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Digital imaging IN DENTISTRY

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Digital imaging

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Digital imaging IN DENTISTRY

  1. 1. DigitalRadiography 1GOOD AFTERNOON..
  2. 2. DIGITAL RADIOGRAPHY BY DR. REVATH VYAS DEVULAPALLI DigitalRadiography 2
  3. 3. Content DigitalRadiography 3 Introduction & History Equipment Digital Image acquisition • Types of receptor • CCD • CMOS • Flat panel detectors • PSP
  4. 4. Content DigitalRadiography 4 Digital Image Processing Digital Radiographic Image Storage Digital Image Communication Advantage and Disadvantages – Overall Conclusion
  5. 5. Introduction  Since the discovery of X-rays in 1895, film has been the primary medium for capturing, displaying, and storing radiographic images.  It is a technology that dental practitioners are the most familiar and comfortable with in terms of technique and interpretation.  Digital radiography is the latest advancement in dental imaging and is slowly being adopted by the dental profession. DigitalRadiography 5 The Journal of Contemporary Dental Practice 2002 3(4):1-13
  6. 6. Introduction  Digital imaging incorporates computer technology in the capture, display, enhancement, and storage of direct radiographic images.  Digital imaging offers some distinct advantages over film, but like any emerging technology, it presents new and different challenges for the practitioner to overcome. DigitalRadiography 6 The Journal of Contemporary Dental Practice 2002 3(4):1-13
  7. 7. DigitalRadiography 7 Radiography Analog Digital Scanner (X-ray digitizer) Computed Radiography (CR) Direct Digital Radiography (DR or DDR)
  8. 8.  A conventional system uses x-ray film to create a latent image.  The film is then processed, creating a manifest image that can be interpreted by a physician.  It is later stored in the file room (physical storage for archival) DigitalRadiography 8
  9. 9.  Method is film-based.  Method may uses intensifying screens.  Film is placed between two screens.  Screens emit light when x-rays strike them.  Film is processed chemically.  Processed film is viewed on view-box (lightbox). DigitalRadiography 9
  10. 10. DigitalRadiography 10 Chemical Processing in film radiography
  11. 11. Problems with Film ?  10% of films are not available when we want them!  15% of films are “hard” to locate or find!  25% of films are “misplaced” or not retrievable (misfiled).  10% of films are lost (referrals, residents, etc.)  Recent study – physicians spend two weeks/year (100 hours/year) trying to locate or find the films they need. DigitalRadiography 11
  12. 12. DigitalRadiography 12 Radiography Analog Digital Scanner (X-ray digitizer) Computed Radiography (CR) Direct Digital Radiography (DR or DDR)
  13. 13. Digital imaging or Digitization ?  Digital Imaging is any modality / method of imaging that creates an image that can be viewed or stored on a computer. DigitalRadiography 13
  14. 14. Pixel  In digital imaging, a pixel [picture element] is the smallest controllable element of a picture represented on the screen DigitalRadiography 14 [Internet] [cited 2014 Apr 10]. Available from http://en.wikipedia.org/wiki/Pixel
  15. 15. Pixel DigitalRadiography 15 [Internet] [cited 2014 Apr 10]. Available from http://en.wikipedia.org/wiki/Pixel
  16. 16. Pixel DigitalRadiography 16 [Internet] [cited 2014 Apr 10]. Available from http://en.wikipedia.org/wiki/Pixel
  17. 17. Analogue to Digital Conversion  The term digital in digital imaging refers to the numeric format of the image content and its discreteness.  Conventional film images can be considered an analog medium in which differences in the size and distribution of black metallic silver result in a continuous density spectrum. DigitalRadiography 17 White SC, Pharoah MJ, Oral Radiology Principles and Interpretation, 6th Edition Mosby 2009
  18. 18. Analogue to Digital Conversion  Digital images are numeric and discrete in two ways: (1) in terms of the spatial distribution of the picture elements (pixels) and (2) in terms of the different shades of gray of each of the pixels. DigitalRadiography 18 White SC, Pharoah MJ, Oral Radiology Principles and Interpretation, 6th Edition Mosby 2009
