Abstract:
A hand held applicator for delivery of microwave energy to skin surfaces is provided that is compact, easily manipulated, precisely positionable and secure against malfunction. Microwave energy of a chosen frequency is supplied for a given duration at a predetermined energy level, via one or more waveguides having a distal end section that is dielectrically loaded and matched to skin impedance. Positioning indicia may be disposed on a single use end cap adjacent the emitter end of the applicator to permit easy visualization by the surgeon or technician. Coolant, such as a pressurized gas refrigerant, is supplied in a burst to the skin surface via an interior solenoid controlled valve. The microwave energy pulse is initiated by control circuits after the effective delivery of coolant is sensed. The initiation of the cycle can be effected by actuation of a switch, movement of the applicator against the skin, or by tracking the movement of the applicator from one position to another. Further, two or more microwave energy emitters may be disposed in the same housing in a compact fashion, and arranged to fire serially at the chosen target locations.

Description:
This application is a continuation of U.S. application Ser. No. 08/904,175, filed Jul. 31, 1997, now U.S. Pat. No. 6,104,959. 
    
    
     FIELD OF THE INVENTION 
     This invention relates to devices and methods for delivering microwave energy to localized areas of the surface of the human body, and more particularly to handheld energy applicators which are compact, readily manipulable, and capable of delivering microwave energy at desired energy doses to discrete target areas of the body. 
     BACKGROUND OF THE INVENTION 
     It has been shown, in the above-referenced co-pending application, that microwave energy can effectively be used to create beneficial histological changes in subdermal, dermal and superficial features, such as blood vessels, skin, wrinkles and hair in the human body. By properly balancing the intensity and total energy applied to a limited surface area, the microwave energy penetrates to a chosen depth and interacts in a manner to effect the desired changes without harm or trauma to the patient. For example, a subdermal skin condition, commonly referred to as spider veins, (telangiectasia) is treatable by energy dosages which penetrate through the dermis to heat localized subdermal areas to above a critical temperature, such as in excess of 60° C. The localized temperature increase causes inflammation of vessel walls, subsequently blocking blood flow and impelling the creation of new blood flow paths, thus eliminating the appearance of spider veins. Other subdermal conditions such as varicose veins, which involve larger, deep tissue vessels, can also be treated because of the penetrating character of the microwave energy. Similarly, collagen tissue and adipose deposits may be treated by microwaves using the same principles. The aspect being treated may also be primarily a surface condition, such as wrinkles, stretch marks, cellulite, warts or dermal lesions. 
     Depilation is a related application in which microwave energy has been found to be particularly useful. For effective depilation the energy penetrates to reach follicular matrices and papillae, attacking the base of hair follicles and minimizing hair regrowth. 
     Microwave wavelengths are selected such that the wave energy preferentially interacts with the targeted tissues, such as blood or vessel walls, to enhance the localized effects of the treatment. Energy doses are kept within a range suitable for both safety and patient comfort. 
     Laser energy, which is widely used for similar purposes, is at much shorter wavelengths which penetrate organic matter much less effectively, and heat by absorption in superficial tissues or hair, but only when the target has the needed light responsive characteristics. Heat is then transferred from the impinged surface into a subdermal or deep tissue area to effect a histological change. The laser energy can be intensified, in order to penetrate more deeply, but still is significantly attenuated and also is much more likely to cause skin burns. For depilation treatments, laser energy must impinge upon light absorptive pigmentation in exposed hair and rely on the side effect of heat transfer to attack the follicular matrices. Light reflection and light rejection at less densely pigmented tissues and follicles diminishes the amount of useful energy, thereby making laser treatment inefficient for such targets. Skin resurfacing treatments, based upon radiative effects on collagen and adipose tissues, for example, are also more efficient where wave energy reaches the target tissue with little attenuation. 
