Abstract:
A medical device, such as a cryogenic biopsy device, includes a disposable unit and a reusable unit. The disposable unit, such as a treatment needle or probe, is at least partially insertable into the body of a medical subject and includes an encodable device for storing information. The reusable unit is connectable to the disposable unit and includes a controller. The disposable unit transfers the information to the controller in the reusable unit. The controller then directs activities of the medical device in response to the information stored in the disposable unit.

Description:
CROSS-REFERENCES TO RELATED APPLICATIONS  
       [0001]     The following patents and/or patent applications are hereby incorporated by reference herein in their entirety:  
         [0002]     U.S. Pat. No. 6,551,255, entitled “Device for Biopsy of Tumors,” filed Oct. 16, 2000; U.S. patent application Ser. No. 10/421,598, entitled “Device for Biopsy of Tumors,” filed Apr. 22, 2003; U.S. Pat. No. 6,789,545, entitled “Method and System for Cryoablating Fibroadenomas,” filed Oct. 4, 2002; and U.S. patent application Ser. No. 10/941,511, entitled “Method and System for Cryoablating Fibroadenomas,” filed Sep. 14, 2004. U.S. patent application Ser. No. 11/210,436, entitled “Rotational Core Biopsy Device with Liquid Cryogen Adhesion Probe,” filed Aug. 23, 2005.  
       STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT  
       [0003]     Not Applicable.  
       REFERENCE TO MICROFICHE APPENDIX  
       [0004]     Not Applicable  
       BACKGROUND OF THE INVENTION  
       [0005]     1. Field of the Invention  
         [0006]     This invention relates generally to medical devices, and, more particularly, to electronically controlled medical devices used to conduct procedures that involve inserting at least part of a sterile object into the body of a medical subject.  
         [0007]     2. Description of Related Art  
         [0008]     Many medical procedures involve inserting a sterile object, such as a needle or probe, into the body of a medical subject, such as a human patient. For instance, certain biopsy procedures involve inserting a needle into a patient and removing a portion of suspect tissue.  
         [0009]     Medical devices for performing these types of procedures can be complex. One such device is described in U.S. Pat. No. 6,551,255. As described therein, a biopsy device includes a source of cryogenic fluid, a mechanism for releasing the cryogenic fluid, a needle for conducting the cryogenic fluid toward an administration site, a cutting cannula for cutting a core of tissue surrounding the needle, and a drive system for advancing and retracting the cannula.  
         [0010]     The design of this biopsy device has evolved over time to become more automated. It has been equipped with a user console, a power source, and a microprocessor. These features allow a biopsy procedure to be conducted largely under electronic control. The microprocessor responds to user button-presses at the console to perform sequences of activities. For example, once a user inserts a biopsy needle into a suspect mass, the user presses a button. The device then automatically performs a sequence of steps, which include administering a designated amount of cryogenic fluid, waiting a designated period of time for tissue to adhere to the needle, and advancing the cutting cannula after the designated period of time expires.  
         [0011]     As this biopsy device has become more complex, it has also become more expensive. Expense is an important factor to consumers of these devices because each device can generally be used only once. After its first use, the device is no longer sterile and is generally discarded.  
         [0012]     To avoid discarding an entire device after a single use, the device has been modified to be more modular. Reusable portions of the device have been segregated from disposable, single-use portions. The disposable parts of the device include the needle and the cutting cannula, i.e., the portions that are actually insertable into the body of a patient. Other portions of the device are reusable. An example of this type of device is disclosed in U.S. patent application Ser. No. 11/210,436, entitled “Rotational Core Biopsy Device with Liquid Cryogen Adhesion Probe.” 
         [0013]     As is known, different biopsy procedures call for needles and cannulas of different gauges, lengths, and/or compositions. There are many reasons for this. One is the type of mass being biopsied—whether it is soft or hard, mobile or immobile, densely or sparsely vascular. Another is the location of the mass within the patient&#39;s body—whether it is close to the surface or deep. Yet another is the context in which the device is to be used. For example, ferrous needles and cannulas should generally be avoided for procedures guided by magnetic resonance imaging (MRI).  
         [0014]     For optimal results, the conduct of a biopsy procedure is preferably varied to account for differences in the gauge, length, and/or composition of the needle and/or cannula used. For instance, greater amounts of cryogenic fluid may be needed for larger needles. Longer delays may be needed between administering the cryogenic fluid and advancing the cannula for larger cannulas.  