  19. 19. Analogue to Digital Conversion  A digital image consists of a large collection of individual pixels organized in a matrix of rows and columns.  Production of a digital image requires a process called analog to digital conversion (ADC) DigitalRadiography 19 White SC, Pharoah MJ, Oral Radiology Principles and Interpretation, 6th Edition Mosby 2009
  20. 20. ADC consists of 2 steps Quantization Sampling DigitalRadiography 20 White SC, Pharoah MJ, Oral Radiology Principles and Interpretation, 6th Edition Mosby 2009
  21. 21. Sampling  Sampling means that a small range of voltage values are grouped together as a single value DigitalRadiography 21 White SC, Pharoah MJ, Oral Radiology Principles and Interpretation, 6th Edition Mosby 2009
  22. 22. Sampling  Narrow sampling better mimics the original signal but leads to larger memory requirements for the resulting digital image DigitalRadiography 22 White SC, Pharoah MJ, Oral Radiology Principles and Interpretation, 6th Edition Mosby 2009
  23. 23. Quantization  Once sampled, every sampled signal is assigned a value.  For the clinician to see the image, the computer organizes the pixels in their proper locations and displays a shade of gray that corresponds to the number that was assigned during the quantization step. DigitalRadiography 23 White SC, Pharoah MJ, Oral Radiology Principles and Interpretation, 6th Edition Mosby 2009
  24. 24. Quantization DigitalRadiography 24 White SC, Pharoah MJ, Oral Radiology Principles and Interpretation, 6th Edition Mosby 2009
  25. 25. Equipment An x-ray machine Digital image receptor • a sensor An analog-to-digital converter Computer and monitor • with appropriate hardware, software, network connection Printer DigitalRadiography 25
  26. 26. DigitalRadiography 26 Lanc¸a L, Silva A, Digital Imaging Systems for Plain Radiography, Springer 2013
  27. 27. Digital Radiography Direct Indirect DigitalRadiography 27 The Journal of Contemporary Dental Practice 2002 3(4):1-13
  28. 28. Direct digital imaging DigitalRadiography 28 Sensor placed in pt’s mouth Exposed to radiation Sensor captures radiograp hic image Transmit image to a computer monitor Image appears on screen within seconds The Journal of Contemporary Dental Practice 2002 3(4):1-13
  29. 29. Indirect digital imaging Exisiting Xray film digitized using CCD camera Scans the image Digitizes displays on computer monitor DigitalRadiography 29 The Journal of Contemporary Dental Practice 2002 3(4):1-13
  30. 30. Types of digital image receptor DigitalRadiography 30 White SC, Pharoah MJ, Oral Radiology Principles and Interpretation, 6th Edition Mosby 2009 1. Solid state technology: • Charge coupled device • Complementory metal oxide semiconductors • Flat panel detectors 2. Photostimulable phosphor plate
  31. 31. Digital image receptors DigitalRadiography 31 Solid State Technology Uses semi-conductor based detectors 1. CCD 2. CMOS 3. Flat Panel Lanc¸a L, Silva A, Digital Imaging Systems for Plain Radiography, Springer 2013
  32. 32. Charge coupled device  Introduced in 1987  1st intraoral digital receptor  Consist of thin wafer of silicon with electronic circuit  Consist of matrix, amplifier in plastic houisng DigitalRadiography 32 White SC, Pharoah MJ, Oral Radiology Principles and Interpretation, 6th Edition Mosby 2009
  33. 33.  A number of manufacturers produce detectors with varying active sensor areas roughly corresponding to the different sizes of intraoral film DigitalRadiography 33
  34. 34. DigitalRadiography 34 Whaites E, Essentials of Dental Radiography and Radiology, 4th edition, 2007
  35. 35. Structure DigitalRadiography 35
  36. 36. Structure DigitalRadiography 36
  37. 37. Exposure to radiation Break the covalent bond in silicon atoms Produce electron hole pair Electron attracted towards most positive potential in device – create charge packet Charge pattern formed from individual pixels forms latent image DigitalRadiography 37
  38. 38. Bucket brigade form of charge transfer Finally transferred to amplifier Transmitted as voltage Analog to digital converter Image display DigitalRadiography 38
  39. 39. Valence Band Mechanism DigitalRadiography 39 +e- e- Photoelectric absorption in Silicon Conduction Band e- +
