Patent Publication Number: US-2005133746-A1

Title: High speed scanning device and film writer for use with radiographic media

Description:
CROSS REFERENCE TO RELATED APPLICATIONS  
      Reference is made to commonly-assigned copending U.S. patent application Ser. No.______ (Attorney Docket No. 86153/NAB), filed herewith, entitled A HIGH SPEED SCANNING DEVICE FOR USE WITH RADIOGRAPHIC MEDIA, by Kerr et al.; and U.S. patent application Ser. No. ______ (Attorney Docket No. 86154/NAB), filed herewith, entitled A HIGH SPEED COUNTERBALANCED TRANSLATION DEVICE FOR USE WITH RADIOGRAPHIC MEDIA, by Kerr et al., the disclosures of which are incorporated herein. 
    
    
     FIELD OF THE INVENTION  
      This invention relates in general to radiography and in particular to scanning a phosphor plate and simultaneously writing to radiography film.  
     BACKGROUND OF THE INVENTION  
      In a photo-stimulatable phosphor imaging system, as described in U.S. Pat. No. RE 31,847, a photo-stimulatable phosphor sheet is exposed to an image wise pattern of short wavelength radiation, such as x-radiation, to record a latent image pattern in the photo-stimulatable phosphor sheet. The latent image is read out by stimulating the phosphor with a relatively long wavelength stimulating radiation such as red or infrared light. Upon stimulation, the photo-stimulatable phosphor releases emitted radiation of an intermediate wavelength such as blue or violet light in proportion to the quantity of short wavelength radiation that was received. To produce a signal useful in electronic image processing, the photo-stimulatable phosphor sheet is scanned in a raster pattern by a beam of light to produced emitted radiation, which is sensed by a photo-detector such as a photo-multiplier tube to produce the electronic image signal. The signal is then transmitted to a separate device, a film writer, which reproduces the scanned image.  
      This system is somewhat cumbersome since it involves a separate scanning unit and film writing unit. It would be desirable to combine the film writing unit and the scanning unit on a common drive to save cost, space, and time.  
      A need has existed for a method to scan radiographic images from radiographic media and then rewrite the scanned image using a film writer that is fast, stable and has a continuous drive system so that the scanning rates are improved and the image quality improves.  
     SUMMARY OF THE INVENTION  
      An embodiment of the present invention is a high speed scanning device and film writer for use with radiographic media. The device includes a first scanning stage adapted for movement in a first and second direction along a first axis and a second scanning stage disposed opposite the first scanning stage adapted for movement in a third and fourth direction along a second axis. The translation device also includes a scanning module mounted on the first scanning stage and a film writer disposed on the second scanning stage. The device also includes a control processing unit to receive scanned images from the scanning module, to convert the scanned images to a digital content, and to transmit the digital content to the film writer. The device also has a continuous drive cable engaging a drive pulley with a drive motor for rotating the drive pulley.  
      The continuous drive cable on the translation device includes a first pin for sequentially moving the scanning stage in from a first to a second position by engaging the first scanning stage slot located in the scanning stage. A second pin in the continuous drive cable moves the balancing stage simultaneously with the scanning stage initially in a third position to the fourth position by engaging the balancing stage slot. In sequence, the first pin moves the balancing stage from the fourth position to the third position while second pin moves the scanning stage from the second position to the first position.  
      An embodiment of the present invention is a single-stage high speed scanning and film writer device for use with radiographic media.  
      An embodiment of the present invention is a method for scanning and writing diagnostic film is comprised by placing a radiographic plate on adjacent a scanning module and inserting a diagnostic film adjacent to a film writer. The method continues by scanning the radiographic plate with a scanning module in a first direction; converting the scanned image to a digital signal; transmitting the digital signal to the film writer; and writing the signal on the diagnostic film. The method continues by repeating these steps until repeating the steps until the image is completely scanned.  