     In these treatment systems, as described in the above referenced application, discrete surface targets are selected and radiated with microwave energy until a target feature or area peripheral to the target area has been excited with energy of chosen intensity and duration. Since a wide beam delivering heating energy to a broad area could undesirably affect non-target regions, energy application should be with a device having a small transmitting end which delivers a narrow energy beam. Because the concentration of electromagnetic wave energy is highest immediately adjacent the transmitting source, the skin surface adjacent the source is cooled so as to minimize overheating, discomfort and trauma. Various expedients for this purpose include use of a cooled, thermally conductive member in contact with the skin, cooling of the skin by expanding a pressurized coolant directed against the skin, and pre-cooling the skin with a frigid element or liquid. It is essential that such sources be used in timed relation to the application of wave energy from the applicator, and that the cooling not interfere with or diminish the applied energy. Moreover, the thermal transfer dynamics should preferably be complementary to the microwave energy application, in terms of time of delivery, thermal gradient in the tissues, and the temperature levels that are maintained. 
     Further, the energy applicator should not impair viewing by the doctor or technician, or occlude the target area, but should preferably permit clear visualization along with precise placement of the applicator at the target surface. The cross-sectional area of the transmitting end of the device, therefore, must be relatively small, and appropriately sized in relation to the target area to be treated. The minimum cross-sectional emitter area is determined by the wavelength chosen and the overall size and mass also have to be suitable for manual handling of the unit. The power level of the energy (watts) and the energy concentration (joules/cm 2 ) that are to be used must also be accommodated in the design of the device. The prior application referenced above has disclosed how the cross-sectional area of the emitter end of the device can be reduced by incorporating dielectric materials. The device must not only be compact, but it should be ergonomically designed for easiest placement and actuation, so that a relatively large target area can be covered by successive applications without redundancy. In addition, the dangers of erroneous energization, excessive exposure, and improper sequencing should be minimized in ways that free the operator from responsibilities for safeguards to the extent possible. 
     SUMMARY OF THE INVENTION 
     Handheld energy applicators in accordance with the present invention are advantageously configured for one hand operation, and contain all operative elements within a housing have a convenient handle that extends or curves into an extension of smaller cross-section which incorporates a transmitting aperture or emitter at its distal end. The distal end is configured to be precisely placeable relative to a target area, and also includes integrated means for delivering a cooling medium at the target area until a temperature level is attained that allows safe delivery of a microwave pulse via the aperture. The energy level and duration of the applied microwave energy for a preferred wavelength are chosen for the treatment desired. 
     In one example of an applicator in accordance with the invention, wave energy from a source is fed to the proximal end of the applicator via a flexible coaxial line, and launched within the applicator into one or more double ridged waveguides extending along the slim distal extension. The ridged waveguide occupies most of the extension and reduces the cross-sectional area needed for a chosen wavelength. The distal end of the extension comprises a short converging tapered or stepped length which preferably includes a dielectric that further reduces the form factor and provides an impedance substantially matching that of the target area. The transmitting aperture is established at a predetermined close spacing to the skin surface at the target area by a terminal spacer which contacts the surface and also includes indicia for precise placement of the applicator relative to a target area to be treated. A coolant line extends along the waveguide within the applicator housing from a pressurized source through a signal-operated solenoid-controlled valve to terminate in an open nozzle section at the distal end. The cycle is initiated by directing expanded coolant across the target area until a selected temperature threshold is attained, then initiating a microwave pulse of selected energy and duration. 
     The complete microwave energy applicator system comprises a self-contained manual unit coupled by flexible lines to a pulse source of microwave energy, a pressurized coolant source, a signal source for actuating the valve and control circuits to control timing and adjust power level and pulse duration of the microwave energy. A temperature sensor is incorporated at the distal end of the applicator to sense that coolant is being effectively delivered before the microwave energy is applied. The switch for the operator may be located at a fingertip position or be responsive to an end-mounted mechanism that can be pressed against the skin to start. Indicator lights on the housing are visible to the operator to denote readiness status and error conditions. 
