Abstract:
A fluoroscopy machine allows programming of a frame rate in the range of multiple seconds per frame and then displays the images at a higher rate in a loop in the radiological theater so as to impart an improved sense of motion to a human observer of a slow physiological processes captured by fluoroscopic studies.

Description:
STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT 
     CROSS REFERENCE TO RELATED APPLICATION 
     BACKGROUND OF THE INVENTION 
       [0001]    The present invention relates to x-ray fluoroscopy systems and the like and in particular to an x-ray fluoroscopy system providing cane capabilities specifically resulting in superior analysis of slowly evolving conditions. 
         [0002]    X-ray fluoroscopy provides real-time x-ray imaging of a patient such as can be important in many interventional procedures (e.g., catheterizations) and in studies of changes in the body over a short period of time (for example, the movement of a contrast agent through the heart or evaluation of the swallowing mechanism). Original fluoroscopy Machines essentially used a continuous x-ray exposure: however, current machines can capture a succession of short, pulsed, low-dose exposures with an image intensifier tube and preserved electronically resulting, in a short moving image of the area of interest. 
         [0003]    In a typical x-ray fluoroscopy system, an x-ray tube is positioned on a gantry opposite an image intensifier and the gantry is movable to position a patient for x-ray acquisition. An electronic camera incorporated into the image intensifier allows the received x-ray image to be displayed on a standard electronic display and stored, for example, as a digital file. The electronic display may hold each acquired image persistently until the next image is obtained to provide the appearance of continuous viewing at frame rates ranging anywhere from 3 to 30 frames per second. Lower frame rates provide a corresponding reduction in patient exposure but with a loss of time resolution and a decrease quality of real time imaging of rapidly moving structures. 
         [0004]    A fluoroscopy machine may provide for cine recording capabilities in which successive images are recorded so that they may be played back in the manner of a movie for later analysis. For example, a series of fluoroscopic images obtained at a high frame rate (e.g., 30 frames per second) can capture the swallowing of a contrast agent and then be played back for review to analyze possible swallowing disorders. 
         [0005]    For certain studies, for example, involving contrast agents moving through the bowel, it may be desirable to monitor the patient over an extended length of time, from several minutes to several hours. Continuous cine operation of the fluoroscopy machine during such extended periods is generally avoided and instead the radiologist may opt to take periodic images manually to monitor the procedure and the progress of the contrast. 
         [0006]    In some cases, for example, when it is desired to locate a perforation of the bowel, such randomly timed manual acquisitions may miss a critical moment of contrast agent escape from the bowel such as may occur over a period of a few seconds in the middle of contrast transit through the gut during an otherwise lengthy procedure. In other cases, such a randomly timed irregular manual acquisition can make it difficult to obtain an intuitive understanding of the dynamics of the observed process. That is, the radiologist, observing the last few images may capture only an imperfect understanding of the timing of the movement of contrast agent through the bowel, or its precise point of escape if leaking, for example. This in turn can hamper the radiologist&#39;s ability to properly time the next exposure, compounding an inability to capture and/or understand the slowly moving process. Additionally if a large amount of contrast escapes before initial detection, it may obscure the underlying source of leak hampering anatomic definition required by the, surgical team considering intervention. 
       SUMMARY OF THE INVENTION 
       [0007]    The present invention provides a fluoroscopy machine that can operate in cine mode with acquisition frame rate measured not in frames per second but seconds per frame. By displaying the slowly acquired data at a higher frame rate in the radiological suite, a “time-lapse” sequence of images in a real-time format can be provided to the radiologist. This not only presents a slowly evolving process at a more interpretable time-scale but allows the acquisition, of a sufficiently long segment at relatively low dose to ensure that a critical moment in the process is not overlooked during gaps in imaging. 
