Abstract:
A storage phosphor reader includes a multicassette autoloader for vertically oriented storage phosphor cassettes, the autoloader having a front, back, and opposite sides. The autoloader includes an input bin for receiving multiple vertically oriented storage phosphor cassettes stacked together in face-to-face contact such that said cassette faces face front and back; wherein each of said cassettes contains a storage phosphor which is removable from said cassette; and an output bin located beside said input bin, said output bin having a storage phosphor read location at which a storage phosphor is removed from and replaced in a storage phosphor cassette positioned at said storage phosphor read location, and having an output region for read cassettes to be subsequently removed from said output bin.

Description:
FIELD OF THE INVENTION 
     The invention relates generally to the field of computed radiography, and in particular to a multicassette autoloader for a storage phosphor reader. More specifically, the invention relates to a multicassette autoloader which receives a stack of vertically oriented storage phosphor cassettes in an input bin, moves the cassettes serially in a short U path from the input bin to a storage phosphor read location in an output bin and then to an output region of the output bin. 
     BACKGROUND OF THE INVENTION 
     Conventional film/screen radiography uses radiographic films which are not reusable. Computed radiography solves this problem by using reusable storage phosphors that can be exposed, read out, erased and reused many times. In order to protect the storage phosphor from damage during use, it is contained in a cassette from which it is removed during the reading and erasing process. One type of storage phosphor reader receives cassettes, one at a time, oriented horizontally. The cassette containing an exposed storage phosphor is presented to the reader horizontally, the storage phosphor is removed from the cassette and moved along a horizontal path, where it is read and then erased before the storage phosphor is replaced in its cassette. The cassette is then removed and a new cassette manually presented to the reader. In order to increase storage phosphor reader throughput and to relieve the reader user of sequentially loading and unloading storage phosphor cassettes, a multi-cassette autoloader was developed (See: U.S. Pat. No. 5,324,957, issued Jun. 28, 1994, inventor Hejazi). The autoloader disclosed in the latter patent is a separate piece of equipment from the storage phosphor reader and utilizes cog belts to index a plurality of horizontally oriented cassettes to a read site where the storage phosphors are removed from the cassettes and transported into and out of the storage phosphor reader. Because the cog belts are designed to accept only one size of cassette, the largest, and because many sized cassettes are used in the medical imaging field, pallets are used to handle smaller sized cassettes. 
     Although the latter autoloader is useful and successful for its intended purposes, it has certain drawbacks. Because the autoloader is a separate piece of equipment, substantial floor space is required to accommodate both the reader and the autoloader. Moreover, the use of pallets requires additional manual operations for the operator and creates storage problems when the pallets are not being utilized. A more compact storage phosphor reader is disclosed in U.S. Pat. No. 6,437,359 B1, issued Aug. 20, 2002, inventors Hall et al. As disclosed in the latter patent, the storage phosphor reader receives a storage phosphor cassette in a vertical orientation, removes the storage phosphor from the cassette, transports the storage phosphor along a vertical path where it is read and erased and replaces the storage phosphor in the cassette. An autoloader for such a vertically oriented storage phosphor reader is disclosed in U.S. Pat. No. 5,493,128, issued Feb. 20, 1996, inventor Boutet. The disclosed autoloader is combined with the storage phosphor reader resulting in the need for less floor space for the combined equipment. Moreover, the vertical autoloader automatically handles storage phosphor cassettes of varying sizes without the use of pallets. The vertical autoloader includes a cassette loading station and a cassette unloading station separated by a read site where an exposed storage phosphor is removed from and replaced in the storage phosphor cassette for vertical processing by the storage phosphor reader. Each of the cassette loading and cassette unloading stations includes a plurality of cassette locating slots defined by movable rear and bottom separators and indexers. The operator must load each cassette individually into a loading slot before the next cassette can be loaded. Moreover, the cassette must be loaded with the face oriented 90 degrees from the direction of loading in order to position it correctly into a cassette location slot. 
