Abstract:
An electrosurgical energy generator apparatus includes a microwave generator configured to supply microwave energy and an RF generator configured to supply RF energy. A power supply is coupled to the microwave generator and the RF generator and is configured to supply power to each of the microwave and RF generators. A first output is coupled to the microwave generator and is configured to deliver microwave energy. A second output is coupled to the RF generator and is configured to deliver RF energy.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a Continuation Application of Ser. No. 10/272,314 with claims the benefit of and priority to U.S. Pat. No. 7,197,363, filed Oct. 15, 2002, which claims the benefit of priority of U.S. Provisional Patent Application Ser. No. 60/373,190 filed Apr. 16, 2002, the entirety of both of which is incorporated herein by reference. 
    
    
     FIELD OF THE INVENTION 
     The invention relates generally to microwave antenna probes which may be used in tissue ablation applications. More particularly, the invention relates to microwave antennas which have curved configurations for insertion into tissue. 
     BACKGROUND OF THE INVENTION 
     In the treatment of diseases such as cancer, certain types of cancer cells have been found to denature at elevated temperatures which are slightly lower than temperatures normally injurious to healthy cells. These types of treatments, known generally as hyperthermia therapy, typically utilize electromagnetic radiation to heat diseased cells to temperatures above 41° C. while maintaining adjacent healthy cells at lower temperatures where irreversible cell destruction will not occur. Other procedures utilizing electromagnetic radiation to heat tissue also include ablation and coagulation of the tissue. Such microwave ablation procedures, e.g., such as those performed for menorrhagia, are typically done to ablate and coagulate the targeted tissue to denature or kill it. Many procedures and types of devices utilizing electromagnetic radiation therapy are known in the art. Such microwave therapy is typically used in the treatment of tissue and organs such as the prostate, heart, and liver. 
     One non-invasive procedure generally involves the treatment of tissue (e.g., a tumor) underlying the skin via the use of microwave energy. The microwave energy is able to non-invasively penetrate the skin to reach the underlying tissue. However, this non-invasive procedure may result in the unwanted heating of healthy tissue. Thus, the non-invasive use of microwave energy requires a great deal of control. This is partly why a more direct and precise method of applying microwave radiation has been sought. 
     Presently, there are several types of microwave probes in use, e.g., monopole, dipole, and helical. One type is a monopole antenna probe, which consists of a single, elongated microwave conductor exposed at the end of the probe. The probe is sometimes surrounded by a dielectric sleeve. The second type of microwave probe commonly used is a dipole antenna, which consists of a coaxial construction having an inner conductor and an outer conductor with a dielectric separating a portion of the inner conductor and a portion of the outer conductor. In the monopole and dipole antenna probe, microwave energy generally radiates perpendicularly from the axis of the conductor. 
     Because of the perpendicular pattern of microwave energy radiation, conventional antenna probes are typically designed to be inserted directly into the tissue, e.g., a tumor, to be radiated. However, such typical antenna probes commonly fail to provide uniform heating axially and/or radially about the effective length of the probe. 
     It is especially difficult to assess the extent to which the microwave energy will radiate into the surrounding tissue, i.e., it is difficult to determine the area or volume of surrounding tissue which will be ablated. Furthermore, when conventional microwave antennas are inserted directly into the tissue, e.g., cancerous tissue, there is a danger of dragging or pulling cancerous cells along the antenna body into other parts of the body during insertion, placement, or removal of the antenna probe. 
     One conventional method for inserting and/or localizing wires or guides is described in U.S. Pat. No. 5,221,269 entitled “Guide for Localizing a Nonpalpable Breast Lesion” to Miller et al. which is incorporated herein by reference in its entirety. Miller describes a wire guide which is delivered into breast tissue through a tubular introducer needle. When deployed, the wire guide cuts into and scribes a helical path about the tissue distal to a lesion while the remainder of the distal portion of the wire guide follows the path scribed by the distal tip and locks about the tissue. However, Miller does not teach any structures for curved microwave antennas or their methods of use for surrounding predetermined regions of tissue for treatment. 
     U.S. Pat. No. 5,507,743 entitled “Coiled RF Electrode Treatment Apparatus” to Edwards et al., which is incorporated herein by reference in its entirety, describes an RF treatment apparatus for hyperthermia at low temperature which is also able to effect microwave treatment via an RF indifferent electrode which forms a helical structure. However, the electrode, which is deployed from an introducing catheter, comprises a hollow tubular structure with fluid ports defined along the structure. 
     Accordingly, there remains a need for a microwave antenna which overcomes the problems discussed above. There also exists a need for a microwave antenna which can be inserted into tissue and which produces a clearly defined area or volume of ablation. Moreover, there is also a need for a microwave antenna which can ablate an area or volume of tissue without ever having to directly contact the ablated tissue. 
     SUMMARY OF THE INVENTION 
     A microwave ablation device is described below which is able to clearly define an ablation region by having the antenna surround at least a majority of the tissue to be ablated without the need to actually penetrate or contact the targeted region of tissue. This is accomplished in part by a microwave antenna probe which has a curved antenna portion ranging in size anywhere from several millimeters to several centimeters depending upon the size of the tissue to be treated. Various conductive materials may be used to fabricate the antenna, such as stainless steel or Nitinol. Moreover, a dielectric coating may be placed over at least a majority of curved antenna to aid with the insertion of the antenna into the tissue as well as to aid in preventing the tissue from sticking to the antenna. 
     The curved antenna portion is preferably curved to form a loop or enclosure which is selectively formed large enough for surrounding a region of tissue. When microwave energy is delivered through the feedline, any part of the feedline or antenna that completes the enclosure becomes part of the radiating portion. Rather than radiating directly along the length of the antenna, as one skilled in the art would normally expect, the curved configuration forms an ablation field or region defined by the curved antenna and any tissue enclosed within the ablation region becomes irradiated by the microwave energy. Thus, the curved antenna also serves as a boundary which is able to clearly define what tissue will be irradiated, thereby reducing the amount of undesirable damage to healthy surrounding tissue. Furthermore, the curved antenna also defines a predictable region of tissue outside the irradiated zone which will also be irradiated. This margin of tissue is generally very predictable and serves to treat the tissue a short distance outside the ablation region to ensure complete treatment of the area. 
     The curved antenna may be formed into a variety of shapes so long as the antenna preferably forms a substantially enclosed loop or enclosure, i.e., the curved antenna surrounds at least a majority of the tissue to be enclosed. Accordingly, the antenna may be formed into shapes such as circles, ellipses, spirals, helixes, squares, rectangles, triangles, etc., various other polygonal or smooth shapes, and partial forms of the various shapes so long as a majority of the enclosed tissue is surrounded. The curved antenna may be looped or wound about the selected tissue region anywhere from about 180° to 360° or greater, relative to a central point defined by the curved antenna. The curved antenna is preferably wound at an angle greater than 180°. 
     Multiple curved antennas may be used in conjunction with one another by positioning separate antennas adjacently or at different angles depending upon the size and shape of the tissue to be treated. Moreover, other variations on the curved antenna may have a single antenna body or feedline with multiple curved antennas extending therefrom. 
     To facilitate desirable placement and positioning of multiple antennas within the tissue to be treated, various alignment assembly devices may be utilized. Such alignment devices may be used to align and securely position the antennas to form various ablation region depending upon the desired results. Furthermore, the various alignment devices may be used to align and position a single antenna or a plurality of antennas deployed during a procedure. 
