Abstract:
These and other objects of the present invention are achieved by an apparatus and process for evaluating an image-wise exposed storage film positioned about a cylindrically-shaped member and linearly passed a cylindrically-shaped slot for interrogation by a light beam wherein a processing assembly is co-axially disposed within a processing chamber formed by the cylindrically-shaped member and wherein the processing assembly includes a plate member disposed for rotation in a plane perpendicular to the axis of the processing chamber and having a pentaprism and a fluorescence light sensor positioned proximate a contact point of the interrogating light beam with the storage film and further including converting electronics for the thus generated fluorescence light wherein after interrogation, the storage film is immediately restored in the same apparatus for subsequent reuse.

Description:
RELATED APPLICATIONS 
     This application claims the benefit of provisional application Ser. No. 60/725,984, filed Oct. 13, 2005. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to radiographic imaging, and more particularly to an improved apparatus and process for digitally retrieving information projected onto a reusable radiographic film and for erasing and restoring the radiographic film immediately after retrieval and in the same assembly. 
     2. Description of the Prior Art 
     Traditional x-ray imaging systems using silver-based films are being replaced by radiographic imaging systems using photo-stimulable phosphor imaging films or substrates eliminating the need for physical storage of the imaged film since digital retrieval of the image information includes input and computer storage permitting viewing of such information on a viewer, such as CRT tube assembly. Additionally, such computer stored image information permits facile electronic transmission to any preselect location obviating physical transfer of the thus formed image on the imaging film. 
     In U.S. Pat. No. 5,874,744 to Goodman, et al., assigned to the same assignee as the present invention, there is disclosed a process and apparatus for processing radiographic information from an anisotropic storage phosphor screen including an opto-electro-mechanical assembly to achieve faster scan of an interrogating beam and including detector and computer assembly, herein incorporated by reference. 
     In U.S. Pat. No. 6,599,014 to Thoms, there is disclosed an assembly for reading flexible storage films wherein the flexible storage film having image-wise projected information is positioned on a cylindrically-shaped surface and is caused to be linearly moved there over while being interrogated or scanned via a slot by a light beam generated in a helical line in a continuous manner from a point disposed at the axis of the cylindrically-shaped surface. The output fluorescence light or signal generated at the actual point the light beam intersects the storage film is received by a large diameter photomultiplier tube disposed proximate the slot. Such output signal is recorded together with positioning encorders to obtain an electrical image of the thus stored x-ray image on the storage foil. The configuration of the photomultiplier and the distance there from to the interpreting electronics results in a signal/noise ratio which while acceptable if advantageously decreased would provide more efficacious end result. 
     As used herein, the term “reusable storage film” is a flexible substrate formed with a layer of a photo-stimulable phosphors which is capable of imaging with ionizing radiation or x-rays which after imaging may be interrogated or scanned with a source of light energy to produce photo-stimulated luminescence information capable of being digitally read and stored. 
     OBJECTS OF THE INVENTION 
     An object of the present invention is to provide an improved apparatus and process for interrogating and interpreting an image on a reusable storage film moving past an accessible slot of an interrogating light beam and thereafter immediately restoring the storage film for reuse. 
     A further object of the present invention is to provide for an improved apparatus and process for interrogating and interpreting an image on a reusable storage film moving past an accessible slot of an interrogating light beam, the apparatus having incorporated therein a light cavity and a source of illumination for erasing the image from the storage film subsequent to the storage film being interrogated by a light beam to energize the image and store same. 
     A still further object of the present invention is to provide for a novel apparatus and process for interrogating and interpreting an image on a reusable storage film moving past an accessible slot of an interrogating light beam wherein the belt and roller assembly of the apparatus is of an extended length so as to engage the storage film from its insertion into the apparatus to a point subsequent to the erasing light cavity. 
     A still further object of the present invention is to provide for an improved apparatus and process for interrogating and interpreting an image on a reusable storage film moving past an accessible slot of an interrogating light beam wherein an erasing light cavity completely removes the stored image from the storage film permitting the immediate reuse of the storage film. 