     Another generally vertically oriented storage phosphor reader is disclosed in U.S. Pat. No. 4,893,011, issued Jan. 9, 1990, inventors Bauer et al. The disclosed apparatus occupies a large floor area and is not provided with an autoloader to handle multiple cassettes of varying sizes. Moreover, the storage phosphor is removed from the cassette at one location and replaced in the cassette at another location resulting in inefficiencies. 
     While such systems may have achieved certain degrees of success in their particular applications, there is a need to provide an autoloader for vertically oriented storage phosphor cassettes of varying sizes which is easy to use, which allows the operator to load multiple cassettes at a time without regard to size and which is easily accessible. 
     SUMMARY OF THE INVENTION 
     According to the present invention, there is provided a solution to the problems and a fulfillment of the needs discussed above. 
     According to one aspect of the invention, there is provided a multicassette autoloader for vertically oriented storage phosphor cassettes, the autoloader having a front, back, and opposite sides, comprising: 
     an input bin for receiving multiple vertically oriented storage phosphor cassettes stacked together in face-to-face contact such that said cassette faces face front and back; wherein each of said cassettes contains a storage phosphor which is removable from said cassette; and 
     an output bin located beside said input bin, said output bin having a storage phosphor read location at which a storage phosphor is removed from and replaced in a storage phosphor cassette positioned at said storage phosphor read location, and having an output region for read cassettes to be subsequently removed from said output bin. 
     The invention has the following advantages. 
     1. An autoloader is provided for a storage phosphor reader which handles vertically oriented storage phosphor cassettes of varying sizes and which is located at the top of the reader, thus occupying the same footprint as the reader. 
     2. The autoloader is easy to use and easily accessible by an operator to load multiple cassettes at a time without regard to size and without the necessity of positioning individual cassettes in the autoloader. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The foregoing and other features, and advantages of the invention will be apparent from the following more particular description of the embodiments of the invention, as illustrated in the accompanying drawings. The elements of the drawings are not necessarily to scale relative to each other. 
         FIG. 1  is a block diagram showing a computed radiography system including an embodiment of the present invention. 
         FIGS. 2 and 3  are respective left and right front perspective views showing a storage phosphor reader including the present invention. 
         FIGS. 4 and 5  are respective front perspective and side elevational, diagrammatic views showing a vertical scanning assembly which can be incorporated in the storage phosphor reader shown in  FIGS. 2 and 3 . 
         FIG. 6  is a top plan, diagrammatic view of the embodiment of the present invention shown in  FIGS. 2 and 3 . 
         FIG. 7  is a top plan, diagrammatic view of the embodiment of  FIG. 6  showing the storage phosphor cassette flow path. 
         FIGS. 8 ,  9 ,  10 , and  11  are respective side elevational, diagrammatic views of the embodiment of  FIG. 6  showing a sequence of cassette handling operations in the input bin. 
         FIG. 12  is a top, plan diagrammatic view of the embodiment of  FIG. 6  showing the stripping of a storage phosphor cassette from the input bin past the bar code scanner. 
         FIG. 13  is a top, plan diagrammatic view of the embodiment of  FIG. 6  showing the stripping of a storage phosphor cassette to the side shuttle at the pre-read location of the output bin. 
         FIG. 14  is a top, plan diagrammatic view of the embodiment of  FIG. 6  showing the homing of the stripper, cassette stack pullback, and cassette lifter mechanism. 
         FIGS. 15 ,  16  and  17  are respective top, plan diagrammatic views of the embodiment of  FIG. 6  showing translation of the storage phosphor cassette from the pre-read location of the output bin to the read location where a storage phosphor is removed from and replaced in the storage phosphor cassette. 
         FIG. 18  is a top, plan diagrammatic view of the embodiment of  FIG. 6  showing engagement of the size changer/light curtain. 
         FIG. 19  is a top, plan diagrammatic view of the embodiment of  FIG. 6  showing engagement of the clamps at the read location. 