     Deployment and positioning of the microwave antennas may also be achieved through one of several different methods. For instance, antennas may be positioned within the tissue using introducers and wires for guiding placement of the antennas. Alternatively, other methods may involve using RF energy to facilitate deployment within the tissue. The microwave antenna is preferably insulated along most of its length, but the distal tip may be uninsulated such that the RF energy may be applied thereto to provide a cutting mechanism through the tissue. The generator used to supply the RF energy may be a separate unit or it may be integrated with the microwave energy generator within a single unit. 
     Moreover, another variation which may be utilized involves creating multiple channels from a single unit by multiplexing and cycling the output. This is particularly useful when using multiple microwave antennas. A channel splitter assembly may be used to create multiple channels by using a single source. Any number of multiple outputs may be used depending upon the desired number of channels and the desired effects. Additionally, the rate of cycling may range anywhere from several microseconds to several seconds over a treatment period of several minutes or longer. 
     Additional features may also be employed, e.g., to enhance the safety of the microwave antennas. For instance, a connection mechanism may allow for antenna connection with an outer shell of a conventional or custom connector. Such a feature may be configured to allow an electrical connection upon fill deployment of the inner conductor of the curved antenna and no electrical connection during antenna deployment. 
     Furthermore, the curved shape of the antenna may allow for various applications within the body aside from tumor ablation. For instance, the curved antenna may be used to treat or seal, e.g., aneurysms, malfunctioning vessels, fistulas, bone metastases, etc., among other conditions or regions of the body. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1A  shows a variation of a microwave antenna assembly having a curved antenna. 
         FIG. 1B  shows a cross-section of the feedline from the antenna assembly of  FIG. 1A . 
         FIGS. 1C and 1D  show cross-sectional and end views, respectively, of a variation of the feedline having plated conductive layers to increase energy transmission. 
         FIGS. 2A to 2G  show different variations which the curved microwave antenna may embody. 
         FIGS. 2H to 2M  show different variations of the microwave antenna with variable antenna lengths. 
         FIG. 2N  shows a variation of the microwave antenna having an inflatable balloon disposed about the curved antenna for changing the effective microwave wavelength. 
         FIGS. 2O and 2P  show another variation of the microwave antenna having a helical antenna portion. 
         FIG. 2Q  shows the antenna variation from  FIGS. 20 and 2P  inserted into breast tissue and surrounding a tumor. 
         FIG. 3A  shows one variation for using multiple curved antennas which are adjacent to one another. 
         FIGS. 3B and 3C  show isometric and end views, respectively, of another variation for using multiple curved antennas to form a cage-like ablation device. 
         FIG. 4  shows another variation for using multiple curved antennas in which the antennas approach the region of tissue from different locations and angles. 
         FIGS. 5A and 5B  show isometric and end views, respectively, of an antenna having a single feedline with multiple antenna loops extending therefrom. 
         FIGS. 6A to 6C  show side, top, and end views, respectively, of an antenna guide assembly variation which may be used to align microwave antennas. 
         FIGS. 7A and 7B  show isometric exploded and assembly views, respectively, of the guide assembly variation of  FIGS. 6A to 6C . 
         FIGS. 8A and 8B  show isometric and end views, respectively, of the antenna guide assembly of  FIGS. 6A to 6C  having microwave antennas positioned within. 
         FIGS. 9A to 9C  show side, top, and end views, respectively, of another variation of antenna guide assembly which may be used to align microwave antennas. 
         FIGS. 10A and 10B  show isometric exploded and assembly views, respectively, of the guide assembly variation of  FIGS. 9A to 9C . 
         FIGS. 11A and 11B  show isometric and end views, respectively, of the antenna guide assembly of  FIGS. 9A to 9C  having microwave antennas positioned within. 
         FIGS. 12A to 12C  show variations on different methods of attaching a curved microwave antenna. 
         FIGS. 13A to 13G  show one variation on deploying and positioning a curved microwave antenna about a tissue region of interest. 
         FIGS. 14A and 14B  show another variation on deploying the curved microwave antenna about a tissue region of interest in which a wire and tube member may be deployed simultaneously. 
         FIG. 14C  shows another variation on deploying the curved microwave antenna about a tissue region of interest in which the inner conductor and dielectric coating may be deployed together as a single unit within the tissue. 
         FIGS. 15A and 15B  show another variation on deploying the curved microwave antenna about a tissue region of interest in which the tube member may be used as an insulator during microwave treatment. 
         FIGS. 15C and 15D  show another variation on deploying the curved microwave antenna about a tissue region of interest in which the antenna is partially assembled in situ prior to microwave treatment. 
         FIGS. 15E and 15F  show another variation on deploying the curved microwave antenna about a tissue region of interest where the inner conductor of the antenna is independently advanced through the tissue. 
         FIGS. 15G and 15H  show one variation on a method for partially assembling the microwave antenna in situ. 
         FIGS. 16A to 16D  show another variation on deploying the curved microwave antenna about a tissue region of interest in which the introducer may remain in place during antenna deployment. 
         FIGS. 17A to 17D  show another variation on deploying the curved microwave antenna using a backstop guide along which the antenna may be guided. 
         FIGS. 18A and 18B  show cross-sectioned variations on the backstop of  FIGS. 17A to 17D . 
         FIGS. 19A to 19D  show a variation on the microwave antenna which has an optional RF energy cutting tip. 
         FIG. 19E  shows a detailed view of one variation on the RF energy cutting tip. 
         FIGS. 20A and 20B  show schematic details of variations of combined microwave and RF energy generators which may be used with the device of  FIGS. 19A to 19E . 
         FIG. 21  shows a schematic detail of a channel splitter assembly which may be used to create multiple channels by using a single source. 
         FIG. 22  shows a cross-sectional view of one variation for connecting the microwave antenna assembly. 
         FIG. 23  shows a cross-sectional view of another variation for connecting the microwave antenna assembly. 
         FIGS. 24A to 24C  show alternative variations for connecting the microwave antenna assembly using protrusions located on the feedline. 
         FIGS. 25A and 25B  show an example of another possible application for the microwave antenna in sealing aneurysms. 
         FIGS. 26A and 26B  show another example of a possible application in coagulating malfunctioning valves in a vessel. 
         FIGS. 27A to 27D  show another example of a possible application in coagulating fistulas formed between adjacent vessels. 
         FIGS. 28A and 28B  show another example of a possible application in treating the soft core of a bone. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Microwave ablation devices typically ablate the tissue surrounding the antenna. The present invention clearly defines an ablation region by having the microwave antenna surround at least a majority of the tissue to be ablated without the need to actually penetrate or contact the ablated tissue. Furthermore, the curved microwave antenna allows for the direct control over the outer extent of the thermal lesion created by the device.  FIG. 1A  shows one variation in microwave antenna assembly  10  which preferably comprises at least microwave antenna  12  electrically connected to generator  22 . Microwave antenna  12  preferably comprises shaft or feedline  14  with a distal end from which antenna or inner conductor  16  extends to define the ablation region  29 , which is described in detail below. The proximal end of feedline  14  preferably comprises coupler  18  which electrically couples the antenna  12  to generator  22  via power transmission cable  20 . The cable  20  is preferably a flexible cable which allows for the positioning of antenna  12  relative to a patient. 