     In an example of an applicator in accordance with the invention, designed for small size and ergonomic advantages, the housing comprises a generally rounded base for retention in the hand between the thumb and forefinger. The base smoothly curves into a smaller diameter end section with a narrowed waist region conforming to the thumb and forefingers and terminating in a distal end at which the transmitting aperture of a waveguide projects. A spacer element, preferably disposable, fits removably over the transmitting aperture and is shaped to provide a predetermined gap, between a skin target area and the end of the waveguide, which confines and directs the coolant within a limited volume having a vent at one side. The coolant line extends from the posterior end of the housing through the base portion, where flow of a gas refrigerant is controlled by a solenoid-operated valve. A photodetection device in the coolant path may be utilized to determine if liquid is present in the refrigerant since this could adversely affect cooling. At the distal end of the housing, a nozzle directs coolant within the limited volume across the face of the transmitting aperture, tangentially along the target area, within the spacer. The spacer includes an egress or venting port which offers low impedance to flow and unrestricted egress of the refrigerant to a deflecting shield which directs the coolant away from the skin. The operator can observe the indicator lights on the top of the base portion of the housing, so as to be assured that a new cycle can be initiated after a prior one is completed. The initiating switch is located conveniently to the tip of a forefinger on the top of the distal end section. Compactness is aided also by a coaxial feedline within the base from its posterior end to a transition coupling into the double ridged waveguide. Another feature provided by the spacer is the inclusion of one or more protruding positional markers, visible to an operator and enabling easy placement of the emitter at a target area. 
     In another example of a device in accordance with the invention, the principal length of the interior waveguide comprises a double ridged waveguide section leading from the proximal end of the housing through the intermediate region, into a step transition joining to a reduced area end cross-section that is dielectric loaded. The distal end includes both a coolant outlet nozzle and a spaced apart thermistor open to the adjacent gap between the transmitting aperture and the skin surface. In this example, placement is facilitated by a target area framing element that is movable axially through a small distance to engage the start switch. When in that position the framing element provides the desired gap between the skin surface and the emitter aperture, at the time of cycle initiation. A solenoid actuated valve straddles the waveguide in mid-region of the housing, so that a coolant line from the pressurized source to the valve is connected through the valve to an output coolant line extending along the waveguide to the distal end. The housing has a bulbous handle sized and configured to be held in the palm with the fingers extending distally to engage the narrow elongated end with a pencil-type grip. The housing exterior has a smooth, curved transition section that merges down into the elongated distal end and keeps the emitter end and indicia in full sight. 
     In yet another example of a device in accordance with the invention, two or more emitter units are positioned to be adjacent in side-by-side or above and below relation to the applicator housing, so that a larger target area can be covered at each position by applying energy pulses to two or more adjacent areas. For the double applicator, two parallel and adjacent double ridged waveguides proximate to the distal end are fed by a single switch within the housing that receives microwave energy from the pulse source. This may be a single pole double throw RF switch, having a single inlet port, for input from a coaxial waveguide along the central axis and with parallel outputs feeding to individual coaxial waveguides coupled separately to the double ridged waveguides. For convenient handling of the unit and delivery of the energy in a direction normal to the skin, the ends of the waveguides are angled, as through a 60° angle, at an elbow region before the adjacent emitter apertures. A user can thus hold this slightly larger unit conveniently, at an acute angle to the surface of the skin, for easiest placement and application of energy. With adjacent emitter apertures, the switch alternates pulses between the emitters at each target position, in timed relation to applied coolant pulses. After energy delivery at a first site, the applicator can then be moved orthogonally relative to the paired emitters to the next position. To provide automatic placement of the transmitting apertures relative to target areas, a tracking wheel device that rolls on the skin surface measures the incremental distance needed to reach the next adjacent target area. A trigger switch responsive to the tracker wheel movement indicates to the user that the unit is in position to begin the next sequence of coolant and microwave pulses, or it automatically triggers the sequence itself. 