         FIGS. 20-22  are top, plan diagrammatic views of the embodiment of  FIG. 6  showing operations preparing for the next scan cycle. 
         FIG. 23  is a top, plan diagrammatic view of the embodiment of  FIG. 6  showing transport of the read storage phosphor cassette from the read location to a post-read location of the output bin and transport of the next unread storage phosphor cassette into the read location. 
         FIGS. 24 and 25  are top, plan diagrammatic views of the embodiment of  FIG. 6  respectively showing transport of the read storage phosphor cassette into a collator and indexing of the collator by one position for eventual removal from the output bin. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     The following is a detailed description of the preferred embodiments of the invention, reference being made to the drawings in which the same reference numerals identify the same elements of structure in each of the several figures. 
     The multicassette vertical autoloader of the present invention is used with a storage phosphor reader which is part of a computed radiography system. In general, computed radiography utilizes the principle that exposure of a storage phosphor to a radiographic image produces a corresponding latent image in the storage phosphor. If the storage phosphor is raster scanned (e.g., by means of a laser) in a storage phosphor reader with light of a first wavelength, the latent image will be emitted as a light image at a second wavelength. The emitted light image is converted into a digital image which can be processed, stored, displayed, and used to produce a hardcopy (film, paper) radiographic image. 
       FIG. 1  shows a generic computed radiography system  10  including the present invention. X-ray source  12  irradiates object of interest  14  (such as a body part) to produce a radiographic image which exposes storage phosphor (SP)  16 . The latent radiographic image stored in storage phosphor  16  is read out in storage phosphor read and erase  18  as a digital radiographic image  20 . The storage phosphor  16  is erased in SP read and erase  18  so that it can be reused. The digital radiographic image  20  can be processed to enhance the image, stored for later use, displayed on a display monitor for diagnostic purposes, transmitted to a remote location and/or used to produce a hard copy print (film or paper). 
       FIGS. 2 and 3  are respective left front and right front perspective views of a storage phosphor reader including an embodiment of the multicassette vertical autoloader of the present invention. As shown, storage phosphor reader  50  includes a housing  52  for supporting the components of reader  50 , such as read module  54  and erase module  56  (both shown in dashed lines in  FIG. 2 ). Multicassette, vertical autoloader  58  is mounted on the top of and forms an integral part of reader  50  and thus occupies the same footprint as reader  50 . Autoloader  58  includes an input bin  60 , an output bin  62  located beside input bin  60 , and a storage phosphor read location  64  located in output bin  62  (shown in greater detail later). Autoloader  58  also includes a front  51 , back  53 , and opposite sides  55  and  57  ( FIG. 6 ). 
     One or more storage phosphor cassettes  66  (each of which contains a storage phosphor which is removable from cassette  66 ) are loaded as a stack into input bin  60  in face-to-face contact and such that the cassette faces face front and back. The foremost cassette  66  in the stack of cassettes  66  is transported from input bin  60  to the storage phosphor read location  64  of output bin  62 . At read location  64 , the storage phosphor contained in cassette  66  is removed from cassette  66  and transported vertically past read module  54  and erase module  56 . The read and erased storage phosphor is then replaced in cassette  66  which is transported out of read location  64  to an output region of output bin  62 . 
     Referring now to  FIGS. 4 and 5  there is shown an exemplary vertical assembly for transporting a storage phosphor from cassette  66 , past read and erase modules  54 ,  56  and then back to cassette  66  (The assembly described in greater detail in U.S. Pat. No. 6,437,359 B1, issued Aug. 20, 2002, inventors Hall et al. can be used or any other suitable assembly). As shown, storage phosphor cassette  66  is held at storage phosphor read location  64  of storage phosphor reader  50  by clamps  68  and  70 . A storage phosphor transport assembly  72  removes storage phosphor  74  from cassette  66  and transports storage phosphor  74  vertically past read module  54  and erase module  56 . Transport assembly  72  then transports storage phosphor  74  vertically to replace it in cassette  66 . The vertical transport directions of storage phosphor  74  are represented by bidirectional arrow  76 . 
