Abstract:
A radiopaque apron configured to overlap an opening of a radiographic imaging apparatus. The apron is a two-layered radiopaque flexible material that extends over the opening. A first layer is large enough to extend across the imaging opening. The second layer has an apron opening smaller than the imaging opening and is positioned between the first layer and the apparatus.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application claims priority to U.S. Patent Application Ser. No. 62/356,122, filed Jun. 29, 2016, in the name of Adam D. Pruyne, and entitled RADIOPAQUE APRON. 
         [0002]    This application is related in certain respects to U.S. Patent Application Publication U.S. 2014/0098930 A1, filed Oct. 8, 2013, in the name of Litzenberger et al., and entitled EXTREMITY IMAGING APPARATUS FOR CONE BEAM COMPUTED TOMOGRAPHY, which is incorporated herein by reference in its entirety. 
     
    
     BACKGROUND OF THE INVENTION 
       [0003]    The invention relates generally to diagnostic imaging and in particular to a cone beam radiographic imaging system used for obtaining volume images of patient extremities. 
         [0004]    3-D radiographic volume imaging has proved to be a valuable diagnostic tool that offers significant advantages over earlier 2-D radiographic imaging techniques for evaluating the condition of internal structures and organs. 3-D imaging of a patient or other subject has been made possible by a number of advancements, including the development of high-speed imaging detectors, such as digital radiography (DR) detectors that enable multiple images to be taken in rapid succession. 
         [0005]    Cone beam computed tomography (CBCT) technology offers considerable promise as one type of diagnostic tool for providing 3-D radiographic volume images. CBCT systems capture volumetric data sets by using a high frame rate digital radiography (DR) detector and an x-ray source, typically affixed to a gantry that rotates about the object to be imaged, directing, from various points along its orbit around the subject, a divergent cone beam of x-rays toward the subject. The CBCT system captures projections throughout the rotation, for example, one 2-D projection image at every degree of rotation. The projections are then reconstructed into a 3D volume image using various techniques such as filtered back projection approaches. 
         [0006]    The CBCT apparatus captures a series of 2D projection images of a patient extremity placed in the imaging bore of the apparatus. A central axis of the rotating source and detector may also define a central axis of the imaging bore. A housing of the CBCT imaging system may be shaped to surround a cylindrical imaging bore. 
         [0007]    In summary, for extremity imaging, one improvement may provide x-ray shielding proximate the imaging bore when a patient extremity is placed therein. Improved radiographic energy shielding provides acceptable radiation scatter levels throughout the scanning or imaging sequence, i.e., during the activation of the x-ray source and its rotation about the central axis. 
         [0008]    A well designed radiopaque apron allows imaging a patient&#39;s extremity with the patient standing or seated comfortably and protected from radiographic energy leakage (scatter). The radiopaque apron may allow the capability to adjust the angle of the central rotational axis to suit patient positioning requirements, thereby improving patient accessibility, so that the patient does not need to contort, twist, or unduly stress limbs or joints that may have been injured in order to provide images of those extremities. The patient may stand or sit with normal posture, for example. 
         [0009]    As described herein, the imaging bore of the CBCT apparatus allows a single imaging apparatus to be configurable for imaging any of a number of extremities, including knee, ankle, toe, hand, elbow, and other extremities. This also includes the capability to operate the imaging system in different imaging modes, including CBCT, two-dimensional (2-D) projection radiography, fluoroscopy, and other tomography modes. The imaging bore size is sufficiently large to accommodate an extremity of a patient but not the body of the patient. As an example, the imaging bore may not be large enough to accommodate a human torso or two patient extremities simultaneously. 
         [0010]    In summary, the capability for straightforward configuration and positioning of the imaging apparatus allows the advantages of CBCT imaging to be adaptable for use with a range of extremities, to obtain volume images under a suitable imaging modality, with the image extremity presented at a suitable orientation under both load-bearing and non-load-bearing conditions, and with the patient appropriately standing or seated and protected from unneeded or excessive radiation. 
