Rad Lec

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Author:
edgarl
ID:
172412
Filename:
Rad Lec
Updated:
2012-09-21 17:50:30
Tags:
ray machine
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Description:
radiation production
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  1. How many cycles of electricity occur in a second, 1/2 second?
    60 cycles, 1/2 second 30
  2. How many impulses of x-rays are generated per second, 1/2 second?
    60, 30
  3. What does the mA measure?
    Quantity or amount
  4. What 2 factors determine quantity of electrons thus x-rays?
    mA and time
  5. What control factor determines the speed of electrons thus the penetrating power of x-rays?
    kVp
  6. What does kVp measure?
    Quality or speed
  7. What control panel setting controls contrast?
    kVp
  8. A radiograph with mostly black and white is called a ______ contrast.
    High scale or short scale
  9. What produces a short scale (high scale contrast)?
    low kVp
  10. What produces a long scale (low scale contrast)?
    High kVp
  11. A radiograph with lots of grays is called a _____contast.
    low scale or long scale
  12. What is the step-down transformer controlled by?
    mA
  13. What is the step-down transformer connected to and heats up?
    Filament wire (low voltage filament circuit)
  14. What is the step-up transformer connected to?
    mA and kVp
  15. What is the step-up transformer controlled by?
    kVp
  16. Which transformer has more turns in the secondary coil?
    Step-up
  17. Which transformer has more turns in the primary coil?
    Step-down
  18. Which is the negatively charged terminal?
    Cathode
  19. Which is the positively charged terminal?
    Anode
  20. What two structures are made of Tungsten?
    Target and filament wire
  21. What is the source of electrons?
    filament wire
  22. What is the source of x-rays?
    Target
  23. What parts are inherent filtration?
    Glass (aperature), Oil bath, and Metal barrier
  24. What part is added filtration?
    filter
  25. Which 3 structures are protective devices?
    filter, PID, and collimator
  26. What does the filter do, what is it made of, and how thick does it have to be?
    • Removes weak, less penetrating x-rays from the beam
    • Aluminum
    • 1.5 under 70 kVp and 2.5 70 and above
  27. What does the collimator do, and what is it made of?
    • Restricts the size of the beam to 2.75 inches
    • Lead
  28. Which PID reduces the radiation exposure the most and how much?
    • long, lead lined, rectangular
    • 50%
  29. What two control panel factors settings control density?
    mA and time
  30. High density film is obtained by increasing the ___or ___.
    mA or time
  31. Low denstiy film is obtained by decreasing the ____or____.
    mA or time
  32. What must be present to produce x-rays?
    • A source of free electrons
    • A high voltage to give them speed
    • A target to stop them
  33. What happens when the low voltage circuit is activated?
    The filament wire heats up and thermionic emission occurs
  34. What happens when the high voltage circuit is activated?
    • There is a potential difference between the cathode and anode
    • Electrons are propelled towards the target
    • X-rays and heat are produced
  35. When are x-rays produced?
    When electrons strike the tungsten target
  36. How much is heat and how much is x-ray that is produced?
    • 99% heat
    • 1% x-ray
  37. Define self-rectification
    X-rays are only produced when the cathode is negative and the anode is positive
  38. Define attenuation
    The removal of x-rays from the beam by absorption or scatter
  39. Radiopaque structures are a result of more or less attenuation of x-rays?
    More
  40. Radiolucent structures are a result of more or less attenuation of  x-rays?
    Less
  41. Attenuation by absorption is?
    Photoelectric effect
  42. Attenuation by scatter is?
    Compton effect
  43. Define Bremstrallen radiation
    When electrons interact with the nucleus of a target atom
  44. Define Characteristic radiation
    When electrons interact with an electron of a target atom
  45. Define Thermionic emission
    The boiling off of electrons into a cloud at the filament wire
  46. Foreshortening
    Too much vertical angulation
  47. Overlapping
    Error in horizontal angulation
  48. Elongation
    Not enough vertical angulation
  49. #00 and 0 film
    children PA and BW
  50. #1 film
    Adult anterior PA
  51. #2 film
    Adult posterior PA and BW
  52. #3 film
    Long adult posterior BW
  53. #4 film
    Occlusal, whole arches
  54. Characteristics or Properties of  X-rays?
    • Can cause a fluorecent screen to glow
    • Can affect a photographic plate
    • Invisible
    • Travel long distances at the speed of light (186,000 mi/sec)
    • Have no mass
  55. Advantages of paralleling and bisecting?
    • Paralleling- less distortion
    • Bisecting- good for shadow palates
  56. Define Density and Contrast
    • Density- overall blackness of the film
    • Contrast- difference in densities within a film
  57. Purpose of intensifying screen
    To intensify the radiation to allow a reduction in radiation exposure time
  58. Why use fast speed film?
    To reduce exposure time
  59. What is the fastest speed film and how much does it reduce exposure time?
    • F speed
    • 60%
  60. To change from 10 mA and 6 seconds to 15 mA exposure time and maintain density?
    • 10 X 6=60 mAs
    • 15x = 60 mAs
    • x = 4 seconds

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