fig1 shows one embodiment of a system 10 , which monitors and controls the use of an operative element 12 . the system 10 is well adapted for association with single use , catheter - based devices . therefore , in the illustrated embodiment , the operative element 12 is part of a catheter - based treatment device 26 . it should be appreciated , however , that the system 10 is also adaptable for use with devices and methods that are not necessarily catheter - based . in the illustrated embodiment , the device 26 includes a handle 28 made , e . g ., from molded plastic . the handle 28 is sized to be conveniently held by a physician , to introduce the catheter tube 30 into the targeted tissue region . the handle 28 carries a flexible catheter tube 30 . the catheter tube 30 can be constructed , for example , using standard flexible , medical grade plastic materials . the catheter tube 30 has a distal end 34 , which carries the operative element 12 . the operative element 12 can support , for example , a device for imaging body tissue , such as an endoscope , or an ultrasound transducer . the operative element 12 can also support a device to deliver a drug or therapeutic material to body tissue . the operative element 12 can also support a device for sensing a physiological characteristic in tissue , such as electrical activity , or for transmitting energy to stimulate or form lesions in tissue . in the illustrated embodiment , the device 26 , in use , is intended to treat dysfunction of sphincters and adjoining tissue regions in the upper gastrointestinal tract , e . g ., in the lower esophageal sphincter and adjacent cardia of the stomach , as well as in the lower gastrointestinal tract , e . g ., in the intestines , rectum and anal canal . still , it should be appreciated that the system 10 can be used in association with other devices and methods used to treat other dysfunctions elsewhere in the body , which are not necessarily sphincter - related . for example , the various aspects of the invention have application in procedures requiring ablation of tissue throughout the body , or treatment of hemorrhoids , or restoring compliance to or otherwise tightening interior tissue or muscle regions . in the illustrated embodiment , one function that the operative element 12 is to perform is to apply energy in a selective fashion to a targeted body region , which , for the purpose of illustration , can be the lower esophageal sphincter , or cardia , or both . the applied energy creates one or more lesions , or a prescribed pattern of lesions , below the mucosal surface of the esophagus or cardia . the subsurface lesions are formed in a manner that preserves and protects the mucosal surface against thermal damage . it has been discovered that natural healing of the subsurface lesions leads to a physical tightening of the sphincter and / or adjoining cardia . the subsurface lesions can also result in the interruption of aberrant electrical pathways that may cause spontaneous sphincter relaxation . in any event , the treatment can restore normal closure function to the sphincter . the structure of the operative element 12 to achieve this result can vary . a representative embodiment is shown in fig2 to 4 , in which the operative element 12 comprises a three - dimensional basket 56 . the basket 56 includes one or more spines 58 , and typically includes from four to eight spines 58 , which are assembled together by a distal hub 60 and a proximal base 62 . in the illustrated embodiment , an expandable structure 72 comprising a balloon is located within the basket 56 . the balloon structure 72 can be made , e . g ., from a polyethylene terephthalate ( pet ) material , or a polyamide ( non - compliant ) material , or a radiation cross - linked polyethylene ( semi - compliant ) material , or a latex material , or a silicone material , or a c - flex ( highly compliant ) material . the balloon structure 72 presents a normally , generally collapsed condition , as fig2 shows . in this condition , the basket 56 is also normally collapsed about the balloon structure 72 , presenting a low profile for deployment into the esophagus 10 . the catheter tube 30 includes an interior lumen , which communicates with the interior of the balloon structure 72 . a fitting 76 ( e . g ., a syringe - activated check valve ) is carried by the handle 28 . the fitting 76 communicates with the lumen . the fitting 76 couples the lumen to a syringe 78 ( see fig3 ) . the syringe 78 injects fluid under pressure through the lumen into the balloon structure 72 , causing its expansion . expansion of the balloon structure 72 urges the basket 56 to open and expand ( see fig3 ). the force exerted by the balloon structure 72 , when expanded , is sufficient to exert an opening force upon the tissue surrounding the basket 56 . each spine 58 carries an electrode 66 ( see fig4 ). in the illustrated embodiment , each electrode 66 is carried within the tubular spine 58 for sliding movement . each electrode 66 slides from a retracted position , withdrawn in the spine 58 ( shown in fig3 ) and an extended position , extending outward from the spine 58 ( see fig4 ) through a hole in the spine 58 . a push - pull lever 68 on the handle 28 is