  40. 40. DigitalRadiography 40 [Internet] [cited 2014 Apr 10]. Available from http://www.vikdhillon.staff.shef.ac.uk/teaching/phy217/detectors
  41. 41. DigitalRadiography 41 [Internet] [cited 2014 Apr 10]. Available from http://www.vikdhillon.staff.shef.ac.uk/teaching/phy217/detectors
  42. 42. DigitalRadiography 42 [Internet] [cited 2014 Apr 10]. Available from http://www.vikdhillon.staff.shef.ac.uk/teaching/phy217/detectors
  43. 43. DigitalRadiography 43
  44. 44. DigitalRadiography 44
  45. 45. DigitalRadiography 45
  46. 46. Bucket brigade form of charge transfer Finally transferred to amplifier Transmitted as voltage Analog to digital converter Image display DigitalRadiography 46
  47. 47. DigitalRadiography 47
  48. 48. CCD  Detectors without flaws are relatively expensive to produce, and expense of the detector increases with increasing matrix size (total number of pixels).  Pixel size varies from 20 microns to 70 microns. Smaller pixel size increases the cost of the receptor.  CCDs have also been made in linear arrays of a few pixels wide and many pixels long for panoramic and cephalometric imaging. DigitalRadiography 48 White SC, Pharoah MJ, Oral Radiology Principles and Interpretation, 6th Edition Mosby 2009
  49. 49. DigitalRadiography 49 CCD Linear array made up of few px wide and many px long Area array White SC, Pharoah MJ, Oral Radiology Principles and Interpretation, 6th Edition Mosby 2009
  50. 50. Linear array DigitalRadiography 50 Whaites E, Essentials of Dental Radiography and Radiology, 4th edition, 2007
  51. 51. Area array DigitalRadiography 51 Whaites E, Essentials of Dental Radiography and Radiology, 4th edition, 2007
  52. 52. Advantages DigitalRadiography 52 Intact images or real time image production and display. Consistent quality X ray sensitivity is 80% greater than conventional film. Elimination of hazardous chemicals used in film processing and lead foil. Computer aided diagnosis
  53. 53. Disadvantages DigitalRadiography 53 High initial cost of system Unknown life expectancy of CCD sensor Rigidity and thickness of the sensor Decreased resolution CCDS cannot be sterilized Hard copy images fade with time
  54. 54. Disadvantages DigitalRadiography 54 Image manipulation can be time consuming. The sensor may not be well tolerated by patients -more time- consuming The cable attached to the sensor is easily damaged and may interfere with sensor Actual area available for image capture may be as little as 60% of the sensor area
  55. 55. Complementary metal oxide semiconductors DigitalRadiography 55 Each pixel is isolated from its neighboring pixels and connected to transistor Electron hole pair generated within pixel Charge transfer to transistor in form of voltage Each transistor voltage is read out separately by frame grabber Stored and displayed as digital gray value Whaites E, Essentials of Dental Radiography and Radiology, 4th edition, 2007
  56. 56. DigitalRadiography 56 AD C
  57. 57. DigitalRadiography 57
  58. 58. Scintillator  A scintillator is a material that exhibits scintillation — the property of luminescence when excited by ionizing radiation.  Luminescent materials, when struck by an incoming particle, absorb its energy and scintillate, (i.e., re-emit the absorbed energy in the form of light) DigitalRadiography 58 [Internet] [cited 2014 Apr 10]. Available from http://en.wikipedia.org/wiki/Scintillator
  59. 59. DigitalRadiography 59 Lanc¸a L, Silva A, Digital Imaging Systems for Plain Radiography, Springer 2013
  60. 60.  These sensors do not require charge transfer, resulting in increased sensor reliability and lifespan.  Require less system power to operate and are less expensive to manufacture  Low cost  Fixed pattern of noise  Smaller active area DigitalRadiography 60
  61. 61. CCD CMOS POWER COSUMPTION. 400mw 40mw SENSITIVITY TO LIGHT Excellent Excellent SENSITIVITY TO X RAYS High Unknown PIXEL SIZE. 40 micron 25 micron COST. High Medium MANUFACTURE. Expensive Cheap BREAKAGE RESISTANCE Low Medium DYNAMIC RANGE Excellent Excellent NOISE. Low High READOUT. Complex Simple EFFICACY. Excellent Fair DigitalRadiography 61