         [0008]    Specifically then, the present invention, in one embodiment, provides a fluoroscopy machine having a gantry system holding an x-ray source operable to provide discrete x-ray exposures according to a control signal and an image intensifier opposite the x-ray source to receive x-rays from the x-ray source during the discrete x-ray exposures and to provide image data. The fluoroscopy machine farther includes input for receiving instructions from a fluoroscopy machine user and a display for receiving the image data. A fluoroscopy control circuit communicates with the x-ray source, image intensifier, and display and operating to: (a) receive instructions through the input identifying an acquisition frame rate in a range providing multiple seconds between each frame, (b) control the x-ray source and image intensifier to obtain a set of time-ordered images at separated acquisitions at the acquisition frame rate; and (c) provide a looping display on the display of the set of time-ordered images in sequence according to a display rate different (accelerated) from the acquisition frame rate. 
         [0009]    It is thus a feature of at least one embodiment of the invention to provide the radiologist with an improved, near real-time understanding of slowly evolving physiological processes when monitored by fluoroscopy imaging. The rolling, accelerated playback of the acquired data aids the radiologist in making decisions about the ongoing imaging including determining whether sufficient data has been collected or whether the parameters for the data collection need to be changed, for example, changing the frame rate, adding additional contrast or adjusting the region of interest. The regular timing of image acquisition helps ensure that critical information is captured for later study and interpretation. 
         [0010]    The fluoroscopy control circuit may further receive a loop length from the input to provide a looping display of a subset of the acquired time-ordered images limited in length by the loop length and terminating at a latest time order image. 
         [0011]    It is thus a feature of at least one embodiment of the invention to automatically present the radiologist the latest data plus enough historical context to provide for a sequence of images conveying motion. 
         [0012]    The fluoroscopy control system may operate to receive frame acquisition instructions by an operator during the obtaining of the time-ordered images to change the acquisition frame rate during the obtaining of the time-ordered images. 
         [0013]    It is thus a feature of at least one embodiment of;the invention to permit the radiologist to change the time granularity of the acquisitions based on the insight provided by the rolling display of recently acquired image data. 
         [0014]    The gantry may include at least one electrically controlled actuator to reposition the gantry, and the fluoroscopy control system may further receive reposition instructions and communicate with the gantry to incrementally reposition the gantry according to the reposition instructions in between each acquisition. 
         [0015]    It is thus a feature of at least one embodiment of the invention to permit a tracking of slowly evolving phenomenon in the patient through a movement of the gantry on an automatic basis keyed to the acquisitions, 
         [0016]    The fluoroscopy control system may operate to receive a start location and stop location of the gantry, and the reposition instructions may provide a constant average velocity of gantry movement independent of acquisition frame rate. 
         [0017]    It is thus a feature of at least one embodiment of the invention to provide a perceptively smooth movement in the resulting display of the acquired data with respect to real time and independent of acquisition rate that assists in understanding the data. 
         [0018]    The fluoroscopy control system may further operate to receive an override instruction overriding the repositioning instructions with an override position causing the gantry to move to the override position. 
         [0019]    It is thus a feature of at least one embodiment of the invention to permit the radiologist to respond to the improved information provided by the looping display to reposition the gantry at any time. 
         [0020]    In one embodiment, the fluoroscopy system may further receive spot film instructions to: (i) record a location of the gantry, (ii) pause the obtaining of the time-ordered images to receive repositioning instructions through the input; (iii) communicate with the gantry to reposition the gantry for obtaining a spot film; (iv) reposition the gantry at the recorded location; and (v) resume obtaining the time.-ordered images. 
         [0021]    It is thus a feature of at least one embodiment of the invention to permit the acquisition of detailed spot films in between serial acquisitions with minimal disruption to the information obtained by the low dose serial acquisitions. 
         [0022]    The fluoroscopy machine may further provide one of an audio and/or visual output perceivable by a patient positioned between the x-ray tube and the image intensifier providing a warning of an x-ray acquisition of the separated acquisitions at a predetermined time interval proceeding acquisition. 