     Other features of devices in accordance with the invention reside in the distal end spacer and the method of cooling the surface of the target area. The spacer, which is essentially a single use disposable device but can be resterilized, is a low cost unitary molded element that removably attaches about the emitter aperture at the distal end of the applicator. In position, it encompasses the emitter but has an opening at the skin surface side that is coextensive and aligned with the emitter aperture. The spacer is dimensioned to maintain the emitter aperture at a predetermined small gap from the skin surface, while defining an interior volume adjacent the skin surface that is open only at one side, used for venting. Coolant gas flowing across the targeted surface from one side of the emitter aperture is thus confined within the volume until it reaches the opposite side of the spacer, where it is vented away from the skin surface, but encounters minimal impedance. 
     The cooling method utilizes the cooling effect of an expanded gas, such as an environmentally approved refrigerant derived from an ambient temperature pressurized source (e.g., a small pressurized vessel). A burst of gas is begun prior to application of microwave energy, and cools the skin surface convectively until a desired threshold temperature is sensed at the venting side by a temperature sensitive device. On sensing the lowering of temperature below the threshold the microwave pulse is initiated, and the coolant flow can be discontinued, at the value although this need not be precise, and flow continues until lines are cleared. The skin surface temperature is reduced, typically in the range of 10-250° C., but with a total open time of the solenoid in the 10-25 MS (milliseconds) range. The cooling penetrates to the upper part of the dermis. The method has been shown to be highly effective in limiting surface irritation and adverse effects from microwave applications. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     A better understanding of the invention may be had by reference to the following description, taken in conjunction with the accompanying drawings, in which: 
     FIG. 1 is a combined block and perspective view of an example of an energy applicator in accordance with the invention having a single waveguide and emitter aperture; 
     FIG. 2 is a side sectional view of the arrangement of FIG. 1, showing further details thereof; 
     FIGS. 3 is different perspective view of the arrangement of FIGS. 1 and 2; 
     FIG. 4 is an exploded fragmentary view, of the distal end of the applicator of FIGS. 1-3 showing a refrigerant nozzle and end spacer that are employed in the arrangement of FIGS. 1-3; 
     FIG. 5 is a different perspective view of the end spacer of FIG. 4; 
     FIG. 6 is a fragmentary perspective view, partially broken away, of an attached spacer device; 
     FIG. 7 is a side cross-sectional view of the installed spacer of FIG. 6, showing the coolant flow therein; 
     FIG. 8 is a perspective view of a different example of an applicator in accordance with the invention; 
     FIG. 9 is side sectional view of the applicator of FIG. 8; 
     FIG. 10 is a top sectional view of the applicator of FIGS. 8 and 9; 
     FIG. 11 is a fragmentary perspective view, partially broken away, showing further details of the distal end of the arrangement of FIGS. 8-10; 
     FIG. 12 is an end view of the distal end of the applicator of FIGS. 8-10; 
     FIG. 13 is an end view of the posterior end of the applicator of FIGS. 8-10; 
     FIG. 14 is a side sectional view of an example of an applicator in accordance with the invention utilizing two side by side waveguides; 
     FIG. 15 is a plan sectional view of the applicator of FIG. 14, showing further details thereof; and 
     FIG. 16 is an enlarged perspective view of a fragment of the arrangement of FIGS. 14 and 15, showing further details of the device for measuring the spacing between target positions. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     FIGS. 1-7 depict an applicator  10  in accordance with the invention including a slim line housing  12  having a streamlined, base portion  14  at the proximal end, and an elongated, narrower distal portion  16  at a substantial angle, but slightly less than 90°. A curved intermediate region merges the bulbous base  14  to the elongated distal portion  16  in a smooth, continuous fashion. The distal portion  16  has a narrowed but smooth merging waist region  18  that provides a natural ergonomic reference for gripping the applicator in pencil-type fashion, with the bulbous base  14  between the thumb and index finger and the forefinger extending distally along the elongated portion  16 , for easiest manipulation. The housing  12  is preferably of a lightweight, insulative material such as molded plastic. 