      The invention and its objects and advantages will become more apparent in the detailed description of the preferred embodiment presented below. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
      While the specification concludes with claims particularly pointing out and distinctly claiming the subject matter of the present invention, it is believed that the invention will be better understood from the following description when taken in conjunction with accompanying drawings.  
       FIG. 1  is a schematic of the invention;  
       FIG. 2  is a schematic of the invention in the first and third positions;  
       FIG. 3  is a schematic of the invention in the second and fourth positions;  
       FIG. 4  is a schematic of the invention in the first and third positions;  
       FIG. 5  is a schematic of the invention second and fourth positions;  
       FIG. 6  depicts a side view of the scanning module;  
       FIG. 7  depicts a side view of the scanning module with a collimator lens;  
       FIG. 8  is a schematic of the system; and  
       FIG. 9  is a schematic of the method of the invention. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION  
      The present invention will be directed in particular to elements forming part of, or in cooperation more directly with the apparatus in accordance with the present invention. It is to be understood that elements not specifically shown or described may take various forms well known to those skilled in the art.  
      The invention was designed for creating higher image quality in scanned radiographic images while providing for a high speed, ultra stable scanning and writing device. In a preferred embodiment, the radiographic images are a phosphorous plate. The invention can include a control processing unit to combine the scanned images from each scanning module and can also include a film writer.  
      Referring now to  FIGS. 1 through 3 , a first scanning stage  10  is adapted for movement in a first direction  11  and a second direction  13  along a first axis  14 . As a second scanning stage  12  is disposed opposite the scanning stage in a balanced relationship, so that the movement of the second scanning stage balances the weight of the scanning stage.  
      The second scanning stage moves in a third direction  15  and a fourth direction  16  along a second axis  17 . It should be noted in the preferred embodiment, the first axis is parallel to the second axis.  
      A scanning module  18  is mounted to the scanning stage for scanning radiographic media  21  that is placed on the scanning stage. The scanner sends a beam of light, exciting the image, to the radiographic plate or sheet, and then the scanner collects the light and sends the collected light to a processor for storage.  
      A film writer  19  is mounted to the second scanning stage to provide a balance. An example of a film writer  19  is a Kodak Drive U Imager  850  available from Eastman Kodak Company of Rochester, N.Y.  
      Preferably the second scanning module is mounted so as to provide a stable device with good balance. Preferably, the second scanning module is mounted so as to provide a counterbalance as well s the additional scanning advantage in the device. In a preferred embodiment, the second scanning module is mounted beneath the radiographic media and the first scanning module is mounted above the radiographic media.  
       FIG. 2  and  FIG. 4  depict the first and second scanning stages  10  and  12  at the first and third positions  25  and  29 , respectively.  FIG. 3  and  FIG. 5  depicts the first and second scanning stages  10  and  12  at the second and fourth positions  27  and  31 , respectively.  FIGS. 2 through 5  depict examples of the possible positions of the four pins  22 ,  30 ,  32 , and  34  in moving the scanning stage  10  and  12 .  
      The scanning module has a housing and a reflective center chamber, such as a mirrored container, in the housing that can have an elliptical design. The module contains a laser that transmits a beam of light onto a radiographic plate, such as a phosphorous plate to create an image with a high sensitivity, around 0.7 mj/cm2, an image quality as good as 300 dpi, and a rate of productivity that is preferably between 80 plates per hour and 120 plates per hour. The module can have a small compact design, such as with a diameter of 15 mm to 23 mm, preferably 20 mm, and a length that creates as an ellipsoid with a surface calculated from the following formula:
 
( x   2 /9.6437 2 )+( y   2 /9.6437 2 )+(( z -11) 2 /17 2 )=1
 
 The scanning module is adapted for emitting light to and collecting light from a photo-stimulatable radiographic sheet, such a phosphorous sheet or other similar radiographic sheet, filtering that light and then converting the light into a digital signal. 
 
      The integrated scanning module can be used for line scanning or swath scanning. To operate the module, a laser disposed in a housing emits a beam of light onto the graphic sheet. In the most preferred embodiment, one laser is used per module. It is contemplated that multiple housing can be connected together, in parallel to form a swath for scanning over multiple spots.  