       BRIEF DESCRIPTION OF THE INVENTION 
       [0011]    A radiopaque apron is configured to overlap an opening of a radiographic imaging apparatus. The apron is a two-layered radiopaque flexible material that extends over the opening. A first layer is large enough to extend across the imaging opening. The second layer has an apron opening smaller than the imaging opening and is positioned between the first layer and the apparatus. 
         [0012]    In one embodiment, an imaging apparatus having a housing includes an imaging opening in the housing for positioning a patient anatomy to be imaged. A radiopaque apron attached to the apparatus is used to cover the opening. The radiopaque apron may have a first layer extending continuously over the opening and a second layers disposed between the first layer and the apparatus, wherein the second layer has an opening centered proximate a central axis of the imaging opening to receive the patient anatomy. 
         [0013]    In one embodiment, a radiopaque apron is configured to cover an imaging opening of an imaging bore of a CBCT imaging apparatus. The apron may include a first continuous layer large enough to extend across the imaging opening, and a second layer adjacent the first layer between the first layer and the imaging apparatus. An opening in the second layer smaller than the imaging opening may be centered on a central axis of the imaging opening. 
         [0014]    This brief description of the invention is intended only to provide a brief overview of subject matter disclosed herein according to one or more illustrative embodiments, and does not serve as a guide to interpreting the claims or to define or limit the scope of the invention, which is defined only by the appended claims. This brief description is provided to introduce an illustrative selection of concepts in a simplified form that are further described below in the detailed description. This brief description is not intended to identify key features or essential features of the claimed subject matter, nor is it intended to be used as an aid in determining the scope of the claimed subject matter. The claimed subject matter is not limited to implementations that solve any or all disadvantages noted in the background. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0015]    So that the manner in which the features of the invention can be understood, a detailed description of the invention may be had by reference to certain embodiments, some of which are illustrated in the accompanying drawings. It is to be noted, however, that the drawings illustrate only certain embodiments of this invention and are therefore not to be considered limiting of its scope, for the scope of the invention encompasses other equally effective embodiments. The drawings are not necessarily to scale, emphasis generally being placed upon illustrating the features of certain embodiments of the invention. In the drawings, like numerals are used to indicate like parts throughout the various views. Thus, for further understanding of the invention, reference can be made to the following detailed description, read in connection with the drawings in which: 
           [0016]      FIGS. 1A-1B  are exploded views of a radiopaque apron; 
           [0017]      FIG. 2  is a close-up view of a portion of  FIG. 1B ; 
           [0018]      FIGS. 3A-3B  show a cross-section and cross-section perspective view, respectively, of the first and second layers of the apron and attachment components; 
           [0019]      FIGS. 4A-4C  illustrates the radiopaque apron of the present disclosure in front, side, and rear views, respectively; 
           [0020]      FIG. 5A  shows a top view of a CBCT imaging apparatus; 
           [0021]      FIG. 5B  shows a perspective view of a CBCT imaging apparatus with an attached radiopaque apron shown in transparent view; and 
           [0022]      FIGS. 6A-6D  are images of the apron in various positions over an imaging opening of a CBCT imaging apparatus. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0023]      FIG. 1A  illustrates the flexible radiopaque apron  100  of the present disclosure in an exploded view showing a flexible first layer  110  of the apron  100  comprising flexible sublayers  103 ,  105  and a flexible border, or edge, piece  101 . A flexible second layer  120  of the apron  100  comprising flexible sublayers  111 ,  113 ,  115  and a flexible border, or edge, piece  117 .  FIG. 1B  shows the first layer  110  and the second layer  120  as they would appear when their respective sublayers  103 ,  105 , and  111 ,  113 ,  115 , are assembled together, with their border pieces  101 ,  117 , respectively. As shown, the first layer  110  may be said to comprise a substantially continuous, planar form while the second layer  120  may be said to comprise a central apron opening, or apron gap,  121 , which central apron opening  121  may include a center point or area  123  illustrated by the symbol +. The central apron opening  121  may include an opening extension  125  extending away from a center  123  of the central apron opening  121  toward a top portion of the second layer  120 . In one embodiment, the central apron opening, or apron gap,  121  is not completely enclosed, or surrounded, by the second layer  120 . Rather, the second layer  120  comprises opposing flap portions  131 ,  133 , that surround a major portion of the central apron opening  121  and almost converge, but do not come together in contact, at a bottom of the central apron opening  121 . 
