radiology

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sweetpea281
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42093
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radiology
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2010-10-13 23:58:43
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ch22
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chapter 22 panoramic radiography
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  1. shows a wide view of the upper and lower jaws
    panoramic film
  2. an extraoral radiographic technique that is used to examin the upper and lower jaws on a single film
    panoramic radiography
  3. the panoramic film provides the dental radiographer with an overall image of the _____ and _____ and is often used to supplement _____ and selected ______ films.
    • maxilla
    • mandible
    • bite-wing
    • periapical
  4. what purposes is the panoramic radiograph used for?
    • evaluate impacted teeth
    • evaluate eruption patterns, growth and development
    • detect disease, lesions and conditions of jaw
    • examin extent of large lesions
    • evaluate trauma
  5. why can't the pano be used to evaluate and diagnose caries, perio or periapical lesions
    not as defined or sharp as intraoral
  6. t/f a pano should not be used as a substitute for intraoral films
    true (unless intraoral is impossible)
  7. what does the term tomo mean?
    section
  8. radiographic technique that allows the imaging of one layer or section of the body while blurring images from structures in other planes
    tomography
  9. the movement of the film and the tubehead produces an image through the process known as..?
    tomography
  10. the pivotal point or axis around which the cassette carrier and xray tubehead rotate is?
    rotation center
  11. what are the three types of rotation centers?
    • double center rotation
    • triple center rotation
    • moving center rotation
  12. which rotation center involves one right and one left rotational centers?
    double center rotation
  13. which rotation has three centers of ration and create a uninterrupted radiographic image of the jaws?
    triple center rotation
  14. which rotation has a continuously moving center that is similar to the arches, creating an uninterrupted image of the jaws?
    moving center rotation
  15. a three-dimensional curved zone in which structures are clearly demonstrated on a panoramic radiograph
    focal trough
  16. the structures positioned outside the ____ _____ appear blurred or indistinct and are not readily visible on the pano
    focal trough
  17. the structures located ____ the focal trough appear reasonable well defined on the resulting pano
    within
  18. who controls the size and shape of the focal trough?
    manufacturer
  19. the ____ the rotation center is to the teeth, the narrower the focal trough
    closer
  20. in most pano machines the focal trough is _____ in anterior region and ____ in posterior regions
    • narrow
    • wide
  21. panoramic units may differ in ____ of rotation centers, the ___ and ____ of the focal trough, and the type of____ transport mechanism used.
    • number
    • size
    • shape
    • film
  22. what are the three main components of the pano unit
    • xray tubehead
    • head positioner
    • exposure controls
  23. the pano xray _____ is similar to the intraoral xray _____
    • tubehead
    • tubehead
  24. the _____ used in the panoramic xray machine is a lead plate with an opening in the shap of a narrow ____ _____
    • collimator
    • vertical slit
  25. the beam passes throught the patient and exposes the film through another___ ____ in the cassette carrier
    vertical slit
  26. the tubehead of the pano unit is ____ in position so the xray beam is directed slightly ____
    • fixed
    • upward
  27. the tubehead of the pano unit always rotates where?
    behind the patients head
  28. the film in the pano unit rotates where?
    in front of the patient
  29. what does a typical head positioner consist of?
    • chin rest
    • notched bite-block
    • forehead rest
    • lateral head supports or guides
  30. who determines the exposure factors for the pano unit
    manufacturer
  31. the _____ and _____ settings are adjustable and can be vaired to accommodate patients of different sizes
    • milliamperage
    • kilovoltage
  32. what exposure factor is fixed and cannot change?
    exposure time
  33. film that is sensitive to the light emitted from intensifying screens
    screen film
  34. the ___ ___ is placed between the two intensifying screens in a cassette holder
    screen film
  35. when the cassette holder is exposed to xray what happens with the screens?
    the screens convert the xray energy into light
  36. what are the two types of light used for screen films?
    • green light
    • blue light
  37. what are the two sizes available for panos?
    • 5 X 12 inch
    • 6 X 12 inch
  38. what are the two basic types of intensifying screens?
    • calcium tungstate
    • rare earth
  39. what kind of light does the calcium tungstate screens emit
    blue light
  40. what color of light does the rare earth screens emit?
    green
  41. which intensifying screen requires less xray exposure?
    rare earth
  42. what intensifying screen is considered faster?
    rare earth
  43. why are rare earth screens recommended?
    less radiation
  44. device that is used to hold the extraoral film and intensifying screens?
    cassette
  45. a cassette may be ___ or ____, ____ or _____ depending on pano unit
    • rigid or flexible
    • curved or straight
  46. all cassettes must be ___ ___ to protect the film from exposure
    light tight
  47. where are the intensifying screens placed?
    each side of the film
  48. t/f a lead apron and a thyroid collar are used on the patient when taking a pano?
    false-no thyroid collar
  49. what is the midsagittal plane?
    imaginary line that divides the patients face into right and left sides
  50. how should the midsagittal plane be positioned?
    perpendicular to the floor
  51. what is the frankfort plane
    imaginary plane that passes throught the top of the ear canal and the bottom of the eye socket
  52. how should the frankfort plane be positioned?
    parallel with the floor
  53. what is a radiopaque artifact seen on pano?
    ghost image
  54. what results in a ghost image?
    radiodense object is penetrated twice by the xray beam
  55. what appears on pano if patients lips are not closed?
    radiolucent shadow over anterior teeth
  56. what appears on pano if the tongue is not in contact with the palate?
    dark radiolucent shadow over apices of maxillary teeth
  57. what plane is wrong if the patients chin is positioned too high
    frankfort plane
  58. what four things are seen on the pano when the frankfort plane is angled upward
    • hard plate and floor of nasal cavity superimposed over roots of max teeth
    • loss of detal in max incisors
    • max incisors appear blurred and magnified
    • reverse smile line
  59. what happens if the frankfort plane is angled downward? (4)
    • mandibular incisors appear blurred
    • loss of detail in anterior apical region
    • mandibular condyles not visible
    • exaggerated smile line
  60. what happens if the patients teeth are anterior to focal trough
    anterior teeth appear skinny and blurred
  61. what happens if patients teeth are posterior to focal trough
    anterior teeth appear fat and blurred
  62. what happens if the midsagittal plane is not centered?
    ramus and post teeth unequally magnified
  63. what if the patient is not standing or sitting with a straight spine?
    cervical spine appears in center of film
  64. what are the four advantages to the panoramic radiograph
    • field size-entire max and man
    • simplicity
    • patient cooperation-no discomfort
    • minimal exposure
  65. what are the four disadvantages of the pano?
    • image quality-not sharp
    • focal trough limitations-objects not seen
    • distortion
    • equipment cost-high

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