Patent Publication Number: US-2012039445-A1

Title: Modular Fixed Beam-Limiting Device For Intraoral X-Ray System

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This application claims the benefit of U.S. Provisional Application No. 61/373,101, filed Aug. 12, 2010, which is hereby incorporated by reference herein in its entirety. 
    
    
     FIELD OF THE INVENTION 
     This invention relates to a radiation protection device that protects patients, as well as clinical staff against excessive x-ray radiation exposure by controlling the x-ray field of exposure. 
     BACKGROUND 
     X-radiation (containing x-rays) is a form of electromagnetic radiation having a multitude of applications. One commonly used application is found in medical diagnostics, such as dental or bone imaging. Thus, while x-ray radiation is useful for medical purposes, the x-ray radiation can be harmful to the human body. As such, overexposure to x-ray radiation should be minimized. One approach to controlling exposure is to limit the x-ray field of exposure by using beam-limiting devices, also known as collimators. Traditionally, beam limiting devices have been available as either variable-aperture beam-limiting devices, or as a set of interchangeable fixed beam-limiting devices. While those configurations provide solutions for various geometric environments, they can also result in a large assortment of parts, difficulty of use, and higher cost. 
     Some conventional intraoral x-ray systems provide multiple interchangeable fixed beam-limiting devices. In these systems, the beam-limiting device body is generally made of an x-ray opaque high-density material, such as Nylon 6/6, filled with barium sulfite powder. The body of the beam-limiting device may include grooves, which accommodate O-rings to provide a snap fit with the x-ray tube housing. Special attachments may be used to provide appropriate shaping of the x-ray beam. 
     Conventional fixed beam-limiting devices are available in various shapes that may be suitable for various medical studies. However, the number of different versions of beam-limiting devices is growing based on radiation regulations, which may be dissimilar in different countries. One drawback of conventional intraoral x-ray systems is that the field replacement of the beam-limiting device requires additional effort and special tools. In addition, conventional designs do not facilitate easy adjustment in order to match a shaped opening (such as a rectangular opening) with the x-ray film or sensor being used. 
     In view of the foregoing, a need exists for beam-limiting devices, such as those used with x-ray systems, that overcome the short-comings of conventional beam-limiting devices. 
     SUMMARY 
     The present invention overcomes the foregoing and other shortcomings and drawbacks of beam-limiting devices heretofore known for use in x-ray systems. While various embodiments are discussed in detail herein, it will be understood that the invention is not limited to these embodiments. On the contrary, the invention includes all alternatives, modifications and equivalents as may be included within the spirit and scope of the present invention. 
     In accordance with one embodiment, a modular beam-limiting device for use with an x-ray machine is provided that includes a base portion having a tubular body adapted to be received on an x-ray tubehead housing, an attachment portion having a tubular body selectively removably couplable to the base portion, at least one first magnet on the base portion, and at least one second magnet or magnetically attractive material on the attachment portion. 
     In accordance with another embodiment, method of securing a modular beam-limiting device to an x-ray machine is provide, the method including the steps of coupling a base portion on an x-ray tubehead housing, wherein the base portion includes at least one first magnet; and selectively removably coupling an attachment portion to the base portion, wherein the attachment portion includes at least one second magnet. The at least one first magnet and the at least one second magnet are polarized in complementary orientations such that the attachment portion is coupled to the base portion by magnetic force. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective view of an x-ray system including an x-ray machine having a beam-limiting device according to an embodiment of the present invention. 
         FIG. 2  is a cross-sectional view of an x-ray machine including an exemplary modular beam-limiting device in accordance with the principles of the present invention. 
         FIG. 2A  is an enlarged view of the encircled area shown in  FIG. 2 . 
         FIG. 3  is an exploded perspective view of the exemplary beam-limiting device of  FIG. 2 . 
         FIGS. 4A-4B  are perspective views depicting a method of aligning a base portion and an attachment portion of an exemplary beam-limiting device in accordance with the principles of the present invention. 
         FIG. 5  is an exploded perspective view of another exemplary beam-limiting device in accordance with the principles of the present invention. 
         FIG. 6  is an exploded perspective view of another exemplary beam-limiting device in accordance with the principles of the present invention. 
     
