Module 9

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Author:
nenyabrooke
ID:
98612
Filename:
Module 9
Updated:
2011-12-08 23:31:24
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Principles Radiation Protection
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Description:
ALARA and Digital Imaging Systems
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  1. What is the conventional measurement unit for dose equivalent when measuring radiation?
    rem
  2. Which unit of measurement measures the ionization in the air?
    roentgen
  3. What unit of measurement is used in the Landau (sp?) Report?
    rem
  4. What are the three pillars of radiation protection?
    • time
    • distance
    • shielding
  5. Which pillar of radiation protection is directly related to dose?
    time
  6. Is it better to use restraints or yourself to hold a patient in position for an x-ray?
    restraints, when possible
  7. When your patient is a baby, to hold a position for an image, you should use:
    A. restraints
    B. yourself
    C. a family member of the patient
    C. a family member of the patient
    (this multiple choice question has been scrambled)
  8. By law, a fluoroscopic unit must have an audible timer that goes off ________________.
    every five minutes
  9. A fluoroscopy pedal on the floor should be of what kind, and why?
    a "dead-man" type of pedal because exposure stops when the pedal is not compressed.
  10. Ideally, when assisting in a fluoro room, you should:
    A. walk out and stand behind the wall
    B. stand behind the doctor
    C. stand beside your patient
    A. walk out and stand behind the wall
    (this multiple choice question has been scrambled)
  11. If you double your distance from your patient during a procedure, you decrease your radiation exposure by a factor of:
    4
  12. Most of the radiation exposure that a technologist receives is from:
    scatter radiation from the patient
  13. Leakage radiation, by law, cannot exceed:
    100 mR per hour when measured at one meter from the tube.
  14. When does the technologist stand in the primary beam?
    never
  15. As you increase your distance from the patient, your exposure will increase or decrease?
    decrease
  16. What is the thickness required in a primary barrier?
    1/16-inch lead equivalency
  17. At 100 kVp or higher, what lead equivalency does a lead apron need to be?
    .5mm lead equivalency
  18. Lead gloves must be made of _____ lead equivalency. This still allows_______________.
    • 0.25mm lead equivalent
    • movement and flexibility
  19. A protective curtain on the control tower of a fluoroscopic machine needs _________ lead equivalency.
    0.25mm lead equivalency
  20. Where should a dosimeter be worn?
    between the chest and the waist in the same place every day. It should not be covered when a lead apron is worn.
  21. Annual Effective Dose:
    5 rem
  22. Annual Effective Dose for a Co-Lin student:
    1 rem
  23. annual dose limit for the lens of the eye:
    15 rem
  24. annual dose limit for the hands:
    50 rem
  25. annual dose limit for the thyroid:
    50 rem
  26. annual dose limit for the feet:
    50 rem
  27. annual dose limit for the skin:
    50 rem
  28. What does ALARA mean?
    "as low as reasonably achievable"
  29. Can we ethically set dose limits for patients?
    no
  30. the minimum standard for source-to-skin distance for stationary equipment is:
    15 inches
  31. The minimum standard for source-to-skin distance for portable fluoroscopic equipment is:
    12 inches
  32. What does PBL stand for, and what is it?
    "Positive Beam Limitation" is basically automatic collimation. It adjusts to limit the radiation field to the image receptor area.
  33. What technical factors decrease the dose to the patient?
    high kVp and low mAs
  34. The optimal kVp range for the AP Spine:
    75-95
  35. The optimal kVp range for the Chest:
    110-120
  36. The optimal kVp range for the Lateral Spine:
    85-100
  37. The optimal kVp range for the Abdomen:
    75-90
  38. The optimal kVp range for the Skull:
    75-85
  39. The optimal kVp range for an Extremity Non-grid:
    55-70
  40. The optimal kVp range for a Extremity with Grid:
    75-85
  41. What does AEC control?
    time (seconds)
  42. The NCRP recommends adding filter material with a minimum of _____ aluminum equivalent to the x-ray tube to absorb the weaker x-rays.
    2.5mm aluminum equivalent
  43. When converting from analog to digital, kVp will generally _________.
    increase by 10-15 kVp (not percent)
  44. Grid Conversion Factor
    No Grid = ?
