Abstract:
A method and apparatus are disclosed for obtaining an x-ray image from an x-ray imaging apparatus using a digital radiography receiver installs a retrofit connection apparatus that adapts the x-ray imaging apparatus for use with the digital radiography receiver by forming a receiver interface channel for communicating signals to and from the digital radiography receiver, forming an operator interface channel for routing at least an input expose signal from an operator control to the connection apparatus and forming a generator interface channel for transmitting at least an output expose signal from the retrofit connection apparatus to an x-ray generator of the x-ray imaging apparatus. An input expose signal over the operator interface channel initiates a reset of the digital radiography receiver over the receiver interface channel before the output expose signal to the x-ray generator is transmitted over the generator interface channel.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This application is a Continuation of commonly assigned, earlier filed copending U.S. patent application Ser. No. 12/956,517, filed on Nov. 30, 2010, issued as U.S. Pat. No. 8,085,901, entitled: FIRING DELAY ON X-RAY EXPOSURE TO PREPARE A RETROFIT DR DETECTOR FOR IMAGE ACQUISITION, in the name of Newman et al., which is itself a Continuation of commonly assigned, earlier filed copending U.S. patent application ser. No. 12/271,962, filed on Nov. 17, 2008, issued as U.S. Pat. No. 7,844,031, entitled: FIRING DELAY ON X-RAY EXPOSURE TO PREPARE A RETROFIT DR DETECTOR FOR IMAGE ACQUISITION, in the name of Newman et al., which itself claims the benefit of: (a) U.S. provisional patent application Ser. No. 60/989,144, filed on Nov. 20, 2007, entitled: FIRING DELAY ON X-RAY EXPOSURE TO PREPARE A RETROFIT DR DETECTOR FOR IMAGE ACQUISITION, in the name of Newman, and (b) U.S. provisional patent application Ser. No. 60/989,151, filed on Nov. 20, 2007, entitled: BUTTON PUSHING MECHANISM FOR A RETROFIT DR DETECTOR, in the name of Urbon; the disclosures of all of which are incorporated by reference. 
    