         [0023]    It is thus a feature of at least one embodiment of the invention to provide an automatic system of alerting the patient and radiologist to the imminent acquisition of x-ray data that can be separated by many seconds. 
         [0024]    The warning may indicate a length of the predetermined time interval preceding the acquisition. 
         [0025]    It is thus a feature of at least one embodiment of the invention to allow the patient and radiologist to anticipate the acquisition of fluoroscopy data, for example, to minimize motion. 
         [0026]    In this regard the fluoroscopy machine may provide audio and/or visual output perceivable by a patient positioned between the x-ray tube and the image intensifier and wherein the fluoroscopy control system further provides breath hold instructions at each acquisition using the one of an audio and visual output. The breath hold instructions may precede each acquisition of the separated acquisitions and instruct the patient to hold his or her breath and may immediately follow each acquisition of the separated acquisitions and instruct the patient to breathe normally. 
         [0027]    It is thus a feature of at least one embodiment of the invention to provide automatic repeated breath hold instructions to the patient to simplify the acquisition of multiple images greatly exceeding the duration of a single breath hold. 
         [0028]    it is thus a feature of at least one embodiment of the invention to provide automatic repeated breath hold instructions to the patient to situate anatomy near the diaphragm at a similar level among exposures, thereby minimizing respiratory motion artifact. 
         [0029]    The fluoroscopy machine may include a proximity sensor for sensing the presence of the radiologist and obtaining acquisitions only if the radiologist is present at a location for viewing the fluoroscopy machine and patient. 
         [0030]    It is thus a feature of at least one embodiment of the invention to ensure proper supervision of the patient in the context of automatic or semiautomatic x-ray exposures. 
         [0031]    The proximity sensor may be selected from the group consisting of a pressure mat, a radio link, a Bluetooth link, and/or a physically, operated electrical switch. 
         [0032]    It is thus a feature of at least one embodiment of the invention to provide radiologist supervision with minimal distraction to the radiologist. 
         [0033]    The fluoroscopy machine may include a memory system for storing data of the separated acquisitions for later review. 
         [0034]    It is thus a feature of at least one embodiment of the invention to permit the preservation of the acquired data for future study and documentation. 
         [0035]    These particular objects and advantages may apply to only some embodiments falling within the claims and thus do not define the scope of the invention. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0036]      FIG. 1  is a perspective view of a simplified fluoroscopy machine suitable for use with the present invention providing an x-ray room monitor for viewing cine images; 
           [0037]      FIG. 2  is a block diagram of the principal elements of the fluoroscopy machine of  FIG. 1  including a computer controller; 
           [0038]      FIG. 3  is a flowchart of the principal components of a program executable by the computer controller of  FIG. 2  and providing the cine acquisition and display; 
           [0039]      FIG. 4  is a detailed flowchart of a set up procedure of the program of  FIG. 3 ; 
           [0040]      FIG. 5  is a detailed flowchart of a time-lapse acquisition procedure of the program of  FIG. 3 ; 
           [0041]      FIG. 6  is a plot of gantry movement synchronized to cine acquisition showing adjustment of frame rate and motion parameters during the acquisition; 
           [0042]      FIG. 7  is a detailed flowchart of a spot acquisition procedure of the program of  FIG. 3 ; and 
           [0043]      FIG. 8  is a schematic representation of a rolling cine display visible in the radiological suite. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
       [0044]    Referring now to  FIG. 1 , a fluoroscopy suite  10  may hold a fluoroscopy machine  12  providing a patient table  14  supporting a patient  16  near a gantry  18 . The gantry  18 , in one embodiment, may provide for a C-arm  20  having opposed ends, one and holding an x-ray source  22  and the other and holding an image intensifier  24  in opposition to the x-ray source  22  along an axis  28  directed through the patient  16  for imaging the patient  16 . 
