Abstract:
A device for treating a tissue region is supplied with a separate usage key card. The usage key card comprises a storage medium, which is formatted to contain an identification code unique to the usage key card. The usage key card is adapted to be read by a remote reader, to download the identification code for processing by a controller for the device. Processing of the identification code by the controller either enables or disables operation of the device according to prescribed criteria. A viewable image is generated on a display screen that changes in response to processing of the identification code.

Description:
RELATED APPLICATIONS  
       [0001]     This application is a divisional of U.S. patent application Ser. No. 10/219,798, filed Aug. 15, 2002, which is a divisional of U.S. patent application Ser. No. 09/574,704, filed May 18, 2000, and entitled “Graphical User Interface for Monitoring and Controlling Use of Medical Devices,” now U.S. Pat. No. 6,464,689, which is a continuation-in-part of U.S. patent application Ser. No. 09/974,750, filed Oct. 10, 2001, and entitled “Systems and Methods for Monitoring and Controlling Use of Medical Devices,” now U.S. Pat. No. 6,827,713, which is a continuation of U.S. patent application Ser. No. 09/495,390, filed Jan. 31, 2000, now abandoned. 
     
    
     FIELD OF THE INVENTION  
       [0002]     The invention is directed to systems and methods for monitoring and controlling use of medical devices.  
       BACKGROUND OF THE INVENTION  
       [0003]     Use of medical devices intended to treat or diagnose conditions of the body can sometimes generate stress on the material or materials from which the devices are made. The material stress can alter the physical characteristics of the devices, making future performance of the devices unpredictable.  
         [0004]     In addition, exposure to blood and tissue during use can entrap biological components on or within many medical devices. Despite cleaning and subsequent sterilization, the presence of entrapped biological components can lead to unacceptable pyrogenic reactions.  
         [0005]     The effects of material stress and damage caused during a single use of a medical device, coupled with the possibility of pyrogen reactions even after resterilization, reasonably justify imposing a single use restriction upon many medical devices.  
       SUMMARY OF THE INVENTION  
       [0006]     The invention provides systems and methods for monitoring and controlling use of medical devices. The systems and methods employ a controller to control operation of the device and a reader to download information to the controller. The systems and methods also include a usage key card adapted to be handled separate from the device and comprising a storage medium formatted to contain an identification code unique to the usage key card. Upon reading by the reader, the identification code is downloaded to the controller. The controller includes a first data state prior to downloading of the identification code. A processing function for processing the identification code enables operation of the device if the identification code correlates in a pre-established manner with the first data state. The processing function operates, in response to enabling operation of the device, to change the first data state to a second data state that prevents subsequent operation of the device in response to downloading of the identification code.  
         [0007]     In one embodiment, the processing function causes the controller to create a table by registering unlike identification codes in memory as they are downloaded by the reader. The controller enables operation of the device when a new identification code is registered in the table.  
         [0008]     In one embodiment, the processing function causes the controller to disable operation of the device when the given identification code matches an identification code in the table.  
         [0009]     In one embodiment, the processing function causes the controller to register in the table, a time period of use of the device. In this arrangement, the processing function causes the controller to disable operation of the device when the time of use exceeds a prescribed period.  
         [0010]     In one embodiment, the device applies radio frequency energy to the tissue region.  
         [0011]     Features and advantages of the inventions are set forth in the following Description and Drawings, as well as in the appended claims. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0012]      FIG. 1  is a diagrammatic view of a system for treating body sphincters and adjoining tissue regions, which embodies features of the invention;  
         [0013]      FIG. 2  is a perspective view, with portions broken away, of a device usable in association with the system shown in  FIG. 1  having an operative element for contacting tissue shown in a collapsed condition;  
         [0014]      FIG. 3  is a perspective view, with portions broken away, of the device shown in  FIG. 2 , with the operative element shown in an expanded condition;  
         [0015]      FIG. 4  is a perspective view, with portions broken away, of the device shown in  FIG. 2 , with the operative element shown in an expanded condition and the electrodes extended for use;  
         [0016]      FIG. 5  is an enlarged view of the operative element shown in  FIG. 4 , with the electrodes extended for use;  
         [0017]      FIG. 6  is a perspective view of a kit containing a device, such as shown in FIGS.  2  to  5 , and a usage key card;  
         [0018]      FIG. 7  is an enlarged, mainly schematic view of the usage key card shown in  FIG. 6 , embodied as a floppy disk, and also showing the pre-formatted files it contains;  
         [0019]      FIG. 8  is a schematic view of a controller, which the system shown in  FIG. 1  incorporates, showing the pre-programmed rules by which information contained on the usage key card shown in  FIGS. 6 and 7  is read and processed;  
         [0020]      FIG. 9  is a schematic view of another processing device that reads information from the usage key card for further processing;  
         [0021]      FIG. 10  is a left perspective views of an integrated generator/controller apparatus for use in association with a disposable treatment device, the apparatus including a graphical user interface (GUI) that aids in monitoring and controlling the incidence of use of the disposable treatment device;  
         [0022]      FIG. 11  is a representative SETUP display that can be implemented by the GUI shown in  FIG. 10  as part of monitoring and controlling the incidence of use of the disposable treatment device;  
         [0023]      FIG. 12  is a representative EXCHANGE display that can be implemented by the GUI shown in  FIG. 10  as part of monitoring and controlling the incidence of use of the disposable treatment device; and  
         [0024]      FIG. 13  is a flow chart showing the various states and modes that the apparatus shown in  FIG. 10  employs in implementing the GUI in monitoring and controlling the incidence of use of the disposable treatment device.  