     Feedline  14  is preferably a coaxial cable, as shown by the cross-section  1 B- 1 B in  FIG. 1B  taken from  FIG. 1A . The feedline  14  may be formed of outer conductor  24  surrounding inner conductor  26 . Conductors  24 ,  26  may be made of a conductive metal which may be semi-rigid or flexible. Most feedlines  14  may be constructed of copper, gold, or other conductive metals with similar conductivity values. Alternatively, feedline  14  may also be made from stainless steel which may additionally be plated with other materials, e.g., other conductive materials, to improve their properties, e.g., to improve conductivity or decrease energy loss, etc. A feedline  14 , such as one made of stainless steel, preferably has an impedance of about 50Ω and to improve its conductivity, the stainless steel may be coated with a layer of a conductive material such as copper or gold. Although stainless steel may not offer the same conductivity as other metals, it does offer strength required to puncture tissue and/or skin. A dielectric material  28  is preferably disposed between outer and inner conductors  24 ,  26 , respectively, to provide insulation therebetween and may be comprised of any appropriate variety of conventional dielectric materials. 
     Furthermore, coaxial cables made from materials such as stainless steel may result in higher energy losses than other conductive materials, e.g. copper, gold, silver, etc.  FIGS. 1C and 1D  show cross-sectional and end views, respectively, of a variation of a feedline  14 ′ which has conductive layers plated within to increase the energy transmission. As shown, the outer surface of inner conductor  26  may be plated with at least one additional conductive material described above in layer  27 . Likewise, the inner surface of outer conductor  24  may be similarly plated with layer  29 , which may be made of the same, similar, or different material as layer  27 . The transmitted microwave energy is typically carried in the outer layers of inner conductor  26  so layer  27  need not be relatively thick. 
     Moreover, the addition of conductive layers  26  and/or  27  may not only increase energy transmission, but it may also aid in decreasing cable losses, decreasing cable heating, and distributing the overall temperature within the cable. 
       FIGS. 2A to 2G  illustrate the different variations which the curved microwave antenna may embody. The size of the curved antenna portion may range anywhere from several millimeters to several centimeters, e.g., a 3 cm diameter or greater, depending upon the size of the tissue to be treated. The microwave antenna  12  may be used in various types of tissue, e.g., liver, breast, etc. In operation, microwave energy having a wavelength, λ, is transmitted through microwave antenna  12  along feedline  14  and antenna  32 . This energy is then radiated into the surrounding medium, e.g., tissue. The length of the antenna for efficient radiation may be dependent at least on the effective wavelength, λ eff , which is dependent upon the dielectric properties of the medium being radiated into. Energy from microwave antenna  12  radiates and the surrounding medium is subsequently heated. A microwave antenna  12  through which microwave energy is transmitted at a wavelength, λ, may have differing effective wavelengths, λ eff , depending upon the surrounding medium, e.g., liver tissue, as opposed to, e.g., breast tissue. Accordingly, to optimize the efficiency at which energy is radiated into the surrounding tissue, antenna length  32  may be varied to match according to the type of tissue surrounding the antenna. Also affecting the effective wavelength, λ eff , are coatings and other structures, e.g., inflatable balloons, which may be disposed over microwave antenna  12 , as discussed further below. 
     Curved antenna  32  is seen in  FIG. 2A  extending from feedline  14  from feedline terminal end  30 . Curved antenna  32  may either be attached to inner conductor  26 , which is within feedline  14 , through a variety of attachment methods (as described below) or antenna  32  may simply be an integral extension of inner conductor  26 . Various conductive materials may be used to fabricate antenna  32 , as above, and it may also be fabricated from shape memory alloys such as Nitinol. Alternatively, if a metal such as stainless steel is used, it may be biased to form the arcuate or curved shape as shown in the figures. Additionally, to help prevent energy from being conducted directly into contacting tissue, a dielectric coating may be placed over at least a majority of curved antenna  32 . This coating may also aid in increasing the amount of radiated energy from antenna  32 . Moreover, the coating is preferably lubricious to aid the insertion of antenna  32  into tissue as well as to aid in preventing tissue from sticking to antenna  32 . The coating itself may be made from various conventional materials, e.g., polymers, etc. 
     The curved antenna  32  portion is preferably curved to form a loop or enclosure which is selectively formed large enough for surrounding a region of tissue, e.g., a lesion or tumor, to be radiated within the patient without making any contact with the tissue. Because no contact occurs between antenna  32  and the tumor, any danger of dragging or pulling cancerous cells along the antenna body into other parts of the body during insertion, treatment of the tissue, or removal of the antenna is eliminated. When microwave energy is delivered through feedline  14 , curved antenna  32  and any part of the feedline or antenna  32  that completes the enclosure becomes part of the radiating portion. However, rather than radiating directly along the length of curved antenna  32 , as one skilled in the art would normally expect, the curved configuration forms an ablation field or region  35  defined by curved antenna  32  and any tissue enclosed within ablation region  35  becomes irradiated by the microwave energy. Thus, because of the variability of antenna  32  and ablation region  35 , the microwave antenna may be used to treat a variety of tissue size ranges and is not constrained by antenna delivery or deployment mechanisms. Any concurrent thermal effects may extend beyond the ablation region  35  outside curved antenna  32  by a short distance, e.g., a few millimeters to several millimeters. Accordingly, curved antenna  32  also defines a predictable region of tissue outside the irradiated zone which will also be irradiated. This margin  33  of tissue is generally very predictable and serves to treat the tissue the short distance outside the ablation region to ensure complete treatment of the area. 
     As previously mentioned, curved antenna  32  may be formed into a variety of shapes so long as antenna  32  preferably forms a substantially enclosed loop or enclosure, i.e., curved antenna  32  surrounds at least a majority of the tissue to be enclosed. Accordingly, antenna  32  may be formed into shapes such as circles, ellipses, spirals, helixes, squares, rectangles, triangles, etc., various other polygonal shapes, and partial forms of the various shapes so long as a majority of the enclosed tissue is surrounded.  FIG. 2A  shows antenna  32  formed into a complete loop in which distal tip  34  loops around to contact a proximal region of antenna  32  while clearly defining ablation region  35 . The contact point between the two is preferably insulated such that no direct metal-to-metal contact occurs. 
     Another variation is shown in  FIG. 2B  in which distal tip  38  of curved antenna  36  is looped greater than 360° relative to feedline terminal end  30 . The curved antenna may be looped or wound about the selected tissue region from about 180° (relative to a central point defined by the curved antenna), where the tissue is just surrounded or partially enclosed by the antenna, to multiple loops where the tissue is surrounded numerous times by the antenna. Separation between the individual loops is shown for clarity and is not intended to be limiting since contact between the loops may occur. The number of times which the tissue is surrounded may be correlated to the desired radiation effects, as discussed in further detail below. 