     Referring now to  FIGS. 6-25  there will be described in greater detail, the structure and operation of a embodiment of the present invention shown in  FIGS. 2 and 3 . Referring to  FIG. 6 , autoloader  58  includes side-by-side input bin  60  and output bin  62 . Storage phosphor read location  64  is located in output bin  62 . Input bin  60  has a first inclined bottom wall  78  and a second reverse inclined bottom wall  80  ( FIG. 8 ) having guides  82  ( FIG. 6 ) to assist in gravity feeding of cassettes  66 . Cassette stack pullback  84  and cassette lifter mechanism  86  are also located in input bin  60 . Cassette stripper  88  transports a cassette  66  from input bin  60  to output bin  62  past bar code scanner  90 . Output bin  62  includes fixed clamp  92 , movable clamp  94 , loaders  96 , unloaders  98 , side shuttle  100 , ejector  102 , stripper  104 , size changer/light curtain  106 , side cog belt  108 , and bottom belts  110 . Cassettes  66  are shown in  FIG. 6  in input bin  60  and output bin  62 . A cassette  66  is also shown at read location  64 . 
       FIG. 7  is a diagrammatic view showing the short-U transport path of cassettes in autoloader  50 . As shown, storage phosphor cassettes  66  of different sizes are stacked face-to-face in input bin  60  such that the cassette faces face front and back (arrows  120  and  122 ). The leading unread cassette  66  in input bin  60  is transported from input bin  60  to output bin  62  (arrows  124  and  126 ). The unread cassette  66  is then transported to storage phosphor read location  64  (arrow  128 ). After the storage phosphor has been replaced in a cassette  66  at read location  64 , the cassette  66  is transported out of read location  64  and into cog belt  108  (arrows  130  and  132 ) which transports the cassette to the front of output bin  62  for removal from autoloader  50  from the front, diagonally, and/or from the side (arrows  134 ,  136 ,  138 ). 
     Referring now to  FIGS. 8-11 , there will be described the operation of cassette stack pullback  84  and cassette lifter mechanism  86 . Cassettes  66  are first guided along first inclined bottom wall  78  before being deposited on second inclined bottom wall  80  in a face-to-face stack against front wall  79  through the assistance of gravity (See  FIG. 8 ). Cassette lifter mechanism  86  lifts the leading cassette  66  (arrow  85 ) to expose the bottom edge of the next cassette  66  ( FIG. 9 ). Stack pullback  84  pulls the stack of cassettes  66  in the direction of arrow  140  away from the foremost cassette  66  up bottom wall  80  in order to reduce the load on the foremost cassette  66  and to separate the cassettes ( FIG. 10 ). Cassette lifter mechanism  86  raises the foremost cassette  66  in the direction of arrow  142  for stripping while cassette stack pullback  84  continues to hold the other cassettes  66  in the stack away from the foremost cassette  66  ( FIG. 11 ). 
     Cassette  66  is first transported by cassette stripper  88  (arrow  201 ) to a barcode scan position ( FIG. 12 ) where the barcode on cassette  66  is read by bar code scanner  90  and verified, and then to a pre-read location  200  in output bin  62  in the direction of arrow  202  ( FIG. 13 ) into contact with side shuttle  100  and loaders  96 . Cassette stripper  88  is returned to the home position (arrow  204 ) in input bin  60  in preparation for transport of the next cassette  66  ( FIG. 14 ). Cassette stack pullback  84  and cassette lifter mechanism  86  are also returned to their home positions. Loaders  96  and side shuttle  100  now transport cassette  66  from the pre-read location  200  to the storage phosphor read location  64  as indicated by arrows  150  ( FIGS. 15 and 16 ). Ejector  102  ejects cassette  66  in the direction of arrow  205  out of side shuttle  100 , and side shuttle  100  and loaders  96  are returned to their home position in the direction of arrows  206  ( FIG. 17 ). Size changer/light curtain  106  is moved in the direction of arrow  208  into place to bias the cassette  66  ( FIG. 18 ), and movable clamp  94  is moved in the direction of arrow  210  into contact with cassette  66  to clamp it with fixed clamp  92  during the read cycle (FIG.  19 ). Ejector  102  and side shuttle  100  are then returned to their home positions to prepare for the next cycle as indicated by arrows  160 ,  162  ( FIG. 20 ). 
