Digital imaging IN DENTISTRY

Digital imaging

1. Digital Radiography 1 GOOD AFTERNOON..

2. DIGITAL RADIOGRAPHY BY Dr. Revath Vyas Devulapalli Digital Radiography 2

3. Content Digital Radiography 3

4. Content Digital Radiography 4

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. Digital Radiography 5 The Journal of Contemporary Dental Practice 2002 3(4):1-13

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. Digital Radiography 6 The Journal of Contemporary Dental Practice 2002 3(4):1-13

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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) Digital Radiography 8

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 ). Digital Radiography 9

10. Digital Radiography 10 Chemical Processing in film radiography

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. Digital Radiography 11

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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. Digital Radiography 13

14. Pixel In digital imaging, a pixel [picture element] is the smallest controllable element of a picture represented on the screen Digital Radiography 14 [Internet] [cited 2014 Apr 10]. Available from http://en.wikipedia.org/wiki/Pixel

15. Pixel Digital Radiography 15 [Internet] [cited 2014 Apr 10]. Available from http://en.wikipedia.org/wiki/Pixel

16. Pixel Digital Radiography 16 [Internet] [cited 2014 Apr 10]. Available from http://en.wikipedia.org/wiki/Pixel

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 . Digital Radiography 17 White SC, Pharoah MJ, Oral Radiology Principles and Interpretation, 6 th Edition Mosby 2009

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 . Digital Radiography 18 White SC, Pharoah MJ, Oral Radiology Principles and Interpretation, 6 th Edition Mosby 2009

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) Digital Radiography 19 White SC, Pharoah MJ, Oral Radiology Principles and Interpretation, 6 th Edition Mosby 2009

20. ADC consists of 2 steps Digital Radiography 20 White SC, Pharoah MJ, Oral Radiology Principles and Interpretation, 6 th Edition Mosby 2009

21. Sampling Sampling means that a small range of voltage values are grouped together as a single value Digital Radiography 21 White SC, Pharoah MJ, Oral Radiology Principles and Interpretation, 6 th Edition Mosby 2009

22. Sampling Narrow sampling better mimics the original signal but leads to larger memory requirements for the resulting digital image Digital Radiography 22 White SC, Pharoah MJ, Oral Radiology Principles and Interpretation, 6 th Edition Mosby 2009

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. Digital Radiography 23 White SC, Pharoah MJ, Oral Radiology Principles and Interpretation, 6 th Edition Mosby 2009

24. Quantization Digital Radiography 24 White SC, Pharoah MJ, Oral Radiology Principles and Interpretation, 6 th Edition Mosby 2009

25. Equipment Digital Radiography 25

26. Digital Radiography 26 Lanc¸a L, Silva A, Digital Imaging Systems for Plain Radiography, Springer 2013

27. Digital Radiography 27 The Journal of Contemporary Dental Practice 2002 3(4):1-13

28. Direct digital imaging Digital Radiography 28 The Journal of Contemporary Dental Practice 2002 3(4):1-13

29. Indirect digital imaging Digital Radiography 29 The Journal of Contemporary Dental Practice 2002 3(4):1-13

30. Types of digital image receptor Digital Radiography 30 White SC, Pharoah MJ, Oral Radiology Principles and Interpretation, 6 th Edition Mosby 2009

31. Digital image receptors Digital Radiography 31 Lanc¸a L, Silva A, Digital Imaging Systems for Plain Radiography, Springer 2013

32. Charge coupled device Introduced in 1987 1 st intraoral digital receptor Consist of thin wafer of silicon with electronic circuit Consist of matrix, amplifier in plastic houisng Digital Radiography 32 White SC, Pharoah MJ, Oral Radiology Principles and Interpretation, 6 th Edition Mosby 2009

33. A number of manufacturers produce detectors with varying active sensor areas roughly corresponding to the different sizes of intraoral film Digital Radiography 33

34. Digital Radiography 34 Whaites E, Essentials of Dental Radiography and Radiology, 4th edition, 2007

35. Structure Digital Radiography 35

36. Structure Digital Radiography 36

37. Digital Radiography 37

38. Digital Radiography 38

39. Valence Band Mechanism Digital Radiography 39 + e - e - Photoelectric absorption in Silicon Conduction Band e - +

40. Digital Radiography 40 [Internet] [cited 2014 Apr 10]. Available from http://www.vikdhillon.staff.shef.ac.uk/teaching/phy217/detectors

41. Digital Radiography 41 [Internet] [cited 2014 Apr 10]. Available from http://www.vikdhillon.staff.shef.ac.uk/teaching/phy217/detectors

42. Digital Radiography 42 [Internet] [cited 2014 Apr 10]. Available from http://www.vikdhillon.staff.shef.ac.uk/teaching/phy217/detectors

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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. Digital Radiography 48 White SC, Pharoah MJ, Oral Radiology Principles and Interpretation, 6 th Edition Mosby 2009