    
    
     DETAILED DESCRIPTION 
       FIG. 1  depicts an exemplary embodiment of an x-ray system  10  that includes a control station  11 , a jointed arm construction  12  including articulating joints  13 A-D and arms  14 A-C, and an x-ray machine  15  having a housing  16  and a modular beam-limiting device  17  in accordance with the principles of the present invention. According to various embodiments, the modular beam-limiting device  17  is not restricted to any particular x-ray machine  15  insofar as the modular beam-limiting device  17  may be adapted to conform to any x-ray machine, without limitation. 
     With reference to  FIG. 2 , a cross-sectional view is provided of the x-ray machine  15  that may be used with an intraoral x-ray system. In the embodiment shown, an x-ray tube  24 , an x-ray shield  26 , and a tubehead housing  28  are disposed within the x-ray machine housing  16 . The modular beam-limiting device  17  includes a base portion  30  and an attachment portion  32 , each having magnets  36 ,  38 . 
     The base portion  30 , which provides support to other components (e.g., the attachment portion  32 ) has a tubular construction and is adapted to be received on the x-ray tubehead housing  28 . The tubehead housing  28  may also include an internal groove  28   a . More specifically, relative to the x-ray tube  24 , the base portion  30  includes a proximal end  30   a  and a distal end  30   b ; the proximal end  30   a  being received in opening of the tubehead housing  28 . O-rings  34 , which are provided on outer surface of the base portion  30  near the proximal end  30   a , are received in circumferential grooves  31   a ,  31   b  and provide frictional engagement to couple the base portion  32  with the tubehead housing  28 . Grooves  28   a  and  31   a  each accommodate a portion of an O-ring thereby providing a snap fit. While the embodiments shown and described herein utilize O-rings to facilitate coupling the base portion  30  to tubehead housing  28 , it will be appreciated that various other methods and structure may alternatively be used. For example, in alternative embodiments, other coupling configurations, which may include screws, pins, threads, or other suitable structure, may be utilized in addition to, or instead of, the O-rings  34  to retain the base portion  30  coupled to the tubehead housing  28 . Distal end  30   b  of the base portion  30  includes magnets  36 . 
     The attachment portion  32  is selectively removably couplable to the base portion  30  for easy removal and replacement and provides the desired collimation of x-ray radiation. The attachment portion  32  includes magnets  38 , which are polarized in a complementary orientation to magnets  36 , such that the attachment portion  32  is magnetically coupled with the base portion  30  when the attachment portion  32  is placed in proximity to the base portion  30  and magnets  36 ,  38  are aligned to at least one distinct angular orientation. Magnets  36 ,  38  are of sufficient strength to provide enough magnetic attractive force to hold in place the base portion  30  and the attachment portion  32 . As shown, the magnets  36 ,  38  are cylindrically formed and may be axially magnetized. It will be appreciated, however, that various other shapes and configurations, including but not limited to cubic or rectangular shapes, may be used. 
     While the embodiments shown and described herein include magnets on both the base portion  30  and the attachment portion  32 , it will be appreciated that various other configurations may alternatively be used. As a non-limiting example, an alternative embodiment may comprise at least one magnet provided in one of the base portion  30  or the attachment portion  32 , and a ferromagnetic substance or a substance that is attracted to a magnet provided on the other of the base portion  30  or the attachment portion  32 , whereby the magnet and the ferromagnetic or magnetically attracted substance provide for coupling of the base portion  30  and the attachment portion  32  in a manner similar to that described above. 
     According to embodiments of the invention, the base portion  30  and the attachment portion  32  may comprise one or more x-ray opaque high-density materials, such as Nylon 6/6 filled with barium sulfite powder. The magnets  36 ,  38  may be incorporated into the base portion  30  and the attachment portion  32  using standard molding techniques. Alternatively, the magnets  36 ,  38  may be added to the base portion  30  and/or the attachment portion  32  after the base portion  30  or attachment portion  32  have been made. For example, as shown in  FIG. 2A , magnets  36 ,  38  may be press-fitted into bores, as indicated by voids  42 ,  43 . Various other methods may also be used. 
     Still referring to  FIG. 2 , the modular beam-limiting device may further include a magnetic field modulator  40  that modifies magnetic fields of the magnets  36 ,  38  in such way that the magnetic force distribution holds the attachment portion  32  in one or more distinct orientation positions relative to the base portion  30 . The magnetic field modulator  40  therefore facilitates easy positioning in order that an operator of the x-ray device  10  may adjust the orientation of an aperture of the modular beam-limiting device  17  with respect to an x-ray film or a sensor. The magnetic field modulator  40  can be made from any material suitable for modifying or shaping the magnetic field generated by the magnets  36 ,  38  so that distinct 