         [0015]     Previously, the need for different needles and cannulas has been managed by providing integrated biopsy devices specifically tailored for different applications. Each device was programmed to perform optimally with the needle and cannula that it included.  
         [0016]     In making the design more modular, however, it has become desirable to allow the reusable portion of the device to be mated with a wide variety of needles and cannulas. This gives rise to a new problem, however: how to ensure that optimal settings are used for the selected needle and/or cannula. What is needed is an effective way of varying the settings of the reusable portion of a device depending upon the particular disposable parts used.  
       SUMMARY  
       [0017]     According to an embodiment of the invention, a medical device for performing a medical procedure includes a disposable unit and a reusable unit. The disposable unit is at least partially insertable into the body of a medical subject and includes an encodable device for storing information. The reusable unit is connectable to the disposable unit and includes a controller for directing actions of the medical device in response to the information stored in the disposable unit.  
         [0018]     According to another embodiment, a medical device includes a housing and a mechanical interface portion. The mechanical interface portion is disposed at least partially within or upon the housing and is adapted for mechanically engaging with a disposable unit. The disposable unit is at least partially insertable into a medical subject and stores information pertinent to the medical procedure. A controller is disposed within the housing for conducting automated steps of the medical procedure. These steps are performed in response to information received from the disposable unit.  
         [0019]     According to a further embodiment, a medical device for performing a medical procedure includes a disposable unit that is insertable into a medical subject. The disposable unit has an encodable device for storing information and an interface portion for mechanically engaging with a reusable unit.  
         [0020]     According to yet another embodiment, a medical device includes a plurality of disposable units and a reusable unit. Each disposable unit is insertable into the body of a medical subject and includes an encodable device for storing information. The reusable unit includes a controller for directing automated actions to be performed by the medical device in response to the information stored in the encodable device. The reusable unit has a mechanical interface portion for mechanically engaging with a respective disposable unit and a communications interface portion for receiving the information from the respective disposable unit.  
         [0021]     According to another embodiment, a method for performing a medical procedure includes engaging a first unit with a second unit. The method further includes conveying information stored in the first unit to the second unit, inserting at least part of the first unit into the body of a medical subject, and performing a medical procedure on the medical subject in response to the copied information.  
         [0022]     According to yet another embodiment, a method for performing a medical procedure includes engaging a first unit with a second unit. The first unit is insertable into the body of a medical subject. The method further includes conveying information stored in the first unit to the second unit and configuring the second unit for performing automated portions of the medical procedure responsive to the information copied from the first unit.  
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0023]     Additional objects, advantages, and novel features of the invention will become apparent from a consideration of the ensuing description and drawings, in which  
         [0024]      FIG. 1  is a side perspective view of a modular biopsy device according to an embodiment of the invention;  
         [0025]      FIG. 2  is a side perspective view of the modular biopsy device of  FIG. 1  separated into a reusable portion and a disposable portion;  
         [0026]      FIG. 2A  is a rear plan view of the disposable portion of the modular biopsy device of  FIG. 1 ;  
         [0027]      FIG. 3  is a block diagram of an embodiment of an encodable device used with the disposable portion of the biopsy device of  FIG. 1 ;  
         [0028]      FIG. 4  is a block diagram of an embodiment of electronic circuitry included within a reusable portion of the biopsy device of  FIGS. 1-2 ;  
         [0029]      FIG. 5  is a flowchart of a process for configuring a reusable portion of a medical device based on information contained in a disposable portion of the medical device;  
         [0030]      FIG. 6  is a front view of a modular treatment device according to an embodiment of the invention;  
         [0031]      FIG. 7  is a front view of the modular treatment device of  FIG. 5  separated into a reusable portion and a disposable portion;  
         [0032]      FIG. 8  is a block diagram of an embodiment of electronic circuitry included within a reusable portion of the treatment device of  FIGS. 6 and 7 ; and  
         [0033]      FIGS. 9-10  are block diagrams of alternative implementations of encodable devices that may be used with the disposable portions of the biopsy device of  FIGS. 1-2  or the treatment device of  FIGS. 6-7 .  
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0034]     As used throughout this document, the words “comprising,” “including,” and “having” are intended to set forth certain items, steps, elements, or aspects of something in an open-ended fashion. Unless a specific statement is made to the contrary, these words do not indicate a closed list to which additional things cannot be added.  