         [0024]    In one embodiment, the second layer  120  may be assembled in a one-piece unitary fashion, or, in another alternative embodiment, it may be formed as a two-piece layer having two substantially symmetrical portions separated by a gap  127  at a top of the second layer  120 . In the alternative embodiment, the sublayers  111 ,  113 ,  115 , and the border piece  117  may each be similarly formed in two pieces before final assembly, or the sublayers  111 ,  113 ,  115 , and the border piece  117  may be cut after assembly and then reassembled in the two-piece embodiment. The border pieces  101 ,  117 , may be formed in the same material as one of their corresponding sublayers, or they may be formed using a different material. In one embodiment, the border pieces  101 ,  117 , include a nylon material attached to their corresponding sublayers by being sewn through their corresponding sublayers. The border pieces  101 ,  117 , may also be clamped, glued, or otherwise attached to their respective sublayers to continuously surround an edge of the first and second layers  110 ,  120 . 
         [0025]    As shown in  FIG. 1A , the sublayer  103  may be formed from a flexible plastic, resin, polyvinyl, rubber, fabric, or a combination thereof, such as a Naugahyde sublayer, and may be designed and used for aesthetic purposes. The layer  105  may contain lead as a radiopaque material or it may include a sheet of material sold as Greenlite manufactured by Infab Corporation of Camarillo, Calif. The sublayer  103  may also contain a radiopaque coating or layer on its side that faces sublayer  105 . In one embodiment, the layers  103 ,  105 , may be stitched together such as along exemplary stitch line  116 . As shown in  FIG. 1A , the sublayers  111 ,  115  may be formed from a flexible plastic, resin, polyvinyl, rubber, fabric, or a combination thereof, such as Naugahyde sublayers, and may be designed and used for aesthetic purposes. The sublayers  111 ,  115 , may contain lead as a radiopaque material or they may each include a sheet of material sold as Greenlite manufactured by Infab Corporation of Camarillo, Calif. The sublayers  111 ,  115 , may also contain a radiopaque coating or layer on their sides that face each other. A sublayer  113  may be included in layer  120  to serve as a stiffener, made from a thin plastic, resin, or rubber material. In one embodiment, the individual pieces  113   a - c  may be selectively formed from a thin polycarbonate, or from a thermoplastic acrylic-polyvinyl chloride material commercially known as Kydex, for example. The sublayer  113  may still be flexible but slightly stiffer than layers  111  and  115 . The sublayer  113  may be formed in one piece, two pieces, or, as shown in  FIG. 1A , in three pieces  113   a ,  113   b , and  113   c.    
         [0026]    Layer  110  may include a pair of attachment elements, such as snaps  106  fixed in sublayer  105  by attaching together separate parts of the attachment elements  106  through holes in the sublayer  105 . Attachment elements, such as snaps,  108 , that mate with attachment elements  106  may be fixed in layer  120  by attaching together separate parts of the attachment elements  108  through holes in the sublayers  111 ,  113 ,  115 . The attachment elements  106  may be connected to attachment elements  108  such as by being detachably attached together in the form of snaps. Layer  120  may further include grommets  112  that pass through holes in the sublayers  111 ,  113 ,  115 . The grommets  112  allow the layer  120  to be attached to a housing of a CBCT imaging apparatus ( FIG. 5A ), using screws as described herein. Alternative embodiments of removable attachment elements  106 ,  108  may include hook and loop fastening material commonly sold as Velcro, magnetic segments, or other suitable attachment embodiments. 