  62. 62. Flat panel detector  Used for medical imaging, extraoral imaging device  Provide large matrix area with pixel of less than 100 µm  Allows imaging of larger areas including head  2 types: direct indirect DigitalRadiography 62 Lanc¸a L, Silva A, Digital Imaging Systems for Plain Radiography, Springer 2013
  63. 63. Flat panel detector DigitalRadiography 63 Indirect flat panel detector: sensitive to visible light use intensifying screen to convert X-ray to light Photoconductor material - aSi Lanc¸a L, Silva A, Digital Imaging Systems for Plain Radiography, Springer 2013
  64. 64. Flat panel detector DigitalRadiography 64 Direct flat panel detector use selenium for efficient X- rays absorption Lanc¸a L, Silva A, Digital Imaging Systems for Plain Radiography, Springer 2013
  65. 65. Flat panel detector  It is a “sandwich” constructions consisting of a scintillator layer, an amorphous silicon photodiode circuitry layer, and a TFT array. DigitalRadiography 65 White SC, Pharoah MJ, Oral Radiology Principles and Interpretation, 6th Edition Mosby 2009
  66. 66. Thin Film Transistor (TFT)  It is a special kind of field-effect transistor made by depositing thin films of an active semiconductor layer  A transistor is a semiconductor device used to amplify and switch electronic signals and electrical power. It is composed of semiconductor material with at least three terminals for connection to an external circuit. DigitalRadiography 66 [Internet] [cited 2014 Apr 10]. Available from http://en.wikipedia.org/wiki/Thin-film_transistor
  67. 67. Flat panel detector  When x-ray photons reach the scintillator, visible light proportional to the incident energy is emitted and then recorded by an array of photodiodes and converted to electrical charges.  These charges are then read out by a TFT array similar to that of direct conversion DR systems. DigitalRadiography 67 Lanc¸a L, Silva A, Digital Imaging Systems for Plain Radiography, Springer 2013
  68. 68. Flat Panel Structure DigitalRadiography 68 Lanc¸a L, Silva A, Digital Imaging Systems for Plain Radiography, Springer 2013
  69. 69. Advantages  Real-time process  With a time lapse between exposure and image display of less than 10 seconds. DigitalRadiography 69
  70. 70. Disadvantages  Large in size so cannot be used intraorally  Expensive DigitalRadiography 70
  71. 71. Photostimulable phosphor plates  Also known as storage phosphor plates (spp), image plates or computed radiography  Flexible, wireless indirect receptors  Available in the same sizes as intraoral films. DigitalRadiography 71
  72. 72. Structure  The PSP material used for radiographic imaging is “ europium doped” barium fluorohalide.  Barium in combination with iodine, chlorine, or bromine forms a crystal lattice.  The addition of europium (Eu + 2 ) creates imperfections in this lattice. DigitalRadiography 72 White SC, Pharoah MJ, Oral Radiology Principles and Interpretation, 6th Edition Mosby 2009
  73. 73. Structure DigitalRadiography 73 Whaites E, Essentials of Dental Radiography and Radiology, 4th edition, 2007
  74. 74. Mechanism  When exposed to a sufficiently energetic source of radiation, valence electrons in europium can absorb energy and move into the conduction band.  These electrons migrate to nearby halogen vacancies (F- centers) in the fluorohalide lattice and may become trapped there in a metastable state. DigitalRadiography 74 White SC, Pharoah MJ, Oral Radiology Principles and Interpretation, 6th Edition Mosby 2009
  75. 75. Valence Band e- Plate prepared Plate exposed X ray photon F Center Eu+2  Eu+3Eu+2 F Center Conduction Band Whaites E, Essentials of Dental Radiograph y and Radiology, 4th edition, 2007
  76. 76. Mechanism  While in this state, the number of trapped electrons is proportional to x-ray exposure and represents a latent image.  When stimulated by red light of around 600 nm, the barium fluorohalide releases trapped electrons to the conduction band. DigitalRadiography 76 Whaites E, Essentials of Dental Radiography and Radiology, 4th edition, 2007
  77. 77. Mechanism  When an electron returns to the Eu + 3 ion, energy is released in the green spectrum between 300 and 500 nm DigitalRadiography 77 Whaites E, Essentials of Dental Radiography and Radiology, 4th edition, 2007
