Abstract:
This invention relates to a stand for a radiography imaging apparatus and comprises: a tower; a clevis having a base movably attached to the tower such that the clevis is movable along the length of the tower, and an arm extending from the base; and, an imaging device holder including a main body pivotably attached to the clevis and extending along a main body axis, and an imaging device mount rotatably attached to the main body such that the mount is rotatable about the main body axis. The stand when in an upright position, enables an imaging device attached to the mount to be placed in multiple positions, including positions to examine both standing and recumbent patients.

Description:
[0001]    This application incorporates by reference all subject matter set out in related U.S. provisional application No. 60/333,252 entitled “Self-Diagnostic System for Optically Coupled Digital Radiography”, No. 60/333,224 entitled “Lens Assembly and Barrel Correction Method for X-Ray System”, and No. 60/333,206 entitled “Balancing Areas of Varying Density in a Digital Image”, and the regularized U.S. patent applications therefor each filed Nov. 25, 2002, as well as the subject matter contained in U.S. provisional application No. 60/333,207 entitled “Positioning Stand for a Radiography Imaging Device”. 
     
    
     
       FIELD OF THE INVENTION  
         [0002]    The present invention is directed generally to an apparatus for use in the field of digital radiography, and in particular to a positioning stand for a digital radiography imaging device.  
         BACKGROUND OF THE INVENTION  
         [0003]    For over a hundred years photographic films have been used to capture and display X-rays for diagnostic purposes. In the last ten years or so, digital radiography has become increasingly popular. Digital radiography refers to the application of digital image processing techniques to projection radiography (x-rays). Digitally recorded x-rays are superior to those recorded with photographic film due to the greater dynamic range of the digital recording system. Furthermore, computer image processing techniques provide a wealth of capabilities to study otherwise obscured details within the image.  
           [0004]    To take a digital radiograph, a digital radiography imaging device is positioned behind a subject. A standard radiographic generator directs radiation through the subject to a fluorescent-imaging screen mounted just behind the front surface of the imaging unit. The imaging screen is the conversion media for radiation to visible light. The fluorescent-imaging screen absorbs the radiographic radiation and emits light of a particular wavelength which closely matches the peak sensitivity of a charge coupled device (CCD) camera. A front-surfaced mirror is positioned at a 45 degree angle inside the imaging unit to direct the radiographic image into the CCD camera. The mirror allows the CCD camera to be positioned out of the direct path of the radiation, effectively shielding it from radiation exposure and prolonging its life. A high-efficiency lens reduces the image and directs it onto the surface of the CCD.  
           [0005]    The visual image formed by the fluorescent-imaging screen is converted into a digital image by the CCD sensor. A control computer converts the image into a medical image file that can be viewed for clinical diagnosis, enhanced and electronically stored with the patient demographic information in a picture archiving system.  
           [0006]    Most digital x-rays systems require at least two detectors per examination room in order to accommodate both standing and recumbent patients. Digital systems by virtue of their high cost and weight tend to be affixed to a wall of an examination room or in a table holder. This tends to be very costly as the detectors typically cost hundreds of thousands of dollars.  
         SUMMARY OF THE INVENTION  
         [0007]    According to one aspect of the invention, there is provided a stand for a radiography imaging device. The stand comprises  
           [0008]    (a) a tower,  
           [0009]    (b) a clevis having a base movably attached to the tower such that the clevis is movable along the length of the tower, and an arm extending from the base;  
           [0010]    (c) an imaging device holder including a main body pivotably attached to the clevis and extending along a main body axis, and an imaging device mount rotatably attached to the main body such that the mount is rotatable about the main body axis,  
           [0011]    the stand when in an upright position, enables an imaging device attached to the mount to be placed in multiple positions, including positions to examine both standing and recumbent patients.  