     The magnetic field modulator  40  may be formed integrally with the base portion  30  or the attachment portion  32 , such as by molding therewith. Alternatively, the modulator  40  may be coupled with the base portion  30  or the attachment portion  32  after the portion has been formed. For example,  FIG. 3  depicts an embodiment having openings  48  in a ring-shaped magnetic field modulator  40  to accommodate studs  50  to thereby attach the modulator  40  to the attachment portion  32 . The studs  50  may be used to secure the ring to the attachment portion during molding, or may be used to attach the ring to the attachment portion  32  after the portion has been formed. Accordingly, other methods, such as adhesive bonding or mechanical coupling, may alternatively be used to attach the modulator  40  to the attachment portion  32 . While this embodiment depicts a modular beam-limiting device  20  wherein a magnetic field modulator  40  is provided on the attachment portion  32  of the device  17 , it will be appreciated that other embodiments may have a magnetic field modulator  40  provided on the base portion  30 , or provided on both the base and attachment portions  30 ,  32 . 
     With continued reference to  FIG. 3 , and referring further to  FIG. 4 , four magnets  36  are provided on the base portion  30  of the beam-limiting device  17 , and four corresponding magnets  38  are provided on the attachment portion  32  of the beam-limiting device  17 . While four magnets are used for each of the base and attachment portions  30 ,  32 , it will be appreciated that various other configurations of magnets may alternatively be used, and which may include more than four magnets, or fewer than four magnets on one or both of the attachment and base portions  30 ,  32  of the modular beam-limiting device  17 . The attachment portion  32  of the modular beam-limiting device  17  in accordance with the principles of the present invention may be easily removed and replaced in the field. 
     In the embodiment shown in  FIG. 3 , the magnetic field modulator  40  comprises an annular ring formed from a material suitable for shaping the magnetic field produced by the magnets. Notches  52  are provided at spaced intervals around the circumference of the rings. The notches  52  create discontinuities in the magnetic field that can be sensed by a user when an attachment portion  32  is coupled with the base portion  30  and rotated to different angular positions. As shown in  FIG. 4A , where magnets  36 ,  38  are not aligned with respect to each other, the magnetic field may provide a noticeably reduced retaining force. Upon rotation of the attachment portion  32  in the direction designated by an arrow  60 , the magnets  36 ,  38  become aligned as shown in  FIG. 4B  thereby maximizing the magnetic force and defining at least one predetermined orientation of the base and attachment portions  30 ,  32 . It will be appreciated that magnetic field modulators  40  in accordance with the principles of the present invention may alternatively be formed in shapes other than annular rings, and may utilize various other structural features to shape the magnetic field generated by the magnets, as may be desired. 
     The beam-limiting device  17  may further include additional components, such as inserts for modifying an aperture of the device  20  and/or an adapter for converting the beam-limiting device  17  to have a longer axial length. The insert and the adapter may be constructed of x-ray opaque high-density materials, such as those materials suitable for use in the base portion  30  and the attachment portion  32 . Accordingly,  FIG. 5  depicts an exemplary modular beam-limiting device  70  including an insert  72  and an adapter  74 . The insert  72  may be received between the base portion  30  and the attachment portion  32 , whereby the insert  72  can be easily removed and replaced, as may be desired. The insert  72  may be formed in an annular ring having an aperture  76  that is less than the base portion aperture  78  to thereby reduce the size of the x-ray beam pathway. The adapter  74  may be used to convert the axial length of the beam-limiting device  70  to the desired dimension. For example, the axial length may be increased from about 200 mm to about 300 mm. In this embodiment, magnets  36 ,  38  and magnetic field modulators  40  as described above are provided at the interface between the base portion  30  and the insert  72 , as well as at the interface between the adapter  74  and the attachment portion  32 . 
       FIG. 6  depicts yet another exemplary embodiment of a beam-limiting device  90  including an insert  92  configured to have a rectangular-shaped aperture  94 . The attachment portion  96  may also have a rectangular-shaped aperture  98 . Accordingly, the rectangular-shaped apertures  96 ,  98  may be aligned. In this embodiment, magnets  36 ,  38  and a magnetic field modulator  40  as described above are provided at the interface between the base portion  30  and the attachment portion  96 . 
     While the present invention has been illustrated by the description of one or more embodiments thereof, and while the embodiments have been described in considerable detail, they are not intended to restrict or in any way limit the scope of the appended claims to such detail. Additional advantages and modifications will readily appear to those skilled in the art. The invention in its broader aspects is therefore not limited to the specific details, representative apparatus and methods and illustrative examples shown and described. The various features of exemplary embodiments described herein may be used in any combination. Accordingly, departures may be made from such details without departing from the scope or spirit of Applicant&#39;s general inventive concept.