    
     FIELD OF THE INVENTION 
     The invention relates generally to digital x-ray imaging and more particularly relates to an apparatus and a method for adapting the timing sequence of a conventional film-based and/or computed radiography (CR) x-ray imaging system for using a retrofit digital radiography (DR) detector. 
     BACKGROUND OF THE INVENTION 
     DR is an alternative to x-ray imaging technologies that rely on photosensitive film layers to capture radiation exposure and thus to produce and store an image of a subject&#39;s internal physical features. With digital radiography, the radiation exposure energy captured on radiation sensitive layers of a digital x-ray detector is converted, pixel by pixel, to electronic image data which is then stored in memory circuitry for subsequent read-out and display on suitable electronic image display devices. One of the driving forces in the success of digital radiography is the ability to rapidly visualize and communicate stored images via data networks to one or more remote locations for analysis and diagnosis by the radiologist, without the delay that results when film must be developed and checked, then packaged and mailed or sent by courier to a remote location. 
     DR is viewed as having some advantages over conventional film-based and earlier computed radiography (CR) systems. For example, DR provides the ability to obtain radiographic image data without the need to move, handle, process, or scan any type of imaging medium following exposure. Data downloaded directly from the DR receiver panel is then available for viewing and diagnosis on-site or at any appropriately networked viewer workstation. 
     Improvements in performance, miniaturization, and packaging have enabled the development of a portable DR receiver panel that is battery-powered and capable of wireless communication for control signals and image data. Among other advantages, this provides a DR receiver panel having a low-profile design that can be compatible with receiver dimensions used for earlier film and CR systems. 
     While DR imaging systems have advantages over earlier film and CR systems, replacing such a earlier x-ray system can be very costly, thereby limiting the availability of DR systems as hospitals attempt to maximize their investment in older equipment and to extend its usable lifetime. 
     To meet the need for the improved capabilities offered by DR imaging, a number of companies that provide x-ray equipment offer retrofit configurations that allow a DR receiver panel to be used with existing x-ray components, in place of a film or CR cassette. Existing retrofit solutions, however, have one or more limitations, in that they: 
     (a) do not allow use of both earlier types of receivers and the newer DR panels. A retrofit that completely converts existing hardware to DR use but prevents the use of film or CR receivers is less desirable, since both film and CR media have particular strengths and may still be preferred in some types of imaging situations. There would be advantages to a retrofit solution that retains the ability to use the imaging system with film or CR receivers as well as allowing the use of DR receivers. 
     (b) do not minimize the impact of the retrofit on system hardware. Regulatory requirements for x-ray equipment make it highly undesirable to tamper with internal circuitry or connections, such as those required for a number of retrofit solutions. Invasive reconfiguration of an x-ray control panel could void existing approvals or certifications of the equipment or could even be in violation of regulatory rules and restrictions in some cases. 
     (c) do not minimize changes to workflow and impact upon patient care. A suitable retrofit solution should add the new capabilities of DR imaging with as little impact as possible on existing practices for positioning the patient and for obtaining exposures. 
     Thus, while various retrofit solutions have been proposed, there remains a need for a DR retrofit that has little or no impact on existing hardware, is minimally invasive with respect to the components of an existing x-ray system, and does not constrain the system&#39;s ability to use earlier film and CR imaging media. 
     SUMMARY OF THE INVENTION 
     An object of the present invention is to advance the art of diagnostic imaging. The invention provides a method and apparatus for retrofitting an existing film-based or CR x-ray imaging apparatus to capture an x-ray image using a DR receiver. A retrofit connection apparatus is provided that adapts the x-ray imaging apparatus for use with a DR receiver. The apparatus provides a receiver interface channel for communicating signals to and from the digital radiography receiver, an operator interface channel for routing at least an input expose signal from an operator control to the retrofit connection apparatus, and a generator interface channel for transmitting at least an output expose signal to an x-ray generator. The apparatus responds to the input expose signal over the operator interface channel by initiating a reset of the digital radiography receiver over the receiver interface channel before transmitting the output expose signal to the x-ray generator over the generator interface channel. 
     Another object of the present invention is to provide a retrofit solution that is substantially non-invasive, reducing or eliminating the likelihood that inspection or re-certification of equipment by regulatory authorities would be required. 