coupled by one or more interior wires to the sliding electrodes 66 . the lever 68 controls movement electrodes between the retracted position ( by pulling rearward on the lever 68 ) and the extended position ( by pushing forward on the lever 68 ). the electrodes 66 have sufficient distal sharpness and strength , when extended , to penetrate a desired depth into tissue the smooth muscle of the esophageal or cardia 20 wall . the desired depth can range from about 4 mm to about 5 mm . in this arrangement ( see fig1 ), the system 10 includes a generator 38 to supply the treatment energy to the electrodes 66 . in the illustrated embodiment , the generator 38 supplies radio frequency energy , e . g ., having a frequency in the range of about 400 khz to about 10 mhz . of course , other forms of energy can be applied , e . g ., coherent or incoherent light ; heated or cooled fluid ; resistive heating ; microwave ; ultrasound ; a tissue ablation fluid ; or cryogenic fluid . a cable 40 extending from the proximal end of the handle 28 terminates with an electrical connector 42 . the cable 40 is electrically coupled to the operative element 12 , e . g ., by wires that extend through the interior of the handle 28 and catheter tube 30 . the connector 42 plugs into the generator 38 , to convey the generated energy to the operative element 12 . the electrodes 66 are formed of material that conducts radio frequency energy , e . g ., nickel titanium , stainless steel , e . g ., 304 stainless steel , or a combination of nickel titanium and stainless steel . in the illustrated embodiment ( see fig5 ), an electrical insulating material 70 is coated about the proximal end of each electrode 66 . when the distal end of the electrode 66 penetrating the smooth muscle of the esophageal sphincter 18 or cardia 20 transmits radio frequency energy , the material 70 insulates the mucosal surface of the esophagus 10 or cardia 20 from direct exposure to the radio frequency energy . thermal damage to the mucosal surface is thereby avoided . the mucosal surface can also be actively cooled during application of radio frequency energy , to further protect the mucosal surface from thermal damage . in the illustrated embodiment ( see fig5 ), at least one temperature sensor 80 is associated with each electrode . one temperature sensor 80 senses temperature conditions near the exposed distal end of the electrode 66 , a second temperature sensor 80 is located on the corresponding spine 58 , which rests against the muscosal surface when the balloon structure 72 is inflated . the system 10 ( see fig1 ) can also include certain auxiliary processing equipment , e . g ., an external fluid delivery apparatus 44 for supplying cooling liquid to the targeted tissue , e . g ., through holes in the spines , and an external aspirating apparatus 46 for conveying liquid from the targeted tissue site , e . g ., through other holes in the spine or elsewhere on the basket 56 . the system 10 also includes a controller 52 . the controller 52 , which preferably includes a central processing unit ( cpu ), is linked to the generator 38 , the fluid delivery apparatus 44 , and the aspirating apparatus 46 . alternatively , the aspirating apparatus 46 can comprise a conventional vacuum source typically present in a physician &# 39 ; s suite , which operates continuously , independent of the controller 52 . the controller 52 governs the delivery of processing fluid and , if desired , the removal of aspirated material . the controller 52 also governs the power levels , cycles , and duration that the radio frequency energy is distributed to the electrodes 66 , to achieve and maintain power levels appropriate to achieve the desired treatment objectives . the controller 52 can condition the electrodes 66 to operate in a monopolar mode . in this mode , each electrode 66 serves as a transmitter of energy , and an indifferent patch electrode ( not shown ) serves as a common return for all electrodes 66 . alternatively , the controller 52 can condition the electrodes 66 to operate in a bipolar mode . in this mode , one of the electrodes comprises the transmitter and an other electrode comprises the return for the transmitted energy . the bipolar electrode pairs can electrodes 66 on adjacent spines , or electrodes 66 spaced more widely apart on different spines . the controller 52 includes an input / output ( i / o ) device 54 . the i / o device 54 allows the physician to input control and processing variables , to enable the controller 52 to generate appropriate command signals . the i / o device 54 also receives real time processing feedback information from the temperature sensors 80 , for processing by the controller 52 , e . g ., to govern the application of energy and the delivery of processing fluid . the i / o device 54 also includes a graphical user interface ( gui ), to graphically present processing information to the physician for viewing or analysis . the handle 28 and the catheter tube 30 form an integrated construction intended for a single use and subsequent disposal as a unit . alternatively , the handle 28 can comprise a nondisposable component intended for multiple uses . in this arrangement , the catheter tube 30 , and components carried