  78. 78. Valence Band e- Plate prepared Plate exposed Plate processed laser Photomultiplier tube X ray photon F Center Eu+2 Eu+3Eu+2  Eu+3Eu+2 F Center F Center Conduction Band Whaites E, Essentials of Dental Radiograph y and Radiology, 4th edition, 2007
  79. 79. Mechanism  Fiberoptics conduct light from the PSP plate to a photomultiplier tube.  The photomultiplier tube converts light into electrical energy.  A red filter at the photomultiplier tube selectively removes the stimulating laser light, and the remaining green light is detected and converted to a varying voltage. DigitalRadiography 79 Whaites E, Essentials of Dental Radiography and Radiology, 4th edition, 2007
  80. 80. PROCEDURE DigitalRadiography 80
  81. 81. PROCEDURE DigitalRadiography 81
  82. 82. Stationary plate scans  Method for "reading" the latent images on PSP plates.  A rapidly rotating multifaceted mirror that reflects a beam of red laser light.  As the mirror revolves, the laser light sweeps across the plate. The plate is advanced and the adjacent line of phosphor is scanned. DigitalRadiography 82 White SC, Pharoah MJ, Oral Radiology Principles and Interpretation, 6th Edition Mosby 2009
  83. 83.  Slow scan direction – direction of psp plate  Fast scan direction – direction of laser light DigitalRadiography 83
  84. 84. Rotating plate scans  Rapidly rotating drum that holds the plate  Consist of Rotation of drum and fixed laser DigitalRadiography 84 White SC, Pharoah MJ, Oral Radiology Principles and Interpretation, 6th Edition Mosby 2009
  85. 85. Advantages Storage phosphor plates can be reused indefinitely Receptor is cordless & flexible Linear or logarithmic response to radiation is available There is wide exposure range & fewer retakes Less radiation is required DigitalRadiography 85
  86. 86. Advantages DigitalRadiography 86 No chemical processing required Image processing of acquired images is available Images can be transferred to easily Images can be easily & inexpensively stored & retrieved Computed aided diagnosis
  87. 87. Disadvantages Receptors must be erased before reuse High initial cost of the equipment The spatial resolution of film exceeds Some of the image processing routines are time – intensive Phosphor plates must be packaged in sterile envelopes possibility of transfer of contaminated material to patient's mouth if integrity of plate's protective envelope is jeopardized DigitalRadiography 87
  88. 88. Imaging processing  Any operation that acts to improve, restore, analyze or in some way change a digital image is a form of image processing.  Some of these operations are integrated in the image acquisition and image management software and are hidden from the user.  Others are controlled by the user with the intention to improve the quality of the image or to analyze its contents. DigitalRadiography 88
  89. 89. Imaging processing DigitalRadiography 89 Image restoration Image enhancement Image analysis Image compression
  90. 90. Image restoration  Raw data enter computer  Preprocessing -- Image corrected for known defects  Adjustment of image intensities  Substitution of defective pixels  Preprocessing operations set by manufacturer DigitalRadiography 90
  91. 91. Image restoration  Depending on the quality of the sensor and the choices made by the manufacturer, a variety of other operations maybe applied to the image before it becomes visible on the display.  They are executed very rapidly and are unnoticed by the user. DigitalRadiography 91 White SC, Pharoah MJ, Oral Radiology Principles and Interpretation, 6th Edition Mosby 2009
  92. 92. Imaging processing DigitalRadiography 92 Image restoration Image enhancement Image analysis Image compression
  93. 93. Brightness DigitalRadiography 93 White SC, Pharoah MJ, Oral Radiology Principles and Interpretation, 6th Edition Mosby 2009
  94. 94. Contrast DigitalRadiography 94 White SC, Pharoah MJ, Oral Radiology Principles and Interpretation, 6th Edition Mosby 2009
  95. 95. Negative Conversion  Useful in visualizing the trabecular pattern of bone  pulp canal and chamber anatomy DigitalRadiography 95
  96. 96. DigitalRadiography 96
  97. 97. DigitalRadiography 97
  98. 98. Colour: DigitalRadiography 98 Whaites E, Essentials of Dental Radiography and Radiology, 4th edition, 2007