         [0025]     The invention may be embodied in several forms without departing from its spirit or essential characteristics. The scope of the invention is defined in the appended claims, rather than in the specific description preceding them. All embodiments that fall within the meaning and range of equivalency of the claims are therefore intended to be embraced by the claims. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0026]      FIG. 1  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.  
         [0000]     I. The Treatment Device  
         [0027]     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.  
         [0028]     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 .  
         [0029]     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.  
         [0030]     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.  
         [0031]     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.  
         [0032]     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.  
         [0033]     The structure of the operative element  12  to achieve this result can vary. A representative embodiment is shown in FIGS.  2  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 .  
         [0034]     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.  
         [0035]     The balloon structure  72  presents a normally, generally collapsed condition, as  FIG. 2  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 .  
         [0036]     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  FIG. 3 ). The syringe  78  injects fluid under pressure through the lumen into the balloon structure  72 , causing its expansion.  
         [0037]     Expansion of the balloon structure  72  urges the basket  56  to open and expand (see  FIG. 3 ). The force exerted by the balloon structure  72 , when expanded, is sufficient to exert an opening force upon the tissue surrounding the basket  56 .  
         [0038]     Each spine  58  carries an electrode  66  (see  FIG. 4 ). 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  FIG. 3 ) and an extended position, extending outward from the spine  58  (see  FIG. 4 ) 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.  
         [0039]     In this arrangement (see  FIG. 1 ), 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.  
         [0040]     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 .  
         [0041]     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.  
         [0042]     In the illustrated embodiment (see  FIG. 5 ), 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.  
         [0043]     In the illustrated embodiment (see  FIG. 5 ), 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.  
         [0044]     The system  10  (see  FIG. 1 ) 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 .  
         [0045]     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.  
         [0046]     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 another 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.  
         [0047]     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.  
         [0000]     II. Monitoring and Control of Reuse  
         [0048]     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 .  
         [0049]     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 .  
         [0050]     In the illustrated embodiment (see  FIG. 6 ), 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.  
         [0051]     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.  
         [0052]     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.  
         [0053]     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.  
         [0054]     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.  
         [0055]     The usage key card  202  can be variously configured. In the illustrated embodiment (see  FIG. 7 ), 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  FIG. 8 ) capable of reading data from and downloading data to the storage medium  204  of the disk  206 .  
         [0056]     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 .  
         [0057]     As  FIG. 7  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 .  
         [0058]     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.  
         [0059]     As  FIG. 8  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.” 
         [0060]     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.” 
         [0061]     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.  
         [0062]     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.  
         [0063]     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.  
         [0064]     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.  
         [0065]     As  FIG. 9  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 .  
         [0066]     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.  
         [0067]     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).  
         [0068]     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 database by processing individual procedure logs.  
         [0069]     As  FIG. 6  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.  
         [0070]     As  FIG. 6  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.  
         [0071]     As  FIG. 7  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 .  
         [0000]     III. Graphical User Interface (GUI) For Monitoring and Controlling Reuse  
         [0072]     In the illustrated embodiment (see  FIG. 10 ), 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 monopolar 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 .  
         [0073]     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 .  
         [0074]     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.  
         [0075]     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 .  
         [0076]     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.  
         [0077]     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.  
         [0078]     Upon boot-up of the CPU (see  FIG. 13 ), 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.  
         [0079]     Upon completion of the START-UP function (see  FIG. 13 ), 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 .  
         [0080]     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 .  FIG. 11  shows a representative SETUP prompt  500 . When graphically implemented, as shown in  FIG. 11 , 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  FIG. 10 ).  
         [0081]     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. 13 ). 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 .  
         [0082]     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 .  FIG. 12  shows a representative EXCHANGE prompt  516 . When graphically implemented, as shown in  FIG. 12 , 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 .  
         [0083]     As shown in  FIG. 12 , 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 .  
         [0084]     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  FIG. 13 ).  
         [0085]     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 .  
         [0086]     The controller  52  includes an UPDATE function  526  (see  FIG. 13 ). 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 .  
         [0087]     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 .  
         [0088]     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.  
         [0089]     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.  
         [0090]     Various features of the invention are set forth in the following claims.