     The applicator  10  receives microwave energy as pulses of chosen duration from a microwave energy source  20  (FIG. 1 only) which is adjustable in power and has a selected frequency range from about 2 to 20 GHz, as described in the above referenced application. Preferably, the source is in the range of about 14 GHz for best matching to a receptive tissue or constituent, such as blood, vascular structure, or hair follicles. A pulse duration control  22  is also coupled to the microwave energy source  20 , which is typically a magnetron, traveling wave tube or other source. Selection of power and duration determines the total energy delivered in a pulse, which is preferably in the range of about 20-30 joules/cm 2  for depilation, and usually within 20-28 joules/cm 2 . The microwave signal is fed from the source  20  via a flexible coaxial feed line  24  to a microwave port  26  at the proximal end of the housing  12 . 
     The applicator system also includes a pressurized gas coolant source  30 , which for cost, convenience and ease of use will typically be a pressurized refrigerant bottle having a nominal pressure of about 50-250 psi, typically about 80 psi. Further, the refrigerant itself is preferably an environmentally non-deleterious compound, such as HFC 134A, or 1,1,1,2 tetrafluorethane, for example. A flexible conduit  32  capable of withstanding the input pressure couples the source  30  to a coolant port  34  at the proximal end of the housing  12 . 
     Control circuits  36  for responding to the appropriate inputs provide signals to the applicator  10  and the pulse duration control  22  to operate the active elements in properly timed relation. 
     The proximal end of the housing  12  also includes a signal coupler port  38  through which electrical lines  39  (FIG. 1) coupled to the control circuits  36  are conducted into and out of the interior of the applicator housing  12 . A pair of indicator lights  40  are disposed on the proximal end of the housing  12 , to indicate various operative conditions, such as power, readiness to operate, and delay interval. The sensors and logic for actuating these indicator lights  40  are conventional, and therefore not depicted in this example. 
     Within the base  14  of the housing  12 , a solenoid-controlled valve  44  for gating the gas coolant flow is mounted with its body along the length of the housing and with the valve portion transversely straddling the central axis of the housing  12 , as best seen in FIG.  2 . An input coolant conduit  46  from the coolant port  34  extends along one side of the housing  12  to an input port  48  on the same side of the solenoid-controlled valve  44 . At the opposite side of the valve portion of the solenoid-controlled valve  44 , an output coolant conduit  50  extends along the housing  12 , from an output port  52  on the valve to the distal end of the housing  12 . The end of the output coolant conduit  50  is open, defining a jet nozzle  54 , which in this example is elliptical in cross-section, to facilitate flow across the target area from one side of the distal end of the housing  12 . Alternatively, the jet nozzle can be disposed in various orientations, including transverse to the skin surface that is to be engaged, or it can branch, prior to the end section, into two or more jet nozzles, for example. The arrangement shown, which is best seen in FIGS. 4 and 6, is however more direct and of proven effectiveness. 
     The central structure within the applicator housing  12 , for microwave transmission, as best seen in FIG. 2, comprises a double ridged waveguide  60  extending along the central region of the distal elongated portion  16 , and receiving energy from a coax to waveguide transition  62  coupled to a coaxial waveguide  64  that leads to a connector  66 , such as an SMA connector at the proximal end of the housing  12 . The double ridged waveguide  60  reduces the cross-sectional dimension needed for the chosen wavelength, and leads to a terminating transition section  67  which converges to an emitter aperture  68  of approximately 6 mm×4 mm size. The transition section  67  is loaded with a dielectric  69  which permits reduction of the emitter aperture  68  to that size. Referring again to FIGS. 1 and 3 in addition to FIG. 2, an initiator switch  70  is directly under a flexible control button  72  which is convenient to the forefinger of an operator holding the applicator  10  in a normal position. An electrical line  74  which carries signals indicating the switch  70  status is coupled back along the waveguide structure  60  to the signal coupler port  38 . A thermistor  75  is positioned at the distal end of the housing  12 , to sense the approximate temperature at the distal end of the applicator  10 . The thermistor  75  indicates the effect of coolant that has been jetted from the nozzle  54  and when the system is ready to operate. A signal line  76  (FIG. 2) from the thermistor  75  returns to the proximal end of the housing  12  and then to the control circuits  36 , which control the initiation and sequencing of the coolant and microwave power cycles. The input coolant line  46  includes a photodetector  77  for sensing the presence of liquid in the coolant at that point. At the narrow end of the distal portion of the housing  12 , O rings  79  are set in grooves to enable the operator to grip the extreme end if desired. 