     Another object of the present invention is to provide a retrofit solution that allows an x-ray system user to use one or more earlier imaging media types in addition to the newer DR receiver panels. 
     These objects are given only by way of illustrative example, and such objects may be exemplary of one or more embodiments of the invention. Other desirable objectives and advantages inherently achieved by the disclosed invention may occur or become apparent to those skilled in the art. The invention is defined by the appended claims. 
     There is provided a method for obtaining an image by using a digital radiography receiver in an x-ray imaging system of a type configured for film or computed radiography. The method comprises: providing a retrofit connection apparatus that adapts the x-ray imaging system for use with the digital radiography receiver by: (a) forming a receiver interface channel for communicating signals to and from the digital radiography receiver; (b) forming an operator interface channel for routing at least an input expose signal from an operator control to the retrofit connection apparatus; and (c) forming a generator interface channel for transmitting at least an output expose signal from the retrofit connection apparatus to an x-ray generator of the x-ray imaging system; in response to the input expose signal routed over the operator interface channel, initiating a reset of the digital radiography receiver over the receiver interface channel; and transmitting the output expose signal to the x-ray generator over the generator interface channel. 
     There is provided an apparatus for x-ray imaging. The apparatus comprises an interface component installed as a retrofit to an x-ray imaging system. The interface component comprises: a mode selector for selecting at least a first mode setting for image capture using a digital radiography receiver and a second mode setting for image capture using a removable film or computed radiography cassette; a receiver interface channel for communication with such a digital radiography receiver, a generator interface channel for communication with an x-ray generator of such a system; an operator interface channel for communication with an operator control for receiving at least a first, preparation signal and a second, expose signal from an operator; and a programmed control logic processor that, when the first mode setting is selected, responds to such a second, expose signal from the operator interface channel by initiating a reset of such a digital radiography receiver over the receiver interface channel before transmitting an exposure signal to an x-ray generator of such a system over the generator interface channel. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The foregoing and other objects, features, and advantages of the invention will be apparent from the following more particular description of the embodiments of the invention, as illustrated in the accompanying drawings. The elements of the drawings are not necessarily to scale relative to each other. 
         FIG. 1A  is a schematic diagram showing a conventional x-ray imaging system. 
         FIG. 1B  shows timing states for using a conventional x-ray imaging system with removable film or CR media. 
         FIG. 2  shows timing states for using a digital radiography detector. 
         FIG. 3  is a schematic diagram showing an x-ray imaging system that has been retrofit according to one embodiment of the present invention. 
         FIG. 4  is a schematic diagram showing a retrofit imaging system that has been retrofit according to a wireless embodiment of the present invention. 
         FIG. 5A  is a schematic block diagram of a conventional operator control console, such as used in the system of  FIG. 1 . 
         FIG. 5B  is a schematic block diagram of an embodiment of a retrofit connection apparatus that uses panel-mounted or tethered switches of the existing imaging apparatus. 
         FIG. 5C  is a schematic block diagram of an embodiment of a retrofit connection apparatus that uses a separate external switch and disables the existing switch for Prep and Expose functions of the apparatus of  FIG. 5B . 
         FIG. 5D  is a schematic block diagram of an alternate embodiment for a retrofit connection apparatus that has connection to both existing and retrofit Prep and Expose switches. 
         FIG. 5E  is a schematic block diagram of an embodiment of a retrofit connection apparatus that mounts a separate switch controller on the operator control console. 
         FIG. 5F  is a schematic block diagram of an embodiment of a retrofit connection apparatus that mounts a separate switch controller on the operator control console for controlling a single two-position pushbutton. 
         FIG. 6  is a schematic diagram showing the configuration, components, and signal handling for an interface and control circuit used in one embodiment of the present invention. 
         FIG. 7A  is a perspective view showing the relative position of Prep/Expose pushbutton on a conventional control console; 
         FIG. 7B  is a perspective view of an operator control console for an x-ray imaging system with a retrofit using a pushbutton control apparatus in one embodiment of the present invention. 
         FIG. 8  is a perspective view of the inner components of the pushbutton control apparatus and shows their relation to the surface of the operator control console. 
         FIG. 9A  is a schematic side view showing pushbutton control apparatus component position at rest in an idle state. 