         [0045]    The C-arm  20  maybe supported between its opposed ends in a collar  26  so that an axis  28  between the x-ray source  22  and image intensifier  21  may be changed in angle about an inferior-superior axis of the patient  16  by movement of the C-arm  20  through the collar  26  or about a lateral angle by angulation of the collar  26  with respect to the track  27 . These movements may be effected by associated motorized actuators to be discussed below. In addition, the collar  26  may be held on a track  27  allowing the collar  26  to be moved laterally (parallel to the patient&#39;s superior-inferior axis) to change a region of imaging. 
         [0046]    Referring also to  FIG. 2 , the fluoroscopy machine  12  may include a control station  30  providing a control computer  32  for control of the fluoroscopy machine  12  by a healthcare professional  34 . In this regard, the control computer  32  may communicate with an electronic display  36  for concurrent display of fluoroscopic images to the healthcare professional  34  and with one or more user input devices  44  such as a mouse and keyboard as is generally understood in the art. 
         [0047]    The control computer  32  further provides for electrical interfaces that allow for control of the image intensifier  24  including the receipt of x-ray image data from that image intensifier  24  and control of the x-ray source  22  to activate the x-ray source  22  and to control imaging parameters such as exposure duration, voltage and current provided to an x-ray tube according to a desired imaging protocol. 
         [0048]    The control computer  32  may further communicate with motorized actuators  46  associated with the gantry  18  to provide the above-described angulation of the axis  28  and lateral movement of that axis  28 . 
         [0049]    The present invention may optionally also provide for one or More proximity sensors such as a pressure mat  48  or radio sensor, for example, the latter using low-power Bluetooth sensing communicating with a tag worn by the healthcare professional  34 , or an RFID tag reader reading a tag worn by the healthcare professional  34  to detect the presence of the healthcare professional  34  in a supervisory capacity. In one embodiment the control computer  32  may communicate with an electronic camera  52  such as may provide for remote observation of the patient and fluoroscopy machine  12  in a signal from the healthcare professional  34  provided through a remote display associated with the electronic camera  52 , for example, by a switch activated by the healthcare professional  34 , which may provide for the proximity signal. 
         [0050]    The control computer  32  may further communicate with a patient communication device  54 , for example, in the form of a lighted sign, display and or audio speaker system that can give the patient  16  and healthcare professional  34  warnings about the imminent activation of the x-ray source  22  and/or automatic breath hold instructions as will also be discussed. 
         [0051]    Generally, the control computer  32  may include one or more processors  38  communicating with a memory  40 , the latter holding a stored program  42  providing specific control of these interconnected features. Referring now also to  FIG. 3 , this program  42  executed by the control computer  32  may initially present the user with the opportunity to set up the parameters of a fluoroscopy acquisition, for example, using the interface elements of the control computer  32  and as indicated by process block  60 . 
         [0052]    As shown in  FIG. 4 , the set up process may begin as indicated by process block  62  with the obtaining of a “scout view” providing a large field of view of the patient defining a region in which the fluoroscopic sequence will be acquired. This scout view scan may be the basis for other settings in the set up process block  60 , for example, defining a trajectory of gantry motion as will be discussed below. 
         [0053]    At succeeding process block  64 , the x-ray exposure protocols, exposure duration, tube voltage, and current may be set. At this time the total length of the study or the total number of exposures and collected images may be set. 
         [0054]    At process block  66  the healthcare professional  34  may enter information defining a trajectory of the gantry  18  in angle, and offset during the acquisition of a fluoroscopic sequence. In one embodiment, the user may locate a starting position and ending position of a fluoroscopic sequence to be acquired, for example by maneuvering the gantry  18  to each of these locations. Alternatively this information may be entered manually and/or marked on the scout view image. A number of discrete locations at which exposures will be taken may be determined by dividing the described movement according to the total length of the study or number of exposures defined in process block  64 . 