at the end of the catheter tube 30 comprise a disposable assembly , which the physician releasably connects to the handle 28 at time of use and disconnects and discards after use . the catheter tube 30 can , for example , include a male plug connector that couples to a female plug receptacle on the handle 28 . to protect patients from the potential adverse consequences occasioned by multiple use , which include disease transmission , or material stress and instability , or decreased or unpredictable performance , the controller 52 includes a module 48 that controls use of the device 26 . in the illustrated embodiment ( see fig6 ), the device 26 is supplied as part of a kit 200 that includes , together with the device 26 , a usage key card 202 . the kit 200 packages the device 26 and usage key card 202 as a unitary , single use item in a sterile fashion within peripherally sealed sheets of plastic film material that are torn or peeled away at the instance of use . the presence of the device 26 and user key card 202 packaged together in the kit 200 verifies to the physician or user that device 26 is sterile and has not be subjected to prior use . the physician or user is thereby assured that the device 26 meets established performance and sterility specifications . no unused device 26 is supplied in the kit 200 without a usage key card 202 , and vice versa . the usage key card 202 incorporates a storage medium 204 that is readable by the module 48 . the storage medium 204 contains information that enables at least two use control and monitoring functions . the first use control and monitoring function of the usage key card 202 occurs prior to use of the device 26 in association with the generator 38 . to enable use of the generator 38 in association with the device 26 , the physician must first present the usage key card 202 for reading by the module 48 . to enable use of the device 26 , the controller 52 must then find that the usage key card 202 meets the criteria necessary for its registration by the controller 52 . the criteria are designed to indicate the absence of a prior use , either in absolute terms or in terms of a period of use outside a predetermined time period . if the criteria are not met , the controller 52 will not register the usage key card 202 , and the controller 52 will also not enable use of the generator 38 in association with the device 26 . further details of the registration function of the controller 52 will be described later . the second use control and monitoring function of the usage key card 202 occurs if the criteria are met and registration of the usage key card 202 occurs . during permitted use of the device 26 in association with the generator 38 , the storage medium 204 of the usage key card 202 remains in the module 48 and receives , via the module 48 , data generated by the controller 52 recording operating parameters and performance of the device 26 . the storage medium 204 of the usage key card 202 retains and organizes the data for further off - line storage and processing . further details of the data retention function will be described later . the usage key card 202 can be variously configured . in the illustrated embodiment ( see fig7 ), the usage key card 202 comprises a computer - readable storage medium 204 housed within a conventional 3 . 5 inch floppy disk 206 . in this arrangement , the module 48 comprises a conventional floppy disk drive 208 ( see fig8 ) capable of reading data from and downloading data to the storage medium 204 of the disk 206 . alternatively , the usage key card 202 can take the form of a pc card , flash memory device , or magnetic card . in these alternative embodiments , the module 48 comprises a data reading and writing device compatible with the storage medium of the card 202 . as fig7 shows , the storage medium 204 of the usage key card 202 contains at least two pre - formatted files 210 and 212 . the first file 210 contains a unique identification code 214 capable of being read by the module 48 and registered by the controller 52 . the second file 212 is formatted to receive and retain operational and performance data generated by the controller 52 to create from it a procedure log 220 . the identification code 214 contained in the first file 210 is created to be unique to the particular usage key card 202 . that is , each usage key card 202 contains its own unique identification code 214 . no two usage key cards share the same identification code 214 . the unique identification code 214 can comprise , e . g ., a serial number uniquely assigned to the particular device 26 found in the kit 200 , or any other unique code that is not repeated for any other usage key card 202 . the code 214 itself can comprise letters , numbers , or combinations thereof . as fig8 shows , the module 48 reads the identification code 214 off the usage key card 202 for input to the controller 52 . this identification code will be called the “ instant identification code .” following pre - programmed rules , the controller 52 constructs and maintains in non - volatile memory a use table 216 . the use table 216 contains all prior identification codes that meet the criteria to be registered by the controller 52 . these identification