      The beam, which is preferably from a Hitachi single mode 635 nm, 35 mW laser or alternatively a multi mode 635 nm, 100 mW laser could be used. The beam is directed at discrete spots on the radiographic plate that already contains latent images.  
      The beam stimulates the radiographic plate to produce light that is collected by the module, in a preferably cylindrical, ellipsoid shaped mirrored container. A minor amount of reflected light may be collected as well.  
      A blue filter is used to selectively pass only the light from the radiographic image to a light detector that is preferably a PMT device, (at least one photo-multiplier tube) or a solid state photodiode. The filter is of the type Hoya 390 or B 410 from Tokyo, Japan or alternatively Schott BG-1 or BG 3 filter available from Schott of Mainz, Germany.  
      The light detector, such as a PMT made by Hamamatsu or a photomultiplier type R7400U available from Japan, receives the filtered light and generates a signal. The signal is transmitted to an analog to digital converter is usable to provide a digital signal. The digital signal is then stored as an image frame in a control processor, such as a computer like as a PC, MAC.  
      Next, the digital image can be processed depending on the needs of the user. For example, the digital image could then be printed on black and white X-Ray film.  
      The scanning module is contemplated for use as an input scanner.  
      Multiple modules can be used to scan a radiographic plate. Alternatively, only one module can be used to scan for individual spots on a plate. Both individual and multiple modules can be used to swath scan, diagonally, multiple spots on the plate.  
      Further, individual modules can be placed on a rotating disc over a stationary plate to achieve faster scanning of an image than with the line scanning method. The use of the modules on a rotating disc provides a more smooth, more even scanning of the image.  
      Alternatively, the plate can be rotated and the modules held stationary to achieve a smooth scan of the image.  
      The high speed counterbalanced scanning device also includes a control processing unit adapted to combine the scanned images from each scanning module. The control processing unit  58  is depicted in the  FIG. 4 .  
      As shown in  FIG. 6 , the high speed counterbalanced scanning device also includes an output device  60 . The scanned image from the device is sent to an analog to digital converter  56  that transmits the image to a control processing unit  58 . The control processing unit  58 , in turn, communicates the image to an output device  60 . The output device  60  writes the image on media.  
      A two pin method can drive the two stages. The invention contemplates that other configurations can also be used to drive the two stages. The figures depict the embodiment of a four-pin method driving the two stages.  
      In particular, a drive cable  20 , which can be a belt or a cable has a first pin  22  for simultaneously engaging with a scanning stage slot disposed in the scanning stage. The first pin  22  engaging the scanning stage slot is pulled by the drive cable and the first pin then moves the scanning stage from a first position  25  as shown in to a second position  27 .  
      The drive cable  20  has a second pin  30  for simultaneously engaging with a second scanning stage slot while the first pin  22  is engaged with the first scanning stage slot. The first pin as connected to the drive cable, moves the first scanning stage in a direction opposite from the second pin as connected to the drive cable engaging the second scanning stage slot from a third position  29  to a fourth position  31 .  
      The drive cable then can engage the second pin  30  with the second scanning stage via the second scanning stage slot and a third pin  32  engages the first scanning stage slot in the first scanning stage. The second pin  30  then moves the second scanning stage in a direction reverse from the fourth position  31  to the third position  29 . The second pin moves the first scanning stage in a direction reverse direction from the second position to the first position. In this second movement, third pin and second pin drive the two stages simultaneously.  
      The drive cable  20  has a fourth pin  34  for engaging the second scanning stage slot and moving the second scanning stage from the third position  29  to the fourth position  31 . Simultaneously with the movement of the second scanning stage using the fourth pin, the third pin engages the scanning stage slot and moves the scanning stage from the first position  25  to the second position  27 .  
      In the fourth cycle, the drive cable has the first pin engaging the scanning stage slot and the fourth pin engages the second scanning stage. The first pin moves the scanning stage from second position to the first position and the fourth pin moves the second scanning stage from the fourth position to the third position. The cycle then repeats itself.  