         FIG. 9B  is a schematic side view showing pushbutton control apparatus component position for actuation of the control panel pushbutton to a first setting. 
         FIG. 9C  is a schematic side view showing pushbutton control apparatus component position for actuation of the control panel pushbutton to a second setting. 
         FIG. 10  is a perspective view of an alternate embodiment for a pushbutton control apparatus used with a control panel that has dual pushbuttons. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     The following is a detailed description of the preferred embodiments of the invention, reference being made to the drawings in which the same reference numerals identify the same elements of structure in each of the several figures. 
       FIG. 1A  shows a conventional x-ray imaging system  10  that provides images on a removable medium, such as a removable film or CR cassette  16 . An operator control console  12  is situated in a control room  14 , shown below the dashed line in  FIG. 1A  and subsequent figures. An x-ray generator  22  is installed in a radiation room  20 , shown above the dashed line. Cassette  16  is placed behind a patient  18  for obtaining the image. Exposure energy is provided by an x-ray tube  24  controlled from x-ray generator  22 . Not shown, but widely used with conventional equipment are also exposure control apparatus, such as Automatic Exposure Control (AEC) devices that measure exposure levels and terminate exposure when a target radiation level has been received. 
     Referring to  FIG. 1A  and to the timing diagram of  FIG. 1B , an operator control switch  28  that is operatively connected to, and operates as a part of, operator console  12  can be in any of three states, as controlled by the x-ray technician. Prior to patient set-up and imaging, the system is in an Idle state. Once the patient is properly positioned for imaging, with cassette  16  in place, the operator pushes switch  28  to advance to a Prep state. This instructs the x-ray system to ready itself for an upcoming exposure. In most systems, pressing the Prep switch, or otherwise entering a command to enter the Prep state, brings the rotor of x-ray tube  24  up to speed as a preparatory step. The operator may set and hold the Prep state, for example, while waiting for the patient to relax or to get into the best position for imaging. The Prep state itself can last from a few seconds to more than a minute in some cases. 
     When the Prep state is complete, an exposure can be taken as soon as the operator advances switch  28  to an Expose state or position. 
     In this sequence, once conditions are suitable for imaging, the operator advances the switch  28  setting to the Expose state. There is a momentary delay period D 1 , typically not more than about 1 millisecond, for response of the x-ray generator control circuitry. Current then goes to the anode of x-ray tube  24 , which emits the ionizing radiation needed for exposure. At the conclusion of exposure, such as following a preset exposure time or when signaled by an AEC device or other exposure sensing device as described earlier, both rotor and anode current are de-energized and the Idle state resumes. 
     As is known to x-ray imaging practitioners, a number of additional conditions must also be satisfied to allow the flow of anode current to the x-ray tube. This includes, for example, requirements that equipment interlock conditions be satisfied and that rotor conditions be acceptable. 
     With different x-ray systems, switch  28  is variously embodied in one of a number of ways. In some systems, switch  28  is a two-position pushbutton mounted on operator console  12 . In other systems, switch  28  is embodied as a bank of two pushbuttons or other controls on or near operator console  12 , or as a tethered handswitch with a two-position pushbutton switch, connected by a cord that allows freer operator movement. 
     To provide a retrofit that allows use of a DR receiver panel as the x-ray detector in place of removable cassette  16  of the conventional system of  FIG. 1A , the timing of the Prep and Expose states must change accordingly. In order to properly condition its sensing components for obtaining an exposure image, a DR receiver panel requires at least one reset cycle. Reset clears any residual noise, such as so-called “dark noise” from the pixels of the DR receiver panel so that the next exposure signal that is received is properly read. Only after reset is confirmed should the exposure energy be provided. It is also advantageous to time the exposure integration of the panel so that it follows close upon reset, rather than being further delayed. 
     The timing diagram of  FIG. 2  shows the sequence of Prep and Expose signals and related operations according to one DR retrofit embodiment of the present invention. As was shown for the conventional timing in  FIG. 1B , pressing the Prep switch initiates x-ray tube rotor spin-up. In addition, this may also change the power mode of the DR receiver panel, particularly for a wireless, battery-powered DR detector. In the embodiment of  FIG. 2 , pressing the Prep switch sets DR receiver panel power from a low or standby level to a high level. During the period between pressing the Prep switch and pressing the Expose switch, normally from about 2-15 seconds, the operator typically observes the patient to assure that the patient remains still during exposure. 