         [0027]    Layer  110  may include a pair of thin metal pieces  102  (only one of which is visible in the view of  FIG. 1A ) each having a threaded hole  104  therethrough that is aligned with a hole through sublayer  105 , the assembly of which is described hereinbelow. The metal pieces  102  may be positioned between sublayers  103  and  105 , and between stitches  116  and the border piece  101  when the layer  110  is fully assembled. Another stitch line  118  ( FIG. 1B ) may be sewn to secure together both layers  110 ,  120 . As described below, the layer  110  may be flapped open using the stitch line  118  as a hinged line. 
         [0028]      FIG. 2  is a close-up view of  FIG. 1B  showing exemplary attachment components for securing together the sublayers  103 ,  105 , of layer  110  and the sublayers  111 ,  113 ,  115 , of layer  120 . The enumerated attachment components in  FIG. 2  are described with respect to only one assembly thereof, but the enumerated attachment components are duplicated proximate a second opposite edge of the layers  110 ,  120  positioned in approximately a symmetric location with respect to the enumerated components&#39; location, as shown hereinbelow. 
         [0029]    The following description may best be understood with reference to  FIGS. 2 and 3A-3B .  FIG. 3A  shows a cross-section view of the attachment components fully assembled to layers  110 ,  120 , as illustrated in  FIG. 4C .  FIG. 3B  shows a perspective view of the cross-section view of  FIG. 3A . A somewhat circular, or coin shaped, magnet  201  includes a hole therethrough to receive a screw  205 . A cover, or cap,  203  includes a hole therethrough to receive the screw  205 , and is shaped on one side to partially enclose the magnet  201 . Both the magnet  201  and the cap  203  each include an annular frustoconical shaped countersink  216 ,  218 , respectively, matching an angle of the head of the screw  205 . The screw  205  screws into the threaded hole  104  of the metal piece  102  through a hole in sublayer  105  after passing through the holes in the magnet  201  and the cap  203 . In this fashion, the assembly of the attachment components for the layer  110  is complete. 
         [0030]    The cap  203  includes a further annular frustoconical countersink  204  to receive an annular frustoconical extension  206  of the cap  209 . The cap  209  includes an annular frustoconical countersink  208  and hole therethrough to receive screw  207 , and is configured to partially enclose somewhat circular, or coin shaped, magnet  211  which also includes an annular frustoconical countersink  212  and hole therethrough to receive the screw  207 . Both annular frustoconical shaped countersinks  208 ,  212 , match an angle of the head of the screw  207 . A symmetrical arrangement of another cap  217 , magnet,  215 , and screw  219 , is configured to be joined together in a similar fashion on an opposite side of layer  120  aligned with the assembly of cap  209 , magnet  211 , and screw  207 . The cap  217  also includes a countersink hole therethrough to receive screw  219 , and partially encloses magnet  217  which also includes a countersink hole therethrough to receive screw  219 . Both the magnet  215  and the cap  217  each include an annular frustoconical shaped countersink (not enumerated) matching an angle of the head of the screw  219 . A cylindrical element  213  having interior threads passes through a hole  214  in the sublayers of layer  120  and through the holes of magnets  211 ,  215 . The screw  207  passes through the hole of cap  209  and the hole of magnet  211  and may be screwed into a first end of cylindrical element  213  from a first direction. The screw  219  passes through the hole of cap  217  and the hole of magnet  215  and may be screwed into a second end of cylindrical element  213  from a second direction. In this fashion, the assembly of the attachment components for layer  120  is complete. The magnets  201 ,  211 ,  215 , interact in an attractive complementary fashion by arranging their polarities as shown by the North and South magnetic pole designations N and S in  FIG. 3B , which arrangement may be reversed with equal effect. 