49. Digital Radiography 49 White SC, Pharoah MJ, Oral Radiology Principles and Interpretation, 6 th Edition Mosby 2009

50. Linear array Digital Radiography 50 Whaites E, Essentials of Dental Radiography and Radiology, 4th edition, 2007

51. Area array Digital Radiography 51 Whaites E, Essentials of Dental Radiography and Radiology, 4th edition, 2007

52. Advantages Digital Radiography 52

53. Disadvantages Digital Radiography 53

54. Disadvantages Digital Radiography 54

55. Complementary metal oxide semiconductors Digital Radiography 55 Whaites E, Essentials of Dental Radiography and Radiology, 4th edition, 2007

56. Digital Radiography 56 ADC

57. Digital Radiography 57

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) Digital Radiography 58 [Internet] [cited 2014 Apr 10]. Available from http://en.wikipedia.org/wiki/Scintillator

59. Digital Radiography 59 Lanc¸a L, Silva A, Digital Imaging Systems for Plain Radiography, Springer 2013

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 Digital Radiography 60

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 Digital Radiography 61

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 Digital Radiography 62 Lanc¸a L, Silva A, Digital Imaging Systems for Plain Radiography, Springer 2013

63. Flat panel detector Digital Radiography 63 Lanc¸a L, Silva A, Digital Imaging Systems for Plain Radiography, Springer 2013

64. Flat panel detector Digital Radiography 64 Lanc¸a L, Silva A, Digital Imaging Systems for Plain Radiography, Springer 2013

65. Flat panel detector It is a “sandwich” constructions consisting of a scintillator layer, an amorphous silicon photodiode circuitry layer, and a TFT array. Digital Radiography 65 White SC, Pharoah MJ, Oral Radiology Principles and Interpretation, 6 th Edition Mosby 2009

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. Digital Radiography 66 [Internet] [cited 2014 Apr 10]. Available from http://en.wikipedia.org/wiki/Thin-film_transistor

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. Digital Radiography 67 Lanc¸a L, Silva A, Digital Imaging Systems for Plain Radiography, Springer 2013

68. Flat Panel Structure Digital Radiography 68 Lanc¸a L, Silva A, Digital Imaging Systems for Plain Radiography, Springer 2013

69. Advantages Real-time process With a time lapse between exposure and image display of less than 10 seconds. Digital Radiography 69

70. Disadvantages Large in size so cannot be used intraorally Expensive Digital Radiography 70

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. Digital Radiography 71

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. Digital Radiography 72 White SC, Pharoah MJ, Oral Radiology Principles and Interpretation, 6 th Edition Mosby 2009

73. Structure Digital Radiography 73 Whaites E, Essentials of Dental Radiography and Radiology, 4th edition, 2007

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. Digital Radiography 74 White SC, Pharoah MJ, Oral Radiology Principles and Interpretation, 6 th Edition Mosby 2009

75. Valence Band e - Plate prepared Plate exposed X ray photon F Center Eu +2  Eu +3 Eu +2 F Center Conduction Band Whaites E, Essentials of Dental Radiography and Radiology, 4th edition, 2007

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. Digital Radiography 76 Whaites E, Essentials of Dental Radiography and Radiology, 4th edition, 2007

77. Mechanism When an electron returns to the Eu + 3 ion, energy is released in the green spectrum between 300 and 500 nm Digital Radiography 77 Whaites E, Essentials of Dental Radiography and Radiology, 4th edition, 2007

78. Valence Band e - Plate prepared Plate exposed Plate processed laser Photomultiplier tube X ray photon F Center Eu +2 Eu +3 Eu +2  Eu +3 Eu +2 F Center F Center Conduction Band Whaites E, Essentials of Dental Radiography and Radiology, 4th edition, 2007

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. Digital Radiography 79 Whaites E, Essentials of Dental Radiography and Radiology, 4th edition, 2007

80. PROCEDURE Digital Radiography 80

81. PROCEDURE Digital Radiography 81

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. Digital Radiography 82 White SC, Pharoah MJ, Oral Radiology Principles and Interpretation, 6 th Edition Mosby 2009

83. Slow scan direction – direction of psp plate Fast scan direction – direction of laser light Digital Radiography 83

84. Rotating plate scans Rapidly rotating drum that holds the plate C onsist of Rotation of drum and fixed laser Digital Radiography 84 White SC, Pharoah MJ, Oral Radiology Principles and Interpretation, 6 th Edition Mosby 2009

85. Advantages Digital Radiography 85

86. Advantages Digital Radiography 86

87. Disadvantages Digital Radiography 87

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. Digital Radiography 88

89. Imaging processing Digital Radiography 89

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 Digital Radiography 90

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. Digital Radiography 91 White SC, Pharoah MJ, Oral Radiology Principles and Interpretation, 6 th Edition Mosby 2009

92. Imaging processing Digital Radiography 92

93. Brightness Digital Radiography 93 White SC, Pharoah MJ, Oral Radiology Principles and Interpretation, 6 th Edition Mosby 2009

94. Contrast Digital Radiography 94 White SC, Pharoah MJ, Oral Radiology Principles and Interpretation, 6 th Edition Mosby 2009

95. Negative Conversion Useful in visualizing the trabecular pattern of bone pulp canal and chamber anatomy Digital Radiography 95

