Rad Mid Term

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edgarl
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173684
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Rad Mid Term
Updated:
2012-09-30 12:46:26
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  1. Adult anterior film or pedo
    Film size #1
  2. Adult posterior film
    #2
  3. Pedo only
    #00, 0
  4. Occlusal film
    #4
  5. Long Bitewing film
    #3
  6. Intraoral film is non-screen film. It does not use an intensifying screen. True or False
    True
  7. Overlapping in the interpromixal spaces is to incorrect _____.
    horizontal angulation
  8. X-rays are regulated on a federal, state, and local level. True or False
    True
  9. Extraoral film is screen film. It is placed inside an intensifying screen. True or False
    True
  10. To view large areas on film such as the whole maxillary arch, you use _____.
    Occlusal film
  11. With extra oral film, it is exposed by light. True or False
    True
  12. What is the purpose of the lead foil in the film packet?
    • To absorb backscatter radiation from reaching the film which causes fogging of the film
    • Absorbs some radiation that would otherwise exit the film and be absorbed by the patient's face
  13. With intraoral film, it is light that primarily exposes the film. True or False
    False
  14. Cone Cutting on a radiograph is caused by ____.
    Failure to cover the film with the field of radiation (cone)
  15. The fuzziness (lack of detail or sharpness) of the outline of an image is ______.
    Penumbra
  16. Interproximal caries can best be detected with _____.
    Bitewings
  17. All of the following are intraoral films used except.
    Panorex, Periapical, Bitewings, Occlusal
    Panorex
  18. Periapical radiographs are mainly used to view, what?
    Apices of the teeth and surrounding structures
  19. Occlusal x-rays are used to view, what?
    A large area such as an entire arch on one film
  20. The efficiency with which a film responds to x-ray exposure is known as film sensitivity or film speed. Which speed is best for reducingradiation to the patient?
    Speed "F"
  21. Which of the following is screen film.
    1, 2, 3, 4, panorex
    panorex
  22. Incorrect vertical angulation will result in an image that is _____ and _______.
    Elongation and Foreshortening
  23. Foreshortening of the image on a maxillary radiograph may be caused by ________.
    vertical angulation being too high (excessives)
  24. Positive vertical is accomplished by pointing the head position indicating device (PID) of the x-ray unit _____.
    Downward
  25. Conditions that radiographs can demonstrate include:
    • Periodontal diseases
    • Calculus
    • Unerupted or supranumerary teeth
    • Caries
  26. What is the purpose of the intensifying screen?
    Increase radiation, to allow a decrease in exposure time
  27. Negative vertical is accomplish by pointing the PID or cone of the x-ray unit ____.
    Upward
  28. Periapicals show one arch and the entire tooth and root and bitewings show crowns of teeth. True or False
    True
  29. What is the term for when radiation is not able to pass freely through and appears white to light gray on an x-ray?
    radiopaque
  30. What are crystals (grains) composed of that cover film?
    Silver Halide
  31. What is the purpose of the dot on a piece of film?
    To help in mounting
  32. On what mounted radiographs is the dot convex (raised)?
    Labial Mounting
  33. When radiation is able to pass freely through and object that appears black to dark gray on film is what?
    Radiolucent
  34. A lead apron with a throid collar should be used for all intraoral films. True or False
    True
  35. All removeable appliances in the patients mouth must be removed before taking x-rays. True or False
    True
  36. Which of the following does not have to be documented in the patients record.
    Total # of takes and retakes, type of x-ray taken, date of exposure, All above must be documented
    All must be documented
  37. What is the most important use of radiographs in the dental practice?
    Diagnosis
  38. What side of the film should be facing the source of radiation?
    White side
  39. Who has the responsibilty to diagnosis and x-ray?
    The Dentist
  40. What is a latent image?
    invisible image produced after exposure and becomes visible
  41. Contrast is the different densities that make up our image. True or False
    True
  42. Elongation of an image on a maxillary radiograph is caused by, What?
    Vertical angulation being too low (insufficient)