       FIG. 21  shows transport of the next unread cassette  66  into the pre-read location  200  by cassette stripper  88  as indicated by arrow  164 . A pre-read location is desirable in order to reduce the total cycle time of the device. This is accomplished by allowing the simultaneous reading of the SP with the next unread cassette being stripped into the pre-read location. After the read cycle is completed and the storage phosphor replaced in cassette  66 , clamp  94  is moved out of contact with the read cassette  66 , size changer  106  moves cassette  66  in the direction of arrow  212  into side shuttle  100 , and unloaders  98  are moved in the direction of arrow  214  into contact with read cassette  66  ( FIG. 22 ). Read cassette  66  is then moved by side shuttle  100  and unloaders  98  into a post read location  170  (arrows  162 ) and loaders  96  and side shuttle  100  move the next unread cassette  66  into read location  64  (FIG.  23 —arrows  164 .). Stripper  104  now transfers read cassette  66  from side shuttle  100  to side cog belt  108  and bottom belts  110  (FIG.  24 —arrow  172 ). Finally, stripper  104  is returned to the home position (arrow  174 ) and side cog belt  108  and bottom belts  110  transport the read cassette  66  forward (arrow  176 ) to output region  178  of output bin  62  for subsequent removal. 
     The invention has been described in detail with particular reference to a presently preferred embodiment, but it will be understood that variations and modifications can be effected within the spirit and scope of the invention. The presently disclosed embodiments are therefore considered in all respects to be illustrative and not restrictive. The scope of the invention is indicated by the appended claims, and all changes that come within the meaning and range of equivalents thereof are intended to be embraced therein. 
     PARTS LIST 
     
         
           10 —computed radiography system 
           12 —X-ray source 
           14 —object of interest (body part) 
           16 —storage phosphor (SP) 
           18 —storage phosphor read and erase 
           20 —digital radiographic image 
           50 —storage phosphor reader 
           51 —front 
           52 —housing 
           53 —back 
           54 —read module 
           55 —side 
           56 —erase module 
           57 —side 
           58 —vertical autoloader 
           60 —input bin 
           62 —output bin 
           64 —storage phosphor read location 
           66 —storage phosphor cassette 
           68 ,  70 —clamps 
           72 —storage phosphor transport assembly 
           74 —storage phosphor 
           76 —bidirectional arrow 
           78 —first inclined bottom wall 
           79 —front wall 
           80 —second reverse inclined bottom wall 
           82 —guides 
           84 —cassette stack pullback 
           85 —arrow 
           86 —cassette lifter mechanism 
           88 —cassette stripper 
           90 —bar code scanner 
           92 —fixed clamp 
           94 —movable clamp 
           96 —loaders 
           98 —unloaders 
           100 —side shuttle 
           102 —ejector 
           104 —stripper 
           106 —size changer/light curtain 
           108 —side cog belt 
           110 —bottom belts 
           120 ,  122 ,  124 ,  126 ,  128 ,  130 ,  132 ,  134 ,  136 ,  138 ,  140 ,  142 —arrows 
           150 —arrow 
           160 ,  162 ,  164 —arrows 
           170 —post read location 
           172 ,  174 ,  176 ,—arrows 
           178 —output region of output bin  62   
           200 —pre-read location 
           201 ,  202 ,  204 ,  205 ,  206 ,  208 ,  210 ,  212 ,  214 —arrows