         [0031]    The completed assembly of layers  110 ,  120 , allows the top portions of the layers  110 ,  120 , to be attached together using exemplary pairs of mating snaps  106 ,  108  ( FIG. 4B ). Similarly, the bottom portions of the layers  110 ,  120 , may be attached together using the mating caps  203 ,  209 , which are drawn together by magnetic attraction generated at least by magnets  201 ,  211 . Alternative embodiments of attachment components usable to attach the bottom portions of the layers  110 ,  120 , may also include hook and loop fastening material commonly sold as Velcro, snaps, or other suitable attachment embodiments. 
         [0032]    Referring again to  FIGS. 1A-1B , the border pieces  101 ,  117 , may be attached to their respective sublayers before or after the sublayers are secured together. In one embodiment, the border pieces  101 ,  117 , may be attached to their respective sublayers simultaneously with attaching the sublayers together such as by sewing the border pieces through their corresponding sublayers. Although the first layer  110  and second layer  120  are shown in an exemplary embodiment as formed from two or more sublayers, the first and second layers  110 ,  120 , may be formed from only one layer or from more than three layers, as desired. In a one-sublayer embodiment, the one-sublayer may be impregnated, coated, deposited, or otherwise combined with a radiopaque material. The sublayers  101 ,  103 , and  111 ,  113 ,  115 , may themselves be secured together using a sewing machine as described herein, or they may be secured together using staples, rivets, or other known components used for securing together materials in the form of sheets. The sublayers  101 ,  103 , and  111 ,  113 ,  115 , may be laminated together, or they may be coated with adhesive on their surfaces that face each other and compressed, heated, ultraviolet light (UV) exposed, or otherwise flexibly attached, as desired. 
         [0033]      FIGS. 4A-4C  illustrate the radiopaque apron  100  of the present disclosure in a front view, side view, and rear view, respectively, with many of the elements described herein enumerated.  FIG. 4A  shows the position of the stitch line  118  which may be used to secure together the layers  110  and  120  such as by machine sewing. Stitch line  116  may be used to sew together the sublayers of layer  110 . Exemplary positioning of the attachment elements  106  of layer  110  are illustrated in  FIG. 4A , which may be used to attach together the upper portions of the layers  110  and  120  using cooperative attachment elements  108  in layer  120 , as shown in  FIGS. 4B and 4C . The nesting fit as between mating attachment components, or caps,  203 ,  209 , is illustrated in the side view of  FIG. 4B , wherein cap  209  is not visible due to its position within the frustoconical countersink  218  of cap  203 . Cap  209  has a similar profile as that shown by cap  217  in  FIG. 4B , however, cap  209  extends from the opposite side of layer  120  into mating cap  203 . 
         [0034]    As shown in  FIG. 4C , the apron opening  121  in layer  120  may be said to have a center  123 , as illustrated by the + symbol. The lower portion of layer  120  includes two flaps  131 ,  133 , separated by a gap which may be measured by the angle  401  delineated by the center  123  and the interior edges of the flaps  131 ,  133 . The angle of the gap may range from a small angle of about 5° to a large angle of over 90° . As shown in  FIG. 4C , angle  401  is slightly more than about 20°. Thus, with an exemplary gap angle  401  of about 20°, the layer  120  may be said to surround the apron opening  121  for about 340°; or with an exemplary gap angle  401  of about 90°, the layer  120  may be said to surround the apron opening  121  for about 270°, for example. In one preferred embodiment, the layer  120  surrounds the apron opening  121  for at least about 180°. 
