Ideal radiography

IDEAL IMAGE CHARACTERISTICS
FACTORS RELATED TO THE RADIATION BEAM
FACTORS RELATED TO THE OBJECT
FACTORS RELATED TO THE TECHNIQUE
FACTORS RELATED TO RECORDING OF THE ROENTGEN IMAGE OF THE OBJECT
DARK/ LIGHT IMAGE  IDEAL IMAGE
IDEAL QUALITY CRIETRIA

1. IDEAL RADIOGRAPHY DR. REVATH VYAS PG II YEAR

2. CONTENTS DEFINITION IDEAL IMAGE CHARACTERISTICS FACTORS RELATED TO THE RADIATION BEAM FACTORS RELATED TO THE OBJECT FACTORS RELATED TO THE TECHNIQUE FACTORS RELATED TO RECORDING OF THE ROENTGEN IMAGE OF THE OBJECT DARK/ LIGHT IMAGE  IDEAL IMAGE IDEAL QUALITY CRIETRIA CONCLUSION REFERENCES

3. DEFINITION An Ideal Radiograph is one that provides a great deal of information , the image exhibits proper density and contrast, have sharp outlines and are of the same shape and size as the object being radiographed . I n HM Worth’s words; “An Ideal Radiograph is one which has desired density and overall blackness and which shows the part completely without distortion with maximum details and has the right amount of contrast to make the details fully apparent”.

4. IDEAL IMAGE CHARATERISTICS

5. IMAGE CHARACTERISTICS Dental radiograph appears as a black-and-white image picture that includes varying shades of gray. Radiolucent (Black or dark areas): A structure that appears radiolucent on a radiograph lacks density and permits the passage of the x-ray beam with little or no resistance. For example , air space appears radiolucent. Radiopaque (White or light areas): Radiopaque structures are dense and absorb or resist the passage of the x-ray beam. For example, enamel, dentin, bone etc. appears radiopaque.

6. The characteristics of an Ideal Radiograph are: Visual characteristic: i . Density. ii. Contrast. B. Geometric characteristics: iii . Sharpness or detail, resolution or definition . iv. Magnification. v. Distortion. C. Anatomical accuracy of radiographic images. D. Adequate coverage of the anatomic region of interest.

7. A diagnostic (ideal) radiograph provides a great deal of information: the images exhibit proper density and contrast have sharp outlines and of the same shape and size as the object.

8. The major imaging characteristics of x-ray film are Radiographic density Radiographic contrast Radiographic speed Film latitude Radiographic Noise Radiographic blurring

9. RADIOGRAPHIC DENSITY The overall degree of darkening of an exposed film is referred to as radiographic density. Measured as the optical density of an area of an x-ray film, where, OPTICAL DENSITY = Log 10 Io Io - intensity of incident light (from view box) It - intensity of light transmitted through the film. It

10. The measurement of film density is also a measure of the opacity of the film . Optical density is means 100% of the light is transmitted Optical density is 1 means 10% of the light is transmitted Optical density is 2 means 1% of the light is transmitted . A film is of greatest diagnostic value when the structures of interest are imaged on the relatively straight portion of the graph, between 0.6 to 3.0 optical density units.

11. Gross fog or base plus fog : an unexposed film, when processed, shows some density caused by the inherent density of the base, added tint and the development of unexposed silver halide crystals. The optical density of gross fog is 0.2 to 0.3 Radiographic density is influenced by Exposure Subject thickness and Subject Density

12. A) Exposure :- The overall film density depends on the number of photons absorbed by the film emulsion  kVp  the no. of photons reaching mA the film and thus  exposure time  density of the radiograph distance b/w, the focal spot & film B) Subject Thickness: The thicker the subject, the more the beam is attenuated and the lighter the resultant image The exposure (either kVp or time) should vary according to the patient’s size to produce radiographs of optimal density.

13. C) Subject Density: The greater the density of a structure within the subject, the greater the attenuation of the x-ray beam . Dense objects (which are strong absorbers) cause the radiographic image to be light and are radiopaque.