           [0012]    In accordance with an aspect of the present invention there is provided a stand for a radiography imaging apparatus comprising: a tower; a mount base slidably attached to the tower for movement between a first position and a second position along the length of the tower; an imaging device holder including a main body pivotally attached to the mount base for movement between a third position and a fourth position and having a main body axis and an imaging device mount rotatably attached to the main body for rotation about the main body axis, whereby the stand, when in an upright postion, enables an imaging device attached to the mount to be placed in multiple positions, including positions corresponding to examining patients in upright and recumbent positions. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0013]    The present invention will be further understood from the following detailed description with reference to the drawings, in which:  
         [0014]    [0014]FIG. 1 illustrates in a perspective view of a radiographic imaging device positioning stand positioning a radiography imaging device for recumbent imaging;  
         [0015]    [0015]FIG. 2 illustrates in a perspective view, the positioning stand, positioning the imaging device for standing imaging;  
         [0016]    FIGS.  3  to  5  illustrate in partially exploded perspective views, the positioning stand of FIG. 1;  
         [0017]    FIGS.  6  to  9  illustrate in partially exploded and assembled perspective views a portion of a tower assembly of the positioning stand;  
         [0018]    [0018]FIG. 10 illustrates in a perspective view of a clevis, pivot assembly, pivot body, and imaging device mounting assembly of the positioning stand;  
         [0019]    [0019]FIG. 11 illustrates in an exploded side view of the clevis, pivot assembly and pivot body;  
         [0020]    [0020]FIG. 12 illustrates in an exploded perspective view, the clevis, pivot assembly and pivot body; and  
         [0021]    [0021]FIG. 13 illustrates in a schematic representation, a radiographic digital imaging system. 
     
    
     DETAILED DESCRIPTION  
       [0022]    Referring to FIG. 1, a positioning stand  10  is provided for a digital radiographic digital imaging device A. A suitable such imaging device that is mountable to the stand  10  is the Xplorer 1700 manufactured by Imaging Dynamics Company Ltd.  
         [0023]    Imaging devices like the Xplorer 1700 are used in medical applications for taking x-ray images of patients. The stand  10  can be articulated to position the imaging device A to take an x-ray of a patient in either a standing or a recumbent position. If the patient is placed on an examination table (not shown) in a recumbent position, the stand  10  positions the imaging device A as shown in FIG. 1, wherein the imaging device A is positioned low enough to slide under the table and rotated such that a scintillator B and a detector face of the imaging device A is facing upwards at the recumbent patient. If the patient is standing (e.g. to take a chest x-ray), the stand positions the imaging device A as shown in FIG. 2, wherein the imaging device is positioned at a height corresponding to the part of the body being imaged (e.g. chest height for chest x-rays) and rotated such that the scintillator B is facing the patient.  
         [0024]    Referring to FIG. 13, when the patient is in position and a part of the patient&#39;s body selected for imaging has been set in place, an x-ray source  100  is turned on and x-rays are directed towards the patient. X-rays passing through the patient are captured by the imaging device  102  and converted into a digital x-ray image. In particular, the x-ray image reaching the imaging device  102  is first converted into visible light by the scintillator  104 . The visible light is then reflected by a mirror  106  towards lenses in a lens assembly  108 , which reduces and directs the visual image onto the surface of a charge coupled device (CCD) camera  110 , which converts the visual image into a digital image. The digital image is then transmitted to a computer  112  for imaging processing and storage.  
         [0025]    Referring to FIG. 1, the key major components of the stand  10  that enable the imaging device A to be positioned in multiple positions are a tower assembly  12 , a clevis  14  vertically movably attached to the tower assembly  12 , an imaging device holder comprising a pivot body assembly  16  that is horizontally pivotally attached to the clevis  14  and an imaging device mount assembly  18  that is rotatably attached to the pivot body assembly  16 .  
         [0026]    Referring to the partial cut-away figures in FIGS.  3 - 5  and  6 - 9 , these components can be seen more clearly. The tower assembly  12  includes  
         [0027]    i. a base  19  with means adapted to securely fasten the stand  10  to the floor (e.g. by bolting);  
         [0028]    ii. a tower housing  20 ;  
         [0029]    iii. a main vertical support member  21  extending vertically from the base  19 ;  
         [0030]    iv. a pair of vertically extending guide rails  22  attached to the front of the support member  21 ;  
         [0031]    v. a pulley assembly  26  that includes cables (not shown) that attach at one end to the carriage  50 , and at the other end to counterweights  61  that move vertically within a channel  32  at the back of the support member  21 ;  
         [0032]    vi. a motor  28  attached to the pulley assembly  26 ; and,  
         [0033]    vii. a guide rail car  52  attached to the carriage  50  and slidably wrapped around the guide rails  22  to help restrict the movement of the carriage  50  in a vertical direction only.  
         [0034]    Referring to FIGS.  6  to  9 , the tower assembly components are presented in more detail.  
