Patent Publication Number: US-2004052408-A1

Title: Method and apparatus for electronically extracting information

Description:
FIELD OF THE INVENTION  
       [0001] The illustrated invention relates generally to the electronic capture, storing and retrieving of information from laboratory samples, and more particularly to machine recognition systems for automatic reading of indicia marked on containers that hold tissue samples.  
       BACKGROUND OF THE INVENTION  
       [0002] Tissue samples such as those used for histological determinations are often stored for long periods of time. There are numerous techniques and equipment available for storing such samples, but in all cases, most histological tissue sample storage systems utilize a system for marking the samples so that they may be correctly inventoried and identifiable for retrieval at a later time.  
       [0003] Cassettes such as those described in U.S. Pat. No. 3,674,396 represent one type of containment, storage and processing container for tissue samples for the purpose of histological determinations. Prior to using these cassettes the user marks the cassette with indicia that is used to identify the cassette. The indicia is typically marked on one face of the cassette with hand-printing using a pen or pencil, or machine-printing, using specialized equipment such as the MicroWriter available from RA Lamb, Eastbourne, UK (www.ralamb.com), although other marking systems such as bar codes may be used. The indicia are generally alphanumeric and are eye-readable by humans. In use, after a tissue sample is processed to remove moisture, it is embedded in paraffin wax to add rigidity and secure it to the cassette. After the sample has been embedded in wax, thin sections may be sliced from the embedded tissue sample on a microtome and placed on microscope slides for subsequent examination. These microscope slides are usually marked in the same manner and with the same indicia as the cassettes in order to relate the two. In some cases, during the embedding stage, excess paraffin wax adheres to the marked face of the cassette, potentially obscuring the markings.  
       [0004] After examination, the cassette and/or slide may then be stored in a sample repository, which typically is located at a remote location from the originating or examination laboratory. As noted, the cassettes and slides may be stored for many years—often for 25 years or more. The samples are usually stored in some kind of chronological order to ease future retrieval, identification and reexamination.  
       [0005] Many thousands of histological sample carriers such as the cassettes and slides described above may be stored for very long periods of time. Accurate inventory control of the stored samples is necessary because it is important to be able to locate a specific block or slide, retrieve it, and re-store it without losing it. This problem is usually addressed by storing the histological blocks and slides in numerical order, but this approach is very labour intensive, and is prone to error. For example, when identifying information marked on a cassette or slide is obscured by paraffin wax, the indicia may be read incorrectly by human technicians. Moreover, when samples are removed for re-examination at a later time, they may not be returned to the proper storage location. There is a need therefore for an automated system for managing the inventory of blocks and slides to address these problems.  
       SUMMARY OF THE INVENTION  
       [0006] A method for electronically representing identification indicia on a tissue block comprises illuminating the indicia, generating a digital image of the indicia and processing the digital image to create an electronic representation of the information. 
     
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
     [0007] These and other objects, features and advantages of the present invention will become apparent upon reference to the following detailed description of the preferred embodiments and to the drawings wherein:  
     [0008]FIG. 1A is a dimetric view of a typical histological tissue cassette marked with typical alphanumeric identifying indicia.  
     [0009]FIG. 1B is a dimetric view of a typical histological microscope slide marked with the same indicia shown in FIG. 1A.  
     [0010]FIG. 2 is an isometric view of an illustrated embodiment of the histological sample carrier image capture device according to the invention;  
     [0011]FIG. 3 is a side elevation view of the histological sample carrier image capture device shown in FIG. 2, with a side panel of the housing removed to expose some internal components.  
     [0012]FIG. 4 is an isometric view of an illumination module used in the image capture device.  
     [0013]FIG. 5 is a schematic diagram of one illustrated embodiment of an illumination electrical circuit.  
     [0014]FIG. 6 is a system diagram comprised of the software system modules for extracting histological sample carrier identification information, and for linking storage location descriptions.  