14. Less dense objects (which are weak absorbers) cause the radiographic image to be dark and are radiolucent. Decreasing densities – enamel, dentin, cementum , bone, muscle, fat and air. Metallic objects ( eg . Restorations) are far denser than enamel and hence better absorbers.

15. 2. RADIOGRAPHIC CONTRAST Defined as the difference in densities between light and dark regions on a radiograph. High contrast Shows both light areas (short gray scale of contrast) and dark areas. Low contrast Composed only of light gray (long gray scale of contrast) and dark gray zones

16. High Low Optimum Contrast Contrast Contrast

17. Subject Contrast: Influenced largely by the subject’s thickness, density and atomic number. Also is influenced by beam energy and intensity. As the kVp of the x-ray beam increases, subject contrast decreases low kVp energies are used, subject contrast increases . “ K VP KILLS CONTRAST” Changing the time or mA of the exposure (KVp constant) also influences subject contrast. If the film is excessively light or dark, contrast of anatomic structures is diminished.

18. B. Film Contrast:- Describes the capacity of radiographic films to display differences in subject contrast, A high-contrast film reveals areas of small difference in subject contrast Properly exposed films have more contrast than underexposed (light films) Film processing influences film contrast. Film contrast is maximized by optimal film processing conditions.

19. Improper handling of the film, such as Storage at too high a temperature, Exposure to excessively bright safe, degrades film lights contrast. Light leaks in the darkroom

20. Fog on an x-ray film results in increase film density in turn reduces the film contrast. Common causes of film fog are Improper safelighting Storage of film at too high a temperature, and Development of film at an excessive temperature or for a prolonged period. Film fog can be minimized by proper film processing and storage.

21. C) Scattered radiation: Scattered radiation results from photons that have interacted with the subject by compton or coherent interactions. Scattered radiation causes fogging of a radiograph. Scattered radiation can be reduced by Use a relatively low kVp Collimate the beam to the size of the film, and Use grids in extraoral radiography.

22. 3) RADIOGRAPHIC SPEED: Refers to the amount of radiation required to produce an image of a standard density. A fast film requires a relatively low exposure to produce a density of 1, whereas a slower film requires a longer exposure Controlled largely by the size of the silver halide grains and their silver content. The films most often used are kodak ultraspeed (group D) and kodak insight (group E or F). Insight film is preferred because it requires only about half the exposure of ultra speed film and offers comparable contrast and resolution.

23. F-speed film is faster than the D-speed film because tabular crystal grains are used in the emulsion of F-speed film. Film speed can be increased by processing the film at a higher temperature Processing in depleted solutions can lower the effective speed. It is always preferable to use fresh processing solutions and follow the recommended processing time and temperature.

24. 4) FILM LATITUDE: Measure of the range of exposure that can be recorded as distinguishable densities on a film. A film with a characteristic curve that has a long straight-line position and a shallow slope has a wide latitude . Wide latitude have lower contrast Wide-latitude films are useful when both the osseous structures of the skull and soft tissues of the facial region must be recorded. A high kVp produces images with a wide latitude and low contrast. Recommended for imaging structures with a wide range of subject densities.

25. 5) RADIOGRAPHIC NOISE: Is the appearance of uneven density of a uniformly exposed radiographic film. Seen on a small area of film as localized variations in density. Primary causes of radiographic noise are A) Radiographic mottle B) Radiographic artifact Radiographic Mottle:- On intraoral dental film, mottle may be seen as film graininess Graininess is most evident when high temperature processing is used. Mottle is also evident when the film is used with fast intensifying screens

26. Two important causes of radiographic mottle in intensifying screens are 1) Quantum mottle – caused by a fluctuation in the number of photons per unit of the beam cross-sectional area absorbed by the intensifying screens. 2) Screen structure mottle is graininess caused by screen phosphors. B) Radiographic Artifacts: Radiographic artifacts are defects caused by Errors in film handling, such as finger prints or bends in the film, or Errors in film processing, such as splashing developer or fixer on a film or marks or scratches from rough handling.

