Image Characteristic & Interpretation


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  • If the viewing area is larger than the film, an opaque mask should be used to eliminate all light from around the periphery of the film.
  • SystemicUnilateral or bilateral
  • Image Characteristic & Interpretation

    1. 1. Dental X-ray Image Characteristics<br />Dr. Walid Samir Salem<br />BDS, MS, MHPE<br />lecturer, Oral Surgery Department<br />Member, Dental education unit<br />College of Dentistry, Qassim University<br />
    2. 2. Dental X-ray image characteristic include both visual & geomatric characteristics. <br />Visual characteristic:<br /><ul><li>Density.
    3. 3. Contrast.</li></ul>Geometric characteristics:<br /><ul><li>Sharpness.
    4. 4. Magnification.
    5. 5. Distortion.</li></li></ul><li>0<br />RADIOLUCENT<br />Dark GraytoBlack<br />A structure that lack density appear radiolucent e.g. soft tissue & spaces <br />
    6. 6. 0<br />RADIOPAQUE<br />White to Light Gray<br />Radiobaque structures are dense & absorb X-ray, e.g. enamel, dentine, & bone.<br />
    7. 7. I) Density <br />Represents the degree of darkening of an exposed x-ray film (white to black)<br />
    8. 8. 0<br />The overall density of the film affects the diagnostic value of the film (ideal density, too light, too dark)<br />
    9. 9. Density influenced by:<br />Exposure factors:<br /><ul><li>mA
    10. 10. kV
    11. 11. Exposure time</li></ul>2. Object thickness<br />3. Object density<br />4. Film fog<br />
    12. 12. Exposure factors (mA, kVp, exposure time). An unnecessary increase in any of these factors results in an increase in film density.<br />Object thickness: the larger the patient’s head, the more x-rays that are needed to produce an ideal film density <br />Object density: determined by type of material (metal, tooth structure, composite, etc.) and by amount of material<br />
    13. 13. FilmFog<br />0<br />Increased film density from causes other than exposure to the primary x-ray beam (scatter, improper safelighting, improper film storage, expired film) <br />fog<br />
    14. 14. 0<br />II) Contrast<br />The difference in densities (blackness) between various regions on a radiograph<br />
    15. 15. 0<br />High Contrast<br />Short Scale<br />Black and White<br />(Few shades of gray)<br />Best for caries detection<br />
    16. 16. 0<br />Low Contrast<br />Long Scale<br />Many shades of gray<br />Best for periapical or periodontal evaluation<br />
    17. 17. Contrast influenced by:<br />0<br />Subject contrast<br />2. kVp<br />3. Film contrast<br />
    18. 18. Subject contrast<br />0<br />Results from varying object densities within patient, this is determined by: thickness, density & composition of the subject <br />
    19. 19. 0<br />kVp<br />Affects energy (penetrating ability) of x-rays.<br />50<br />60<br />70<br />80<br />90<br /> 100<br />40<br />
    20. 20. Film contrast:<br />0<br />It refers to the characteristics of the film that influence the radiographic contrast, it is incorporated into film by manufacturer.<br />
    21. 21. FilmFog<br />0<br />Film fog makes the whole film darker, making it harder to see the density differences (contrast)<br />fog<br />
    22. 22. I) Sharpness <br />Measures how well the details (boundaries/edges) of an object are reproduced on a radiograph.<br />The fuzzy unclear area that surround the image is termed penumbra. <br />
    23. 23. Penumbra <br />(pene=almost + umbra= shadow)<br />Def.: Zone of unsharpnessalong the edge of images in a radiograph<br />The larger the penumbra, the less sharp the image will be <br />
    24. 24. Target (focal spot) <br />Umbra<br />Penumbra<br />(complete shadow) <br />
    25. 25. Sharpness influenced by:<br />Focal spot size<br /> Source–object (teeth) distance<br /> Object (teeth)-film distance<br /> Intensifying screens<br /> Film crystal size<br /> Motion<br />
    26. 26. Decrease focal spot size, increase sharpness<br />Object <br />Umbra <br />Penumbra<br />Target <br />
    27. 27. Target<br />Umbra<br />Penumbra<br />Increase source-object distance, increase sharpness<br />Teeth<br />film<br />
    28. 28. Target<br />Umbra <br />Penumbra<br />Decrease object-film distance, increase sharpness<br />Teeth<br />film<br />film<br />
    29. 29. Intensifying screens decrease sharpness<br />0<br />
    30. 30. 0<br />Film crystal size<br />The faster film contain larger crystal size that produce less image sharpness, and vice versa.<br />Unsharpness occur because the large crystals don’t produce object outline as well as smaller.<br />
    31. 31. Patient motion decreases sharpness<br />0<br />
    32. 32. 0<br />II)Magnification<br />Increase in size<br /> Magnification affected by:<br /> Source-object distance<br /> Object-film distance<br />
    33. 33. Target<br /> 16”<br />Magnification <br />0<br />Increase source-object distance, decrease magnification<br />Target<br /> 16”<br />Target<br /> 8”<br />Decrease object-film distance, decrease magnification<br />
    34. 34. 0<br />III) Distortion<br />Change in the true shape or size of the object<br />Distortion affected by:<br /> 1. Film-teeth relationship<br /> 2. Beam alignment<br />
    35. 35. 0<br />Paralleling<br />
    36. 36. 0<br />Bisecting angle<br />
    37. 37. 0<br />
    38. 38. 0<br /> Ideal Radiograph<br />Image same size as object<br />Image same shape as object<br />Image has good detail<br />Image has good density and contrast<br />
    39. 39. 0<br />Mandibular molar periapical film comes closest to satisfying properties of an ideal radiograph<br />(either paralleling or bisecting)<br />
    40. 40.