     SUMMARY OF THE INVENTION 
     These and other objects of the present invention are achieved by an apparatus and process for evaluating an image-wise exposed storage film positioned about a cylindrically-shaped member and linearly passed a cylindrically-shaped slot for interrogation by a light beam wherein a processing assembly is co-axially disposed within a processing chamber formed by the cylindrically-shaped member and wherein the processing assembly includes a plate member disposed for rotation in a plane perpendicular to the axis of the processing chamber and having a pentaprism and a fluorescence light sensor positioned proximate a contact point of the interrogating light beam with the storage film and further including converting electronics for the thus generated fluorescence light wherein after interrogation, the storage film is immediately restored in the same apparatus for subsequent reuse. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Further objects and advantages of the present invention will become more readily apparent by reference to the following detailed description thereof when taken with the accompanying drawings wherein like numerals designate like parts throughout and wherein: 
         FIG. 1  is a partial cross-sectional view of the optical cavity and transport mechanism of a scanner of the prior art; 
         FIG. 2  is a partial cross-sectional view of the optical cavity and transport assembly of a scanner assembly of the present invention having restoration assembly; 
         FIG. 3  is a partial cross sectional view of the optical cavity illustrating a second embodiment of the transport assembly in conjunction with the restoration assembly; 
         FIG. 4  is a front view of the scanner assembly of  FIG. 3  with the transport assembly removed; and 
         FIG. 5  is a partial top view of the relationship between the transport assembly and plate pressure rollers of the transport assembly illustrated in  FIG. 3 . 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       FIG. 1  is a partial cross-sectional view of the optical cavity  12  of a scanning mechanism  10  as presently exists in the prior art. Within the optical cavity  12 , there is positioned a laser tube assembly  14  which transmits a light source to a pentaprism  16  centrally mounted within the optical cavity  12  on a shaft  18  secured to a pentaprism motor  20 . Also mounted on shaft  18  are a pair of fly wheels  22  and  24 . The light source from the laser tube assembly  14  is redirected as a light beam by the pentaprism  16 , to a scanning slit  26 . It is passed this scanning slit  26  that a photo-stimulable phosphor imaging plate  28  is passed having a latent image thereon. 
     The photo-stimulable phosphor imaging plate  28  is inserted into a slot  30  where it is engaged by a transport mechanism  32 . The scanner detects the presence of a photo-stimulable phosphor imaging plate  28  by an LED emitter  34  and associated fiber optic plate  36  to indicate to the scanning mechanism that the imaging plate  28  is positioned for reading. A transport frame, generally indicated as  38 , is comprised of a driver roller  40 , idler roller  42 , and tension roller  44  initiate movement of a transport belt  46  by means of a transport motor  48  causing the photo-stimulable phosphor imaging plate  28  to pass through a set of light sealing brushes  50  and thence in front of the scanning slit  26  where the photo-stimulable phosphor imaging plate  28  is interrogated by the light beam. The latent image on the photo-stimulable phosphor imaging plate  28  is excited by the light beam and its contents collected by photomultiplier  52  and then stored in a CPU unit for viewing and archival purposes. 
     The photo-stimulable phosphor imaging plate  28  after having been read, is transported by means of the transport belt  46  and associated drive rollers, etc. from the scanning assembly  10 . At this time, the photo-stimulable phosphor imaging plate  28  would require eraser or restoration to remove the latent image thereon so that the photo-stimulable phosphor imaging plate  28  could be reused. One manner of erasing the photo-stimulable phosphor imaging plate  28  is to expose the imaging plate  28  to a light source for a time sufficient to allow for erasure and subsequent restoration of the plate for reuse. See U.S. Pat. No. 6,778,776 assigned to the same Assignee as the present application for one manner of accomplishing restoration of such an imaging plate. 
     Applicant&#39;s contribution to the scanning arts in this application is a scanner assembly  10  in which the photo-stimulable phosphor imaging plate  28  is erased or restored within the assembly after having been interrogated such that the photo-stimulable phosphor imaging plate  28  exiting the scanner assembly has had its latent image removed, is restored, and immediately ready for reuse.  FIG. 2  is a partial cross-section of the scanning assembly  10  of the present invention. 
     The interior of the optical cavity  12  remains generally identical to the prior art thus described. However, the scanner assembly is provided with a light erasing cavity  60  positioned in the path of the photo-stimulable phosphor imaging plate  28 , but subsequent to the scanning slit  26  where the latent image on the photo-stimulable phosphor imaging plate  28  is interrogated. In  FIG. 2 , the light erasing cavity  60  is positioned below the scanning slit  26  and in communication with the pathway of the photo-stimulable phosphor imaging plate  28  by means of an erasing slit  62 . Positioned within the light erasing cavity  60  is a light source  64  in communication with a power source so as to direct a light beam through the erasing slit  62  and onto the photo-stimulable phosphor imaging plate  28  as it passes the erasing slit  62 . In the configuration illustrated in  FIG. 2 , the light source is an array of multiple red/red orange LED&#39;s aimed radially outwardly so that the light emitted passes through the erasing slit  62 . Additionally, the walls of the eraser cavity  60  may be mirrored to enhance the light emanating from eraser slit  62 . 