       FIG. 2C  shows another variation in which distal tip  42  of curved antenna  40  is wound greater than 360° relative to feedline terminal end  30  but where antenna  40  is formed into a more elliptical shape. In this variation, antenna  40  forms overlapping region  31  with a distal portion of feedline  14 . In such an overlapping area, overlap region  31  of feedline  14  may form part of antenna  40 .  FIGS. 2D to 2F  show the distal tips  46 ,  50 ,  54  of each of curved antennas  44 ,  48 ,  52 , respectively, with various degrees of enclosure. Although numerous different shapes and partial shapes may be utilized, the enclosure is preferably formed in a looped configuration with at least a partial overlap between the distal tip and either a portion of the feedline  14  or with the antenna itself. If the overlap is formed with feedline  14 , as shown in  FIG. 2D , a portion of feedline  14  itself may act as part of the antenna  44  when power is applied. If a separation exists between distal tip  50  and feedline terminal end  30 , as shown in  FIG. 2E , then a distance, d, between the two is preferably less than 3 cm, and more preferably less than 1 cm such that an ablation region is clearly defined by the antenna. Accordingly, feedline  14  over the distance, d, may form part of the radiating antenna  48  in such a configuration. Otherwise, various other shapes or partial shapes may be utilized. 
     An alternative variation is shown in  FIG. 2G  where feedline  56  is extended into a curved portion  58  to partially define the ablation region. Curved antenna  60  may be used to complete the enclosure. Curved portion  58  is shown forming an arc of about 180°, but it may be formed into any curved portion with varying degrees of curvature to partially form the ablation region. 
     An optional method for optimizing the length of the antenna to the target tissue site may involve adjusting the length of the antenna itself to optimize the amount of microwave energy which is delivered to specific tissue types such that the effective wavelength, λ eff , is matched to the surrounding tissue medium type. For instance, depending upon the tissue type, the microwave antenna may be shortened in length to increase the frequency with which the energy is delivered efficiently. Alternatively, antenna length may also be shortened to decrease the frequency as certain frequencies are more efficient at delivering energy in certain tissue types. 
     Shorter antenna lengths may easily be inserted within the matching tissue type with relative ease; however, longer antenna lengths may present a challenge in deployment and placement within the tissue. One method of adjusting for antenna length is seen in the variation shown in  FIG. 2H . Curved antenna  61  extends from feedline  14 , as in other variations, but has an additional distal portion  63  which doubles back around curved antenna  61  from tip  62 . Distal antenna portion  63  may lie within the same plane as curved antenna  61  or it may optionally be positioned at an angle relative to antenna  61 . In either case, tip  62  may be configured to have a cutting edge to facilitate insertion into the tissue, or it may also be optionally configured to provide an RF energy cutting tip, which is described in greater detail below. 
     While distal antenna portion  63  is shown in  FIG. 2H  as doubling back along nearly the entire length of curved antenna  61 , it may be sized to any practical length to match the tissue type. For instance,  FIG. 2I  shows a variation in which distal antenna portion  64  extends back from tip  62  only partially along the length of curved antenna  61 . Another variation is shown in  FIG. 2J  in which curved antenna  65  has a looped portion  66  extending partially along the length of curved antenna  65 . Looped portion  66  may be any appropriate length of antenna which is simply formed into a looped or coiled structure. The portion  66  may also be located anywhere along the length of curved antenna  65 . 
     Additional variations are shown in  FIGS. 2K and 2L  in which any number of double-back portions of the antenna may be formed.  FIG. 2K  shows curved antenna  67  with two doubled portions  68  along its length. This variation is not limited by the number of doubled portions but may include any number as necessary to achieve the desired radiative and geometric effects.  FIG. 2L  shows another variation in which curved antenna  69  has a distal portion  71  doubling back along antenna  69 , and which also has an additional proximal portion  73  formed in another plane relative to the plane formed by antenna  69 . 
       FIG. 2M  shows a variation which is similar to that shown in  FIG. 2J  but in which the antenna is formed entirely into a looped or coiled antenna  75 . The coiled antenna  75  may have a coil diameter which is uniform along the length of antenna  75  or it may optionally have a variable coil diameter along its length. The coiled antenna  75  allows for a microwave antenna having a relatively large antenna length constrained within an area no larger than some of the other variations described herein. 
     As discussed above, the effective wavelength, λ eff , of the microwave radiation may also be affected, aside from antenna length, by coatings and other structures which may be disposed over the microwave antenna. Accordingly, a layer of insulative material may be varied in thickness over at least a majority of the length of the curved antenna to achieve a matched effective wavelength. Alternatively, an inflatable balloon  77  may be disposed over the length of curved antenna  52 , as shown in  FIG. 2N  to also match the effective wavelength. Balloon  77  may be in a deflated state during the deployment of antenna  52  within the tissue. Once antenna  52  has been desirably positioned, balloon  77  may be filled with a liquid, e.g., saline, water, etc., until it has inflated sufficiently about antenna  52 . The size of balloon  77  may be varied according to the desired radiative effects, the length of antenna  52 , as well as the type of tissue which the antenna  52  will be inserted within. 
     As described above, an antenna may be looped about the region of tissue to be ablated any number of times. The multiple coils or loops may all be wound within the same plane or alternatively, they may be wound in a spiral or helical configuration.  FIGS. 2O to 2Q  show a variation in which a helically configured antenna  80  may comprise a straightened portion or feedline  81  and a helical portion  88  which is insertable within the tissue.  FIG. 2O  shows a top view of a variation on the antenna  80  which is similar in configuration to the device shown and described in U.S. Pat. No. 5,221,269 to Miller et al., which has been incorporated above by reference in its entirety. As seen in this variation, helical portion  88  comprises antenna  83  which is configured into a tapering helical pattern to form an ablation region  85  within the helical portion  88 , as better shown in the cross-section  2 P- 2 P in  FIG. 2P . Antenna  83  may terminate in a tapered distal tip  84  to facilitate antenna entry into the tissue. Helical portion  88  may alternatively be formed into a coiled section in which multiple coils are formed with a uniform diameter. The number of coils antenna  83  forms may be determined by the optimal antenna length desired according to the tissue type being treated, as described above in detail. 
     As seen in  FIG. 2Q , antenna  83  is shown as having been inserted into breast  87  to treat tumor  86 . Antenna  83  may be inserted within breast  87  in an uncoiled and straightened configuration through an introducer (not shown). Antenna  83  is preferably made from a shape memory alloy, e.g., Nitinol or some other similar alloy, such that as distal tip  84  is inserted within the tissue, it may be preconfigured to form the helical shape as antenna  83  is further inserted within the tissue. As antenna  83  is advanced, distal tip  84  may form the helical shape about the tumor  86 , or some region of tissue to be ablated, within the formed ablation region  85 . 
     To ablate larger regions of tissue, multiple microwave antennas may be used in conjunction with one another.  FIG. 3A  shows two antennas, first feedline  70  and second feedline  70 ′, positioned adjacent to one another such that their respective antennas, first antenna  72  and second antenna  72 ′, are positioned to ablate a larger region of tissue over a distance within their combined ablation regions  74 . Another variation using two antennas is shown in  FIGS. 3B and 3C  in which first and second feedlines  70 ,  70 ′ are positioned adjacent to one another with their respective antenna portions  72 ,  72 ′ being positioned to interloop with one another.  FIG. 3C  shows an end view of  FIG. 3B  in which the interlooped antennas  72 ,  72 ′ may be seen to form ablation region  74  within the combined areas of the antennas. The caged ablation region  74  is effective in completely encapsulating a region of tissue to be ablated within a spherical ablation region. Other shapes, e.g., spheroid, ovoid, ellipsoid, etc., may alternatively be formed by a combination of the two antennas  72 ,  72 ′ positioned appropriately or any number of antennas as practical or desired. 