     [0015]FIG. 7 is a system diagram representing the software modules for changing the recorded status of tissue blocks. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT  
     [0016] Referring now to FIG. 1A, one type of a histological sample carrier  10  used in connection with the present invention, and specifically of the cassette type described in U.S. Pat. No. 3,674,396, is shown generally at  10 . Histological sample carrier  10  comprises a plastic tissue cassette  12  having opposed side surfaces  13  and  14 , and a bottom surface  15 . Tissue cassette  12  includes an indicia face  16 , which is provided for marking with information such as alphanumeric identifying indicia. Indicia face  16  is angled relative to bottom surface  15 , as illustrated. In FIG. 1A, indicia face  16  is shown marked with hand-written alphanumeric, eye-readable indicia  18  for block identification purposes. Readable indicia  18  may likewise be machine-written. A tissue sample is embedded in paraffin-wax  19 , which is secured to cassette  12  and which is illustrated as a rectangular block of wax. The tissue sample embedded within the block of wax  19  is not shown in the present illustrations.  
     [0017] As noted above, tissue samples are acquired for examination from a histological sample carrier such as the tissue cassette  12  shown in FIG. 1A by slicing a thin section of the paraffin wax  19  that includes the tissue, then placing that sample on a slide. A typical glass microscope slide  20  for this purpose is illustrated in FIG. 1B, and comprises a transparent glass surface  22  and a slide indicia face  24 . Slide indicia face  24  serves the same purposes as indicia face  16  of tissue cassette  12 —that is, for marking the slide with sample identifying information. In FIG. 1B slide  20  is marked with hand-written alphanumeric indicia  26  that are the same as indicia  18  written on tissue cassette  12 .  
     [0018] As used herein, the term “histological sample carrier” refers generally to a tissue-retaining member for holding histological tissue samples for storage, processing, examination and the like. The tissue cassette  12  illustrated in FIG. 1A and the slide  20  shown in FIG. 1B are two examples of histological sample carriers, but the term as used herein is not intended to be limited by these two examples.  
     [0019] Turning now to FIG. 2, generally designated at  28  is an example of an image capture device that may be used to capture identifying information written on a histological sample carrier. Image capture device  28  includes a housing  30 , which provides an opaque enclosure for the device components and a consistent indexing surface  32  for cassette bottom surface  15  when cassette  12  is placed on indexing surface  32  in the orientation shown in FIG. 2. Housing  30  may be fabricated from plastic or sheet metal and the like. A histological sample carrier  10  such as cassette  12  may be indexed on indexing surface  32  by placing side surface  13  coincident with a vertical surface that extends upwardly from indexing surface  32  to define a lip  36 . Lip  36  is formed as part of a step  34  that may in turn be fabricated as a part of housing  30 . The cassette  12  is oriented as shown in FIG. 2 on indexing surface  32  such that angled surface of indicia face  16  is abuts and is coincident with a heated borosilicate glass plate  38 , or equivalent type of glass plate, which is oriented relative to indexing surface  32  such that the glass plate  38  is angled relative to the indexing surface at the same angle that indicia face  16  is angled relative to bottom surface  15  of cassette  12 . As described below, glass plate  38  is heated to such a temperature as to quickly liquefy paraffin wax found on cassette indicia face  16 .  
     [0020] A series of ridges  40  project outwardly from the surface of the glass plate  38  and are formed on glass plate adjacent the indexing surface  32  near step  34 . Ridges  40  extend in a direction generally perpendicular to the plane of the indexing surface  32 , and function as scraping members for removal of liquefied excess paraffin wax that is scraped from indicia face  16 , as described below, and channel the liquefied wax down the outward facing surface of the glass plate  38  (“outward” referring to the direction outside of housing  30 ) and into a removable collecting tray  42 . Ridges  40  are preferably a hardened coating material deposited on glass plate  38  in vertical lines that are about 0.5 mm thick. Except for a rectangular region identified in FIG. 2 as transparent window  44 , the entire inward-facing surface of glass plate  38  (“inward” referring to the interior of housing  30 ) is coated with an opaque coating material that limits the transmission of light through the glass plate. Transparent window  44 , which is located toward the lateral side of glass plate  38  opposite ridges  40 , as shown in FIG. 2, permits cassette indicia face  16  to be viewed by camera  52  as described below and thus defines an image acquisition window.  