         [0035]    Stopper assembles  44  are provided at each end of each guide rail  22  to prevent the carriage  50  from sliding off the guide rails  22 . Stopper assembles  44  are attached to the tower assembly  12  by bracket  42  and includes stop  46  and  48 .  
         [0036]    The carriage  50  is attached to guide rail brackets  52 , which are slidable along respective guide rails  22 ; the tolerances are relatively fine between brackets  52  and rails  22  to prevent any play that might upset the position of the imaging device A and cause binding under motion.  
         [0037]    Referring particularly to FIGS. 8 and 9, a pulley system is used to provide counterweighting of the carriage and the components attached to the carriage  50 , i.e. the clevis  14 , pivot body assembly  16 , mount assembly  18 , and imaging device A. This reduces the load on motor  28 , and allows for designing a non-motorized stand wherein the vertical position of the imaging device A can be adjusted manually. Of the pulley system, only pulleys  26  are shown attached to the top of the tower assembly  12 . Not shown are cables for each pulley that have the carriage  50  attached to at one end, and counterweights  61  attached to at the other end. The counterweights are generally cylindrical to conform to the shape of the channel  32 .  
         [0038]    Referring now to FIGS.  10 - 12 , the clevis  14  has a base that is adapted to attach to the carriage  50 , and a C-shaped arm  64  extending generally horizontally from the base. The ends of the arm are adapted to receive a pivot assembly  16 . The pivot assembly  16  is shown in exploded form in FIGS. 11 and 12 and comprises a number of parts to enable it to pivot about the clevis  14 , and to secure it to the arm  64 , and to lock the pivot body assembly  16  from pivoting. In particular, vertical solenoid rotation release  70  has pin that is spring loaded in a locked position; when power is applied to the solenoid, the pin is moved into an unlocked position to allow the pivot body assembly  16  to pivot. The pin threads through threaded pin  72 . Various seals and bearings  74 ,  76 ,  80 ,  82 ,  84 ,  86 ,  88  facilitate the pivoting of pivot assembly  16 .  
         [0039]    The pivot assembly  66  is thus pivotable in the horizontal plane, and has attached thereto the pivot body assembly  16 . The pivot body assembly  16  has a main body  98  that is adapted to be pivotably attached to the pivot assembly; locking sleeve  92 , pin guide  94 , pin  96  cooperate with the rotation release solenoid  70  to lock the main body assembly  16  in place. At the bottom of the main body  98  is attached a sag adjustment system comprising components  102 ,  104 , and  106  that allow an operator to compensate for sagging of the main body assembly  16  caused by the weight of the x-ray imaging device A attached thereto.  
         [0040]    Main body  98  is generally cylindrical and extends along a pivot body axis. The imaging device mount assembly  18  is rotatably attached to an end of the pivot body assembly  16 . The pivot body assembly  16  is adapted to allow the mount assembly  18  to rotate about the pivot body axis. The pivot body is shown in exploded form in FIGS. 11 and 12 and comprises the following components:  
         [0041]    a connector face  108  that is adapted to connect to a mating component of the imaging device A;  
         [0042]    a cylindrical plate  110  that fastens against main body  98  to secure crossed roller bearing  112  in place;  
         [0043]    rotational body  114  that is attached to connector face  108  and inner race of roller bearing  112 , thereby allowing connector face  108  to rotate relative to the main body  98 ;  
         [0044]    spline gear  116  that is movable along the main body axis to lock and unlock the mount assembly  18  from rotational movement;  
         [0045]    a cylindrical plate  118  to fasten spline gear within main body  98 ;  
         [0046]    rotational solenoid assembly that when unpowered, is spring loaded to bias spine gear into a locked position, and when powered, pulls spline gear into an unlocked position.  
         [0047]    When assembled, it can be seen that the components of the stand  10  cooperate to allow the stand to be articulated about three axes, namely the clevis is movable vertically along tower assembly  12 , the pivot body assembly  16  is movable pivotably in the horizontal plane about the clevis  14 , and the imaging device mount assembly  18  is movable rotatably about the pivot body axis of the pivot body assembly  16 . This articulation enables the imaging device A to be precisely positioned to take x-ray images of patients in recumbent, standing, or other positions.  
         [0048]    While the preferred embodiment of the invention has been illustrated and described, it will be appreciated that various changes can be made therein without departing from the scope and spirit of the invention.