    41. 41. Radiographic Interpretation basic<br />Dr. Walid Samir Salem<br />BDS, MS, MHPE<br />lecturer, Oral Surgery Department<br />Member, Dental education unit<br />College of Dentistry, Qassim University<br />
    42. 42. Objectives:<br /><ul><li>The importance of radiographic interpretation.
    43. 43. The difference between interpretation & diagnosis.
    44. 44. Rules of radiographic interpretation.
    45. 45. Image analysis.
    46. 46. Steps of interpretation.</li></li></ul><li>The importance of interpretation:<br />Radiographic interpretation is an essential part of the diagnostic process. The ability to evaluate & recognize what is revealed by a radiograph enable us to detect diseases, lesions & conditions which can’t be identified clinically.<br />
    47. 47. Interpretation Vs. Diagnosis:<br />Interpretation refers to an explanation of what is viewed on a radiograph while diagnosis refers to the identification of disease by examination or analysis.<br />In other words the interpretation is a step in the diagnosis.<br />
    48. 48. Rules of radiographic interpretation<br />The area to be examined must be completely shown at optimal angulations<br />All the boundaries of the area of interest must be shown with normal structures around it.<br />Knowing and familiarity with all normal anatomical landmarks as well as all various pathological conditions that may affect the area of interest.<br />Optimum viewing condition.<br />
    49. 49. Viewing condition:<br />Ideally, should include the following:<br /><ul><li>Ambient light in the room should be reduced.
    50. 50. Intraoral radiographs should be mounted.
    51. 51. Light from the view-box should be of equal intensity across the viewing surface.
    52. 52. The size of the view-box should accommodate the size of the film.
    53. 53. A magnifying lens allows detailed examination of small regions of the film.</li></li></ul><li>0<br />
    54. 54. 0<br />
    55. 55. Image Analysis:<br />The first step in image analysis is to use a systemic approach to identify all the normal anatomy present in an image.<br />Avoid limiting your attention to one particular region of the film.<br />
    56. 56. Steps of interpretation<br />Localization.<br />Observation.<br />General consideration.<br />Interpretation.<br />Correlation.<br />
    57. 57. Localization<br />Localized or generalized<br />Position in the jaw<br />Single or multiple<br />Size<br />
    58. 58. How to identify the position of the periapical film?<br />Embossed dot identify right from left and the anatomical land mark to identify the jaw and the area.<br />
    59. 59. Upper left<br />Lower left<br />
    60. 60. Upper right premolar<br />Lower anterior<br />
    61. 61.
    62. 62. Observation<br />All shadows, other than the localized shadows of the normal landmarks must be observed.<br />For example: shadows in crowns, cervical area, roots, restorations, size of root canals, periodontal membrane space, periapical area, alveolar crest, foreign bodies, integrity of bone …………<br />
    63. 63. General consideration<br /><ul><li>A radiograph shows only 2 dimensions of a 3 dimensional object (width and height but not the depth)
    64. 64. Cervical burnout: usually appears as cervical RL and misinterpreted by caries; this occurs due to less density and more penetration of rays.
    65. 65. Pulp exposure never to be determined from radiograph but only the proximity to the pulp. </li></li></ul><li>Interpretation<br />Studying the features of teeth and bone:<br />Teeth<br />Study the whole tooth,(crown, root enamel, pulp….), number of teeth and finally supporting structures, (Periodontal membrane space, lamina dura, alveolar crest) <br />
    66. 66. Bone<br />Changes in bone may include:<br />1- Changes in density.<br />2- Changes in the margin<br />3- Changes inside the lesion.<br />4- Effect on surrounding tissues.<br />5- Changes in structure<br />
    67. 67. Correlation<br /><ul><li>The final step is to correlate all of the radiographic features to reach a radiographic differential diagnosis.
    68. 68. Then to draw a final diagnosis, we have to correlate other data as case history, clinical examination, and other diagnostic aids with the radiographic differential diagnosis.</li></li></ul><li>0<br />