  99. 99. Imaging processing DigitalRadiography 99 Image restoration Image enhancement Image analysis Image compression
  100. 100. DigitalRadiography 100 White SC, Pharoah MJ, Oral Radiology Principles and Interpretation, 6th Edition Mosby 2009
  101. 101. b) Diagnosis:  Three basic steps of image analysis are :  Segmentation - most critical step.  Feature extraction  Object classification.  The goal of segmentation is to simplify the image and reduce it to its basic components.  This involves subdividing the image, thus separating objects from the background. DigitalRadiography 101
  102. 102. b) Diagnosis:  Objects of interest are defined by the diagnostic task, for example, a tooth, a carious lesion, a bone level, or an implant.  A unique set of values for a certain combination of features can lead to classification of the object.  Automated cephalometric landmark identification is an example. DigitalRadiography 102
  103. 103.  Dental subtraction radiography (Ruttimann et al, 1981) was found to be a feasible method that increases the accuracy of detection of density changes between serial radiographs DigitalRadiography 103
  104. 104.  When two images of the same object are registered and the image intensities of corresponding pixels are subtracted, a uniform difference image is produced.  If there is a change in the radiographic attenuation between the baseline and follow-up examination, this change shows up as a brighter area when the change represents gain and as a darker area when the change represents loss DigitalRadiography 104
  105. 105.  The strength of digital subtraction radiography (DSR) is that it cancels out the complex anatomic background against which this change occurs.  Subtraction radiography requires two images , which are exposed with the same geometry DigitalRadiography 105
  106. 106. DigitalRadiography 106
  107. 107. Imaging processing DigitalRadiography 107 Image restoration Image enhancement Image analysis Image compression
  108. 108. Image compression  Process of file reduction.  To reduce computer storage space and facilitate image retrieval and transmission.  Compression becomes a more important issue as the number of patient records and image files to be stored increases over time  Two types: lossless and lossy DigitalRadiography 108 White SC, Pharoah MJ, Oral Radiology Principles and Interpretation, 6th Edition Mosby 2009
  109. 109. DigitalRadiography 109 LOSSLESS LOSSY Donot discard any image data Discard image data Maximum compression rate < 3:1 Range from 12:1 to 28:1 More memory to manipulate Less memory Retrieval and transmission slow quick White SC, Pharoah MJ, Oral Radiology Principles and Interpretation, 6th Edition Mosby 2009
  110. 110. Laser Printer DigitalRadiography 110
  111. 111. Image Storage:  The use of digital imaging in dentistry requires an image archiving and management system that is very different from conventional radiography.  Storage of diagnostic images on magnetic or optical media raises a number of new issues that must be considered.  The file size of dental digital radiographs varies considerably, ranging from 200 KB for intra oral images to as much as 6 MB for extraoral images. DigitalRadiography 111 White SC, Pharoah MJ, Oral Radiology Principles and Interpretation, 6th Edition Mosby 2009
  112. 112. Image Storage:  Once in a digital format, critical image data can be deleted or modified.  The backup media suitable for external storage of digital radiographs include external hard drives, digital types, CDs and DVDs. DigitalRadiography 112 White SC, Pharoah MJ, Oral Radiology Principles and Interpretation, 6th Edition Mosby 2009
  113. 113. COMMON PROBLEMS IN DIGITAL IMAGING 1. Noisy Images 2. Non uniform image density 3. Distorted Images 4. Double Images DigitalRadiography 113 White SC, Pharoah MJ, Oral Radiology Principles and Interpretation, 6th Edition Mosby 2009
  114. 114. Noisy Images DigitalRadiography 114
  115. 115. 2.Non uniform image density: DigitalRadiography 115
  116. 116. 3. Distorted Images: DigitalRadiography 116
  117. 117. 4. Double Images: DigitalRadiography 117
  118. 118. Damaged Image receptors:  Scratched phosphor surface mimicking root canal filling A and retake B. DigitalRadiography 118
