to have a diameter of 5-16 French (F.) and a length of approximately 1-18 cm. 
     FIG. 3 shows a detailed diagram of the structure of receiving antenna  20 . Receiving antenna  20  includes an antenna portion  30  connected via a coaxial transmission line  32  to diagnosis and treatment station  14 . 
     Antenna  20  further includes an RF reflector  34  and an RF director  36 , located at the end of dielectric members  38  and  40 , respectively. RF reflector  34  and RF director  36  are constructed by forming a metallic coating on dielectric members  38  and  40 . RF reflector  34  and RF director  36  serve to improve the gain of antenna portion  30  by forming a three element Yagi array. The length of RF reflector  34  is generally commensurate with, or longer than, the length of antenna portion  30 , while the length of director  36  is generally shorter (e.g., 75% of antenna length). 
     Reflector  34 , in addition to increasing the gain of antenna portion  30 , reflects microwave electromagnetic energy from radiating microwave probe  10  back towards the tissue. Reflector  34  can be differently shaped, such as having semi-cylindrical shape, to better reflect microwave electromagnetic energy back towards the tissue. 
     Thus, with their reflectors and directors, each one of receiving microwave probes  12  reflect the radiated energy back towards tissue mass  11 . In combination, all of the receiving microwave probes  12  cause multiple reflections within tissue mass  11 . The result of the multiple reflections is similar to a result of a microwave resonant cavity i.e., the multiple reflections increase the uniformity of the heat applied to the tissue mass. 
     Receiving antenna  20  is shown in FIG. 3 as being configured for providing heat pipe temperature control. Receiving antenna  20  includes antenna portion  30 , a heat exchanger  56  and a flexible RF coaxial transmission line  32  connecting antenna portion  30  to diagnosis and treatment station  14 . Antenna portion  30  is formed by a hollow conductive pipe  60  and a dielectric sheath  70  extending substantially the entire length of the conductive pipe. Conductive pipe  60  is one part of coaxial transmission line  32  for transmitting energy from antenna portion  30  to diagnosis and treatment station  14 . At diagnosis and treatment station  14 , antenna portion  30  can be selectively either grounded or open circuited. 
     When used as a heat pipe, conductive pipe  60  also functions as a capillary wick for a liquid or gas  62  passing therethrough. The capillary action is accomplished by having a relatively larger diameter portion  66  at antenna portion  30  to provide evaporative cooling, and a relatively smaller diameter “wick” portion  67  extending between portion  66  and heat exchanger  56 . Larger diameter portion  66  is approximately λ/2 in length. At a junction  71 , wick portion  67  extends beyond transmission line  32  to the heat exchanger  56  in the form of a dielectric tube  69 . 
     When used in applications where cooling is required, heat exchanger  56  acts as a condenser having a refrigerant (e.g., cryogenic fluid). A pressure mechanism  140  under the control of diagnosis and treatment station  14  is used to control the amount and rate at which the fluid is delivered to antenna portion  30 . 
     Receiving antenna  20  also includes several temperature sensors positioned at various points within receiving antenna  20 . In particular, a temperature sensor  42  is placed on RF reflector  34 . Another temperature sensor  44  is placed on RF director  36 . Other temperature sensors (not shown) can also be placed along the walls of receiving antenna  20  or cannula  22 . Sensors  42 - 44 , and the other temperature sensors in receiving antenna  20 , can be in the form of fiber optic sensors surrounded by a dielectric outer envelope. One example of a fiber optic sensor of this type is described in U.S. Pat. No. 4,700,716. 
     Antenna portion  30 , RF reflector  34 , and RF director  36  are fixed in position by potting them in a solid material within a tube (not shown), for example, by placing them in a tube and filling the tube with liquid, hardenable TEFLON® polymer. The tube can then be easily inserted into the cannula  22  for use by a physician. 
     Receiving antenna  20  also includes a transformer  54  provided by the combination of conductive pipe  60 , an outer conductive coaxial sheath  64 , dielectric sheath  70 , and a metallic cylinder  73 . Outer conductive coaxial shield  64  surrounds dielectric sheath  70  and extends along the length of conductive pipe  60  until terminating at a point just before larger diameter portion  66 . Metallic cylinder  73  is approximately one-quarter wavelength in length and covers outer conductive coaxial shield  64 , thereby electrically shorting the pair of members at point A. This electrical short presents an effective open circuit (high impedance) along the transmission line one-quarter wavelength away from the short. 