         [0035]      FIGS. 1 and 2  show an example of a medical device  100  according to an embodiment of the invention. The medical device  100  is adapted for acquiring biopsy samples of suspect masses, such as fibroadenomas. The device  100  includes a housing  110 , a user console  112 , a knob portion  114 , and a nose portion  116 . A cutting cannula  118  and a biopsy needle  120  extend from the nose portion  116 . The biopsy needle  120  has a sharp distal tip  120   d  and is disposed coaxially within the cutting cannula  118 . The cutting cannula  118  is both translatable along the axis of the biopsy needle  120  and rotatable about the axis of the biopsy needle  120 .  
         [0036]     The nose portion  116  is threadedly attached the housing  110 . By unscrewing the nose portion  116  from the housing  110 , the device  100  can be separated into two distinct portions: a reusable portion  210  and a disposable portion  212 . A threaded region  220  extends from the housing  110  of the reusable portion  210  and mates with a complementarily threaded region  240  (See  FIG. 2A ) at the rear of the nose  116  of the disposable portion  212 .  
         [0037]     The reusable portion  210  includes components that may be used repeatedly for performing a large number of biopsy procedures. These include the housing  110 , user console  112 , and knob  114 . The reusable portion  210  also includes internal components (not shown), such as a battery, an electronic controller, a motor and gearbox, and various pneumatic tubes and valves. The knob  114  can be unscrewed for inserting a canister of compressed gas, such as CO 2  or N 2 O, which provides both a source of cryogenic fluid and a source of pneumatic pressure.  
         [0038]     The disposable portion  212  is preferably used only once. It includes the nose portion  116 , the cutting cannula  118 , and the biopsy needle  120 . The disposable portion  212  also includes a rear portion  230 , which fits within the housing  110  of the reusable portion  210 . The rear portion  230  includes a coring mechanism (not shown) for both translating and rotating the cutting cannula  118  with respect to the biopsy needle  120 . The reusable portion  212  has a proximal end  212   p , which is adapted for receiving compressed gas from the reusable unit  210 .  
         [0039]     A biopsy device substantially as described above is disclosed in U.S. patent application Ser. No. 11/210,436, entitled “Rotational Core Biopsy Device With Liquid Cryogen Adhesion Probe,” which is hereby incorporated by reference.  
         [0040]     In contrast with prior devices, however, the device  100  includes an encodable device, housed within the disposable portion  212 , for storing information. In the example shown in  FIGS. 1 and 2 , the encodable device is preferably an electronic circuit encapsulated within the nose portion  116 . When the disposable portion  212  is attached to the reusable portion  210 , a circuit is formed between the disposable portion  212  and the reusable portion  210 .  
         [0041]     Preferably, each of the threaded regions  220  and  240  is composed of or includes a conductive material. An electrical contact, such as a ring  222  of conductive material, is preferably disposed at the front of the housing  110  proximate to the threaded region  220  and electrically insulated from the threaded region  220 . An electrical contact, such as a spring-loaded pin  224 , is preferably disposed at the rear of the nose  116  and is electrically insulated from the conductive material within the threaded region  240 .  
         [0042]     Both the pin  224  and the conductive material of the threaded region  240  are electrically connected to the encodable device. In addition, both the ring  222  and the conductive material on the threaded region  220  are electrically connected to the controller within the housing  110 . The encodable device thus forms an electrical circuit with the controller when the disposable portion  212  is attached to the reusable portion  210 .  
         [0043]      FIG. 3  shows the encodable device  310 . The encodable device  310  is preferably encapsulated within the nose portion  116  of the disposable portion  212 . The device  310  preferably electrically interfaces with its environment via two conductors. One conductor, such as a wire, is run from one terminal of the device  310  to the pin  224 . Another conductor, such as a wire, is run from another terminal of the device  310  to the threaded region  240 .  
         [0044]     The encodable device is preferably a “1-wire®” nonvolatile memory circuit, such as a DS28E04-100 available off-the-shelf from Dallas Semiconductor Corp. of Dallas, Tex. The DS28E04-100 includes a 4 kb EEPROM (Electronically Erasable Programmable Read-Only Memory). As is known, “1-wire” circuits are able to manage serial communications with their environments and receive power from their environment via only two conductors. These circuits are thus well suited for compact implementations in which it is desirable to minimize the number of electrical interconnections.  