    No Grid = 1
  45. Grid Conversion Factor
    5:1 = ?
    5:1 = 2
  46. Grid Conversion Factor
    6:1 = ?
    6:1 = 3
  47. Grid Conversion Factor
    8:1 = ?
    8:1 = 4
  48. Grid Conversion Factor
    10:1 = ?
    5
  49. Grid Conversion Factor
    12:1 = ?
    5
  50. Grid Conversion Factor
    16:1 = ?
    16:1 = 6
  51. Will changing from a 5:1 grid to a 10:1 grid increase or decrease technical factors?
    increase
  52. Because of the change from analog to digital, is there an increased worry about habitual overexposure or underexposure?
    overexposure
  53. Does the latitude range widen or narrow when changing from analog to digital imaging?
    it widens
  54. Are technical factors for density easier to see in analog or digital imaging?
    analog
  55. Does automatic rescaling increase or decrease chances to be able to see changes in technical factors?
    decrease
  56. What is the symbol for Roentgen?
    What is its SI Unit equivalent?
    • R
    • Coulomb/Kilo
  57. What is "rad" the symbol for?
    What is its SI equivalent?
    • Radiation Absorbed Dose
    • gray (Gy)
  58. What is "rem" the symbol for?
    What is its SI Unit equivalent?
    • Radiation Equivalent in Man
    • sievert (Sv)
  59. Increase time of exposure, the dose ___________.
    increases
  60. Increase distance to exposure site, your dose _________.
    decreases
  61. Increase shielding, the dose __________.
    decreases
  62. Leakage radiation is when:
    x-rays escape from the tube housing
  63. What are the two main forms of shielding?
    • structural shielding
    • individual lead shielding
  64. What are the two main types of structural shielding?
    • primary barriers (1/16th inch of lead)
    • secondary barriers (1/32-1/64 inch of lead)
  65. What is the range of thickness for a lead thyroid shield?
    0.25-.5mm of lead equivalent
  66. Where do your store individual shields?
    What do you NOT do to them when storing them?
    • On wall hooks, if possible, or at least laid flat or rolled.
    • Never fold, as it can cause cracks (checked annually)
  67. The bucky slot cover minimum is ______ lead equivalency.
    0.25mm
  68. If you increase kVp, you ___________ entrance skin exposure (ESE).
    decrease
  69. Where is a contact shield placed?
    between the x-ray tube and the radiosensitive organs of the patient (usually the gonads). They come in contact with the patient.
  70. Does collimation reduce or increase the patient's radiation dose?
    reduce
  71. Does collimation improve or hamper radiographic contrast?
    improve
  72. Three main reasons we use technique charts in both analog and digital imaging:
    • to maintain a consistent signal intensity
    • to maintain a consistent radiographic contrast
    • they balance image quality with patient dose
  73. The three main types of technique charts:
    • fixed kVp
    • variable kVp
    • technique charts designed for use with automatic exposure control (AEC) systems
  74. What is an optimal kVp?
    the ability of the x-ray beam to penetrate the anatomical structures without causing additional scattered radiation
  75. _________ is added to the area just beneath an x-ray tube to absorb weak x-rays created inside the device that add very little to the image and greatly increase patient dose.
    Filtration
  76. What is the use of using a grid?
    it absorbs scattered radiation from the patient before it reaches the image receptor and degrades the image.
  77. When using a grid, must you increase or decrease technique to compensate?
    increase
  78. Shadow Shields don't have to touch a patient when used properly. True or False?
    True
  79. PBL reduces patient dose by automatically ________ the radiation field size.
    reducing
  80. Digital imaging algorithms can make a digital image look acceptable no matter what technical factors we use. True or False?
    False
  81. Changing the visual appearance of a digital image to match the accepted appearance for a given anatomical structure is known as automatic resolution. True or False?
    False
  82. Using kVp levels that are too _______ can result in an image with too much _______ which degrades image quality.
    • high
    • noise
  83. The primary controller of contrast in digital imaging is kVp. True or False?
    False
  84. Using kVp to adjust for grid ratio increases in digital imaging is a viable way to adjust technique without affecting image quality. True or False?
    True.
  85. As the speed class of operation increases, noise _______.
    increases
  86. The speed class of operation for an analog image receptor is fixed. True or False?
    True

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