27. 6. RADIOGRAPHIC BLURRING Sharpness – ability of a radiograph to define an edge precisely (e.g., dentino enamel junction, a thin trabecular plate). Resolution , or resolving power , is the ability of a radiograph to record separate structures that are close together. Usually measured by radiographing an object made up of a series of thin lead strips with alternating radiolucent spaces of the same thickness. The resolving power is measured as the highest number of line pairs per millimeter. Panoramic film-screen combinations can resolve about five line pairs per millimeter . Periapical film has better resolving power, can delineate clearly more than 20 line pairs per millimeter.

28. Radiograph of a resolving power target consisting of groups of radiopaque lines and radiolucent spaces. Numbers at each group indicate the line pairs per millimeter represented by the group .

29. Sharpness A B Distance (mm) Density D 1 D 2 5 10 15 20 The boundary between two areas A & B appears very sharp

30. Unsharpness A Distance (mm) Density D 1 D 2 .2 .4 .6 .8 The boundary between two areas A & B appears unsharp B The steeper the slope the more sharp the image appears. The shallower the slope the more blurred the image

31. Sharpness, unsharpness & lack of sharpness No image is perfectly sharp Every image has a certain lack of sharpness Unsharpness is an objective concept which can be measured Sharpness is our subjective perception of unsharpness , and depends on contrast and unsharpness

32. Contrast & perception of unsharpness We judge one image boundary to be sharper than another, even though they are both equally unsharp , if the contrast of the first image is greater .

33. Image sharpness in extraoral radiographic projections is lost because. Visible light and UV radiation emitted by the screen spread about beyond the point of origin and expose a film area larger than the phosphor crystal Intensifying screens with large crystals are relatively fast, Fast intensifying screens have a relatively thick phosphor layer, image sharpness maximized by ensuring as close a contact as possible between the intensifying screens and the film. 3) The presence of image on each side of a double-emulsion film also causes a loss of image sharpness through parallax. In intraoral images, parallax is most apparent when wet films are viewed.

34. Radiographic blur is caused by Image receptor (film and screen) blurring Motion blurring, and Geometric blurring Image receptor blurring: with intraoral dental x-ray film, the size and number of silver grains in the film emulsion determines image sharpness. Finer the grain size  finer the sharpness slow-speed films have fine grains and faster films have larger grains. 2. use of intensifying screens in extra-oral radiography has an adverse effect on image sharpness.

35. In intensifying screens parallax distortion contributes to image unsharpness because light from one screen may cross the film base and reach the emulsion on the opposite side. Problem can be solved by incorporating dyes into the base B) Motion Blurring: Image sharpness also can be lost through movement of the film, subject or x-ray source during exposure. C) Geometric Blurring: Several geometric factors influence image sharpness Image sharpness is improved by Using as small focal spot area as possible Increasing the distance between the focalspot ad the object (and film) Reducing the distance between the object and the image receptor (film)

36. Parallax unsharpness results when double emulsion film is used because of the slightly greater magnification on the side of the film away from the X-ray source.

37. FACTORS RELATED TO RADIATION BEAM

38. IDEAL EQUIPMENT POINT SOURCE OF FOCAL SPOT IDEAL TARGET MATERIAL WITH high atomic number a high melting point, high thermal conductivity, and low vapor pressure Safe and accurate Capable of generating X-rays in the desired energy range and with adequate mechanisms for heat removal

39. IDEAL EQUIPMENT Small Easy to maneuver and position Stable , balanced and steady once the tubehead has been positioned Easily folded and stored Simple to operate and capable of both film and digital imaging Robust .

40. Ideal Distance from the focal spot on the target to the skin. The required focus to skin distances ( fsd ) are: — 200 mm for sets operating above 60 kV — 100 mm for sets operating below 60 kV

41. Ideal X-ray beam characteristics The ideal X-ray beam used for imaging should be: Sufficiently penetrating, to pass through the patient and react with the film emulsion or digital sensor and produce good contrast between the different shadows Parallel , i.e. non-diverging, to prevent magnification of the image Produced from a point source, to reduce blurring of the edges of the image, a phenomenon known as the penumbra effect.