     The applicator  10  also includes a spacer  80  for detachably mounting on the protruding portion of the waveguide  60  at its distal end. The spacer  80  is preferably disposable, so that it can be replaced on a single use basis by fitting it frictionally on to the end of the waveguide. As seen in FIGS. 5 and 6, the spacer  80  defines a boundary about the transmitting aperture  68 , confining an interior volume  82  and providing a precise axial separation, here about 0.020 inches of the aperture  68  from the skin surface. This enables the applicator  10  to be held against the skin of a subject while precisely maintaining the chosen distance between the transmitting aperture and the subject to allow for cooling while preventing skin damage. The jet nozzle  54  for refrigerant is positioned at one side to feed into this interior volume  82 , which has an internal wall  83  defining an egress port  84  (FIG. 5) on the opposite side from the nozzle  54 . Thus the expanding gas refrigerant flows across the surface of the skin to be irradiated, between the transmitting aperture  68  and the skin, and passes through the port  84  in a lateral direction. A curved or angled deflector wall  86  forming a part of the spacer  80  directs the gases that move through the port  84  away from the skin so that cooling is limited to the area that is receiving microwave energy. The outer periphery of the spacer  80  here includes two visible indicator markers  88 ,  89  each in the form of a tapered projection or fin. In this example, two orthogonally disposed locator fins  88 ,  89  each centered as to a different side of the transmitting aperture  68  are shown. More or fewer may be used, depending on the particular procedure and the nature of preparatory target markings placed on the skin. 
     Referring again to FIGS. 1-7, this applicator  10  is compact, and held in one hand in a natural manner. Additionally, the indicator markers  88 ,  89  on the spacer  80  enable correct placement at the target area since they can be seen by the user regardless of the angle of the view. Typically, removable marks will be placed on the skin of the patient prior to initiation of the procedure, and the markers  88 ,  89  can be placed relative to these for successive applications. 
     The base  14  is held, pencil style, against the palm of the hand and between the fingers and points in the direction of the elongated end  16 , which facilitates instinctive placement at the target area on the patient&#39;s skin. Here is it assumed, for purposes of illustration only, that the therapeutic procedure involved is depilation, so that the wattage and duration are selected to give an appropriate amount of joules/cm 2 , using the adjustable microwave source  20  and pulse duration control  22  as operated by the control circuits  30 . Suitable results are obtained with total dosage levels of the order of 20-28 joules/cm 2  for 10-50 MS delivered to the applicator. In a specific practical example for depilation the dosage level was about 24-25 joules/cm 2  delivered in a 25-30 MS pulse with a surface temperature drop, caused by the coolant, of about 12° C. Initially, however, coolant flow is used to assure that the skin temperature will be lowered by pre-cooling. The pressurized coolant source  30  constantly pressurizes the line  32  and the internal coupling up to the input port  48  of the solenoid control valve  44 . Checking the indicator lights  40  (FIG. 1) the operator has verification that the sequence can be initiated, after correctly placing the spacing marker fins  88 ,  89  at the distal end of the applicator  10  against a chosen area, usually premarked with lines or dots on the skin surface. Such placement assures that the transmitting aperture  68  at the distal end is precisely in position. By pressing the control button  72  on the applicator  10 , the initiator switch  70  is actuated, signaling the control circuits  36  to commence the controlled cycle. To begin, the solenoid control valve  44  is actuated to open the coolant line  50  from the output port  52  on the valve  44 , thus directing a flow of expanding coolant from the jet nozzle  54  along the skin across the target area. The characteristic flow pattern, best seen in FIG. 7, chills the skin surface by convection as the expanding refrigerant gas flows within the limited internal spacer volume  82 . The gas moves without restriction under the barrier  83 , through the vent opening  84 , and then is deflected away from the skin surface at the deflector  86 . Because the internal volume  82  defines a precise and small separation between the emitter aperture  68  and the skin surface, and because outward side flow is blocked, the skin surface is efficiently cooled. The coolant pulse is usually from 10-25 MS long, and a temperature drop of about 10-25° C. is typically sufficient at the skin surface, although the thermal gradient extends partially into the dermis. At the end of the coolant pulse, when the valve is again closed, some flow continues until the lines are clear. 