     Since an additional process is now being performed in the scanner in addition to the interrogation process on the photo-stimulable phosphor imaging plate  28 , the transport assembly  32  for transporting the photo-stimulable phosphor imaging plate must be extended. Whereas in the scanner assembly of the present art, the transport belt need only transport the photo-stimulable phosphor imaging plate  28  a distance sufficient for it to pass in front of the scanning slit  26  for interrogation and then to exit the scanner, the transport assembly for the present invention must be of longer configuration in order to transport the photo-stimulable phosphor imaging plate  28  past the erasing slit  62 . In the configuration illustrated in  FIG. 2 , the number of plate pressure rollers  39  is increased to accommodate the additional distance and the transport belt  46  is also extended. 
       FIG. 3  is a cross sectional view of the optical cavity and transporter means illustrating a second embodiment of the transporter means which does not require a reengineering of the transport means of the existing prior art in order to be able to transport the photo-stimulable phosphor imaging plate  28  past the eraser cavity  60 . In this configuration, additional idler rollers  42 A is in belt communication with the drive rollers  40  of the original transport assembly  32 . Idler rollers  42 A are positioned below the eraser cavity  60  and adjacent additional pressure plate rollers  39 A. In this configuration, the original transport belt  46  would transport the photo-stimulable phosphor imaging plate  28  past the eraser cavity  60  and then the lower pressure plate roller  39  and the idler rollers  42 A would engage the photo-stimulable phosphor imaging plate  28  and transport it out of the scanner assembly  10  or to a depository for reuse. This embodiment provides for more efficient use of the transport means of the prior art with minor reengineering. The relationship between the idler rollers  42 A and the lower pressure plate rollers  39 A is illustrated in  FIG. 5 . 
       FIG. 4  is a side view of the scanning assembly  10  illustrating the plate pressure rollers  39 A and their positioning within each vertical passageway in which the photo-stimulable phosphor imaging plate  28  is transported. There are multiple transport means  32  associated with a scanner to accommodate multiple sized imaging plates hence there are multiple sets of plate pressure rollers. Still further reference can be had to provisional application 60/693,020 of Applicant&#39;s directed to a belt and roller drive for the transport of an imaging plate within an opto-electrical mechanical scanning assembly. 
       FIG. 5  illustrates the relationship between lower pressure plate rollers  39 A and idler rollers  42 A of the  FIG. 3  embodiment. A bracket  70  is attached to the optical scanner on which the lower plate pressure rollers  39 A are mounted. Lower plate pressure rollers  39 A are mounted on bearings on an idler axle  71  which is spring loaded with the center plate pressure roller being of slightly larger circumference than those on either side. The lower idler rollers  42 A are in communication with the drive roller  40  by means of a timing belt  35 . In the configuration illustrated in  FIG. 5 , the idler rollers  42 A are fixedly mounted on shaft  41  with the circumferential periphery  43  in tangential contact with the outer plate pressure rollers  39 A such that the imaging plate passes thereby in an arcuate relationship. 
     The transport mechanism embodiments of  FIGS. 2 and 3  can positively engage the photo-stimulable phosphor imaging plate  28  from its insertion point  30  to its ejection point and allows for an erasing light cavity  60  to be positioned in the scanner assembly  10  subsequent or downstream from the scanning slit  26  with the erasing light cavity having an erasure slit  62  and light source  64  which allows for the photo-stimulable phosphor imaging plate to be erased and restored and ready for reuse immediately after it has been interrogated and read. It will be recognized that many different light sources can be utilized to erase the photo-stimulable phosphor imaging plate and restore it for reuse. Applicant&#39;s use of an array of multiple red/red orange LED&#39;s is for explanatory purposes, but this wave length is well suited for such erasing and for not interfering with the data acquisition as this wave length is filtered out by the blue filter on the photo-multiplier tube. 
     While the present invention has been described with respect to the exemplary embodiments thereof, it will be recognized by those of ordinary skill in the art that many modifications or changes can be achieved without departing from the spirit and scope of the invention. Therefore it is manifestly intended that the invention be limited only by the scope of the claims and the equivalence thereof.