     [0021] A second step  46  located on indexing surface  32  defines a vertical indexing surface at a lip  45 . When a cassette  12  is placed on indexing surface  32  such that side surface  14  abuts and is coincident with lip  45  of step  46 , and such that cassette indicia face  16  abuts and is coincident with glass plate  38 , cassette bottom surface  15  rests upon indexing surface  32 . In this position, cassette indicia face  16  is aligned precisely with transparent window  44  so that the indicia face is within the field of view of a camera contained in housing  30 , as described below. The perimeter dimensions of transparent window  44  are sized somewhat smaller than the perimeter size of cassette indicia face  16  so as to reduce the amount of ambient light that enters housing  30  from the exterior thereof, which could affect the camera brightness settings. By limiting the amount of ambient light entering the interior of the housing, accurate, consistent and repeatable results are obtained. Typically, the width and height of transparent window  44  may be approximately 0.5 mm less than the respective width and height of cassette indicia face  16 . In addition, all objects outside of the device housing  30  are obstructed from the camera&#39;s field of view except for cassette indicia face  16 , as it is visible to the camera through transparent image acquisition window  44 .  
     [0022] A micro-switch  47 , typically a pushbutton type switch, is mounted within pushbutton switch enclosure  48  in such a way that it is activated by cassette  12  side edge  14  when the cassette is located on indexing surface  32  with cassette indicia face  16  oriented such that it aligns with transparent window  44  and is thus within the camera&#39;s field of view. Micro-switch  47  is connected across the contacts of an image capture button built into camera  52  as described below. It will be appreciated that micro-switch  47  is but one example of a switch useful to activate the camera, and that it may be replaced with equivalent devices such as a reflective photo sensor that provides all the functionality of pushbutton micro-switch  47  in a non-contact manner.  
     [0023] Enclosure indexing surface  32 , including attached steps  34  and  46 , may be removed by the user for cleaning by unscrewing thumbscrews  49  and  50 . Other components of the apparatus are also removable for cleaning.  
     [0024] Referring now to FIG. 3, image capture device  28  defines an enclosure for a universal serial bus (USB) digital camera  52 . A camera  52  suitable for use with image capture device  28  may be obtained from any one of numerous commercial sources. One suitable camera is the Logitech QuickCam™ Pro 3000, available from Logitech of Fremont, Calif. (www.logitech.com). In one illustrated embodiment, the USB cable of camera  52  is connected to printed circuit board (PCB)  54 , shown in schematic form in FIG. 5. Camera  52  includes an image capture button that when activated sends a signal via the USB cable to cause a connected computer to capture an image from camera  52 . In the illustrated embodiment, micro-switch  47  is connected across the contacts of the image capture button so that image captures may be triggered by activation of micro-switch  47 . Camera  52  has a field of view shown by optical paths  56  and  58 . The centerline  60  of the camera&#39;s field of view is normal to and centered on opening  62  in the illumination device light block  64  and transparent window  44  in glass plate  38 .  
     [0025] As noted above, glass plate  38  is heated to liquefy any paraffin wax that may have accumulated on indicia face  16  of cassette  12 . In the preferred embodiment a heating element  66  is secured by adhesive to the inward-facing surface of glass plate  38 . Heating element  66  is preferably a resistive heating element, and more preferably about 2 mm thick, which is capable of maintaining the temperature of the outer-facing surface of glass plate  38  at a temperature above the melting point of all paraffin waxes that may be used to secure tissue samples to histological sample carriers. The preferred temperature for glass plate  38  is approximately 70 degrees Celsius, although it will be appreciated that this temperature may be adjusted widely and according to specific needs.  