42. exposure button oil filter filament X-ray Machine Components

43. The smaller the focal spot (target), the sharper the image (teeth) will be. During x-ray production, a lot of heat is generated. If the target is too small, it will overheat and burn up. Line Focus Principle

44. Line Focus Principle Apparent (effective) focal spot size (looking at target surface through PID) Actual focal spot size (looking perpendicular to the target surface) PID

45. Line Focus Principle Apparent (effective) focal spot size Actual focal spot size Target Cathode (-) Anode (+) PID

46. FACTORS CONTROLLING THE X-RA Y BEAM Exposure time Tube current (mA) Tube Voltage (kVp) Filtration Collimation Inverse square law

47. 1. Exposure time X-ray Energy (keV) Number of X-rays 70 2 sec 1 sec maximum energy average energy (no change) (no change) Exposure time is doubled, the number of photons generated is doubled, photon energies is unchanged.

48. The quantity of radiation produced by an-x-ray tube is directly proportional to the tube current and the time the tube is operated. Quantity of radiation = Time x Tube current 2. Tube Current (mA):

49. mA (milliamperes) X-ray Energy (keV) Number of X-rays 70 10 mA 5 mA maximum energy average energy (no change) (no change)

50. mAs or mAi milliamperes (mA) x seconds (s) milliamperes (mA) x impulses (i) 60 impulses = 1 second 10 mA x .5 seconds = 5 mAs 20 mA x .25 seconds = 5 mAs mAi = 60 x mAs

51. Increasing the KVp results in increase in The number of photons generated Their mean energy, and Their maximal energy . Higher the KVp greater the penetrability of the beam through matter. 3. Tube Voltage (KVp)

52. KVP (KILOVOLT PEAK) X-ray Energy (keV) Number of X-rays 70 90 90 kVp 70 kVp maximum energy average energy

53. Half Value Layer (HVL) :- The HVL is the thickness of an absorber, required to reduce by one half the number of x-ray photons passing through it. As the average energy of an X-ray beam increases, so does its HVL.

54. Only photons with sufficient energy to penetrate through anatomic structures and reach the image receptor are useful for diagnostic radiology. Filtering an x-ray beam with aluminum preferentially removes low-energy photons, thereby reducing the beam intensity while increasing the mean energy of the residual beam. 4. Filtration:

55. Inherent filtration : a. Glass wall of the x-ray tube b. Insulating oil and c. Barrier Material 0.5 to 2mm of aluminum External filtration : Aluminium Disks . Total filtration = Inherent filtration + External filtration . Total Filtration 1.5mm of aluminum to 70KVp 2.5mm for all higher voltages.

56. Inherent Glass window of x-ray tube Added Aluminum filter (s) Total 70 kVp 1.5 mm 2.5 mm Total Filtration Oil/Metal barrier

57. filter PID

58. To reduce the size of the x-ray beam therefore the volume of irradiated tissue. Round and rectangular collimators most frequently used in dentistry. Scattered radiation minimized by collimating the beam. 5. Collimation

59. collimated beam collimator target (x-ray source) front views side view Collimation 2.75 inches (7 cm) = maximum diameter of circular beam or maximum length of long side of rectangular beam at end of PID.

60. Collimator Al Filter

61. Collimators - may either have a round or rectangular opening.

62. Circular collimator : cone shaped beam - 2.75 inches in diameter considerably larger than the size of two intraoral periapical films c) increased skin dose to the patient. R ectangular collimator : a) restricts the size of the X-ray beam to an area slightly larger than a size of 2 intraoral b) significantly reduces the patient exposure

63. Collimation: Reduces the exposure area Number of scattered photons reaching the film-improves image quality

64. Quality Quantity average energy number of x-rays

65. (1 ) (2 ) Quality vs. Quantity kVp mA Time Filtration No change No change

66. The intensity is inversely proportional to the square of the distance from the source. I 1 /I 2 =(D 2 ) 2 /(D 1 ) 2 If a dose of 1 gray (GY) is measured at a distance of 2m a dose of 4GY will be found at 1m and 0.25 GY at 4m. 6. Inverse Square Law

67.  kVp  the no. of photons reaching mA the film and thus exposure time  density of the radiograph distance b/w, the focal spot & film “KVP KILLS CONTRAST”

68. FACTORS RELATED TO OBJECT

69. Subject Thickness: The thicker the subject, the more the beam is attenuated and the lighter the resultant image Subject Density: The greater the density of a structure within the subject, the greater the attenuation of the x-ray beam. Dense objects (which are strong absorbers) cause the radiographic image to be light and are radiopaque. Subject Contrast: Influenced largely by the subject’s thickness, density and atomic number.