      The effect of these pin engagements in the stage slots using the drive cable is to achieve a smooth second scanning continuous motion of one stage relative to the other stage while providing continuous smooth scanning and writing.  
      A drive pulley  44  connects to a drive motor  46  for rotating the drive pulley and thereby moving the drive cable with the pins. Four idler pulleys,  48 ,  50 ,  52 , and  54  can be used with the drive cable  20  to support motion of the drive cable.  
      The invention contemplates a two pin embodiment of the invention described above wherein a high speed second scanning and writing device is used. In this embodiment, the device has a scanning stage having a scanning stage slot. The scanning stage is adapted for movement in a first direction and a second direction along a first axis. The device further has a second scanning stage having a second scanning stage slot. The second scanning stage is disposed opposite the scanning stage and is adapted for movement in a third direction and a fourth direction along a second axis. Two (or more) scanning modules can be used, at least one on the scanning stage.  
      A continuous drive cable is connected to and engages a drive pulley with drive motor for rotating the drive pulley. The cable, which can be a belt includes: a first pin for sequentially moving the scanning stage from a first position to a second position by engaging the scanning stage slot, and a second pin for moving the second scanning stage simultaneously with scanning stage from a third position to a fourth position by engaging the second scanning stage slot. Next, the first pin moves the second scanning stage from the fourth position to the third position while second pin moves the scanning stage from the second position to the first position.  
      This embodiment contemplates that the first axis is parallel to the second axis.  
      Both embodiments of the invention contemplate that the speed of the scanning module is between 10 inches per second and 80 inches per second, preferably 45 inches per second.  
       FIG. 6  is a depiction of a side view of a scanning module for use within the invention. The scanning module has a housing  100  with a channel  120  and the first and second openings  140  and  160 . The scanning module also has cylindrical center chamber comprising a mirrored surface.  
      Within the housing  100 , the scanning module has a laser  180  is oriented to generate a beam of stimulating electromagnetic radiation through the channel  120  into the first opening  140 . The beam is preferably between 390 and 400 nm in size. The beam flows through the first opening  140  onto a stimulated spot  270  on a photo-stimulatable radiographic sheet  280 . Light  340  is emitted from the stimulated spot and reflected light  360  bounces from the radiographic sheet  280  to enter the first opening  140 . The emitted light  340  is then transmitted from the center channel out of the second opening  160  to the filter  320 . The filter  320  only permits the light emitted from the stimulated spot  270  to pass to the light detector  300 .  
      In a preferred embodiment, the center chamber  250  has the following dimensions: a length between 20 mm and 30 mm, preferably about 25 mm; a height between 20 mm and 25 mm, preferably about 20 mm; and a width between 20 mm and 25 mm, preferably about 20 mm.  
      Returning to  FIG. 6 , the light detector  300  is disposed in the second opening for receiving light from filter  320  also disposed at the second opening of the housing.  
      In the most preferred embodiment, the housing  100  can be a one-piece molded structure of a strong polycarbonate, a strong plastic, or a metal. A preferred overall dimension of the housing is a height of 54 mm, a width of 35 mm, and a length of 25 mm.  
      Alternatively, the housing  100  can be a two-piece construction. In the two-piece construction, the two halves can be joined by conventional attaching devices, such as a latch, welds, or one or more screws.  
       FIG. 7  depicts an embodiment of a scanning module  18  for emitting light to and collecting light from a photo-stimulatable radiographic sheet. The housing  100  includes a channel  120 , a first opening  140 , and a second opening  160 . The laser  180  is disposed in the housing and generates a beam  190  of stimulating electromagnetic radiation through the channel  120  into the first opening  140 . The beam  190  can in one embodiment pass through a collimator lens  500  prior to passing out of the channel  120 .  