     Transformer  54  minimizes the reflected power seen by receiving element  30 . Equally important, transformer  54  also prevents leakage of antenna currents along the outside structure of antenna  20 . By appropriate selection of operating parameters, transformer  54  can be designed to provide both a minimum reflection coefficient as well as minimum leakage within the same frequency range. 
     Having described receiving microwave probes  12 , we will now describe in general terms radiating microwave probe  10 . A detailed description of radiating antenna probe  10  can be found in U.S. patent application Ser. No. 09/248,165, filed Feb. 9, 1999, incorporated herein by reference (hereinafter, referred to as “the &#39;165 application”). Referring back to FIG. 1, radiating microwave probe  10  includes a collinear antenna  16  having a set of radiating antennas  16 A,  16 B,  16 C deployed within a cannula  18 . Cannula  18  is constructed to be inserted into a portion of the body, typically through a body opening or passage, a small incision, or by using internal stylets. Cannula  18  is preferably sized to have a diameter of 1-3 mm and a length of 2-6 cm. 
     The amplitude and phase of the radiation from each one of radiating antennas  16 A,  16 B,  16 C is independently controlled by diagnosis and treatment station  14 , so that their respective electromagnetic fields constructively add within, and subtract outside, a targeted tissue mass With this approach, a radiation pattern with desired narrow beamwidth and direction provides relatively high temperature and a focused heating to the tissue mass. Additionally, radiating antennas  16 A,  16 B,  16 C can also have a heat pipe structure similar to receiving microwave probes  12 , thereby improving the temperature control at the interface of radiating microwave probe  10  with the targeted area. Radiating antennas  16 A,  16 B,  16 C thereby can have the same structure as that shown in FIG. 3 for receiving element  30 , except that antenna portion  30  would be optimized for transmission rather than reception. 
     Referring to FIG. 4, diagnosis and treatment station  14  includes a microprocessor  102 , a memory unit  104 , and a bus  106 . Diagnosis and treatment station  14  also includes three subsystems for connection to radiating and receiving microwave probes  10  and  12 . These subsystems are the power and measurement subsystems S 1 , temperature control units S 2 , and pressure mechanisms S 3 . Each of these subsystems are connected to bus  106  and are under control of application programs stored in memory unit  104  and executed by microprocessor  102 . These subsystems will be shown and described as having connections for four devices, although other embodiments can include more connections. 
     Power and measurement subsystems S 1  include an output port  86  coupled to a microwave power source  88  capable of, for example, providing approximately 5-25 watts of continuous wave power at 915 MHZ or 2450 MHZ to radiating microwave probe  10 . Port  86  is coupled to power source  88  through a bidirectional coupler  90 A. A fraction (e.g., 20 dB) of the microwave power source  80  is tapped from couplers  90 B,  90 C,  90 D and provided to vector voltmeter (or measurement analyzer)  92  through a sequence of rotary switches  94 ,  96 ,  98 . Note that power source  88  is capable of driving antennas  16 A,  16 B,  16 C of radiating microwave probe  10  independent of one another. 
     Power and measurement subsystems S 1  also includes several input ports  80 ,  82 ,  84  for connection to receiving microwave probes  12 . Input ports  80 ,  82 ,  84  are coupled to electronic switches  91 A,  91 B,  91 C through bi-directional coupler  90 B,  90 C,  90 D, respectively. A fraction (e.g., 20 dB) of the microwave energy received at each one of receiving microwave probes  12  is tapped from couplers  90 B,  90 C,  90 D and provided to vector voltmeter  92  through rotary switches  94 ,  96 ,  98 . A switch controller  100  is used to select one of ports  80 ,  82 ,  84 ,  86  being examined at any given time. A  30 dB attenuator is connected at the output of rotary switch  98  to protect vector voltmeter  92  from excessive power levels. Electronic switches  91 A,  91 B,  91 C, under control of application programs running on microprocessor  102 , can either connect an antenna of a receiving microwave probe to ground or allow the antenna to be open circuited. 
     Temperature control units S 2  include ports  110 ,  112 ,  114 ,  116 , each of which is connected, respectively, to a dedicated temperature control unit  120 ,  122 ,  124 ,  126 . Each one of temperature control units  120 ,  122 ,  124 ,  126  is connected to bus  106  and is under control of application programs running on microprocessor  102 . Each one of ports  110 ,  112 ,  114 ,  116  is connected to temperature sensors in one of the receiving microwave probes  12  or radiating microwave probe  10 . Temperature control units S 2  provide signals to microprocessor  102  indicative of the temperature at the probes. 