96. Digital Radiography 96

97. Digital Radiography 97

98. Colour : Digital Radiography 98 Whaites E, Essentials of Dental Radiography and Radiology, 4th edition, 2007

99. Imaging processing Digital Radiography 99

100. Digital Radiography 100 White SC, Pharoah MJ, Oral Radiology Principles and Interpretation, 6 th Edition Mosby 2009

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. Digital Radiography 101

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. Digital Radiography 102

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 Digital Radiography 103

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 Digital Radiography 104

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 Digital Radiography 105

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107. Imaging processing Digital Radiography 107

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 Digital Radiography 108 White SC, Pharoah MJ, Oral Radiology Principles and Interpretation, 6 th Edition Mosby 2009

109. Digital Radiography 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, 6 th Edition Mosby 2009

110. Laser Printer Digital Radiography 110

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. Digital Radiography 111 White SC, Pharoah MJ, Oral Radiology Principles and Interpretation, 6 th Edition Mosby 2009

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. Digital Radiography 112 White SC, Pharoah MJ, Oral Radiology Principles and Interpretation, 6 th Edition Mosby 2009

113. COMMON PROBLEMS IN DIGITAL IMAGING Noisy Images Non uniform image density Distorted Images Double Images Digital Radiography 113 White SC, Pharoah MJ, Oral Radiology Principles and Interpretation, 6 th Edition Mosby 2009

114. Noisy Images Digital Radiography 114

115. 2.Non uniform image density : Digital Radiography 115

116. 3. Distorted Images : Digital Radiography 116

117. 4. Double Images : Digital Radiography 117

118. Damaged Image receptors: Scratched phosphor surface mimicking root canal filling A and retake B. Digital Radiography 118

119. Image artifacts resulting from excessive bending of the PSP plate and excessive bending has resulted in permanent damage to the phosphor plate Digital Radiography 119

120. PSP circular artifact as a result of plate damage and localized swelling of the protective coating from disinfectant solution on work surface Digital Radiography 120

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. Digital Radiography 121

122. Malfunctioning CCD sensor resulting from rough handling (dropped sensor ) The sensor produces geometric image artifacts Digital Radiography 122

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 Digital Radiography 123

124. Digital Radiography 124 Imaging Step Film CCD/CMOS PSP Receptor preparation. None Place protective plastic sleeve over receptor Receptor must be connected to computer and patient identifying information entered for acquisition/archiving software Erase plates Package plates in protective plastic envelope Receptor placement. Film holding devices Film may be bent to accommodate anatomy Specialised receptor holder Inflexible and bulkiness Receptor cable Discomfort Film holding devices Bending of receptor may irreversibly damage it Exposure. Simple exposure Computer must be activated before exposure Simple exposure

125. Digital Radiography 125 Imaging Step Film CCD/CMOS PSP Processing. Dark room Processing chemicals Processing time Hazardous wastes Image acquisation and display is almost immediate Dim light envt Processor must be programmed with patient and detector information so that images are identified, preprocessed and stored properly Display Preparation. Film mounts Software – digital mount Individual mount Digitally rotated Display A room with subdued lighting and a masked viewbox Any light source subdued lighting A computer and display with app. Software Size of the display restrict the no. of images Image Duplication. Inferior to original and sometimes non-diagnostic Electronic copies may be stored on variety of media without loss of image quality Output on Film or paper is inferior and non-diagnostic

126. ADVANTAGES OF DIGITAL IMAGING Digital Radiography 126

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. Digital Radiography 127 Dentomaxillofacial Radiology 1995; 24: 250

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: Digital Radiography 128 Dentomaxillofacial Radiology 2012,41(3)203-210

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 Digital Radiography 129 The British Journal of Radiology 1991,64(763)591-595

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. Digital Radiography 130 Journal of Endodontics 2007, 33(1) 1–6

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. Digital Radiography 131 Brennan J. Journal of Orthodontics 2002 (29) 66–69

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 Digital Radiography 132 Brennan J. Journal of Orthodontics 2002 (29) 66–69

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. Digital Radiography 133 Brennan J. Journal of Orthodontics 2002 (29) 66–69

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. Digital Radiography 134 Brennan J. Journal of Orthodontics 2002 (29) 66–69

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. Digital Radiography 135

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 . Digital Radiography 136 Brennan J. Journal of Orthodontics 2002 (29) 66–69

137. Medico-legal Many insurance companies in the USA are accepting digital images as valid attachments when the claims are electronically claimed. Digital Radiography 137 Dentomaxillofacial Radiology 2000, 12(4)292-297

138. DISADVANTAGES OF DIGITAL IMAGING Digital Radiography 138

139. Cost Currently the cost of Intra oral sensor – 1.2 – 2 lakh Extra oral machins – 10 - 15 lakh Digital Radiography 139

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. Digital Radiography 140 Brennan J. Journal of Orthodontics 2002 (29) 66–69

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. Digital Radiography 141 Brennan J. Journal of Orthodontics 2002 (29) 66–69

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. Digital Radiography 142 Dentomaxillofacial Radiology 2000, 12(4)292-297

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. Digital Radiography 143

144. Thank You… Digital Radiography 144