     [0026] An illumination light block  64  according to the illustrated embodiment is shown in FIG. 4. Light block  64  is configured to cast shadowless, diffused and consistent illumination onto the indicia face of the histological sample carrier, such as indicia face  16  of cassette  12 , to facilitate accurate and repeatable electronic capture of the indicia written thereon. The illumination block  64  comprises a light block  64  that is fabricated from a translucent material that assures good transmission of light through the light block. As examples, light block  64  may be fabricated of plastics such as 7328 sign white acrylic, or glass, both of which provide sufficient transmission and diffusion of light from light sources. Light is provided by four 5 mm white lights  70 ,  72 ,  74  and  76 , which preferably are white light emitting diodes (LEDs) as shown in the drawing figures. Lights  70  through  76  are powered by an appropriate power source, and in the case of LEDs, by a 5 volt power source that may conveniently be provided through the computer-to-camera USB cable connected to PC board  54  as shown schematically in FIG. 5. Each of the four LEDs  70  through  76  are inserted into and secured within the opposite ends of two 5 mm diameter cross-drilled holes  78  and  80  drilled through light block  64 , such that the annular rim at the base of each LED (such as rim  75  on LED  76 ) is coincident with light block face  77 . White light emitted from the LEDs  70  through  76  or other light equivalent source is scattered radially from holes  78  and  80 , evenly illuminating the outer surfaces of light block  64 . Referring back to FIG. 3, it may be seen that light block  64  is mounted in housing  30  such that surface  79  of light block  64  is coincident with window  44 . When the light block is mounted in this manner and LEDs  70  through  76  are illuminated, shadowless light is cast upon the indicia face of the histological sample carrier through transparent window  44  of glass plate  38 .  
     [0027] Those of ordinary skill in the art will readily appreciate that any other equivalent illumination devices may be substituted for LEDs  70  through  76 , and that the illumination devices may be powered by a separate power supply.  
     [0028] An opening  62  is formed through light block  64  in a position to allow the full area of indicia face  16  of cassette  12  to be viewed by camera  52 . Stated in another way, opening  62  allows the entire indicia face  16  to be within the field of view of camera  52 .  
     [0029] In FIG. 5 a representative circuit diagram of selected circuits of PCB  54  is represented schematically. USB cable  90  of camera  52  is connected via cable  91  to a controller such as a processor of an external computer  93  or another controller through PCB  54 . It will be appreciated that computer  93  may just as well be incorporated into housing  30  to provide a self-contained unit. LEDs  70 ,  72 ,  74 , and  76  are connected in parallel to the USB +5 volt power wire through current-limiting resistors  82 ,  84 ,  86  and  88 , typically of 330-ohm resistance.  
     [0030] In FIG. 6, the software system is shown schematically in terms of representative modules. Camera  52  continually processes images in software module  94  and the images are displayed on display associated with computer  93 . Digital image adjustment for brightness and other optical characteristics are controlled by module  96  and is preset by the user to achieve the greatest contrast between indicia  18  and cassette indicia face  16 , based upon factors such as cassette color and ambient light intensity. When the user places a histological sample carrier such as cassette  12  correctly on indexing surface  32  such that indicia markings  18  are within the camera&#39;s field of view and micro-switch  47  is activated, image capture module  98  is activated and camera  52  generates a digital image of the indicia face  16 . The image thus captured is redisplayed by the display associated with computer  93  and is automatically processed by optical character recognition (OCR) module  100 . Software useful for OCR module  100  includes commercially available products such as EasyOCR, which is available from Euresys S.A., Anglur, Belgium (www.euresys.com). The processed output from OCR module  100  comprises a captured electronic representation of the information conveyed by the indicia  18 .  
     [0031] In the preferred embodiment, the resulting electronic representation of the information conveyed by the indicia is displayed by module  102  for user confirmation of the accuracy of the information. After user confirmation of the electronic representation, the information displayed by module  102  is automatically linked with the preset description of the physical storage location of module  104  and saved in database  106 , such as the database software product called Access™, which is available from Microsoft Corporation (www.microsoft.com). Moreover, the physical storage location is automatically incremented to the next physical storage location each time a sample is processed. In another embodiment, the electronic representation of the information conveyed by the indicia of module  102  is made available for use by another computer software program, eliminating the need for modules  104  and  106 .  