     Pressure mechanisms S 3  include ports  130 ,  132 ,  134 ,  136  for connection to conductive pipes  60  of receiving microwave probes  12 . If one or more of antennas  16 A,  16 B,  16 C of radiating microwave probe  10  are configured as a heat pipe, then those antennas can also be connected to one of ports  130 ,  132 ,  134 ,  136 . Each one of ports  130 ,  132 ,  134 ,  136  is coupled to a dedicated pressure mechanism  140 ,  142 ,  144 ,  146 , respectively. Each one of pressure mechanisms  140 ,  142 ,  144 ,  146  is in turn connected to bus  106  and is under control of application programs executed by microprocessor  102 . 
     We will now describe the operation of microwave diagnosis and treatment system  1 . Referring to FIGS. 1-4, briefly, during operation, radiating microwave probe  10  is positioned and operated within tissue to radiate microwave electromagnetic magnetic energy towards two or more receiving microwave probes  12  through a targeted area of the tissue. The radiated electromagnetic energy can have a frequency in a range between about 0.3 and 10 Ghz, and a power level in a range between about 1 mwatts and 150 watts. Preferably, the radiated electromagnetic energy has a frequency of 915 MHZ or 2450 MHZ, at a power level of about 5-25 watts. Microwave receiving probes  12  are positioned within the tissue to receive and reflect back toward the targeted area the radiated electromagnetic energy. 
     Diagnosis and treatment station  14  controls the heat treatment applied by radiating and receiving microwave probes  10  and  12 , and performs tissue diagnostic and inquiry operations. 
     During heat treatment of a targeted area, in response to electrical signals from temperature control unit S 2 , diagnosis and treatment station  14  controls power source  88  of power and measurement analysis subsystems S 1  to generate electrical signals with the appropriate amplitude and phase characteristics so that radiating microwave probe  10  provides a focused beam in the direction of the targeted area. 
     Additionally, based on the signals indicative of the temperatures at radiating and receiving microwave probes  10  and  12 , diagnosis and treatment station  14  controls pressure mechanisms S 3  to convey heating or cooling fluid within antenna portion  30  of receiving microwave probes  12  to allow rapid and precise adjustment of the temperature at the interface between the antenna portions  30  and surrounding material. Hence, diagnosis treatment station  14  regulates heat at the boundary of a targeted tissue mass to ensure that heating applied to the tissue is substantially limited to the targeted tissue mass. One technique for achieving increased control over the applied heat is to simultaneously apply heat and cold to the tissue. Further details concerning the thermodynamic operation of heat pipes suitable for use in antenna  20  are described in U.S. Pat. No. 5,591,162, entitled “Treatment Method Using a Micro Heat Pipe Catheter”, which is incorporated herein by reference. 
     As stated above, diagnosis and treatment station  14  also performs diagnostic functions. To do so, vector voltmeter  92  intermittently between heat applications measures amplitude and phase of the voltage induced on the receiving microwave probes  12 . Application programs running on microprocessor  102  use the results of these measurements to determine magnitude and phase of a S 12  scattering parameter between the electromagnetic energy radiated by radiating microwave probe  12 . The measured value of the S 12  scattering parameter is directly related to physical and electrical properties of a portion of the targeted tissue mass lying between the two probes, including its density and water content, polarization qualities, electrolyte composition, reflectance, blood flow velocity, and changing electrical properties over time. Another parameter that can measured is the input impedance of the radiating probe  10 . 
     The measured values can then be displayed to the user. These measured values, together with other measurements, such as variance in phase and magnitude of signals received at the various receiving microwave probes  12 , can be used to construct an image of the tissue under examination using conventional microwave tomography techniques. One technique for doing so is to change the position of radiating microwave probe  10  in a predetermined manner and to measure the various parameters as the position of the probe changes. In addition, measurements at low power levels can be taken and then compared to measurements at higher power levels, the results indicating the change in characteristics of the tissue as the tissue is heated. Diagnosis and treatment station  14  can then use these measurements to construct an image of the tissue under examination. 
     It should be noted that, when one of receiving microwave probes  12  is not providing signal information with respect to the voltages induced at its antenna, that probe can be used to act substantially as a reflector by allowing the antenna to be open circuited, substantially as a heat pipe by grounding the antenna, or as both. 