         [0045]      FIG. 4  shows an example of electronic circuitry disposed within the housing  110  of the reusable portion  210 . The circuitry includes a controller  410 . The controller preferably includes a microprocessor. The controller  410  is operatively connected to the user console  112 , for receiving user input, in the form of button presses, and for illuminating various indicators for displaying status. The controller  410  is also operatively connected to a motor  414 , for controlling the application of pneumatic pressure to various parts of the device  100 . A power source, such as a battery  416 , provides electrical power, via a switch  418 , for operating the controller  410 , the user console  112 , and the motor  414 . The switch  418  is preferably integrated with the knob portion  114  (see  FIG. 1 ) in a manner that causes the switch  418  to be closed when the knob  114  is turned.  
         [0046]     The controller  410  preferably establishes a connection to the encodable device  310  via a pair of conductors, such as wires  420 . One of the wires  420  is connected between the controller  410  and the conductive material of the threaded region  220 . The other of the wires  420  is connected between the controller  410  and the conductive ring  222 . Connection between the controller  410  and the encodable device  310  is made when the disposable portion  212  is attached to the reusable portion  210 .  
         [0047]      FIG. 5  shows a process in which a medical device can be used in accordance with the invention. At step  510 , a disposable unit is engaged with a reusable unit. The disposable unit stores information pertinent to the conduct of the medical procedure. At step  512 , the information, or “data,” stored in the disposable unit is conveyed to the reusable unit. At step  514 , the disposable unit, or a portion thereof, is inserted into a medical subject. Certain steps of the medical procedure are then performed in response to the data conveyed (step  516 ).  
         [0048]     Applying this process in the context of the device  100 , the disposable portion  212  is engaged with the reusable portion  110 . Electrical, mechanical, and pneumatic connections between the disposable and reusable portions are made. Data stored in the encodable device  310  is then copied to the controller  410 . An incision is made in a medical subject in the vicinity of a suspect mass, such as a fibroadenoma. The biopsy needle  120  is inserted into the suspect mass, generally under ultrasound or MRI guidance. The user then operates a control on the user console  112  to initiate certain automated aspects of the process. The controller  410  responds to the user control by executing a series of actions. These actions are based, in whole or in part, on the data conveyed from the encodable device  310 .  
         [0049]     The encodable device  310  can be made to store a wide range of data pertinent to the conduct of the biopsy procedure. For example, the encodable device  310  may store the gauge (i.e., diameter), length, composition, and cooling power of the biopsy needle  120 , as well as the gauge, length, and composition of the cutting cannula  118 . The encodable device  310  can be made to store an indication of whether the biopsy needle  120  and/or cutting cannula  118  are MRI-compatible, e.g., whether they contain any ferrous material. The encodable device  310  can also store information about the mass being biopsied, and how much cooling is required with that mass to obtain an adequate sample.  
         [0050]     According to one variant, the encodable device  310  stores parameters for conducting a biopsy procedure. The controller  410  reads the parameters and adjusts its activities accordingly. For example, one parameter can describe the period of time over which cryogenic fluid is conducted to the biopsy needle  120  before the cannula  118  is advanced. The controller  410  responds to this parameter by timing the application of cryogenic fluid and advancing the cannula when the desired time limit is reached.  
         [0051]     Another parameter may describe a desired temperature that the biopsy needle  120  should attain before the cutting cannula  118  is advanced. In this instance, the biopsy needle  120  is equipped with a temperature measuring device, such as a thermocouple, which is electrically connected back to the controller  410 . The controller responds to this parameter by monitoring the temperature of the biopsy needle  120  and advancing the cannula  118  when the measured temperature reaches the desired temperature.  
         [0052]     According to another variant, the encodable device  310  stores code for conducting all automated portions of the biopsy procedure. The code can be in the form of object code directly readable by the controller  410 . Rather than simply specifying parameters, an entire program is uploaded to the controller. The controller  410  then executes the code to conduct all of the functions associated with cooling the biopsy needle  120  and advancing the cannula  118 .  
         [0053]     In the examples given above, the data stored in the encodable device  310  is used for controlling the operation of the biopsy device  100 . Data can be stored in the device  310  for other purposes, as well. An adapter (not shown) can be provided for connecting a disposable portion  212  of the device  100  to a computer. The computer can then read and display the data stored in the encodable device  310 . This data may include, for example, the name of the patient for whom the disposable portion  212  is intended, or for whom it was used. It may include portions of the patient&#39;s medical history, or special instructions for conducting the biopsy procedure.  