     Pressing the Expose switch sends a reset signal to the DR receiver panel. Reset of DR detector image-sensing circuitry typically takes no more than about 300 milliseconds, shown as time period D 2  in  FIG. 2 . An optional acknowledgement signal is received from the DR receiver panel when reset has been completed. In one embodiment, the reset acknowledgement is required in order for x-rays to be generated and anode current is not provided until a positive acknowledgement of reset has been received back from the DR receiver panel. This helps to prevent exposing the patient to the x-ray radiation when the DR panel is not ready to form an image. Anode current that drives x-ray generation is provided for a period D 3  that is usually no more than about 500 milliseconds. The integration period of the DR receiver panel is typically about 1 second and begins just before anode current is provided, extending past the time when anode current is stopped. In  FIG. 2 , period D 1  is again caused by x-ray generator control circuitry and represents the timing interval between the time integration begins at the DR receiver panel and the time x-rays are emitted (anode current ON). 
     It is noted that the timing diagram of  FIG. 2  is exemplary and admits a number of modifications within the scope of the present invention. For example, the reset signal could alternately be provided from the moment the Prep switch is depressed, so that exposure and integration can begin more quickly following depressing the exposure switch. Delay time periods D 1 , D 2 , and D 3  can vary in duration from those described. Timing, rather than positive reset acknowledgement, may be used to delay exposure (that is, with respect to  FIG. 2 , to delay anode current ON) for a brief period following selection by the operator in order to allow an interval for DR receiver panel reset before continuing. However, as noted earlier, requiring an actual acknowledgement of reset from the DR receiver panel itself may be more advantageous and may help to prevent wasted exposures where there is an equipment problem or communication difficulty. 
     As can be appreciated by comparing the timing diagram of  FIG. 2  with the conventional timing shown in  FIG. 1B , the retrofit task for using a DR receiver panel with an existing film or CR media system has an added measure of complexity: changing the timing sequence to allow sufficient delay for reset of the DR receiver panel sensing circuitry and timing the integration period of the DR receiver panel circuitry to just overlap the period during which x-rays are generated. Implementing this change also requires communication with the DR panel, both to initiate reset operation and, optionally, to receive confirmation that reset has been completed. As noted earlier in the background section, modifications to existing equipment are preferably not invasive, such as requiring that an existing x-ray operator control console have parts replaced or be rewired internally. As yet another complication, it would be considered disadvantageous to disable the existing operation scheme so that only the DR receiver panel could be used once the retrofit is installed and film or CR media were thus rendered unusable. It would be much more favorable to allow selectable use of either removable media, that is, either film or CR cassettes, or the DR receiver panel. 
     The schematic diagram of  FIG. 3  shows a retrofit imaging system  50  that substitutes a DR receiver panel  40  in place of cassette  16  and makes the necessary changes to x-ray exposure timing according to one embodiment of the present invention using wired connections. An interface and control circuit  30  communicates between DR receiver panel  40  and other components of this system. Image data itself goes to an imaging processor  32 , such as a computer or workstation that is in communication with a display  34 . A generator interface channel  70  connects interface and control circuit  30  to operator control console  12  by means of a connection apparatus  38  for providing Prep and Expose signals with the appropriate timing. An operator control switch  29  is connected to interface and control circuit  30  by an operator interface channel  72  for operator control, in place of switch  28  used in the conventional system of  FIG. 1A . Switch  29  may be a tethered switch as in  FIG. 3  or may be configured to mechanically control existing switches mounted on control console  12 . A DR receiver interface channel  42  is provided between DR receiver panel  40  and interface an control circuit  30  by an ethernet cable connection or other type of high-speed data transfer link and may include other control signal lines for sending and receiving reset information and commands. 
     The schematic diagram of  FIG. 4  shows retrofit imaging system  50  in an alternate, un-tethered embodiment. Here, a wireless communications link is provided for receiver interface channel  42  between DR receiver panel  40  and interface and control circuit  30 . A transceiver  52  is connected to or provided as part of DR receiver panel  40  and communicates with a transceiver  48  that is connected to or provided as part of interface and control circuit  30 . In one embodiment, battery power is also provided within DR receiver panel  40 , so that no external wiring is required to the panel for operation. In another embodiment, only a power cord connection to DR receiver panel  40  is needed; the transmission channel to interface and control circuit  30  is wireless. 