     The thermistor  75  signal detecting a reduced temperature is returned to the control circuits  36 , until a threshold is reached indicating sufficient cooling at the site. If no reduction is sensed the microwave energy is not delivered. In normal operation, however, within less than 20 milliseconds, the pulse duration control  22  is triggered by detection of a temperature below the threshold. The triggering actuates the microwave source  20  to deliver the energy pulse for effecting microwave penetration and histological change in the target region. Under the conditions stated the desired changes are not accompanied by irritation or trauma. 
     In a second example of an applicator  100  in accordance with the invention, referring now to FIGS. 8-13, the applicator housing  112  has a slim line base  114  with a projection  118  providing a reference for an operator who holds base  114  in his hand. The base merges toward an elongated distal end  116  and terminates at an emitter or transmitting aperture as previously described. However, the interior waveguide  160  (FIGS. 9-11) comprises a double ridged waveguide coupled at an SMA connector  26  (as in FIGS. 4 and 2) to an input feed coaxial waveguide  128  coupled to the posterior end of the housing  112 . In the distal portion  116  of the housing  112 , the rectangular waveguide  160  joins at a step transition  161  to a reduced height end section  166  that is filled with a dielectric material  170  (FIG. 11 only) comprising a loading element that extends to the emitter aperture  172  on the waveguide  160 . Tuning screws  162  provided in the double ridged waveguide  160  enable electrical matching of waveguide impedance. A jet nozzle  154  for gas coolant extends from a coolant line  155  as previously described. 
     Adjacent its distal end, the housing  112  has a streamlined, enlarged side extension  176  which incorporates a small switch  178  from which an actuator finger  179  extends distally out from the distal end of the housing  112 . The electrical line  181  (FIGS. 9 and 10) which carries signals indicating the switch  178  status is coupled back along the waveguide structure  160  to a signal or coupler port  38 . A target framing element  182  transverse to the longitudinal axis of the waveguide structure  160  is at the same time parallel to the skin surface to be engaged. The framing element  182  defines an interior opening  184  (FIGS. 10-12) that encompasses and borders the emitter aperture  172  of the waveguide structure  160 , and may also include guide markings  185  visible to the operator of the applicator  100  to precisely indicate the boundaries of the emitter aperture  172 . The switch  178  may be manually operated. Alternatively, however, as shown here, one side of the target framing element  182  is coupled to the switch actuator finger  179 , which is spring loaded. The target framing element  182  is biased toward the extended position, but closes the switch  178  circuit as it is pushed toward the distal end of the housing when the user pushes the applicator  100  against the target skin area. A thermistor  90  may again be mounted on the distal end of the housing  112  to sense the approximate temperature and indicate whether coolant has been jetted from the nozzle when the system is ready to operate. 
