DHE 116 CHAPTERS 2 3 6 9 Quiz#2

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  1. Radiolucent
    Portion of the image that is dark or black
  2. Radiopaque
    Portion of the image that is light or white
  3. Density
    The degree of darkness or image blackening (ex. light image has little density, dark image has more density)
  4. Contrast
    Refers to the many shades of gray that separate the light and dark areas
  5. High kV results in high or low contrast?
    Low contrast
  6. Low kV results in high or low contrast?
    High contrast
  7. 3 professional goals in dental radiography?
    Patient protection, operation protection, and patient education
  8. What three conditions must exist for x-rays to be produced?
    • A source of free electrons (cathode)
    • High voltage to impart speed to the electrons (kV)
    • A target that is capable of stopping the electrons (anode)
  9. Cathode
    • Negative electrode
    • Tungsten wire/filament
    • Focusing cup
    • heats incandescent (red hot)
  10. ______ is vacuum tube that produces X-rays an energy converter
    X-ray Tube
  11. focal spot
    • small area on the target on the anode toward which the electrons from the focusing cup of the cathode are directed
    • x-rays originate from here
  12. Anode
    • Positive electrode
    • Tungsten target
    • Copper stem/radiator
    • 20* angle
    • 1 direction = primary beam
  13. What happens when you push that button?
    • You get the wave
    • IONIZING radiation is produced
    • Creates e- cloud of energy
    • Heats = speed Releases the invisible x-rays in a Wave
  14. The anode contains a copper stem/radiator, what is the purpose of it?
    Heats up and absorbs the generated heat (it is a good conductor)
  15. What is the purpose of the cathode?
    To supply electrons to make the X-rays
  16. What is the purpose of the anode?
    The tungsten target found inside stops/slows down the electrons (converting the kinetic energy into X-ray energy)
  17. Describe the process of producing radiation inside the tube head
    • 1. Cathode creates a cloud of electrons (quantity of electrons controlled by the mA)
    • 2. Tungsten wire/filament heats up and excites the electrons, shooting them into the anode
    • 3. Electrons bounce off of the focal spot on the tungsten target found on the anode
    • 4. Primary beam then shoots out of the PID
  18. Quality (energy strength) of the beam is controlled by what setting?
    kVp
  19. Quantity (amount of X-rays/electrons) is controlled by what setting?
    mA
  20. Port seal
    Determines the size of the beam, exiting the tube head
  21. Lead Collimator
    Restricts the beam once exiting the port seal
  22. What is produced in result of lead collimator restriction?
    Primary/useful beam
  23. Central ray
    The X-ray in the center of the primary beam
  24. What is the preferred wavelength in dental radiography?
    Short and fast, primary beam is strong
  25. What wavelength should we stay away from as hygienists?
    Long
  26. What determines the mA setting?
    Patient's mass
  27. Voltage (kVp)
    Force the electrons to push through the mass, penetration ability
  28. Amperage (mA)
    • amount of current in tube and available # of free e-
    • the Quantity (amount) of radiation affects how dark or light the whole radiograph looks.
    • This is DENSITY.
    • The denser the e- cloud (controlled by mA) the darker the image
  29. ______ is x-rays of many different energies & must be filtered to allow only x-rays with sufficient energy to reach the oral structures
    Polychromatic beam
  30. _____ = tube potential…. highest voltage to which the current in the tube rises during an exposure  1,000 V / (kVp – kilovoltage peak)
    Kilovolt peak (kVp
  31. What happens if you increase the speed of e- in the tube ? Or increase the Voltage (kVp)?
    • Too dark
    • Lowers contrast (too grey)
  32. What happens if you Lower the speed of e- / voltage (kVp)?
    Image increases in contrast and  the image is too light
  33. _____  determines the speed of the e- and therefore the penetrability of the x-rays produced
    kVp
  34. ______ e- over to tungsten target & controls the amount of attraction of e- to the target (which is 1%) other 99% is absorbed in the tube (*slide 22)
    KvP pulls
  35. What happens with a decrease in number of (e-)? Or a Lower mA?
    Image becomes too grainy
  36. What happens when you increase # of e- in the conductor? Or UP the mA?
    Image is too dark
  37. Long scale contrast
    Low contrast, lots of grays (high kVp)
  38. Short scale contrast
    High contrast, less gray and more black/white