     Alternatively, first and second feedlines  70 ,  70 ′ may be positioned to approach the region of tissue to be ablated from different locations and at different angles, as seen in  FIG. 4 , such that the combined effect of the first and second antennas  72 ,  72 ′ may form a complete loop or shape and ensures complete coverage of the ablation region  76 . In either of these variations, any number of antennas may be used as practicable depending upon the size of the tissue to be ablated as well as the desired effect from the ablation. 
     Alternatively, a single feedline  78  having multiple antennas  80  which define an ablation region  82  over some distance may be utilized, as seen in the  FIG. 5A . In this variation, a plurality of antennas, i.e., two or more, may extend from a single feedline  78  to form an enlarged ablation region. Because a single feedline is used, a single incision in a patient is required while a relatively large area of tissue may be ablated with the single device.  FIG. 5B  shows an end view of the variation from  FIG. 5A  and shows the multiple antennas  80  extending from the single feedline  78 . Multiple antennas  80  may be positioned in any variety of configurations relative to one another depending upon the areas of tissue to be ablated. 
     Alternative embodiments which may be utilized for forming caged ablation regions using multiple antennas may be seen in PCT publication WO 01/60235 to Fogarty et al. entitled “Improved Device for Accurately Marking Tissue”, which is incorporated herein by reference in its entirety. Similarly, multiple antennas may be used to form caged embodiments for surrounding tissue within an ablation region using configurations similar to the tissue marking devices described in the publication. 
     To assist in aligning multiple antennas for ablating larger regions of tissue, various alignment guides may be used to provide for uniform or consistent antenna placement within the tissue to be treated. One variation may be seen in  FIGS. 6A to 6C  which shows side, top, and end views, respectively, of antenna guide assembly  180 . Guide assembly  180  may be used to align microwave antennas parallel to each other in one variation as shown in  FIG. 3A . In use, a distal end of a microwave antenna may be advanced through proximal entry  186  of guide assembly  180 , through guide passage  184  and out through distal port  188  such that a portion of the microwave antenna extends beyond distal port  188  for insertion into the tissue region to be treated. The antenna may be releasably locked into position within guide assembly  180  by locking assembly  190 . 
     The guide assembly  180  itself may be comprised of guide body  182 , which may be made as an integral unit from a variety of materials, e.g., various polymers or plastics, etc. Guide body  182  may have an outer surface configured to be held by a surgeon or physician. Within the guide body  182 , one or more guide passages  184  may be defined through the length of guide body  182  for holding and aligning the microwave antennas. Although this variation shows two passages  184  for aligning two antennas, this is merely illustrative and other variations may be employed for aligning any number of antennas as practicable, e.g., a single antenna or three or more. 
     As further shown, guide body  182  also defines proximal entry  186  through which the antennas may be advanced into passages  184  and through distal ports  188 . The antennas may be further positioned through locking assembly  190  located within guide body  182  and used to temporarily lock the antennas in place. The antennas may be locked within assembly  190  by locking mechanism  192  which may be keyed to lock against the antenna. To release a locked antenna, locking assembly  190  may further have release latches  194  which are configured to release locking mechanism  192  to release the antenna. Locking assembly  190  may be held in place within guide body  182  by retaining members  196 , which may be configured as threaded or snap-fit members for engagingly attaching onto a portion of locking assembly  190 . 
     To align the microwave antennas with guide assembly  180 , guide body  182  may define longitudinal alignment channels  198  along the lengths of each guide passage  184 . Alignment channels  198  may extend through guide body  182  from guide passages  194  to the outer surface of guide body  182  and they may be aligned parallel to each other along the length of guide assembly  180 , as shown in  FIG. 6B . The microwave antennas used with guide assembly  180  may be configured to have a corresponding protrusion (not shown) extending from the feedline body and the protrusion may be keyed to align with and travel through alignment channels  198 . It is the alignment of the keyed antenna with the alignment channels  198  which may force the antennas to desirably align with each other such that the looped antennas extend parallel to one another. 
       FIGS. 7A and 7B  show isometric exploded and assembly views, respectively, of guide assembly  180 . The exploded view in  FIG. 7A  shows release latches  194  aligned with locking mechanism  192 . Latches  194  may be aligned and held in position with pins  200  relative to mechanism  192 . Ferrules  202  may also be used for placement within locking mechanism  192  to facilitate antenna alignment. 
       FIGS. 8A and 8B  show isometric and end views, respectively, of antenna and guide assembly  210 . First  212  and second  212 ′ antenna feedlines are shown in this variation as having been positioned within guide body  182  such that first  214  and second  214 ′ looped antennas are parallel to one another. As shown in  FIG. 8B , antennas  214 ,  214 ′ may be positioned and maintained in this parallel manner for treatment of regions within tissue. Although shown in this variation as having parallel antennas, the possible orientations of the antennas are not so limited. Other relative positions for the antennas may be utilized depending upon the desired effects. 
     Another variation for facilitating antenna positioning is shown in  FIGS. 9A to 9C . In this variation, antenna guide assembly  220  similarly has guide body  222  with guide passages  224  defined throughout the assembly  220  and ending in distal port  232  through which microwave antennas may be positioned. Locking assembly  226  may also similarly comprise locking mechanism  228  for temporarily locking the antennas into position. Locking mechanism  228  is located within guide body  222  and held thereto via retaining members  236 , which may be any of the retaining members as described above. Release latch  230  may be used to release locking mechanism  228  for releasing locked antennas. This variation  220 , however, may be used when the antennas are desirably angled relative to one another, similar to the antenna placement variation shown in  FIGS. 3B and 3C . Accordingly, alignment channels  234  may be formed within guide body  222  such that the channels  234  are angled away relative to each other. 
     As shown in  FIGS. 10A and 10B , which are isometric exploded and assembly views, respectively, of guide assembly  220 , alignment channels  234  may be angled relative to one another such that they are angled away. Both or either channel  234  may be angled at various angles, α, depending upon the desired antenna positioning, e.g., 30°, 45°, etc. Alternatively, they may be angled towards one another as practicable. 
       FIGS. 11A and 11B  show isometric and end views, respectively, of antenna and guide assembly  240 . The antennas used with this guide variation may also be configured to have protrusions such that they are keyed to align within the channels  234  at specified angles. For instance, as shown in  FIG. 11A , first  242  and second  242 ′ feedlines may be positioned through guide body  234  such that first  244  and second  244 ′ antennas are interlooped with one another to form an enclosed ablation region, as described above. Depending upon the angle at which either or both antennas  244 ,  244 ′ are positioned relative to one another, a variety of shapes may be formed by the antennas, as further discussed above. 
     As further mentioned above, the curved antenna may either be attached to the inner conductor, which is disposed within the feedline, through various attachment methods or the antenna may simply be an integral extension of the inner conductor.  FIG. 12A  shows a cross-sectioned side view of the terminal end of feedline  14 . As seen, outer conductor  24  surrounds inner conductor  90  and is separated by dielectric  28 . The point where inner conductor  90  begins to form the curved antenna, outer conductor  24  and dielectric  28  end while inner conductor  90  continues on to form an integrally attached antenna. 