     The double ridged waveguide  160 , which is substantially smaller than a regular rectangular waveguide in cross-sectional area, provides a first concentration of electrical field energy, and the reduced height section, which is dielectric filled, not only reduces the area further, but matches the electrical impedance to the skin surface. Consequently, the applicator  100  is easily manipulated, and the flexible input lines, including a flexible input coax line, provide no interference to handling and placement. 
     In this manner, the surgeon or technician, or other operator, can be immediately ready to target another adjacent location and initiate the timed cycle when the circuits are ready. 
     The same basic sequence of application cycles is also used in an alternative applicator  200 , seen in FIGS. 14-16, which is substantially similar in the manner of operation as to the coolant, pulsed microwave energy delivery, and control system. Thus redundant internal details of this structure are not specifically shown and reference can be made to FIGS. 1-13 for such aspects. These includes the valve actuated coolant system, the sensors and control circuits, the internal wiring, a manually operated control switch and other details which have been omitted for clarity. In the arrangement of FIGS. 14-16, the housing  202  has a relatively low height handle portion  204  tapering down to a distal end  206  of narrower width. The housing  202  contains two side by side double ridged waveguides  210 ,  212 , which may include reduced height distal sections that are dielectric loaded, as in the prior example of FIGS. 7-12, although these are not shown. The waveguides  210 ,  212  do, however, include angled distal end sections  214 ,  215 , the angle in this example being approximately 600 relative to the principal longitudinal axis of the waveguides  210 ,  212 . The distal end  206  of the housing  202  similarly is angled in a like manner, enabling the applicator  200  to be held in a convenient position, spaced from the body surface of the recipient so that guide markers on an indicia frame or element (which may correspond to that of the examples of FIGS. 1-13) at the end can readily be visualized to enable the target area to be selected. 
     As an alternative to a manual control switch, as seen in FIGS. 14-16, the distal end  206  of the housing includes a pair of tracking wheels  217 ,  219  beneath the angled ends of the waveguides  210 ,  212 , the wheels  217 ,  219  being interconnected by a shaft  220  mounted in the housing distal end  206 . A smaller hub enclosing a rotary encoder element  222  generates an electrical signal or a mechanical impulse whenever the tracking wheels  217 ,  219  go through a selected angular increment. The rotary encoder element  222  may be an optical encoder or a mechanical device with detent surfaces, to provide impulses to a switch  224  at the successive increments. The angular increments are chosen to correspond in linear distance to the height of the emitter apertures in the waveguides  214 ,  215  at the distal end  206 , and the switch  224  provides a signal to the control circuits, as in the example of FIGS. 1-6, to repeat the firing procedure. That is, when the applicator is ready to trigger and the proper position is reached, the flow of coolant is initiated, a thermistor detects the level of satisfactory cooling, and the microwave source is pulsed for the selected duration. 
     In this example, however, the two waveguides  210 ,  212 , are operated alternately. For this purpose, an input coax line  230  feeds into a central input of a single pole double throw RF switch  234 , which has two coax outputs  236 ,  237  feeding to SMA connectors  240 ,  241  each coupling into a different double ridged waveguide  210  or  212  and providing a coax to rectangular waveguide transition. Signals from the control circuits (see FIG. 1) alternate the input microwave energy between the two ridged waveguides  210 ,  212  as operation proceeds through successive positions. 
     The tracking wheel arrangement thus provides measurements and control signals as the applicator  200  is moved between positions. Once pulses have been emitted from the two emitter apertures at a given selected location, the applicator  200  is simply rolled along the skin surface a distance measured by the tracking wheel combination. Without raising the applicator  200  off the skin surface, the operator is informed by an indicator light, a distinct sound, or even a tactile impression, such as a vibration, that the precisely determined next location has been reached. In this manner, while also firing microwave pulses alternately from the two adjacent emitters, the operating doctor or technician can proceed immediately between successive positions, and total application time can be significantly reduced. 
     While there has been described above and illustrated in the drawings various forms and modifications in accordance with the invention, it will be appreciated that the invention is not limited thereto but encompasses all variations and alternatives in accordance with the appended claims.