         [0055]    Normally the automatic control of the gantry  18  will be such as to provide a constant average speed of movement of the gantry  18  between the starting position and stopping position using discrete repositioning events in between each x-ray exposure when the gantry  18  is not moving. Alternatively, a trajectory may be associated with changing speeds of movement and angulation of the C-arm  20 . As will be discussed further below, the trajectory may be modified at any time by the healthcare professional  34  and may be interrupted to obtain spot films and the like. 
         [0056]    At subsequent process block  68 , starting acquisition frame rates and output frame rates may be entered by the healthcare professional  34 . The acquisition frame rate will define a separation in time between successive exposures of the patient and will include frame rates that have multiple seconds between frames, for example, 3 to 10 seconds between frames, but may also provide for standard cine frame rates providing multiple frames per second as well as much lower frame rates. 
         [0057]    In contrast, the output frame rate will be the frame rate at which the acquired images will be output on the display  36  in the radiology suite  10  as will be discussed below. Typically this output rate will be dictated by a desire to avoid “flicker” or “stuttering” being a noticeable blinking or stopping between each frame such as interferes with the perception of continuous motion. For example, the output rate may range between one and 30 frames per second and will typically be in excess of 10 frames per second. Nevertheless an arbitrarily wide range of output rates may be selected including frame rates which change as a function of the particular image of the sequence. 
         [0058]    At process block  68 , a maximum loop duration may be set or default value may be provided defining a maximum loop of images that will be displayed before repeating as will also be described below. 
         [0059]    Referring again to  FIG. 3 , after completion of the set up process, assuming no spot film is requested (as determined by decision block  70 ) the program  42  proceeds to process block  72  to begin a time-lapse acquisition of fluoroscopic images using the trajectory and acquisition rate entered during the set up process of process block  60 . 
         [0060]    Referring to  FIG. 5 , the time-lapse acquisition of process block  72  is synchronized by a time measurement indicated by decision block  74  which determines the elapsed time since a previous acquisition of a fluoroscopic image and a desired series of fluoroscopic images. When that, elapsed time exceeds the time between acquisitions required by the preset acquisition frame rate, program  42  proceeds to process block  76 . 
         [0061]    At process block  76  a determination is made as to whether the fluoroscopy machine  12  and patient  16  are being supervised by the healthcare professional  34  as may be required by regulations or practice guidelines. This supervision may be established, for example, by an entry by a healthcare professional  34  on the keyboard of the control computer  32  or the pressing and holding of an electrical switch, or may be established automatically or semi-automatically, for example, by the healthcare professional  34  standing on the pressure mat  48  or being in the proximity of the control computer  32 . In this latter example, the proximity may be measured by any of the proximity sensors  50  discussed above. In some options, supervision may be provided through remote viewing by the healthcare professional  34 , for example, through camera  52 . In this case supervision may be established using a remote signal provided by the healthcare professional  34  through a remote monitor communicating with camera  52 . 
         [0062]    If proper supervision is established, then at process block  78 , a warning indicator is provided, for example, to the patient  16  through patient communication device  54  or on the display  36 . This warning prevents unexpected activation of the x-ray machine and may be a simple tone or light or may provide the communication of a number of seconds or the like for an x-ray exposure that will be initiated, for example, using a countdown. 
         [0063]    At succeeding process block  80 , breath hold instructions may be provided to the patient, for example, by an audible message indicating that the patient should take a moderate breath and then hold his or her breath. At process block  82 , an x-ray exposure is initiated at the current gantry  18  position using the parameters provided in the set up steps of process block  60 . Breath release instructions are then provided to the patient  16  at process block  84  informing the patient  16  that they may breathe normally. 
         [0064]    At process block  86 , the gantry  18  may be repositioned according to the trajectory defined at process block  66  to stop at the next location for an exposure. At process block  88 , the acquired image from the image intensifier  24  resulting from the exposure of process block  82  is stored as part of a sequence of images each ordered according to the order of acquisition and tagged with a time and technique. This stored data may be reviewed later using the control computer  32  or other computer by playing the data in sequence at various playback rates or “scrubbing” the data forward and backwards to provide animation. In addition, individual frames of the data may be reviewed. 