         [0035]      FIG. 5A  shows a top view of an exemplary CBCT imaging apparatus  500 , such as described in the Patent Application Publication U.S. 2014/0098930 A1 identified above and incorporated herein by reference.  FIG. 5B  shows a perspective view of the housing  501  portion of  FIG. 5A . The CBCT imaging apparatus  500  comprises a C-shaped housing  501  enclosing radiographic source and detector components for imaging patient anatomies that are positioned in the imaging opening  505  proximate a central axis  507 , indicated by the symbol ×, of the imaging opening  505 .  FIG. 5A  shows the imaging apparatus  500  and the imaging opening  505  uncovered by the radiopaque apron  100 . In a top view, as shown in  FIG. 5A , the imaging opening  505  may be said to have an approximate circular shape, or at least a portion of the opening  505  may be shaped as an arc of a circle. The imaging opening  505  extends through an entire depth D ( FIG. 5B ) of the housing  501  to form an imaging volume that may be referred to herein as an imaging bore. The imaging bore formed by the housing  501  defines a somewhat cylindrical imaging volume wherein a patient anatomy may be positioned for radiographic imaging. The top surface  503  of the housing  501  (facing the reader in  FIG. 5A ) and bottom surface (not shown), opposite the top surface, form two major surfaces of the housing  501 . An interior circumferential housing surface extends between and connects the top and bottom surfaces thereby forming the somewhat cylindrical imaging bore surrounding the central axis  507 . The radiation source and detector each may orbit a patient anatomy positioned in the imaging bore at the central axis  507  to obtain various radiographic images of the patient anatomy. Portions of the housing  501  may be fabricated with metal, fiberglass, plastic, or other suitably rigid material. According to one embodiment, all of, or portions of, the top surface  503  and the opposite bottom surface (not shown) are substantially flat. 
         [0036]      FIG. 5B  illustrates the radiopaque apron  100  of the present disclosure attached to the top surface  503  of the housing  501 . The apron  100  is shown in a transparent view, wherein an outline of the second layer  120  can be seen beneath the first layer  110  that covers it (see e.g.,  FIG. 4A ). A center  123  of the layer  120  apron opening  121  is positioned over the imaging opening  505  such that it is proximate to or coincides with the central axis  507  of the imaging opening  505 . Attachment components  521 ,  523 , for attaching the radiopaque apron  100  to a top surface  503  of the housing  501  are shown in  FIG. 5A . Attachment components  521  may include threaded holes for receiving screws that pass through grommets  112  in layer  120  of the radiopaque apron  100 . Thus, the radiopaque apron  100  may be somewhat permanently attached to the housing  501  of imaging apparatus  500  depending on the type of screws used. In one embodiment, the apron  100  may not be detached from the housing  501  without the use of at least one tool. Attachment components  523  may include caps that magnetically mate with the caps  217  of the radiopaque apron  100 . In one embodiment, attachment components  523  may each include a magnet and a cap each having a hole therethrough, and a screw to attach the assembly to a threaded hole in the top surface  503  of the housing  501 . Such an assembly of magnet, cap, and screw may resemble the magnet  201 , the cap  203 , and the screw  205  shown in  FIG. 2 . Because the cap  217  on layer  120  resembles the cap  209  which nests within the cap  203 , the cap  217  would also nest into a cap positioned as an attachment component  523  having a similar or identical construction as cap  203 . The magnet within the housing attached cap would be oriented to attract the magnet  215  thereto, thereby securing layer  120  to the top surface  503  of the housing  501  by magnetic force. In turn, layer  110  may be secured to the layer  120  by magnetic force, as described herein. 
         [0037]      FIGS. 6A-6D  illustrate the radiopaque apron  100  of the present disclosure attached to a housing of an imaging system ( FIG. 6A ); with the first layer  110  folded up and the second layer  120  extending over the edges of the imaging opening  505  ( FIG. 6B ). A center of the apron opening (+)  123  may be positioned proximate a central axis (×)  507  of the imaging opening  505  as shown in  FIG. 6B . Either or both flaps of the second layer  120  may also be folded up, as desired, as shown in  FIGS. 6C-6D . 
         [0038]    This written description uses examples to disclose the invention, including the best mode, and also to enable any person skilled in the art to practice the invention, including making and using any devices or systems and performing any incorporated methods. The patentable scope of the invention is defined by the claims, and may include other examples that occur to those skilled in the art. Such other examples are intended to be within the scope of the claims if they have structural elements that do not differ from the literal language of the claims, or if they include equivalent structural elements with insubstantial differences from the literal language of the claims.