70. FACTORS RELATED TO TECHNIQUE

71. IDEAL PROJECTION GEOMETRY

72. The basic principles of projection geometry (shadow casting) The focal spot should be as small as possible Focal spot to object distance should be as long as possible. Object to film distance should be as small as possible. Long axis of object and film planes should be parallel. X-ray beam should strike the object and film planes at right angles. There should be no movement of the tube, film or patient during exposure ( given by Manson and Lincoln)

73. The anatomy of the oral cavity does not always allow all these ideal positioning requirements to be satisfied. In an attempt to overcome the problems, two techniques for periapical radiography have been developed: The paralleling technique The bisected angle technique.

74. Paralleling cone technique has the potential to satisfy four of the five ideal requirements mentioned earlier. However, the anatomy of the palate and the shape of the arches mean that the tooth and the image receptor cannot be both parallel and in contact. So, the image receptor has to be positioned some distance from the tooth.

75. IDEAL PATIENT POSITIONING For intraoral radiography the patient should be positioned comfortably in the dental chair, ideally with the occlusal plane horizontal and parallel to the floor. For most projections the head should be supported against the chair to minimize unwanted movement.

76. FOR IOPA

77. FOR OCCLUSAL

78. For BITE-WING

79. The tab or bite-platform should be positioned on the middle of the film packet and parallel to the upper and lower edges of the film packet. The film packet should be positioned with its long axis horizontally for a horizontal bitewing or vertically for a vertical bitewing. The posterior teeth and the film packet should be in contact or as close together as possible. The posterior teeth and the film packet should be parallel — the shape of the dental arch may necessitate two separate film positions to achieve this requirement for the premolars and the molars.

80. In the horizontal plane, the X-ray tube head should be aimed so that the beam meets the teeth and the film packet at right angles, and passes directly through all the contact areas. In the vertical plane, the X-ray tubehead should be aimed downwards (approximately 5°-8° to the horizontal) to compensate for the upwardly rising curve of Monson. The positioning should be reproducible.

81. • Assessment of caries and restorations — films should be well exposed and show good contrast to allow differentiation between enamel and dentine and to allow the enamel — dentine junction (EDJ) to be seen . • Assessment of periodontal status — films should be under-exposed to avoid burn-out of the thin alveolar crestal bone.

82. For OPG

83. IDEAL RECEPTOR POSITIONING The ideal requirements for the position of the image receptor and the X-ray beam, relative to a tooth include : The tooth under investigation and the image receptor should be in contact or, if not feasible, as close together as possible The tooth and the image receptor should be parallel to one another

84. The image receptor should be positioned with its long axis vertically for incisors and canines, and horizontally for premolars and molars with sufficient receptor beyond the apices to record the apical tissues The X-ray tubehead should be positioned so that the beam meets the tooth and the image receptor at right angles in both the vertical and the horizontal planes The positioning should be reproducible .

85. Factors related to recording of the roentgen image of the object.

86. IDEAL FILM STORAGE Ideally films should be stored: • In a refrigerator in cool, dry conditions • Away from all sources of ionizing radiation • Away from chemical fumes including mercury and mercury-containing compounds • With boxes placed on their edges, to prevent pressure artefacts.