       FIGS. 3 and 4  also show an optional sensor  56  for detecting a level of anode current that indicates active x-ray emission from x-ray tube  24 . Anode current sensing by sensor  56  can be used to indicate that signal integration at DR receiver panel  12  should be terminated. It should be observed that the use of this additional sensor can also be done in a non-invasive manner and may therefore be preferable to other methods such as detecting or interrupting a termination signal from an AEC device, as described earlier, for example. 
     The schematic block diagram of  FIG. 5A  shows how switch  28  conventionally has been connected to provide Prep and Expose signals in operator control console  12 . A control board  58  within operator control console  12  accepts signals from switch  28  by means of a connector  54  that mates with a connector  53  that is in communication with control board  58 . Switch  28  can be provided by a single two-position switch as already discussed, with one position for the Prep signal, the other for the Expose signal; or by multiple switch elements, one switch element for the Prep signal, the other for the Expose signal, as illustrated in  FIG. 5A . Switch  28  may be panel-mounted or tethered, as described earlier. The schematic block diagrams of  FIGS. 5B ,  5 C,  5 D,  5 E, and  5 F then show how the conventional arrangement of operator control console  12  connections is changed in different embodiments of connector apparatus  38 . 
     Referring to one embodiment of a retrofit apparatus  62  in  FIG. 5B , switch  28  of the original system is used with the retrofit connection of connector apparatus  38 . Connector  54  is removed from connector  53  on control board  58  and re-connected to interface and control circuit  30  to form operator interface channel  72 . Interface and control circuit  30  then uses timing as discussed with regard to  FIG. 2  and conditions the signals from switch  28  on operator interface channel  72  to provide the needed delay and provides the conditioned signals over generator interface channel  70  at a connector  55  to control board  58 . Switch  28  in such an embodiment may be panel-mounted or tethered. In one embodiment, connector  53  is externally mounted as a jack or plug for tethered switch  28  connection, making it particularly straightforward to provide the retrofit arrangement of connection apparatus  38 . 
     Still referring to  FIG. 5B , an optional mode selector  68  is provided for interface control circuit  30  in one embodiment. Mode selector  68  can be used to specify operation of control logic in interface and control circuit  30 , in order to enable either the signal timing of a first mode shown in  FIG. 1A  when removable media (film or CR cassette) is used or the signal timing of a second mode shown in  FIG. 2  when a DR receiver panel is used. Other types of mode selector can be provided, including a programmed or operator-entered computer instruction that specifies either mode, entered from a touchscreen, keyboard, keypad, or mouse or other type of pointer, for example. Using a mode selector switch or other mode selection mechanism, the same x-ray imaging apparatus can provide imaging on either removable media or the DR digital receiver panel, allowing the operator to choose the imaging mode of preference. 
     Referring to the alternate embodiment of retrofit apparatus  62  shown in  FIG. 5C , existing switch or switches  28  are not used with the retrofit arrangement of connection apparatus  38 . Here, connector  54  is disconnected from control board  58  or otherwise bypassed, and a cover  66  is applied over switches  28 , preventing these switches from being seen and used. Tethered switch  29  on operator interface channel  72  substitutes as the switch for sending Prep and Expose signals to interface and control circuit  30 . Connection is provided over generator interface channel  70  from interface and control circuit  30  to inner control board  58 . 
     The schematic block diagram of  FIG. 5D  shows an alternate embodiment of retrofit apparatus  62  in which mode selector  68  would not be necessary, since both switches  28  and  29  are connected. In this embodiment, generator interface channel  70  connects to control board  58  at a second connector  53 ′. Cover  66  is removable or has an access door or panel, allowing the technician to obtain images from removable film or CR media using switch  28  when exposed; for DR receiver panel imaging, the technician uses switch  29 . 
     Yet another alternate embodiment of retrofit apparatus  62  is shown in  FIG. 5E . This embodiment of connector apparatus  38  mounts a switch controller  60  over a pair of switches  28 . Switch controller  60  mechanically manipulates each of switches  28  for sending Prep and Expose signals, respectively, to control board  58 . The operator uses one or two switches  29  to send Prep and Expose signals. Switches  29  can be separately mounted or tethered, or can be mounted on switch controller  60 . No internal re-wiring is needed with this embodiment; switch controller  60  includes an appropriate type of actuator, such as one or more solenoids, for example, selectively energized in order to operate existing switches  28  under control of interface and control circuit  30  with this embodiment. Generator interface channel  70  is thus used to manipulate existing pushbutton switches in this embodiment. In one embodiment, cover  66  can be removed for use when it is desirable to obtain an image on a removable film or CR cassette, using switches  28  rather than using the DR receiver panel using one or two switches  29 . 