  119. 119.  Image artifacts resulting from excessive bending of the PSP plate and excessive bending has resulted in permanent damage to the phosphor plate DigitalRadiography 119
  120. 120.  PSP circular artifact as a result of plate damage and localized swelling of the protective coating from disinfectant solution on work surface DigitalRadiography 120
  121. 121.  PSP image artifact resulting from plate surface contamination  This artifact was caused by a glove powder smudge that prevented proper scanning of the affected area of the PSP plate. DigitalRadiography 121
  122. 122.  Malfunctioning CCD sensor resulting from rough handling (dropped sensor)  The sensor produces geometric image artifacts DigitalRadiography 122
  123. 123.  Improper use of image processing tools, such as filters, may result in false-positive findings. An edge enhancement filter was applied to the panoramic image, which produced radiolucencies at restoration edges simulating recurrent caries  These radiolucencies are not present in a follow-up intraoral image DigitalRadiography 123
  124. 124. DigitalRadiography 124 Imaging Step Film CCD/CMOS PSP Receptor preparation. None 1) Place protective plastic sleeve over receptor 2) Receptor must be connected to computer and patient identifying information entered for acquisition/archiving software 1) Erase plates 2) Package plates in protective plastic envelope Receptor placement. 1) Film holding devices 2) Film may be bent to accommodate anatomy 1) Specialised receptor holder 2) Inflexible and bulkiness 3) Receptor cable 4) Discomfort 1) Film holding devices 2) Bending of receptor may irreversibly damage it Exposure. Simple exposure Computer must be activated before exposure Simple exposure
  125. 125. DigitalRadiography 125 Imaging Step Film CCD/CMOS PSP Processing. 1) Dark room 2) Processing chemicals 3) Processing time 4) Hazardous wastes Image acquisation and display is almost immediate 1) Dim light envt 2) Processor must be programmed with patient and detector information so that images are identified, preprocessed and stored properly Display Preparation. Film mounts 1) Software – digital mount 1) Individual mount 2) Digitally rotated Display 1) A room with subdued lighting and a masked viewbox 2) Any light source 1) subdued lighting 2) A computer and display with app. Software 3) Size of the display restrict the no. of images Image Duplication. Inferior to original and sometimes non- diagnostic 1. Electronic copies may be stored on variety of media without loss of image quality 2. Output on Film or paper is inferior and non-diagnostic
  126. 126. ADVANTAGES OF DIGITAL IMAGING DigitalRadiography 126
  127. 127. Dose reduction  Dose reductions of up to 90 per cent compared to E speed film have been reported by some authors in the diagnosis of caries.  Although some researchers do claim dose reductions compared with conventional extra-oral film, in practice the background noise rises to unacceptable levels.  It is now accepted that there is no appreciable reduction compared with films used in conjunction with rare earth intensifying screens. DigitalRadiography 127 Dentomaxillofacial Radiology 1995; 24: 250
  128. 128. Image manipulation  This is perhaps the greatest advantage of digital imaging over conventional film.  It involves selecting the information of greatest diagnostic value and suppressing the rest.  Manufacturers provide software programmes with many different processing tools, however some are more useful than others and these include: DigitalRadiography 128 Dentomaxillofacial Radiology 2012,41(3)203-210
  129. 129. 1. Contrast enhancement  This can effectively compensate for over or under exposure of the digital image.  It has been shown that contrast enhancement of CCD devices were more accurate than E-speed film for detecting simulated caries under orthodontic bands DigitalRadiography 129 The British Journal of Radiology 1991,64(763)591-595
  130. 130. 2. Measurements  Digital callipers, rulers and protractors are some of the many tools available for image analysis.  Many authors have reported on their application in cephalometric analysis.  The images can also be superimposed onto each other and onto digital photographs. DigitalRadiography 130 Journal of Endodontics 2007, 33(1) 1–6