87. IDEAL DARK ROOM CONDITIONS General cleanliness (daily), but particularly of work surfaces and film hangers (if used). Light-tightness (yearly), by standing in the darkroom in total darkness with the door closed and safelights switched off and visually inspecting for light leakage

88. 1. Darkroom lamp 2 . Electric fan, 3 . Rack for drying films, 4. Storage rack for intraoral hangers, 5 . Bulletin board, 6. Exposure and processing chart for dental X-ray films, 7. Drip pan, 8 . Shelf, 9 . Timer, 10 . Utility safe lamp, 11 . Goose neck faucet, 12 . Loading area, 13 . Processing area, 14 . Splash board , 15 . Hot and cold water valves, 16 . 8 × 10 dental processing tank, 17 . Utility sink , 18 . Supply cabinet for chemicals, cassettes and other accessories Schematic Darkroom Layout

89. Safelights (yearly), to ensure that these do not cause fogging of films. Checks are required on: Type of filter — this should be compatible with the colour sensitivity of film used, i.e. blue, green or ultraviolet Condition of filters — scratched filters should be replaced Wattage of the bulb — ideally it should be no more than 25 W Their distance from the work surface — ideally they should be at least 1.2 m (4 ft ) away Overall safety (i.e. their fogging effect on film) T he simple quality control measure for doing this is known as the coin test .

90. COIN TEST

91. Chemical solutions These should be: Always made up to the manufacturers‘ instructions taking special precautions to avoid even trace amounts of contamination of the developer by the fixer, e.g. always fill the fixer tank first so that any splashes into the developer tank can be washed away before pouring in the developer Always at the correct temperature Changed or replenished regularly — ideally every 2 weeks — and records should be kept to control and validate these changes Monitored for deterioration. This can be done easily using radiographs of a step-wedge phantom:

92. Cassettes Regular cleaning of intensifying screens with a proprietary cleaner Regular checks for light-tightness, as follows: 1 . Load a cassette with an unexposed film and place the cassette on a window sill in the daylight for a few minutes 2. Process the film — any ingress of light will have fogged (darkened) the film

93. Cassettes Regular checks for film/screen contact, as follows: 1. Load a cassette with an unexposed film and a similar sized piece of graph paper 2. Expose the cassette to X-rays using a very short exposure time 3. Process the film — any areas of poor film/screen contact will be demonstrated by loss of definition of the image of the graph paper. A simple method of identification of films taken in similar looking cassettes, e.g. a Letraset letter on one screen.

94. Digital phosphor storage plates • Regular cleaning • Regular visual checks for scratches or other defects

95. IDEAL VIEWING CONDITIONS H uman visual system is capable of distinguishing only about 60 gray levels at any time under ideal viewing conditions. Considering the typical viewing environment in the dental operatory, the actual number of gray levels that can be distinguished falls to less than 30 . So, ideal viewing conditions are required for better diagnosis

96. • An even, uniform, bright light viewing screen (preferably of variable intensity to allow viewing of films of different densities) (see Fig. 18.1) • A quiet, darkened viewing room • The area around the radiograph should be masked by a dark surround so that light passes only through the film • Use of a magnifying glass to allow fine detail to be seen more clearly on intraoral films • The radiographs should be dry.

97. DARK/ LIGHT RADIOGRAPH  IDEAL RADIOGRAPH

98. REDUCTION An overexposed or grossly overdeveloped film will be too dark for convenient viewing , owing to the excessive deposit of silver which obscures the image detail. A photographic reducer contains an oxidizing agent , potassium ferricyanide which oxidizes the silver to silver ferrocyanide , which in turn is dissolved by the solution of sodium thiosulphate .

99. This is known as the Farmer’s Reducer and consists of two solutions : Solution A : Potassium ferricyanide 75 grams + Water to make 1000 ml. Solution B : Sodium thiosulphate crystals 240 grams . + Water to make 1000 ml .

100. Method : Take one part of Solution A and four parts of Solution B, and add twenty seven parts of water. Immerse the radiograph in the mixed solution and watch carefully. When the film has been sufficiently reduced , it should be washed in running water for 30 minutes .

101. The process of reduction should be carried out in a weak artificial light, as bright light causes rapid deterioration of the solution. The Solution A and Solution B should be mixed just prior to their use .

102. Chemical intensification of radiographs A radiograph may be too light because of, underexposure, under development or both. Instead of repeating the radiograph , chemical intensification may be done. Most of the intensification methods act by converting the silver which forms the image into a compound which is more opaque, more colored or of a different physical form .