codes will be called the “ registered identification codes .” following pre - programmed rules , the controller 52 compares the instant identification code 214 to all registered identification codes contained in the table 216 . in the absence of a match between the instant identification code and any registered identification code , the controller 52 updates the table , i . e ., the controller 52 registers the instant identification code by adding it to the table 216 . upon registering the usage key card 202 , the controller 52 also enables use of generator 38 in association with the device . the presence of a match between the instant identification code and any registered identification code indicates the usage key card 202 has been previously read by the module 48 , which reflects a prior use of the device 26 or another device not packaged with the card 202 . in this circumstance , the controller 52 does not add the duplicative identification code to the table 216 and does not enable use of the generator 38 in association with any device 26 . preferably , the controller 52 outputs to the gui notice of prior use . in an alternative arrangement , the controller 52 maintains for each registered identification code in the table 216 a time record 218 . the time record 218 contains a value reflecting the period of time during which energy was applied by the generator 38 during the previous permitted use . in this embodiment , when a match occurs between the instant identification code and a registered identification code , the controller 52 ascertains whether the time period of previous use contained in the record 218 is less than a prescribed maximum time period , e . g ., 45 minutes . if so , the controller 52 enables a subsequent operation of the generator 38 in association with the device 26 , but only for the time period remaining . the controller 52 updates the time record 218 as further use occurs . the controller 52 preferably outputs to the gui the time period of permitted use remaining . if the controller 52 ascertains that the time period of previous use equals or exceeds the prescribed maximum time period , the controller 52 does not enable use of the generator 38 . preferably , the controller 52 outputs to the gui notice of prior use . as fig9 shows , the second file 212 contained on the storage medium 204 of the usage key card 202 is formatted to receive , via the module 48 , data that is generated by the controller 52 during permitted use of the device 26 in association with the generator 38 . the file 212 retains the data in a formatted array according to pre - programmed rules to create a procedure log 220 . the content of the formatted log 220 can vary . for example , the log 220 can document , by date of treatment and number of treatments , the coagulation level ( i . e ., the depth at which the electrodes are inserted ), the time duration of energy application , the magnitude of energy delivered by each electrode , and the coolant flow rate . the procedure log 220 can also record at pre - established intervals ( e . g ., every 5 seconds ) the temperatures of the electrodes and surrounding tissue , along other parameters , e . g ., sensed impedance and power delivered by each electrode . the procedure log 220 preferably records these values in a pre - formatted data base format , to enable import of the values as data base items for storage , processing , and retrieval by an off - line data processing device 222 having a compatible data base processing application . the off - line data processing device 222 reads processing log data from the usage key card 202 ( via a floppy disk drive 230 or otherwise compatible reading device ). the device 222 can process the data in various ways according to the rules of the data processing application . the device 222 can , e . g ., create a print - formatted record of the procedure log 220 for printing in a hard copy version . the device 222 can also , e . g ., process the procedure logs for multiple devices and patients , to create historical patient treatment records , patient reimbursement records , and the like for storage or retrieval . the device 222 thereby makes possible the establishment and maintenance of an archival patient data base by processing individual procedure logs . as fig6 shows , the kit 200 can also include a label 224 that is pre - applied or that can be applied by the physician to the usage key card 202 . the label 224 receives manually transcribed , visually readable information pertaining to the usage key card 202 , e . g ., the name of the patient being treated by the device 26 , the date of treatment , and the like . in this way , usage key cards 202 can itself be physically stored and indexed . as fig6 also shows , the kit 200 can also include instructions 232 for using the usage key card 202 in the fashion described . for example , the instructions 232 can instruct the physician as to the need for having the usage key card 202 read by the module 48 , in order to enable use of the device 26 in association with the generator 38 . the instructions 232 can also instruct the physician regarding the content of the procedure log and the subsequent off - line processing options that are available . as fig7 shows , the storage medium 204 of the usage key card 202 can also contain at least one additional formatted file 226 that provides device information 228 , which characterizes the device 26 supplied in the kit 200 . for example , the device information 228 , when read by the module 48 , can identify the type of device 26 in terms of its operational characteristics , the inclusion of temperature sensing , and reuse criteria ( e . g ., no reuse after a single use , or multiple uses permitted up a prescribed maximum number of uses , or multiple uses permitted up to a maximum time period of use , or multiple uses permitted up to a maximum application of rf energy ). the file 226 can also condition the gui to display the desired images and data formats , which change depending upon the treatment procedure using the device ( e . g ., treatment of gerd , fecal incontinence , or urinary incontinence ). in one arrangement , the controller 52 can compare the device characteristics with the operational characteristics of the controller 52 and generator 38 , and disable operation of the device 26 should the characteristics of the device 26 be incompatible with the characteristics of the controller 52 and / or generator 38 . in the illustrated embodiment ( see fig1 ), the radio frequency generator 38 , the controller 52 with i / o device 54 , and the fluid delivery apparatus 44 ( e . g ., for the delivery of cooling liquid ) are integrated within a single housing 400 . the i / o device 54 includes input connectors 402 , 404 , and 406 . the connector 402 accepts an electrical connector 408 , to which the connector 42 of the selected treatment device 26 is electrically coupled for use . the connector 404 accepts an electrical connector 410 coupled to a patch electrode 412 ( for mono - polar operation ). the connector 406 accepts an pneumatic connector 414 coupled to a conventional foot pedal 416 , when , when depressed , causes the delivery of radio frequency energy to the electrodes 66 on the device 26 . these connectors 402 , 404 , and 406 couple these external devices to the controller 52 . the i / o device 54 also couples the controller 52 to an array of membrane keypads 422 and other indicator lights on the housing 400 , for entering and indicating parameters governing the operation of the controller 52 . the i / o device 54 also couples the controller 52 to a display microprocessor 474 . in the illustrated embodiment , the microprocessor 474 comprises , e . g ., a dedicated pentium ®- based central processing unit . the controller 52 transmits data to the microprocessor 474 , and the microprocessor 474 acknowledges correct receipt of the data and formats the data for meaningful display to the physician . in the illustrated embodiment , the dedicated display microprocessor 474 exerts no control over the controller 52 . in the illustrated embodiment , the controller 52 comprises an 68hc11 processor having an imbedded operating system . alternatively , the controller 52 can comprise another style of processor , and the operating system can reside as process software on a hard drive coupled to the cpu , which is down loaded to the cpu during system initialization and startup . the display microprocessor 474 is coupled to a graphics display monitor 420 in the housing 400 . the controller 52 implements through the display microprocessor 474 the graphical user interface , or gui , which is displayed on the display monitor 420 . the gui can be realized , e . g ., as a “ c ” language program implemented by the microprocessor 474 using the ms windows ™ or nt application and the standard windows 32 api controls , e . g ., as provided by the windows ™ development kit , along with conventional graphics software disclosed in public literature . the display microprocessor 474 is also itself coupled to the floppy disk drive 208 , previously described . the display microprocessor 474 can also be coupled to a keyboard , printer , and include one or more parallel port links and one or more conventional serial rs - 232c port links or ethernet ™ communication links . upon boot - up of the cpu ( see fig1 ), the operating system implements the start - up function 510 for the gui 424 . the gui 424 displays an appropriate start - up logo and title image ( not shown ) , while the controller 52 performs a self - test . upon completion of the start - up function ( see fig1 ) , the controller 52 conducts a check function 512 . the function 512 checks for the presence of a usage key card 202 in the floppy disk drive 208 . as before described , a valid usage key card 202 is a prerequisite for using a given treatment device 26 . the absence of a usage key card 202 causes the controller 52 to command the display microprocessor 474 to generate a setup prompt 500 on the graphics display monitor 420 . fig1 shows a representative setup prompt 500 . when graphically implemented , as shown in fig1 , the setup prompt 500 leads the operator in a step - wise fashion through the tasks required to enable use of the generator 38 . a first graphic field displays one or more icons and / or alpha - numeric indicia 502 that prompt the operator to connect the electrical connector 42 of the treatment device 26 to the connector