      Another embodiment is a system for emitting light to and collecting light from a photo-stimulatable radiographic sheet and then storing the image. The system includes a scanning module  18  for emitting light to and collects light from a photo-stimulatable radiographic sheet. The scanning module is the same as the module of  FIG. 6 .  
      In another embodiment, individual modules can be placed on a rotating disc over a stationary plate to achieve faster scanning of an image. The use of the modules on a rotating disc provides a smooth, even scanning of the image.  
       FIG. 8  illustrates one or more scanning modules that could be used in this system. Further the light detector  300  is shown in communication, such as by a wireless link, with an analog to digital converter  56  adapted to receive signal from the light detector  300 .  
      A control processing unit  58  converts signal to signal from the analog to digital converter  56 . The control processing unit  58  is capable of storing the now digital signal.  
      The system includes an output device  60  adapted to receive the digital signal from the control processing unit (CPU)  58 . The CPU can be a computer, PC or MAC for compiling signals from one or more modules. The output device can be a film writer, printer, or display.  
      In another embodiment, the invention is a single-stage high speed scanning and film writer device for use with radiographic media. The embodiment has a scanning stage with a scanning stage slot adapted for movement in a first direction and a second direction along a first axis. A scanning module mounted is located on the scanning stage.  
      The embodiment also includes a film writer disposed on the scanning module. The film writer writes the scanned image onto a diagnostic film. A control processing unit in the device is adapted to receive scanned images from the scanning module, to convert the scanned images to a digital content, and to transmit the digital content to the film writer.  
      The single-stage high speed scanning and film writer device also includes a continuous drive cable engaging a drive pulley with drive motor for rotating the drive pulley. The drive system is made of a pin for moving the scanning stage from a first position to a second position by engaging the scanning stage slot, and then in reverse from the second position to the first position.  
      Another embodiment is a method for scanning and writing diagnostic film. As shown in  FIG. 9 , the method begins by placing a radiographic plate on adjacent a scanning module  800  and inserting a diagnostic film adjacent to a film writer  905  and scanning the radiographic plate with a scanning module in a first direction  910 . The scanned image is next converted to a digital signal  915  and transmitted to the film writer  920 . The signal is then written on the diagnostic film  925 .  
      The method continues by scanning the radiographic plate with a scanning module in a second direction  930 ; converting the scanned image to the digital signal; and transmitting the digital signal to the film writer. The signal is written on the diagnostic film.  
      Continuing with  FIG. 9 , the method ends by repeating the steps of scanning, converting, transmitting, and writing until the image is completely scanned  935 .  
      The invention has been described in detail with particular reference to certain preferred embodiments thereof, but it will be understood that variations and modifications can be effected within the scope of the invention.  
     Parts List  
     
         
           10  first scanning stage  
           11  first direction  
           12  second scanning stage  
           13  second direction  
           14  first axis  
           15  third direction  
           16  fourth direction  
           17  second axis  
           19  film writer  
           20  drive cable  
           21  radiographic media  
           22  first pin  
           25  first position  
           27  second position  
           29  third position  
           30  second pin  
           31  fourth position  
           32  third pin  
           34  fourth pin  
           44  drive pulley  
           46  drive motor  
           48  first idler pulley  
           50  second idler pulley  
           52  third idler pulley  
           54  fourth idler pulley  
           56  analog to digital converter  
           58  control processing unit  
           60  input-output device  
           100  housing  
           120  channel  
           140  first opening  
           160  second opening  
           180  laser  
           190  beam  
           250  cylindrical center chamber  
           270  stimulated area or spot  
           280  radiographic sheet or media  
           300  light detector  
           320  filter  
           340  emitted light  
           360  reflected light  
           500  collimator lens  
           800  placing radiographic plate adjacent scanning module  
           905  inserting diagnostic film adjacent film writer  
           910  scanning radiographic plate with scanning module in first direction  
           915  scanned image converted to digital signal  
           920  digital signal transmitted to film writer  
           925  signal written on diagnostic film  
           930  scanning radiographic plate with scanning module in second direction  
           935  image completely scanned