     An alternative variation is seen in  FIG. 12B  in which a separate antenna  94  is mechanically affixed or attached to inner conductor  92 , which may extend partially from outer conductor  24 . The mechanical connection between antenna  94  and inner conductor  92  may be accomplished by a variety of methods, only a few of which are described herein. Connector  96  may be used to electrically and mechanically join each of the terminal ends of inner conductor  92  to antenna  94  through connector lumen  98 , e.g., by a simple mechanical joint, or by soldering both ends together and additionally soldering connector  96  over the joint. Aside from solder, a conductive adhesive may similarly be used. Alternatively, each of the terminal ends may be crimped together by connector  96 . 
     Another variation may have each of the terminal ends threaded in opposite directions so that inner conductor  92  may be screwed into connection with antenna  94  via a threaded connector lumen  98 . If a separate antenna is utilized, then one made from the same material as inner conductor  92  may be used. Alternatively, an antenna  94  made from a shape memory alloy, e.g., Ni—Ti alloy (Nitinol), may be attached. However, any oxide layers which may form on the surface of the shape memory alloy is preferably removed by using, e.g., a reamer, prior to attachment. An alternative attachment which may be utilized is shown in  FIG. 12C  in which a tubular antenna  100  having an antenna lumen  102  may be attached to inner conductor  92  by partially inserting the conductor  92  within lumen  102  prior to mechanical fixation. The tubular antenna  100  may then be similarly attached to inner conductor  92  using the various methods described above, e.g., soldering, crimping, adhesives, etc. 
     Insertion and placement of the microwave antenna within the body of a patient may be accomplished through one of several different methods. One method is shown in  FIGS. 13A to 13G , which show the deployment and placement of a microwave antenna about a region of tissue to be ablated. Once a region of diseased tissue, e.g., a tumor, has been located within a patient&#39;s body, e.g., within the breast or the liver, a microwave antenna may be deployed in vivo to effect treatment. As seen in  FIG. 13A , introducer  114  may be inserted through skin surface  112  in an area adjacent to the tumor  110 . Wire  116 , which may be held within introducer  114  during insertion or inserted afterwards, may then be advanced through introducer  114  and through the tissue surrounding tumor  110 . Wire  116  is preferably made of a shape memory alloy which is preformed to have a curvature in any of the shapes described herein, although it is shown in the figure as a circular loop. This curvature is selectively preformed such that wire  116  is able to at least substantially surround tumor  110  while being advanced without contacting the exterior of tumor  110 . 
     Once wire  116  has been desirably positioned around tumor  110 , introducer  114  may be removed from the tissue area while maintaining the position of wire  116 , as shown in  FIG. 13C . Then, as shown in  FIG. 13D , a flexible guide tube  118  may be advanced over wire  116  preferably all the way to the distal tip of wire  116 . Once tube  118  has been positioned, wire  116  may then be withdrawn, as seen in  FIG. 13E , and microwave antenna  12  may be advanced within tube  118  such that antenna  16  substantially surrounds tumor  110 , as seen in  FIG. 13F . Then tube  118  may be withdrawn from the area while maintaining the position of microwave antenna  12  about tumor  110  for treatment to be effectuated, as seen in  FIG. 13G . 
     An alternative method of deployment is shown in  FIGS. 14A and 14B . Introducer  114  may be positioned as above, but wire  116  and tube  118  may be deployed simultaneously rather than sequentially, as seen in  FIG. 14A . Once the two have been desirably positioned, wire  116  may be withdrawn from tube  118 , as shown in  FIG. 14B , and the microwave antenna  12  may be inserted and positioned as above. 
     Another variation for deployment is shown in  FIG. 14C  where once introducer  114  has been positioned through skin surface  112 , or some other tissue interface, inner conductor  117  surrounded by dielectric  115  may be advanced together through the tissue to enclose tumor  110  within an ablation region. As such, inner conductor  117  and dielectric  115  may be integrally formed into a single unit; alternatively, inner conductor  117  may be slidably disposed within dielectric  115  but advanced simultaneously. The introducer  114  in this variation may be adapted to be used as an outer conductor during microwave energy transmission through the device. 
     Another variation for deployment and use of the microwave antenna  12  is shown in  FIGS. 15A and 15B . Microwave antenna  12  may be positioned within tube  118 , as above and as in  FIG. 15A . However, rather than withdrawing tube  118  entirely from the tissue, it may be partially withdrawn until it covers only the feedline of microwave antenna  12  such that it may be used as an insulator between the shaft or feedline and the surrounding tissue, as shown in  FIG. 15B . 
     A similar variation may be seen  FIGS. 15C and 15D . In this variation, the inner conductor portion with antenna  16  extending therefrom and the surrounding dielectric  28  may be formed without an outer conductor surrounding dielectric  28 . Introducer  114  may be used as the outer conductor in constructing the microwave antenna in situ prior to treating the tissue.  FIG. 15C  shows introducer  114  having been positioned within the tissue adjacent to tumor  110 . Antenna  16  and dielectric  28  may be advanced within introducer  114  until dielectric  28  is preferably at the distal end of introducer  114  within the tissue. With antenna  16  surrounding tumor  110  and dielectric  28  properly positioned within introducer  114 , ablation of the tissue may be effected with introducer  114  acting as the outer conductor for the microwave antenna. 
     Another alternative is shown in  FIGS. 15E and 15F  in which introducer  114  and dielectric  28  may be first positioned within the tissue. Once they have been desirably positioned, antenna  16  (inner conductor) may be advanced independently through both dielectric  28  and introducer  114  for placement around tumor  110 , as shown in  FIG. 15F . 
       FIGS. 15G and 15H  show one variation which allows a microwave antenna to be assembled in situ within the tissue, as described above. Once introducer  114  has been positioned within the tissue, dielectric  28  and antenna  16  may be advanced within introducer  114  from proximal end  119  of introducer  114 . Alternatively, they may already be disposed within the introducer  114  during placement within the tissue. In either case, coupler  18  leading to the generator may be electrically connected to antenna  16  at its proximal end and coupler  18  may be advanced distally into mechanical attachment with proximal end  119  such that dielectric  28  and antenna  16  are advanced distally out of introducer  114  and into the tissue. The mechanical attachment between coupler  18  and proximal end  119  may be accomplished by any variety of mechanical fastening methods, e.g., crimping, adhesives, threaded ends, friction fitting, etc. Other examples of antennas which may be assembled in situ are described in further detail in U.S. Pat. Nos. 6,306,132 and 6,355,033 (both to Moorman et al.), each of which is incorporated herein by reference in their entirety. Techniques and apparatus as disclosed in these patents may be utilized in the present invention as examples of assembling the microwave antennas. 
     Yet another variation for the deployment is shown in  FIGS. 16A to 16D .  FIGS. 16A and 16B  show the insertion and positioning of introducer  114  and wire  116  adjacent to tumor  110 , as described above. However, rather than withdrawing introducer  114  from the tissue, it may be maintained in position while tube  118  is advanced over wire  116  to provide strength to tube  118  as it is advanced over wire  116  through the tissue, as seen in  FIG. 16C .  FIG. 16D  shows wire  116  having been withdrawn from tube  118  and microwave antenna  12  having been advanced through tube  118  while introducer  114  is maintained in position. The operation of microwave antenna  12  may subsequently be accomplished with or without the presence of introducer  114 . 