         [0054]     The encodable device  310  is preferably programmed with appropriate parameters, code, or other information, in the factory where it is assembled. However, the device  310  is also preferably programmable by the user. The computer adapter, described above, preferably allows a user to both read from and write to the device  310 . A user may thus modify parameters or store additional information in the encodable device  310  prior to performing the medical procedure.  
         [0055]     The controller  414  can preferably write to the encodable device  310  in situ, while the reusable and disposable portions are mated together. The controller  414  preferably monitors activities of the biopsy device  100  during each biopsy procedure, and stores diagnostic information related to any errors or anomalies in the encodable device  310 . A user can access this diagnostic information after the biopsy procedure to explore the nature of the error or anomaly.  
         [0056]     To prevent unauthorized access, the data stored in the encodable device  310  is preferably encrypted. The controller  414  is provided with an encryption key for decoding data received from the encodable device  310 .  
         [0057]     The biopsy device  100  offers numerous benefits. Disposable portions having needles and cannulas of different gauges, lengths, and compositions can be used with a single reusable portion. Settings for performing the biopsy with the selected probe needle and cannula are automatically adjusted to optimal values.  
         [0000]     Alternatives  
         [0058]     Having described one embodiment, numerous alternative embodiments or variations can be made. For instance, the invention is not limited to a biopsy device.  
         [0059]      FIGS. 6 and 7  show an example of a cryogenic treatment device  600  according to an alternative embodiment of the invention. Like the biopsy device  100 , the treatment device  600  is separable into a reusable portion  710  and a disposable portion  712 .  
         [0060]     The reusable portion  710  includes a control unit  610 . The control unit  610  is preferably plumbed to two cryogenic sources, a first tank  640  containing compressed Argon gas and a second tank  650  containing compressed Helium gas. The control unit  610  has pneumatic connector  724  and an electrical connector  726 . The control unit preferably includes electronic and pneumatic components for controlling the application of pressurized Argon and Helium gas to the connector  724 . It also includes electronic components for measuring the temperature of the thermocouple by measuring a voltage applied to two terminals of the connector  726 .  
         [0061]     The disposable portion  712  includes a hand-held unit  614 , a hollow treatment needle  612 , and a flexible tube  616 . The flexible tube  616  encloses a pneumatic tube (not shown), which extends from a distal tip  612   d  of the treatment needle  612  to a pneumatic connector  624 . The flexible tube  616  also encloses an electrical cable  620 , which extends from a thermocouple (not shown) attached within the treatment needle  612  to an electrical connector  626 . The electrical cable  620  preferably emerges from the flexible tube  616  via a hole  622  in the flexible tube  616 .  
         [0062]     During operation, the connectors  624  and  626  are respectively mated with the connectors  724  and  726 . An incision is made in a medical subject, in a vicinity of a mass to be treated, and the treatment needle  612  is inserted into the mass, generally under ultrasound or MRI guidance. A user then operates one or more controls on the control unit  610 . In response, the control unit  610  performs a sequence of timed actions, such as applying pressurized Argon or Helium gas to the disposable portion. These actions may be adjusted based on temperature readings from the thermocouple.  
         [0063]     A treatment device substantially as described above is disclosed in U.S. Pat. No. 6,789,545, entitled, “Method and System for Cryoablating Fibroadenomas,” which is hereby incorporated by reference.  
         [0064]     In contrast with the prior device, however, the treatment device  600  includes an encodable device  750  for storing information. The encodable device  750  is preferably housed within the hand-held unit  614  and is wired back to the control unit  610  via the cable  620  and connector  626 . The encodable device  750  is preferably of the same type as that described above, i.e., a “1-Wire” DS28E04-100, from Dallas Semiconductor. To accommodate the encodable device, the treatment device disclosed in U.S. Pat. No. 6,789,454 is modified. The cable  620  is modified to carry four wires instead of the two previously needed for the thermocouple, and the connectors  626  and  726  are changed to four conductor connectors. Changes are also made within the control unit  610  to accommodate the additional wiring and functionality.  
         [0065]      FIG. 8  shows an example of electronic circuitry disposed within the control unit  610  of the reusable portion  710 . The control unit  610  includes an electronic controller  810 , which preferably includes a microprocessor. The controller  810  is coupled to a user console  822 , for receiving commands from a user and providing status to the user. The controller  810  is coupled to a thermocouple meter  824 , for measuring a voltage generated by the thermocouple (via the connector  726 ). It is also coupled to one or more actuators  814 , for controlling the application of Argon and Helium to the pneumatic connector  724 . A power source, such as a battery  816 , provides electrical power, via a switch  818 , for operating the controller  810 , the user console  822 , the actuators  814 , and the thermocouple meter  824 .  