     [0032] Referring now to FIG. 7, a software system for retrieving information about histological sample carrier storage location is described. Use of this system allows a user to rapidly identify the physical location of a specific histological sample carrier for retrieval. Module  108  processes queries for the retrieval of histological sample carrier location description data based on the block identification indicia entered by the user. Possible results of this query are displayed by module  110 . The user selects the desired result from a list of possible candidates, and the user is given the option of modifying the status of the selected histological sample carrier through electronically marking the block status. As examples, the status could be modified to “removed” in module  112  if the selected histological sample carrier were to be removed from the physical storage location. The database is then updated by module  114 . In addition, an audit trail or report of block identification indicia, locations, date, and status may be generated in response to user prompts.  
     [0033] Representative Use of the Invention  
     [0034] In use, the user activates and initializes the software system and selects a block storage location. With the image capture device powered so that heating element  66  is on, the user then places a histological sample carrier such as a cassette  12  onto image capture device  28  such that bottom surface  15  is in contact with indexing surface  32 , cassette side surface  13  is in contact with lip  36  of sheet metal step  34 , and cassette indicia face  16  is in contact with glass plate  38 . The user then slides block  10  in the horizontal direction along indexing surface  32  in the direction indicated by arrow A in FIG. 2, all the while maintaining contact between cassette surfaces  15  and  16 , and indexing surface  32  and glass plate  38 , respectfully. Paraffin wax that may have found its way onto indicia face  16  is liquefied by the heated glass plate and is removed by the scraping action provided by ridges  40 . The liquefied wax removed from indicia face  16  in this manner is channelled into collection tray  42  for removal.  
     [0035] The user continues moving cassette  12  in the direction indicated by arrow A until side surface  14  of cassette  12  is moved into contact with pushbutton micro-switch  47 , thereby depressing and activating the switch. At the same time, side surface  14  abuts lip  45  and the cassette is at this time correctly positioned for data acquisition by computer  93 . With switch  47  activated an electronic image of cassette indicia markings  18  is captured by software system module  98  using camera  52 . The captured image is automatically processed by OCR module  100 . The resulting electronic representation of the information conveyed by the indicia is displayed by module  102  for user confirmation that the electronic representation is the same as the written indicia. If the user confirms a match between physical cassette indicia  18  as displayed by module  94  and the electronic representation of the information displayed by module  102 , the information of module  102  is automatically linked with the preset description of the physical storage location of module  104  and stored in database  106 . If the user does not confirm, the electronic representation of the information conveyed by the indicia of module  102  may be edited by the user to match the physical cassette indicia markings of module  94  using any number of computer input devices, such as a keyboard. The data is then saved in database  106  as described before.  
     [0036] When the user wants to remove a block or slide from the physical storage location, computer database  106  is queried by module  108  using any of the following criteria; sample identification indicia, date, comment, status, or known location, or other location information that may be used. Possible matches, including descriptions of the storage location, are displayed by module  110 . The user updates database  106  to indicate that the block or slide is removed and then proceeds to remove the block or slide from the physical storage location.  
     [0037] The preceding detailed descriptions, specifically of FIGS. 2 and 3, describe the histological sample carrier image capture device  28  as it may be configured for use with a cassette  12  as shown in FIG. 1A. The image capture device  28  may be configured for use with a histological sample carrier such as microscope slide  20 , either by modification of the indexing surfaces relative to the camera&#39;s field of view, or by providing secondary loci on the indexing surfaces for reading indicia on indicia face  24 .  
     [0038] Those of ordinary skill in the art will recognize that many different yet equivalent configurations of the image capture apparatus as well as the data extraction method may be used without departing from the scope and spirit of the present invention. As one example, the device  28  may be set up for automated placement and indexing of histological sample carriers on the indexing surface. Thus, a cassette  12  may be loaded into a carriage assembly configured for automated reciprocating movement along the axis defined by arrow A, while maintaining the indicia surface  16  and bottom surface  18  of cassette  12  in the proper orientation relative to the indexing surface  32  and glass plate  28 , as described above. The image capturing components of the invention as detailed above coordinate with the carriage movement to automatically capture and display the indicia.  
     [0039] Therefore, while the present invention has been described in terms of various preferred embodiments, it will be appreciated by one of ordinary skill that the spirit and scope of the invention is not limited to those embodiments, but extend to the various modifications and equivalents as defined in the appended claims.