         [0065]    Referring again to  FIG. 3 , if the total length of the acquisition has not been reached (measured in time or exposures), the program  42  may then check for new settings from the healthcare professional  34 , for example, frame rates per decision block  90 , and if there are no new settings return to the top of process block  72  and repeat this process at the, next frame interval. 
         [0066]    If at decision block  90  there are new settings desired by the healthcare professional  34  during the scan, the program proceeds to process block  92  to input those new settings in the manner of process block  60  and then returns to the top of decision block  70 . These new settings may include, for example, a change in acquisition rate or in the endpoint of the trajectory. In such circumstances, a new trajectory may be calculated with discrete exposure locations according to the new inputs. Generally the new exposure locations are selected so as to preserve average speed of the gantry  18  before and after the new settings if the endpoint of the trajectory has not been changed. 
         [0067]    Referring now to  FIG. 6 , an initial trajectory of the gantry  18  may provide, for example, a trajectory  93  at a first acquisition frame rate  94 . Although this trajectory  93  is shown as a simple one-dimensional movement, it should be generally understood that this trajectory may be in multiple dimensions of angulation and translation. 
         [0068]    At time t 1  the attending healthcare professional  34  may change the frame rate to a faster acquisition rate  96  to provide for higher time resolution, based on the healthcare professional&#39;s anticipation of an event that will require additional accuracy (greater temporal resolution) in the recording. The time-linear trajectory  93  of the gantry  18 , if not changed during the new settings of process block  92 , will continue at the same time rate unaffected by the change in acquisition time. 
         [0069]    At time t 2 , the healthcare professional  34  may enter a new trajectory speed, for example, by changing the study time or endpoint. In this example, the healthcare professional  34  has stopped the gantry  18  to obtain multiple fluoroscopic images over time at a given location. Again this change in the trajectory may operate independently of the acquisition rate  96 . 
         [0070]    Referring to  FIGS. 3 and 6 , at decision block  70 , at any time during the acquisition of the sequence of fluoroscopic images, the healthcare professional  34  may indicate a desire to make a spot film to provide additional detail of the patient at that instant in time. This request which may be entered through the control computer  32  causes the program  42  to proceed to process block  100 . 
         [0071]    Referring also to  FIG. 7 , at process block  100 , the current location of the gantry  18  is stored per process block  102  and the gantry  18  moved, for example, by healthcare professional  34  control per process block  104  to the location where the spot film will be acquired. This movement is shown in  FIG. 6  by new trajectory  93 ′. During this spot film acquisition, ongoing acquisition of the sequence of fluoroscopic images is suspended. 
         [0072]    At process block  106 , the healthcare professional  34  makes the exposure of the spot film. Following, this exposure, as indicated by process block  108 , the control computer  32  executing the program  42  may return the gantry  18  to its previous location as indicated by trajectory  93 ″ to resume acquisition of the fluoroscopic sequence. Depending on the length of time required to obtain the spot film, one or more scheduled fluoroscopic acquisitions at the acquisition rate  96  may have been skipped. These missing images maybe indicated by black frames in the displayed image to preserve time continuity or may be simply omitted, causing a jump in time at the point where these images would have been displayed. In one embodiment, upon completion of the spot film, the gantry  18  may be returned to a position where it would have been if the acquisition process had not been interrupted. In any case, acquisition of a regular sequence of fluoroscopic images then proceeds until the time or image limit previously entered by the healthcare professional  34  in the set up process block  60 . 
         [0073]    Referring now to  FIGS. 3 and 8 , during the acquisition of a sequence of fluoroscopic images indicated at process block  72 , a display routine  110  operates in parallel, to display currently acquired image data  111  of that sequence of fluoroscopic images. As shown in  FIG. 8  this display process will generally loop as indicated by loop arrow  112  through a sequence of fluoroscopic images acquired at process block  82  of  FIG. 5  up to a maximum number of those images described in the set up of process block  60 . Each loop will present on the display  36  a movie-like presentation of the acquired images in a greatly accelerated manner such as provides a perception of motion to a process that may be too slow for motion to be directly perceived. Repeating the loop provides an essentially continuous representation of the motion revealed by the fluoroscopic images for review by the healthcare professional  34 . 