103. A number of commercially available intensifying solutions are present: In-4 Chromium intensifier. In-5 Silver intensifier Copper iodide intensifying solution. XR-10 intensifying solution. Line Toner solution— this is made of three solutions: Solution A : Diglycolic acid 60 grams Sodium Hydroxide 36 grams Water 750 ml Solution B: Boric nitrate 14 grams Potassium fluoride 1 gram Water 100 ml Solution C: Potassium ferricyanide 5 grams Sodium nitrite 1 grams Water 100 ml

104. The processed radiograph which is of low density is immersed in the intensifying solution for a period of three to eight minutes depending upon the density increase required.

105. IDEAL QUALITY CRIETERIA

106. For IOPA The image should have acceptable definition with no distortion or blurring. The image should include the correct anatomical area together with the apices of the tooth/teeth under investigation with at least 3–4 mm of surrounding bone. There should be no overlap of the approximal surfaces of the teeth .

107. The desired density and contrast for film captured images will depend on the clinical reasons for taking the radiograph, e.g. to assess caries, restorations and the periapical tissues films should be well exposed and show good contrast to allow differentiation between enamel and dentine and between the periodontal ligament space, the lamina dura and trabecullar bone. to assess the periodontal status films should be underexposed to avoid burnout of the thin alveolar crestal bone

108. The images should be free of coning off or cone cutting and other film handling errors. The images should be comparable with previous periapical images both geometrically and in density and contrast.

109. For OPG All the upper and lower teeth and their supporting alveolar bone should be clearly demonstrated The whole of the mandible should be included Magnification in the vertical and horizontal planes should be equal The right and left molar teeth should be equal in their mesiodistal dimension

110. The density across the image should be uniform with no air shadow above the tongue creating a radiolucent (black) band over the roots of the upper teeth The image of the hard palate should appear above the apices of the upper teeth Only the slightest ghost shadows of the contralateral angle of the mandible and the cervical spine should be evident

111. There should be no evidence of artefactual shadows due to dentures, earrings and other jewellery The patient identification label should not obscure any of the above features The image should be clearly labelled with the patient’s name and date of the examination The image should be clearly marked with a R ight and/or L eft letter .

112. For Bite-wing The image should have acceptable definition with no distortion or blurring. The image should include from the mesial surface of the first premolar to the distal surface of the second molar — if the third molars are erupted then the 7/8 contact should be included. The occlusal plane/bite platform should be in the middle of the image so that the crowns and coronal parts of the roots of the maxillary teeth are shown in the upper half of the image and the crowns and coronal parts of the roots of the mandibular teeth are shown in the lower half of the image, and the buccal and lingual cusps should be superimposed .

113. The maxillary and mandibular alveolar crests should be shown. There should be no overlap of the approximal surfaces of the teeth. The desired density and contrast for film captured images will depend on the clinical reasons for taking the radiograph, e.g. to assess caries and restorations films should be well exposed and show good contrast to allow differentiation between enamel and dentine and to allow the enamel–dentine junction (EDJ) to be seen .

114. to assess the periodontal status films should be underexposed to avoid burn-out of the thin alveolar crestal bone The image should be free of coning off or cone cutting and other film handling errors. The image should be comparable with previous bitewing images both geometrically and in density and contrast.

115. CONCLUSION AN IDEAL RADIOGRAPH IS AN END PRODUCT OF SEVERAL FACTORS WHICH NEEDS TO BE FOLLOWED IN DAY TO DAY RADIOGRAPHY. IDEAL RADIOGRAPH HELPS NOT ONLY IN PROPER DIAGNOSIS BUT ALSO IN PROPER TREATMENT PLANNING AND ALSO TO SEE THE TREATMENT OUTCOME.

116. REFERENCES WHITE AND PHAROAH - 6 TH EDITION ERIC WHAITES – 3 RD EDITION HERRING AND HOWERTON – 3 RD EDITION WEUHRMANN – 5 TH EDITION KHARJODKHER – 2 ND EDITION

117. THANK YOU 