cable 408 . a second graphic field displays one or more icons and / or alpha - numeric indicia 504 that prompt the operator to insert a valid user key card 202 ( i . e ., floppy disk ). a third graphic field displays one or more icons and / or alpha - numeric indicia 506 that prompt the user to select the standby - ready button 430 on the housing 400 ( see fig1 ). with the treatment device 26 connected and a user key card 202 inserted in the floppy disk drive 208 , the actuation of the standby - ready button 430 causes the controller 52 to enter the stand - by mode 508 ( see fig . in the stand - by mode 508 , the controller 52 executes the registration function 514 , to determine whether the user key card 202 inserted in the drive 208 contains a valid identification code 214 . the identification code 214 will not be deemed valid when the code already exists in the use table 216 of the controller 52 with a time record 218 equal to or greater than the prescribed maximum , thereby indicating a completed prior use of the device 26 . when the identification code 214 is not valid , the registration function 514 commands the display microprocessor 474 to generate an exchange prompt 516 on the graphics display monitor 420 . fig1 shows a representative exchange prompt 516 . when graphically implemented , as shown in fig1 , the exchange prompt 516 leads the operator in a step - wise fashion through the tasks of replacing the previously used device 26 and its key card 202 with a new device 26 and its associated key card 202 . as shown in fig1 , a first graphic field displays one or more icons and / or alpha - numeric indicia 518 that prompt the operator to disconnect the electrical connector 42 of the previously used treatment device 26 and to connect a new treatment device 26 . a second graphic field displays one or more icons and / or alpha - numeric indicia 520 that prompt the operator to remove the old user key card 202 and insert the new key card 202 that accompanied the new treatment device 26 in the kit 200 . a third graphic field displays one or more icons and / or alpha - numeric indicia 522 that prompt the user to again select the standby - ready button 430 on the housing 400 . with the new treatment device 26 connected and the new user key card 202 inserted in the floppy disk drive 208 , selection of the standby - ready button 430 causes the controller 52 to again enter the stand - by mode 508 , and again execute the registration function 514 ( see fig1 ). the presence of a valid identification code 214 on the user card 202 causes the controller 52 to enter the ready mode 524 . the operator deploys the treatment device 26 to the intended treatment site . the operator locates the electrodes 66 in the desired orientation . when delivery of radio frequency energy is desired , the operator depresses the foot pedal 416 ( or selects the standby - ready button 430 ). in the illustrated embodiment , the controller 52 executes a prescribed pause state 528 ( e . g ., 8 seconds ), and then commands the generator 38 to apply radio frequency energy through the electrodes 66 carried by the treatment device 26 . the controller 52 includes an update function 526 ( see fig1 ). the update function 526 registers the time period during which radio frequency energy is applied using the device 26 . the time is entered into the time record 218 of the use table 216 maintained by the controller 52 . after a prescribed maximum period of use is registered ( e . g ., sixty minutes ), the update function 526 interrupts application of radio frequency energy to the electrodes 66 , and prevents further delivery by the generator 38 to the particular device 26 . in this circumstance , the update function 526 causes the controller 52 to generate the exchange prompt 516 . as previously described , the exchange prompt 516 requires the operator to replace the existing device 26 and its key card 200 with a new device 26 and its associated key card 200 . in the illustrated embodiment , while radio frequency energy is being applied during the ready mode 524 , the controller 52 preferably monitors impedance and / or temperature conditions at the treatment site . the controller 52 enters a default mode 530 and returns to the pause state 528 when certain localized impedance and / or temperature conditions are sensed , e . g ., when impedance is outside a prescribed range ( for example , less than 50 ohms or greater than 1000 ohms ); or electrode tip temperature exceeds 100 degrees c . ; or tissue surface temperature exceeds 50 degrees c . in the pause state 528 , the controller 52 prevents the application of radio frequency energy through the electrodes 66 for a prescribed period of time ( e . g ., 8 seconds ), after which operation of the generator 38 using the foot pedal 416 or standby - ready button 430 is restored . other details of the gui during operation of the device 26 can be found in co - pending u . s . patent application ser . no . 09 / 305 , 123 , filed may 4 , 1999 and entitled “ graphical user interface for association with an electrode structure deployed in contact with a tissue region ,” which is incorporated herein by reference . various features of the invention are set forth in the following claims .