     The block diagram of  FIG. 5F  shows components in an embodiment of retrofit apparatus  62  using switch controller  60 , mounted onto operator control console  12  and controlling the operation of pushbutton switch  28 . Generator interface channel  70  connects to switch controller  60  and, based on the position of switch  29  as set by the operator, provides signals to actuators on switch controller  60  that urge pushbutton switch  28  into Prep or Expose positions, as described earlier. Switch  29  can be separately mounted or tethered, or can be mounted on switch controller  60 , so that both operator interface channel  72  and generator interface channel  70  can follow the same basic path between switch controller  60  and interface and control circuit  30 . No internal re-wiring is needed with this embodiment. Further details on configuration and operation of this device are given subsequently. 
     The schematic block diagram of  FIG. 6  shows the functional components and signal connections of a retrofit apparatus  62  with interface and control circuit  30  in additional detail, with particular emphasis on its components as they relate to retrofit timing control. Components of retrofit apparatus  62  are generally outlined within the dashed-line boundaries. A control logic processor  46 , which may be a microprocessor or other logic processing device having stored programmed instructions or may be implemented in hardware, runs the timing sequence for Prep and Exposure stages, as was described earlier with respect to  FIG. 2 . Prep and Expose signals from switch  29  are directed to control logic processor  46  for delay of the Expose signal timing, as described previously. In embodiments where the Prep signal only has the function of energizing the x-ray rotor, as shown in  FIG. 2 , the Prep signal may alternately bypass control logic processor  46 , as indicated in a dotted line connection in  FIG. 6 . 
     Continuing with  FIG. 6 , a communication interface circuit  44  provides the needed interface for control and command data over receiver interface channel  42  with DR receiver panel  40 . Communication interface circuit  44  is used to send the reset command, to receive confirmation of reset completion, and to terminate integration where sensor  56  or other device is used. Additional circuitry, not shown in  FIG. 6 , would be used for obtaining image data from DR receiver panel  40  through interface and control circuit  30  and for passing this image data on to imaging processor  32  and display  34 , as shown earlier in  FIGS. 3 and 4 . 
     As shown in  FIG. 6 , connection apparatus  38 , using an arrangement of components such as those shown in  FIGS. 5B ,  5 C,  5 D,  5 E, and  5 F provides the Prep and Expose signals from control logic on interface and control circuit  30  to operator control console  12  over generator interface channel  70 . As described earlier, connection between connection apparatus  38  and operator control console  12  can be in any of a number of forms. 
     The perspective view of  FIG. 7A  shows a conventional control console  12  having a single Prep/Exposure pushbutton control  28 . The perspective view of  FIG. 7B  then shows an embodiment with switch controller  60  as a type of pushbutton control apparatus mounted onto operator control console  12 . Switch controller  60  has a cover  66  and an optional access panel  74 , in a retracted position in  FIG. 7B , allowing selection of an alternate timing mode in one embodiment. A bypass switch  78  is accessible by sliding back access panel  74 . Pressing bypass switch  78  enables the operator to bypass operation using the pushbutton control apparatus of switch controller  60 , one option for specifying the mode when CR or film receivers are alternately used for imaging with the x-ray system. 
     Switch controller  60  mounts onto operator control console  12  in an appropriate manner. Mechanical fasteners can be used. In one embodiment, switch controller  60  is mounted onto operator control console  12  using adhesive material, such as a pressure-sensitive adhesive (PSA), for example. 
       FIG. 8  is a perspective view of some of the inner components that are mounted within protective outer cover  66  of the pushbutton control apparatus, switch controller  60  of  FIG. 7B  in this embodiment, and shows their relation to the surface of operator control console  12 . Based on operator use of switch  29  (as shown, for example, in  FIGS. 5F and 6 ), the inner mechanism of switch controller  60  operates to urge pushbutton  28  to one of its operating positions by moving one end of a rocker arm  84 , supported at a pivot  86 . Actuators  80  and  82  cooperate to provide the needed force against pushbutton switch  28 . In one embodiment, actuators  80  and  82  are solenoids. Alternate types of actuators  80  and  82  include motor driven shafts, lead screws, or cams, or other actuation devices driven magnetically, pneumatically, or using air pressure, for example. 
     The sequence of  FIGS. 9A ,  9 B, and  9 C shows the mechanical interaction of switch controller  60  components in the embodiment of  FIG. 8 , again with cover  66  removed. To give an idea of the relative amount of switch movement that is needed for pushbutton switch  28 , exemplary values for the position of switch  28  are as follows in one typical embodiment: 
     
