VIII

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syntheral1
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25386
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VIII
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2010-06-30 21:04:20
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  1. Radiographs were first discoevred in 1895 by....who say his own hand bones
    Wilhelm Roentgen

    he was exploring the properties of Hittorf-Crookes cathod ray tube
  2. The short the wavelength the ______ penetrating it is.
    more

    shorter wavelengths are more penetrating because there are more waves of radiation hitting the target in a certain time period
  3. bundles of energy (photons, which move at the speed of light) that consist of particles and waves of electromagnetic radiation.
    particulate radiation
  4. as photons interact with electrons in the xray tube head, they remove the electrons from atoms. this produces the negative or positive imbalanced ions of
    ionizing radiation
  5. sudden deceleration of negatively charged electron as it passes near a positive nucleus, become attracted to it
    Bremsstrahlung or braking radiation
  6. xray radiation which is absorbed by the patient result in radioopaque areas. this absorption is called
    attenuated
  7. photons may exit the patient, and are exposed on radiographic films as radio_____ areas.
    radiolucent areas
  8. classic scatter radiation also called _______ or _______ occurs when a low energy xray photon that is unable to eject an electron from an atom excites the e instead. the photo fails to survive, though the excited e produces a new photo to be ejected from the atom
    coherent or Thompson effect
  9. when a high-speed photo ejectcauses an outer orbit electron to drop down in the auses an outer orbit electron to drop down in the space left empty by the ejected electron.
    Characteristic radiation or photoelectric effect


    This action emits energy. The electron that was originally ejected from the inner orbit is called a recoil electron.
  10. result of a high-energy photon ejecting a loosely bound outer orbit electron after the two collide. in this case, energy is being absorbed
    Compton effect
  11. when xray photons intermingle with water and oxygen of human tissue, the result is
    free radicals
  12. Tissue Sensitivity
    High: Lymphocytes, bone marrow, reproductive cells, thyroid glands in children, intestine, endocrine glands, skin, oral mucosa

    Moderate: developing bone and cartilage, connective tissue, small vasculature

    Low: mature bone and cartilage, salivary glands, thyroid glands in adults, kidneys, liver, muscles, nerve tissue
  13. What is the most sensitive tissue to radiation?
    lymphocytes
  14. How sensitive is bone marrow to radiation?
    High
  15. How sensitive is reproductive cells to radiation
    high
  16. How sensitive are children's thyroid glands to radiation
    high
  17. How sensitive are intestines to radiation
    high
  18. How sensitive are endocrine glands to radiation
    high
  19. How sensitive is skin to radiation
    high
  20. How sensitive is oral mucosa to radiation
    high
  21. How sensitive is developing bone and cartilage to radiation
    moderate
  22. How sensitive is connective tissue to radiation
    moderate
  23. How sensitive are small vasculatures to radiation
    moderate
  24. How sensitive is matuer bone and cartilage to radiation
    low
  25. How sensitive are salivary glands to radiation
    low
  26. How sensitive are thyroid cells in adults to radiation
    low
  27. How sensitive are kidneysto radiation
    low
  28. How sensitive is the liver to radiation
    low
  29. How sensitive are muscles to radiation
    low
  30. How sensitive is nerve tissue to radiation
    low
  31. the safest place to stand when exposing xrays to a patient is
    90-135 degree at the side of patient and away from primary beam
  32. lead aprons should be how thick?
    .25 mm
  33. how far away should you stand from an xray beam?
    6 ft
  34. what is the maximum permissible dose (MPD) for dental personnel?
    5.0 rem/year
  35. what is the maximum permissible dose for the general public?
    .5 rem/year
  36. maximum accumulated exposure accounts for age....
    5 for every year of their age after the 18th year.

    formula: 5(age - 18)
  37. amount of radiation absorbed that would cause biological death
    lethal dose
  38. the period from the time of exposure to the actual occurrence of a biological effect from radiation
    latent period
  39. two ways to measure radiation:
    Roentgen (R), rads, and rems

    and

    SI system, coulombs per kilogram. Gray, Sievert, and coulombs/kg
  40. 100 rad = ? Gy
    100 rad = 1 Gy
  41. 100 rems = ? Sv
    100 rems = 1 Sv
  42. 1 R = ? C/kg
    1 R = 2.58 x 10(-4) C/kg
  43. cathode contains the..
    filament, which produces electrons
  44. filament produces
    electrons
  45. when the heated filament "boils off" electrons in a cloud which surrounds the filament
    Thermionic emission
  46. Cathode is controlled by
    milliamperage
  47. percentage of electrons converted into radiographic electrons, and heat
    1% radiographic