  131. 131. 3. 3-D reconstruction  This application can be theoretically used to reconstruct intra- and extra-oral images.  The uses range from profiling root canals to visualizing facial fractures in all three dimensions. DigitalRadiography 131 Brennan J. Journal of Orthodontics 2002 (29) 66–69
  132. 132. 4. Filtration  The addition of filters to the airspace around the face can clarify the soft tissue profile if the original soft tissue image was poor DigitalRadiography 132 Brennan J. Journal of Orthodontics 2002 (29) 66–69
  133. 133. Time  Much time is gained especially with the CCD system where the image is displayed at the chairside immediately post exposure.  Although a lag time between scanning and the appearance of an image exists with the PSP method it is still substantially faster than conventional developing processes in general use. DigitalRadiography 133 Brennan J. Journal of Orthodontics 2002 (29) 66–69
  134. 134. Storage  Storage was initially a problem before the development of DVDs and CD ROMs as three peri-apical images would fill a floppy disc.  However, now a CD ROM can hold over 30,000 images.  This means that images can be stored cheaply and indefinitely. DigitalRadiography 134 Brennan J. Journal of Orthodontics 2002 (29) 66–69
  135. 135. Teleradiology  Teleradiology is the transmission of radiological patient images, such as x-rays, CTs, and MRIs, from one location to another for the purposes of sharing studies with other radiologists and physicians.  This had the advantages of not losing radiographs in the post and saving time if an urgent appointment is required. DigitalRadiography 135
  136. 136. Environmentally friendly  No processing chemicals are used or disposed of. Both CCD sensors and the PSP plates are capable of being reused for many thousands of exposures.  They can, however, become scratched and damaged if not handled carefully. DigitalRadiography 136 Brennan J. Journal of Orthodontics 2002 (29) 66–69
  137. 137. Medico-legal  Many insurance companies in the USA are accepting digital images as valid attachments when the claims are electronically claimed. DigitalRadiography 137 Dentomaxillofacial Radiology 2000, 12(4)292-297
  138. 138. DISADVANTAGES OF DIGITAL IMAGING DigitalRadiography 138
  139. 139. Cost Currently the cost of Intra oral sensor – 1.2 – 2 lakh Extra oral machins – 10 - 15 lakh DigitalRadiography 139
  140. 140. Sensor dimensions  These are still quite bulky for the CCD system and awkward to position due to trailing fibre optic wires.  The original problem of small sensor active areas has been rectified and the same amount of information can be captured as conventional film. DigitalRadiography 140 Brennan J. Journal of Orthodontics 2002 (29) 66–69
  141. 141. Cross-infection control  Each intra-oral sensor and plate must be covered by a plastic bag, and this bag is changed between patients.  However, if they become directly contaminated there is no way of sterilizing them and they should be discarded regardless of expense. DigitalRadiography 141 Brennan J. Journal of Orthodontics 2002 (29) 66–69
  142. 142. Medico-legal  Concerns have been raised in the past about the ability to manipulate the images for fraudulent purposes.  Manufacturers of software programmes have installed ‘audit trails’, which can track down and recover the original image. DigitalRadiography 142 Dentomaxillofacial Radiology 2000, 12(4)292-297
  143. 143. Conclusion  The technology is now available to run a practice almost paper free.  It is theoretically possible to store clinical notes, photographs, radiographs, and study models on disc, and refer or consult online.  Research is also continuing into the development of a credit card sized ‘smart card’, which could carry a patient’s medical and dental notes along with their radiographic images.  It is important that advances in technology are accepted and the benefits that they produce utilized in order that clinical practice and patient care continue to improve. DigitalRadiography 143
  144. 144. Thank You… DigitalRadiography 144

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