     Another variation on the deployment of the microwave antenna is shown in  FIGS. 17A to 17D . In this variation, a backstop guide  120  may be utilized rather than a wire  116  or tube  118 . Backstop guide  120  is a guide which is preferably configured to define a channel along the length of the backstop  120  within which a microwave antenna  12  may be advanced through or along for positioning antenna  16  about tumor  110 . Backstop  120  is preferably made from a shape memory alloy, e.g., Nitinol, which is preconfigured to assume a looped or curved shape for positioning itself about a region of tissue. Variations on the cross-section of backstop guide  120  are shown in  FIGS. 18A and 18B .  FIG. 17A  shows backstop  120  being advanced through skin  112  adjacent to tumor  110 . As backstop  120  is further advanced, it preferably reconfigures itself to surround the tissue region to be ablated, e.g., tumor  110 , as seen in  FIG. 17B . Once backstop  120  has been desirably positioned, microwave antenna  12  may be advanced along backstop  120  as antenna  16  follows the curve defined by backstop  120  around tumor  110 , as seen in  FIG. 17C . Finally, once microwave antenna  12  has been positioned, backstop  120  may be withdrawn from the tissue area, as seen in  FIG. 17D , so that treatment may be effected. 
       FIGS. 18A and 18B  show cross-section variations of backstop  120 .  FIG. 18A  shows one variation where backstop  120 ′ has a channel  122  which has a rectangular configuration and  FIG. 18B  shows another variation in which backstop  120 ″ has a channel  124  having a rounded channel. When the microwave antenna  12  is deployed using the backstop  120 , antenna  16  is preferably guided during deployment through the tissue by traversing within or along channels  122  or  124 . Although only two variations on the backstop cross-section are shown, other shapes for the backstop and channel may be utilized and is not intended to be limiting. 
     A microwave antenna may be deployed either using an introducer and tube, as described above, or it may be inserted directly into the tissue to surround or enclose the tissue region of interest. In either case, during deployment the antenna may encounter resistance from some areas of tissue, particularly in some tissue found, e.g., in the breast. When the microwave antenna encounters resistance, the antenna may simply be pushed through by applying additional force; however, there could be a potential for buckling of the antenna and unnecessary tissue damage. Thus, RF energy may also be utilized with the microwave antenna for facilitating deployment within the tissue. One variation comprises applying RF energy at the distal tip of the antenna as a cutting mechanism during antenna deployment. The microwave antenna is preferably insulated along most of its length, but the distal tip may be uninsulated such that the RF energy may be applied thereto. To utilize the RF energy cutting mechanism at the distal tip, the antenna may be made from Nitinol or other metal. Alternatively, if the tubular antenna variation  100  from  FIG. 12C  is utilized, a metallic wire may be routed through antenna lumen  102  to the distal tip so that the wire may be used as the RF cutting tip. This wire would be connected to a generator which may supply both the RF and microwave energy. The metallic wire may be made of, e.g., Tungsten or some other appropriate conductive material. 
     An example of using the RF cutting tip is shown in  FIGS. 19A to 19D . After introducer  114  has been positioned adjacent to tumor  110 , feedline  130  and antenna  132  may be advanced therethrough. Cutting tip  134  may simply be pushed forward through tissue so long as no resistance is encountered, as shown in  FIGS. 19A and 19B . Once resistance from the tissue is encountered, RF energy may be supplied to antenna  132  to activate cutting tip  134 , as seen in  FIG. 19C . With the RF energy on, antenna  132  may be further advanced, as seen in  FIG. 19D , while cutting tip  134  cuts through the obstructive tissue. The RF energy may simply be left on the entire time antenna  132  is advanced through the tissue, or it may be applied or turned on only as needed as cutting tip  134  encounters resistance from the tissue. Once antenna  132  has been desirably positioned about tumor  110 , the RF energy, if turned on, may be switched off and the microwave energy may be switched on to effect treatment within the newly created ablation region  136 . 
       FIG. 19E  shows a detailed view of one variation of cutting tip  134 . As shown, antenna  132  may comprise an inner conductor which is preferably covered by insulation  138 . To effect the cutting mechanism, distal tip portion  140  may be exposed such that when RF energy is supplied to antenna  132 , the exposed tip portion  140  may be utilized to heat and cut through the tissue directly encountered by tip portion  140 . The distal tip portion may optionally be tapered or appropriately shaped, such as in a trocar configuration, to further enhance the cutting tip. 
     Given the small amount of surface area of tip portion  140 , a low power RF generator may be utilized and can be built into an integral unit along with the microwave generator. Alternatively, the optional RF generator may be physically separated from the microwave generator and may be electrically connected as a separate unit.  FIG. 20A  schematically shows a variation on generator unit  150  which combines microwave generator module  154  with RF generator module  156  into a single unit  150 . Both modules  154 ,  156  may be supplied by a single power supply  152  also contained within unit  150 . Power supply lines  158  may electrically connect the modules  154 ,  156  to power supply  152 . A separate line  160  (e.g., cable) may connect microwave module  154  to microwave antenna  132  and another line  162  may connect RF module  156  to cutting tip  134 . Alternatively, the separate lines  160 ,  162  may be connected into a single line  164  which is electrically connected to both antenna  132  and cutting tip  134  to alternately supply the power for both the microwave and RF energy through the singular connection. 
       FIG. 20B  shows another variation on generator unit  150  in which separate lines  160 ,  162  are connected into a single output  165 , which may be connected to antenna  132  and cutting tip  134 . Also shown are optional switches  166  and  168 , which may be connected to microwave and RF modules  154 ,  156  via lines  167 ,  169 , respectively. Switches  166 ,  168  may be optionally utilized to enable the surgeon or physician to select the desired output from either or both modules  154 ,  156  at any time. Switches  166 ,  168  may accordingly be separate switches or combined-into a single unit located remotely from generator unit  150 . Furthermore, they may be made in one variation as hand-operated switches or in another variation as foot-operated switches or any variety of actuation switches as may be known in the art. 
     In addition to utilizing integrally combined RF and microwave generators, another variation which may be utilized involves creating multiple channels from a single unit by multiplexing and cycling the output. This is particularly useful when using multiple microwave antennas, as shown in  FIGS. 3 and 4 , since the effects of multiple channel generators, which typically requires the use of multiple generators, are accomplished by using a single generator and results in a much lower power consumption. For instance, a three channel 100 W generator system would require about three times the power, i.e., 300 W, as used by a single channel system if the power were produced for each channel simultaneously. 
     Accordingly,  FIG. 21  schematically shows channel splitter assembly  170  which may be used to create multiple channels by using a single source with multiplexing. A single microwave generator module  154  having, e.g., a 100 W output, may create a single channel A. The single channel A may be switched between several separate channel outputs A 1  to A N  created by channel splitter  172 . Any number of multiple outputs may be used depending upon the desired number of channels and the desired effects. In use, the output may be cycled through the range of outputs  176  through multiple channels A 1  to A N  or in any other manner depending upon the lesion to be created. Moreover, the rate of cycling may range anywhere from several microseconds to several seconds over a treatment period of several minutes or longer. 