  39. What contrast scale do we prefer in dental radiography?
    Long scale contrast
  40. Describe the matter if the image was too dark (high density)
    Matter was flooded with radiation
  41. Describe the matter if the image was too light (low density)
    No radiation went through/penetrated through matter
  42. What type of radiation are we producing in the tube head?
    Ionizing radiation
  43. Where do the electrons forming the electron cloud in the cathode come from?
    We steal them! Taken from the most outer shell (L shell) of atom
  44. Bremsstrahlung Radiation (aka general radiation)
    Majority and primary kind of ionizing radiation, radiation produced
  45. Secondary radiation
    Beam hits the matter, however it is absorbed in the patient's soft tissue
  46. Scatter radiation
    Radiation deflects, beam hits all directions while hitting matter
  47. What two factors determines the absorption of the X-ray beam?
    Patient mass and energy of the beam itself
  48. Coulombs/per kilogram (C/kg)
    Unit of electrical charge
  49. Gray (Gy)
    Unit of energy deposited into the matter
  50. Sievert (Sv)
    • Measure protection, biological effects with different types of radiation on a human
    • ex. 1 xray = 1 factor = 1 Sv
  51. ALARA
    As low as reasonably achievable
  52. What is the collimator size at the end of the PID?
    2.75 inches
  53. What is the target? (Target Surface Distance)
    Anode
  54. What is the surface? (Target Surface Distance)
    Sensor
  55. ______ are made up of atoms
    ELEMENTS
  56. What is the distance? (Target Surface Distance)
    Beam from target (anode) exiting the PID must go through the object (tooth)
  57. ______ smallest part of an element
    atom
  58. atom + atom =
    molecule
  59. The innermost orbit or energy level is the __ shell, the next is the __ shell, and so on up to __ shells
    • K
    • L
    • 7
  60. the number of positively charged protons is ____to the number of negatively charged orbiting electrons = ______
    • EQUAL
    • stable atom
  61. ____ atoms that have gained or lost e- (unstable)
    ION
  62. ____ Ion = loss of an e-
    Positive
  63. ______ Ion = the lost (-) charged e-
    Negative
  64. ____ – is the joining of a (-)e- and (+) proton
    Ion pair
  65. ____ -  formation of ion pairs
    Ionization
  66. Why is this IONIZATION important
    ¢When an atom is struck by an x-ray photon an e- maybe dislodged causing the  -E          to form.          This creates energy in the form of incandescent (heat). (+) will try to find stability = ionizing radiation
  67. _____ = release and movement of energy through space
    Radiation
  68. Any radiation that produces ions is called
    ionizing radiation
  69. _______ The distance from the crest of one wave to the crest of the next wave
    Wavelength
  70. _____ number of waves emitted per second
    Frequency
  71. ______ produce lower frequency (lower energy) and less penetrating power, and “soft radiatioN
    LONG WAVE LENGTHS
  72. _______produce higher frequency (high energy) more penetrating power, and “hard radiation.”
    Type of radiation we use.
    SHORTER WAVE LENGTHS
  73. Properties of X-rays
    • X-rays consist of electromagnetic bundles (quanta) the are called photons during Bremsstrahlung (or Braking) Radiation
    • Are invisible
    • Travel in straight lines
    • Travel at speed of light
    • Have no mass or weight

    • Have no charge
    • Interact with matter causing ionization
    • Can penetrate opaque tissues and structures
    • Now you know the reason why we need to be VERY CAREFUL
  74. _____= x-ray passes through matter and is weakened and disappears / the transferring of this energy is called ionization
    Absorption
  75. 4 probabilities exist with this ionizing radiation as it passes though a patient’s matter:
    • No interaction = x-ray passes through, atom unchanged = < 9% of the x-ray beam passes thru without interaction
    • Coherent scattering = e- vibrates/rattles without loss of energy < 8 % of the x-ray beam contains coherent scatter
    • Photoelectric effect = the collision of e- and photons to form kinetic energy creating and ion pair< > 30% of the x-ray beam interacts this way with matter
    • Compton scattering = partial e- interaction by ejecting an e- creating a new & weaker x-ray photon
    • < > 60% of the x-ray beam interacts this way with matter

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DHE 116 CHAPTERS 2 3 6 9 Quiz#2
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2017-09-25 00:09:38
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