     In addition, diagnosis and treatment station  14  can display continuous readings of temperature changes at boundaries of a simulated or an ultrasound image of the targeted tissue mass. A schematic template of the targeted tissue mass representing the anatomy can be displayed with superimposed different colors representing different temperature ranges at different regions of the targeted area. Similarly, real-time or pre-recorded fluoroscopy, CAT scan, MRI, or ultrasound images can be superimposed with different colors representing different temperature ranges at different regions of the targeted area. Thus, the therapist or surgeon is able to determine, in real time, the target site and the effectiveness in applying heat from the system. Monitor  14 ′ can display the temperature detected by each of the sensors as a function of time and provide beginning and end points for the treatment. 
     Based on signals received from the sensors, diagnosis and treatment station  14  is capable of issuing warning messages to be displayed on monitor  14 ′ when temperatures exceed predetermined threshold values. Diagnosis and treatment station  14  may also automatically shutdown power source  88  if, for example, the temperatures remain high for an unacceptable time period or if a fault is detected in the system. Diagnosis and treatment station  14  also includes memory for storing statistical data including patient information, current laboratory data, as well as all data collected during the procedure. 
     FIGS. 5A-5C show examples of manners in which radiating and receiving probes  10  and  12  can be positioned relative to one another and various targeted tissue areas  11 . A physician can determine the optimum positioning based on the nature of the tissue to be treated, ease of access to that tissue, and the desired treatment. Note that broken lines in FIGS. 5B and 5C indicate targeted tissue masses defined by receiving microwave probes  12 . 
     To position transmitting and receiving microwave probes  10 ,  12  within the body, various techniques may be used. For example, radiating and receiving microwave probes  10  and  12  can be positioned under the guidance of ultrasound, X-Ray, CAT scan, or fluoroscopy through natural body passages or openings, or small incisions, depending on the targeted tissue mass. In addition, endoscopes can be used to direct and/or deliver the probes to the targeted tissue mass. Alternatively, internal stylets can be used to deliver the probes. Radio-opaque internal stylets can be used to puncture the tissue and to enter into the patients body under guidance of guidance of ultrasound or fluoroscopy. After delivering the probes, the stylets can be removed. 
     Transmitting and receiving microwave probes  10 ,  12  can be used for various types of therapy. For example, transmitting and receiving microwave probes  10 ,  12  can be used to treat malignant and benign tumors, cysts, inflammatory conditions (hyperthermic low temperatures), rheumatic conditions and joint involvement (hyperthermic low temperatures), and muscle injuries. When treating cysts (such as hydrocoeles, spermatocoeles, or renal cysts), transmitting microwave probe  10  can be inserted into the cysts and heat the fluid therein to destroy the lining cells to reduce the mass of the cyst. Receiving microwave probes  12  can be located on the outside of the cysts to act as heat sinks and to reflect the microwave energy back toward the cyst. 
     Transmitting and receiving microwave probes  10 ,  12  can also be used to create a thrombus in an artery to occlude, for example, by inserting transmitting microwave probe  10  at a desired point and heating that point to cause localized clotting. Receiving microwave probes  12  enhance the localization of the applied heat. Transmitting and receiving microwave probes  10 ,  12  can also be used to locally heat infected tissue (e.g., cystitis or prostatitis) to destroy or hinder the infecting bacteria or viruses. 
     In body openings such as the bladder, transmitting microwave probe  10  can be inserted into the opening and receiving microwave probes  12  can be inserted to be located on the walls of the opening. The lining cells, which could be pathologic with a thin layer of widespread tumor, infection, or inflammation, can then be treated. 
     Transmitting and receiving microwave probes  10 ,  12  can be used for adjunctive therapies to increase effectiveness of other types of therapy such as chemotherapy and radiation therapy. 
     Other embodiments are within the scope of the claims. 
     For examples, receiving and transmitting microwave probes  10 ,  12  may be configured for delivering chemotherapeutic agents, heat sensitizers or cyropreservatives to the tissue. The delivered material can work synergistically with the microwave treatment. Chemotherapeutic agents may be better absorbed by heated tissue and tumor. Heat sensitizers allow to have an equivalent effect at a lesser power. Cyropreservatives allow a lower temperature to be attained before the tissue is destroyed by cellular ice crystallization. 
     In some embodiments of the receiving and transmitting microwave probes  10 ,  12  may be configured to not apply heat or cold to tissue adjoining portions of the probe. For example, one side of the heat pipe may be covered by insulating material so as to protect the tissue at that side of the probe. Such insulating material would then protect healthy tissue at one side of probe, while not affecting the heat or cold applied to the tissue to be treated. 
     In some embodiments, passive reflectors sized and configured to have contours of parts of the patient&#39;s body (e.g., breast or knee) may be used to enhance reflection and focusing microwave energy in parts of the body.