     Controller  174 , which is preferably in electrical communication with channel splitter  172  may be used for several purposes. It may be used to control the cycling rate as well as the order of channels in which the output is cycled through. Moreover, controller  174  may be an automatic system or set by the technician or physician. An automatic system may be configured to detect the electrical connection to the antenna and to control the delivery of the energy to the antenna. The detection may be achieved by either a passive or active component in the system which may monitor reflections from the antenna to determine whether a proper connection is present. A controller set by the technician or physician may be configured to require manual initiation for energy delivery to begin. 
     Additional features which may be utilized for the microwave antennas may include certain safety features. For instance, a connection mechanism may allow for antenna connection with an outer shell of a conventional or custom connector. It may be configured such that an electrical connection may be achieved upon full deployment of the inner conductor curved antenna such that no electrical connection is maintained during deployment. Such a feature could allow an operator to safely assemble and deploy the device without premature microwave antenna activation. 
       FIG. 22  shows a cross-sectional view of one variation for connecting microwave antenna assembly  300 . In this variation, connector shell  302  may extend from connector  304  and attach to a proximal end of feedline  306 . Inner conductor  308  may extend throughout the length of the assembly  300  from pin  310 , which may connect to a cable leading to a microwave power generator, and end in curved antenna  312  for deployment within the tissue. The connector shell may contain a feedline, as shown in  FIG. 22 . To advance curved antenna  312  from within feedline  306  into tissue, receiving connector end  316  of connector shell  302  may be advanced into contact with proximal end  314  of feedline  306 . As connector end  316  comes into physical contact with proximal end  314 , curved antenna  312  may be advanced out of feedline  306  and into the tissue. Also, retaining member  318 , which may simply be a protrusion or other fastener as known in the art, may provide a secure contact between connector shell  302  and feedline  306 . Furthermore, retaining member  318  may be an electrically conductive contact such that it also provides a secure electrical communication path between connector shell  302  and feedline  306  to allow for the microwave energy to be transmitted between the two. This feature may also act as a safety feature in that curved antenna  312  is preferably fully deployed out of feedline  306  before the electrical connection is made between feedline  306  and connector shell  302 . 
       FIG. 23  shows a cross-sectional view of another variation for connecting microwave antenna assembly  320 . This variation  320  shows connector shell  322  which may be shortened from the previous variation  300 . As shown, proximal end  328  of feedline  326  may receivingly extend into connector shell  322  and into contact with retaining member  330 , which may be configured similarly as above. Inner conductor  332  may extend through assembly  320  from pin  336  within connector  324  to curved antenna  334 . As feedline  326  is placed into secure electrical contact with connector shell  322  via retaining member  330 , curved antenna  324  may be advanced distally out of feedline  326 . 
     In addition to or in place of the retaining members described above, protrusions may instead be placed on an outer surface of the antenna feedline. As shown in  FIG. 24A , one variation may be seen in antenna assembly  340 . Connector  342  may be seen prior to connection with a proximal end of feedline  344 . Inner conductor  346  is shown extending through connector  342  and feedline  344 , while plating layer  348  may be seen upon an outer surface of feedline  344 . Layer  348  may be made from a conductive material, e.g., solder, or other conductive metal.  FIG. 24B  shows another variation in antenna assembly  350  which has a layer of plating  352  having tapered edges to facilitate insertion of feedline  344  within connector  342 .  FIG. 24C  shows yet another variation in antenna assembly  354  in which multiple separate layers  356  of plating may be utilized. These variations are merely illustrative and any number of other various configurations may be utilized depending upon the desired results. 
     Any of the antenna variations and methods for use and deployment described herein may be utilized in a variety of medical treatments aside from tumor ablation. For example, a curved microwave antenna be used to seal an aneurysm  360  extending from a body vessel  364 , as seen in  FIG. 25A . In such use, the surgeon or physician may inject a contrast agent into the patient&#39;s circulatory system. Then, with the assistance of an X-ray imager, e.g., a fluoroscope, the surgeon may locate the aneurysm  360 . Introducer  366  of the antenna device may be inserted into the tissue and the tip of introducer  366  may be placed adjacent to neck  362  of aneurysm  360 . Curved antenna  368  may be deployed around neck  362  of aneurysm  360 , as seen in  FIG. 25B . Microwave energy may be directed through curved antenna  368  to ablate neck  362  located within the ablation region. Curved antenna  368  may then be retracted back into introducer  366  and the device may be then withdrawn from the subject&#39;s body. 
     In another example of application, curved antenna  368  may be utilized to occlude vessel  370  as shown in  FIG. 26A . As shown, curved antenna  368  may be deployed around the tissue of interest, in this case vessel  370  instead of the neck of an aneurysm. The vessel  370  in this example has a malfunctioning valve  372 . Microwave energy may be directed through curved antenna  368  and into vessel  370 , which is positioned within the ablation region of antenna  368 , to induce a coagulated region  374  of blood to halt the flow of blood in the vessel  370 , as shown in  FIG. 26B . 
     In yet another example, the microwave antenna may be used to treat a fistula. As shown in  FIG. 27A , in a normal condition, e.g., an artery  380  and, e.g., a vein  382 , are located adjacent to each other and typically have blood flow that is isolated from each other. An abnormality known as a fistula  384  may permit the passage of blood flow from, e.g., an artery  380  to a vein  382 , as shown in  FIG. 27B . Curved microwave antenna  368  may be used to seal the fistula  384  between the two blood vessels  380 ,  382  using methods similarly described above, as shown in  FIG. 27C . Once the energy has been applied, the fistula  384  may form coagulated region  386  and seal fistula  384 , as shown in  FIG. 27D . 
     In addition to sealing hollow body organs, any of the antenna variations described herein may additionally be used for the ablation of bone metastases, e.g., osteoid osteomas, osteoblastomas, spinal metastases, etc. Due to the ablation region created by the curved microwave antenna, using the antenna is a viable option for treating such conditions or for alleviating pain. To effect microwave energy treatment in regions within bone, the curved antenna may be inserted through a biopsy needle using any of the methods described above. 
     As shown in one example in  FIG. 28A , introducer  394  may be inserted within bone  390  through cortical bone and into, e.g., the medullary cavity  392 . Once the distal end of introducer  394  has accessed cavity  392 , feedline  398  and curved antenna  396  may be inserted through introducer  394  and deployed within cavity  392 . This example illustrates antenna  396  as having multiple curved antennas; however, a single curved antenna or a plurality of curved antennas may be used depending upon the desired results. Once antennas  396  have been deployed within cavity  392 , the antennas may be used to ablate regions of the soft core of bone  390 , e.g., to de-nerve the region for pain reduction, or to kill cancerous cells, etc.  FIG. 28B  shows another example in which a number of separate curved antennas  400 ,  402  may be introduced into cavity  392  to ablate the region. Antennas  400 ,  402  may be introduced and positioned adjacently to one another in a parallel configuration, as shown or described above or using any number of guide assemblies described above, or at various angles relative to one another. Although only two antennas are shown in the  FIG. 28B , any number of antennas may be utilized as practicable. Any number of antenna configurations may also be utilized, as described above, as practicable depending upon the desired ablation results. 
     The applications of the microwave antenna and methods of use discussed above are not limited to regions of the body but may include any number of further treatment applications. Other treatment sites may include areas or regions of the body such as other organ bodies. Moreover, various other antenna shapes and partial shapes may be utilized beyond what is described herein. Modification of the above-described assemblies and methods for carrying out the invention, and variations of aspects of the invention that are obvious to those of skill in the art are intended to be within the scope of the claims.