         [0074]    Normally the length of the loop will be truncated so as to provide easy comprehension of the physiological activity immediately preceding the current state of the patient. This loop length may be set during the set up described with respect to process block  60 . For example, if the set up describes a loop consisting of five sequential fluoroscopic images (greatly reduced in number for the purpose of this explanation), if three fluoroscopic images have been obtained and denoted A, B, and C, the display of process block  110  will loop through each of those images A, B, and C at the display rate (set at process block  60  but which may be adjusted at any time by the healthcare professional  34 ). This loop allows the healthcare professional  34  to immediately see the progress, of any contrast material on the fluoroscopic scan with the newly accessible dimension of accelerated motion that would otherwise be difficult to perceive through a real time display of the image data  111  at its acquisition frame rate. 
         [0075]    As additional images  111 , (e.g., five frames denoted A-E) are acquired, the length of the loop may be increased up to the preset maximum level here shown as five frames. When seven frames have been acquired (indicated by images A-G), only the most recently acquired frames (C-G) will be part of the loop. In this way the most recent data is always displayed together with the recent history of that recent image to provide context. 
         [0076]    As each image data  111  is acquired, the image data  111  may be tagged, for example, by a tag  114  with data entered by the healthcare professional  34  at the control computer  32 , for example, including volumes of contrast infused into the patient at that time. Alternatively this information may be automatically extracted from an infusion pump. This tag  114  may be accessed at any time by the physician reviewing the images  111  to provide additional context for the images presented. 
         [0077]    Certain terminology is used herein for purposes of reference only, and thus is not intended to be limiting. For example, terms such as “upper”, “lower”, “above”, and “below” refer to directions in the drawings to which reference is made. Terms such as “front”, “back”, “rear”, “bottom” and “side”, describe the orientation of portions of the component within a consistent but arbitrary frame of reference which is made clear by reference to the text and the associated drawings describing the component under discussion. Such terminology may include the words specifically mentioned above, derivatives thereof, and words of similar import. Similarly, the terms “first”, “second” and other such numerical terms referring to structures do not imply a sequence or order unless clearly indicated by the context. 
         [0078]    When introducing elements or features of the present disclosure and the exemplary embodiments, the articles “a”, “an”, “the” and “said” are intended to, mean that there are one or more of such elements or features. The terms “comprising”, “including” and “having” are intended to be inclusive and mean that there may be additional elements or features other than those specifically noted. It is further to be understood that the method steps, processes, and operations described herein are not to be construed as necessarily requiring their performance in the particular order discussed or illustrated, unless specifically identified as an order of performance. It is also to be understood that additional or alternative steps may be employed. 
         [0079]    References to “a computer” and “a processor” or “the microprocessor” and “the processor,” can be understood to include one or more processors that can communicate in a stand-alone and/or a distributed environment(s), and can thus be configured to communicate via wired or wireless communications with other processors, where such one or more processor can be configured to operate on one or more processor-controlled devices that can be similar or different devices. In particular the control computer described above may be distributed among multiple processing machines. Furthermore, references to memory, unless otherwise specified, can include one or more processor-readable and accessible memory elements and/or components that can be internal to the processor-controlled device, external to the processor-controlled device, and can be accessed via a wired or wireless network. 
         [0080]    Physical operation of a switch refers to using one&#39;s hand or foot or the like to activate the switch. 
         [0081]    It is specifically intended that the present invention not be limited to the embodiments and illustrations contained herein and the claims should be understood to include modified forms of those embodiments including portions of the embodiments and combinations of elements of different embodiments as come within the scope of the following claims.