         [0066]     The controller  810  preferably establishes a connection to the encodable device  750  via a pair of conductors, such as wires  820 , which are routed to pins of the connector  726 . Connections between the controller  810  and the encodable device  750  are made when the disposable portion  712  is attached to the reusable portion  710 .  
         [0067]     As with the biopsy device  100 , optimal conduct of a medical procedure involving the treatment device  600  depends upon proper settings. For example, certain treatment settings are optimally set in response to the gauge, length, and/or composition of the treatment needle, the cooling power of the treatment needle, and the shape of the treatment zone, as well as other factors. These settings describe, for example, the amount of cryogenic fluid to be applied, the sequence of fluid applications, and the timing between fluid applications, all of which are controlled by the (reusable) control unit  610 .  
         [0068]     The encodable device  750  preferably stores these settings. As described above in connection with the biopsy device  100 , these settings may be stored as parameters that the controller  810  reads and applies for adjusting the conduct of a treatment procedure. Alternatively, an entire code section or program for conducting the medical procedure can be stored on the encodable device  750 . The code is copied to the controller  810 , and the controller runs the program.  
         [0069]     The invention is not limited to cryogenic biopsy and treatment devices. It may be used in connection with any type of medical device that includes disposable and reusable portions.  
         [0070]     As described herein, the encodable device is preferably a 1-wire device that both receives power and communicates with its environment via two conductors. This is not required, however. The encodable device can be any type of device, component, or assembly, that stores information that is readable by the reusable portion of the device.  
         [0071]      FIG. 9  shows an alternative implementation of the encodable device. Here, a nonvolatile memory circuit  920  is used in connection with a parallel-to-serial converter  922 . The parallel-to-serial converter  922  communicates serially with the controller  410 / 810  in the reusable portion  110 / 710 , but communicates with the nonvolatile memory circuit  920  using parallel data. Power is supplied from the reusable portion.  
         [0072]      FIG. 10  shows another implementation of the encodable device. Here, a nonvolatile memory circuit  1010  is coupled to an optical isolator for communicating with the controller on the reusable portion via one or more optical fibers. A local power source  1014  is included with the disposable portion to power the nonvolatile memory circuit  1010  and the optical isolator  1012 . If the memory circuit  1010  operates with parallel data, a parallel-to-serial converter, like the one shown in  FIG. 9 , may be included between the optical isolator  1012  and the memory circuit  1010 . Communication to the reusable portion can then be achieved using a single optical fiber. This implementation may be preferred in applications where it is necessary to maintain strict electrical isolation between the medical device and the patient.  
         [0073]     Another implementation of the encodable device is an RFID (Radio Frequency Identification) device. The RFID device is made to store information, such as one or more parameters associated with the disposable portion of the device. The reusable portion would then include an RF port for reading the RFID device. When the disposable portion is brought within close proximity of the reusable portion, the RF port is directed to read the information.  
         [0074]     The encodable device may also be implemented as an optically readable code, such as one or more barcodes. The reusable portion can be equipped with an optical reader, such as a barcode reader. By sweeping the barcode(s) with the barcode reader, the information encoded in the barcode(s) is then transferred to the reusable portion to be used in conducting a medical procedure.  
         [0075]     A very simple implementation of the encodable device is a resistor. The reusable portion of a medical device can be equipped with a resistance measuring device, such as an ohmmeter. Resistors having different resistances could thus be made to indicate different parameters or groups of parameters. For instance, a 3 kilo-ohm resistor could indicate a 3 gauge needle, whereas a 5 kilo-ohm resistor could indicate a 5 gauge needle. Arrays or circuits of resistors or other analog components can be used to store information, as can arrays or circuits of digital components.  
         [0076]     As shown and described, electrical connections between the reusable and disposable portions of the devices  100  and  600  are made using two conductors. Alternatively, more conductors may be used, such as for conveying digital signals in parallel form. In addition, the mechanical, electrical and pneumatic connections between the reusable and disposable portions may be integrated together, as they are for the biopsy device  100 . Alternatively, they may be separated, as are the electrical and pneumatic connections for the treatment device  600 .  
         [0077]     Those skilled in the art will therefore understand that various changes in form and detail may be made to the embodiments disclosed herein without departing from the scope of the invention and appended claims.