       
         
               
               
               
             
           
               
                   
                   
               
               
                   
                 Selected  
                 Range of Switch  
               
               
                   
                 State 
                 28 Movement 
               
               
                   
                   
               
             
             
               
                   
                 Idle 
                   0-1.3 mm 
               
               
                   
                 Prep 
                 1.5-2.6 mm 
               
               
                   
                 Expose 
                 5.5-6.7 mm 
               
               
                   
                   
               
             
          
         
       
     
       FIG. 9A  shows the pushbutton control apparatus at rest in an idle state. Pivot  86  is shown within an outlined rectangle to indicate that this point is held stationary by cover  66 , which is removed for  FIGS. 9A-C . 
       FIG. 9B  is a schematic side view showing switch controller  60  component position for actuation of the control panel pushbutton to a first setting, the Prep setting for most x-ray systems. As shown by the dashed-outline arrow, actuator  82  is energized, pulling upward on the corresponding section of rocker arm  84 . Actuator  80  is de-energized. A shaft  88  provides the upward support for moving rocker arm  84 , using leverage from pivot  86 . A wheel  90  at the end of rocker arm  84  provides a mechanical interface with reduced friction against pushbutton  28 . 
     The schematic of  FIG. 9C  shows switch controller  60  component position for actuation of the control panel pushbutton to a second setting, the Expose setting. Here, actuator  80  is energized, pulling upward on the end of rocker arm  84 . Actuator  82  remains energized, but is already at the end of its travel path. Rocker arm  84  lifts off of shaft  88  in this embodiment, as it is pivoted into this next position. 
     In one embodiment using solenoids, the use of two solenoids is advantaged over the use of a single actuator. It can be difficult to obtain a single solenoid capable of the full travel path for each signal position. Moreover, each solenoid has simple operation in the embodiment described with respect to  FIGS. 9A-9C , having only fully energized or de-energized states. 
     The alternate switch controller  60  embodiment of  FIG. 10  shows an arrangement of internal components in which the pushbutton control apparatus of switch controller  60  mounts to a panel having separate Prep and Expose switches  28  as described earlier with reference to  FIG. 5E , rather than the single-pushbutton embodiment for the devices shown in  FIGS. 7B-9C . Switch controller  60  again has two actuators  80  and  82 , one for controlling each of the two switches  28 . Pressing the Prep switch  29 , on the left side in the embodiment of  FIG. 10 , energizes actuator  80  for pressing Prep switch  28  on control console  12 . Pressing the Expose switch  29  on the right side in this embodiment sends a signal to control logic processor  46  in interface and control circuit  30  ( FIG. 5E ). Drive current that energizes actuator  82  for pressing the Expose switch is transmitted through control logic processor  46 . The Expose signal then goes to control board  58 . 
     The invention has been described in detail with particular reference to a presently preferred embodiment, but it will be understood that variations and modifications can be effected within the spirit and scope of the invention. For example, various types of cable connections can be used for forming each interface channel, in this case, providing Prep and Expose signals from interface and control circuit  30  over generator interface channel  70 . Wired or wireless communication could be used from interface and control circuit  30  over any individual interface channel  42 ,  70 , and  72 . 
     The presently disclosed embodiments are therefore considered in all respects to be illustrative and not restrictive. The scope of the invention is indicated by the appended claims, and all changes that come within the meaning and range of equivalents thereof are intended to be embraced therein. 
     PARTS LIST 
     
         
           10 . x-ray imaging system 
           12 . Operator control console 
           14 . Control room 
           16 . Film-based or computed radiography cassette 
           18 . Patient 
           20 . Radiation room 
           22 . x-ray generator 
           24 . x-ray tube 
           28 . Operator control switch 
           29 . Operator control switch 
           30 . Interface and control circuit 
           32 . Imaging processor 
           34 . Display 
           38 . Connection apparatus 
           40 . DR receiver panel 
           42 . DR receiver interface channel 
           44 . Communication interface circuit 
           46 . Control logic processor 
           48 . Transceiver connected to interface and control circuit  30   
           50 . Retrofitted imaging system 
           52 . Transceiver connected to DR receiver panel  40   
           53 ,  53 ′,  54 ,  55 . Connector 
           56 . Sensor of anode current in  24   
           58 . Control board 
           60 . Switch controller 
           62 . Retrofit apparatus 
           66 . Cover 
           68 . Mode selector 
           70 . Generator interface channel 
           72 . Operator interface channel 
           74 . Access panel 
           78 . Bypass switch 
           80 ,  82 . Actuator 
           84 . Rocker arm 
           86 . Pivot 
           88 . Shaft 
           90 . Wheel 
         D 1  Delay period after Expose state of  28   
         D 2  Reset period of DR receiver panel  40   
         D 3  Period of anode current for x-ray generator  22