  43. Which film is placed in the mouth long Vertically?
    Anterior films
  44. Which film is placed in the mouth long horizontally?
    posterior films
  45. When mounting radiographs, which one is best to aid in mounting?
    Right and left bitewings
  46. What is functioning of the outer portion (covering) of the film packet?
    To protect from moisture and light
  47. What effect does crystal (grain) size have on speed or sensitivity of the film?
    The larger the crystal, the faster the film
  48. When changing from "D" speed film to "E" speed film what happens to exposure time?
    Decreases 50%
  49. Density on a radiograph refers to:
    The overall degree of blackness of a single film
  50. Extra oral screen film uses an intensifying screen and is exposed by light. True or False.
    True
  51. Overlapping in the interporximal spaces is due to what?
    horizontal angulation
  52. In the bisecting technique, what is the only principle of shadowcasting.
    close film to object distance
  53. In the paralleling technique, the central ray is directed at what angle?
    90 degree to the film and tooth
  54. Which film is also called the long cone technique?
    Paralleling
  55. Who is the father of the science of radiation protection?
    Rollins
  56. Interproximal caries are best detected by what type of radiograph?
    Bitewings
  57. X-rays were discovered in 1895 by who?
    Roentgen
  58. Why is the paralleling technique recommended over the bisecting technique?
    It gives a less distorted image
  59. The ability of x-rays to penetrate some objects better than others is known as what?
    Differential Absorption
  60. Properties of X-rays
    • Can cause fluorescent screen to glow
    • Can affect a photographic plate
    • Invisible
    • Travel long distances at 186,000 mi/sec
    • Has no mass or weight
  61. Principles of Shadow casting
    • Source- small as possible
    • Long distance b/w source and object
    • Short distance b/w object and film
    • film and object parallel
    • 90 degree angle of x-ray beam
  62. X-rays are now known to belong to the ____spectrum.
    electromagnetic
  63. True or False. In Bisecting the film and tooth should be close.
    True
  64. What is the best way to reduce unnecessary radiation to the patient?
    Fast speed film
  65. Properties of a Cathode Ray
    • Causes fluoscence in certain cases
    • Travels short distances
    • Has Negative charged particles
    • Have Mass or weight
  66. What anatomical structure is used to locate the molars?
    Outer canthus of the eye
  67. What anatomical structure is used to locate the premolars?
    inner canthus of the eye
  68. What angle is the central ray directed in the bisecting technique?
    90 degrees to the imaginary line dividing the long axis of the tooth.
  69. What effect does the film sensitivity (spped) have on the radiograph image?
    The faster the film, the poorer the image
  70. What material is the filament wire and target made of?
    Tungsten
  71. What is the function of the diaphragm or collimator?
    To restrict the size of the beam
  72. The mA is a measurement of the _____ and the kVp measures the _____ of an electrical current.
    Quantity, Quality
  73. In the step up transformer, which coil has more turns?
    Secondary
  74. The number of electrons produced are controlled by what?
    mA and time
  75. Define Self-rectification
    X-rays are produced only when the electrical cycle is going from (-)  cathode to (+) anode
  76. What term means the boiling off of electrons?
    Thermionic emission
  77. When electrons are converted to x-ray energy and heat, what percentage is heat and what percentage is x-ray?
    • 99% Heat
    • 1% x-ray
  78. The speed or force of electrons and penetrating power of the x-ray beam is controlled by what?
    kVp
  79. What is attenuation of x-rays by absoption?
    Photoelectric effect
  80. What is Attenuation by scatter?
    Compton effect
  81. To get more penetrating x-ray, you would increase the what?
    kVp
  82. What is the source of the x-ray in the dental tube?
    Target
  83. What is the source of the electrons in the dental tube?
    filament wire
  84. How many impulses of x-rays are produced in 1/2 a second?
    30
  85. What controls the contrast of the radiograph?
    kVp
  86. What is the filter thickness required for a machine operating at and above 70 kVp?
    2.5mm aluminum
  87. What is the purpose of the aluminum filter?
    To remove weak, less penetrating x-rays from the beam
  88. What should the diameter of the beam not exceed at the patient's face?
    2.75 inches
  89. When a electron is stopped or slowed by the nucleus of a target atom is what?
    Bremstrahlung
  90. When an electron is stopped or slowed by the outer shell electron of a target atom is what?
    Characteristic
  91. The mA sends a current through the what?
    step down transformer to the filament wire
  92. What happens when the electric current is allowed to flow through the low voltage circuit?
    The filament wire heats up
  93. Adjustments in exposure time are made in order to control what?
    Density of film
  94. What is the collimator made of?
    Lead
  95. How are x-rays generated?
    Electrons striking the target
  96. High scale (short-scale) contrast exhibits what?
    pretty much black and white tones
  97. Approximately, how much does a rectangular PID reduce radiation exposure compared to the circular one?
    50%
  98. 3 Protective Devices
    Collimator, filter, and PID
  99. Conditions for x-rays to be produced
    • Source of free electrons
    • High voltage to give them speed
    • And a target to stop them
  100. What happens when a high voltage circuit is activated?
    • Potential difference b/w cathode and anode
    • Electrons are propelled toward the target
    • X-rays are produced
    • Heat is produced
  101. If an operator wishes to change from 15 mAs with a 2 second exposure time to 10 mAs and maintain the same density, what would be the exposure time?
    3 seconds
  102. Short scale (high) contrast is achieved by what?
    decreasing kVp
  103. If the operator wants to change from a short scale contrast to a long scale contrat and maintain the same density, what should be done?
    Increase the kVp and Decrease the mA or time
  104. Attenuation
    The removal of x-ray photons from the beam by absoption or scatter.
  105. Radiopaque structures attenuate more or less.
    More
  106. What are the inherent filtrations?
    • Oil
    • Glass aperature
    • Metal Barrier.

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