    99% heat
  48. Cathod charge, Anode charge...?
    • To remember whether the cathode and anode are positive or negative, and in which direction the electrons travel, think about wanting a grade of
    • C- to go to an A+!!
  49. anode contains
    focal spot on tungsten target
  50. regulation states that aluminum filter must be ___ mm for xray exposure below 70 kVp, and ___ mm for exposures greater than 70 kPv
    • less than 70 kPv = 1.5 mm
    • greater than 70 kPv = 2.5 mm
  51. utilization of lead diaphragms to restrict the size of the beam
    Collimation

    does so through a round or rectangular aperture (opening) of the position indication device (PID)
  52. wire sensor that is placed like a regular radiographic film in the oral cavity.
    Direct digital imaging
  53. scans and digitizes a radiographic film onto the monitor, this method uses a CCD camera to scan in the radiograph
    Indirect digital imaging
  54. utilizes reusable imaging plate that is coated with phosphor.
    Storage phosphor imager
  55. Cathodes control the milliamperage which in turn controls the amount of electrons boiling off...which in turns effects the
    quantity of radiation
  56. work capcity of an xray unit is measured in volts or..kilovots peak (kVp). this controls the
    quality of radiation
  57. Increasing kilovoltage results in
    shorter more frequent wavelengths

    decreasing kilovolt peak yields high contrasts, which increasing kVp yields low contrast.
  58. Decreasing the kVp to 65-70 kVp will...
    allow for more contrast between black and white, excellent for caries detection
  59. Increasing the kVp will (75-90 kVp)
    decrease the contrast, more shades of gray, excellent for determing bone levels
  60. Contrast and kVp are in what type of mathmatical relationship?
    inverse, as one goes up the other goes down
  61. radiographic films are coated on both sides with green gelatin called emulsion, emulsions are made up of...
    silver halide crystals (silver bromide and silver iodide)
  62. Film speeds range from A to F. The high speed films requires less radiation exposures....but most dental radiographic films are
    D and E speed.

    E speed film needs about fifty percent less exposure than D-speed film
  63. Film size..
    0
    1
    2
    3
    4
    • 0: children
    • 1: mixed dentition, or anterior
    • 2: adult dentitions, both perapicals and bitewings
    • 3: long bitewings
    • 4: occlusal films
  64. SLOB rule (Same Lingual, Oppisite Buccal)
    to determine where an object is in a radiograph

    • 1 film taken normally
    • 2 film taken (for example) 20 degrees mesially

    • if the object moves mesially as well it is on the lingual side
    • if the object moves distally it is on the buccal aspect
  65. too much vertical angulation results in
    short teeth
  66. not enough vertical angulation equates to
    elongated teeth
  67. umbra is the main shadow, the side shadows are called
    pneumbra
  68. A small focal point will yield a
    sharper radiographic image

    (more parallel rays, less rifraf)
  69. object (tooth) to film distance should be
    short, to decrease magnification
  70. source (xray) to film distance should be
    increased to reduce magnification
  71. Manual processing films temperature and time
    • 68 F for 5 min
    • or
    • 72 F for 4 min

    (automatic processors function at a higher temperature)
  72. developing solution is a combination of
    hydroquinone and elon

    • hydroquinone: producing contrast, changes the latent image in the silver halide crystals to black metallic silver.
    • elon: generating details, prodcues gray tones of the latent image.

    Sodium carbonate or potassium hydroxide softens and swells the emulsion to provide an access for hydroquin and elon to contact the silver bromide crystals.

    Sodium sulfite, preserves, reduces oxidation

    potassium bromide and potassium iodidie are restrainers that reduce the action potential of developing solution
  73. hydroquinone
    found in developing solution, produces contrast by changing the latent image of the silver halide crystals to black metallic silver
  74. elon
    elon: generating details, prodcues gray tones of the latent image.
  75. softens and swells the emulsion to provide an access for hydroquin and elon to contact the silver
    bromide crystals.
    Sodium carbonate or potassium hydroxide softens and swells the emulsion to provide an access for hydroquin and elon to contact the silver bromide crystals.
  76. Sodium sulfite
    in developing solution, preserves and reduces oxidation
  77. potassium bromide and potassium iodidie
    restrainers that reduce the action potential of developing solution
  78. fixer solution is composed of
    ammonium or sodium thiosulfate: fixing agent that eliminates unexposed, under developed silver halide crystals

    acetic acid or sulfuric acid: neutralizes the developing solution to inhibit its action

    Sodium sulfite: reservative

    aluminum chloride or alumnium sulfide: to shrink emulsion
  79. a dark room needs to be what size?
    16 square feet in size
  80. saftey light in dark room needs to be
    set 4 ft above working surfaces and 15 watts or less
  81. If a radiograph comes back clear with nothing on it then
    it was never exposed
  82. if a radiograph is completely black than
    it was exposed to light
  83. if a radiograph is too dark then
    temperature of developing solutions is too warm
  84. a green film indicates
    it was not fixed enough
  85. black streaks on a film indicate
    bent film
  86. white streaks on a film indicate
    scratch, torn emulsion
  87. the inverted Y is composed of
    anterior wall of nasal floor and the wall of the sinus
  88. automatic processing requires what temp and tiem?
    83 F for 5 min
  89. lead disk that shapes and directs the beam
    Collimation
  90. what directs the xray beam from the cathode to the anode
    focusing cup, found in cathode and directs the beam to the anode
  91. acidifier of fixing solution
    acetic acid
  92. swells and softens emulsions
    sodium carbonate
  93. shrinks and hardens emulsions
    ammonium sulfate
  94. what chemical is found in both developing and fixer solutions?
    sodium sulfite, preservative

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