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

Transcript

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