Rad Expo Exam 2

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Rad Expo Exam 2
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2013-10-23 00:31:29
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Rad Expo Exam 2
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  1. The amount of filtration required to reduce the exposure of the beam to half of its original intensity is defined as:

    Select one:
    HVL
  2. What is filtration's relationship with density?

    Select one:
    inverse
  3. Setting identical exposure factors, which type of x-ray unit will produce the greatest heat?

    Select one:
    High frequency
  4. What causes the anode heel effect to occur?

    Select one:
    The angle of the target
  5. Total filtration in the x-ray beam includes:

    Select one:
    B and C
  6. Which element is added filtration usually made of?

    Select one:
    Al
  7. Which of the following constitute inherent filtration? Choose all that apply

    Select one or more:
    • Oil surrounding the tube
    • Glass envelope
    • Mirror inside the collimator
  8. Due to the anode heel effect, the differences in intensities between the ends of the x-ray field can be as much as:

    Select one:
    45%
  9. The amount the voltage varies during an x-ray exposure is known as:

    Select one:
    Voltage ripple
  10. ____________ will extend  x-ray tube life.
    Select one:
    Warming up the tube after 2 hours of nonuse
  11. An exposure of 100 kVp, 800 mA, and 0.1 seconds is a safe expsoure.
    Select one:
  12. What is the MAIN purpose of filtration?

    Select one:
    Decrease patient dose
  13. Which of the following types of filtration produce a more uniform exposure to the image receptor?

    Select one:
    Compensating
  14. What is the most common type of generator used today?

    Select one:
    High frequency
  15. Effective compensation for the anode heel effect would involve positioning:

    Select one:
    the thinnest portion of the part under the anode
  16. Why are instantaneous load tube rating charts used?
    An instantaneous load tube rating chart is used to determine whether a particular exposure would be safe to make and to determine what limits on kVp, mA, and exposure time must be made to make a safe exposure. (p.37)
  17. X-ray tubes operating above 70 kVp must have total filtration of at least _________ of aluminum, or its equivalent.

    Select one:
    2.5 mm
  18. Which of the following practices will extend the life of the x-ray tube?
    1. Use low mA and longer exposure time.
    2. Warm up the tube as appropriate.
    3. Hold down the rotor button for a long time, to keep the tube warmed up.

    Select one:
    1 & 2 only
  19. Low energy photons are desirable in the x-ray beam because they contribute to image quality.

    Select one:
  20. How many heat units (in HU) will result from an exposure made on a single phase x-ray unit using 400 mA, 0.2 seconds, and 70 kVp?
    5600 HU
  21. What is the formula for heat units?

    Select one:
    mA x exposure time x kVp x generator factor
  22. An exposure of 80 kVp, 1000 mA, and 0.01 seconds is a safe expsoure.

    Select one:
  23. What is filtration's relationship with contrast?

    Select one:
    inverse
  24. The intensity of the x-ray beam is greater on the

    Select one:
  25. The differences in intensities on the anode and cathode sides can be as much as?
    45%
  26. Define "half-value layer"
    "Half-value layer" is the amount of filtration that reduces the intensity of the beam to one-half its original value.
  27. Filtration of the x-ray beam results in:

    Select one:
    Increased beam quality
  28. As collimation decreases, exposure to the IR increases.

    Select one:
  29. Significant collimation requires an increase of _____________ of the mAs.

    Select one:
    30 to 50%
  30. What effect does increasing the kVp have on scatter radiation?

    Select one:
    increases
  31. Technologist should always be aware of limiting the x-ray field size for which 2 reasons?

    Select one or more:
    • scatter
    • patient dose
  32. What occurs when scatter radiation strikes the film?

    Select one:
    Radiographic contrast decreases.
  33. What effect does body part size have on scatter radiation?

    Select one:
    The thicker the part, the more scatter
  34. Which of the following beam restricting devices is best at limiting unsharpness surrounding the radiographic image?

    Select one:
    collimator
  35. The purpose of the mirror inside the collimator is to:

    Select one:

    d.
    Project a light field onto the patient
  36. What shape is the unrestricted x-ray beam?

    Select one:
    cone
  37. As collimation decreases, density:

    Select one:
    increases
  38. A beam restricting device that has 2 or 3 sets of lead shutters is a(n):

    Select one:
    Collimator
  39. Decreasing collimation results in:

    Select one:
    A larger field size
  40. When using a digital flat-panel detector:

    Select one:

    The radiographer must adjust the collimator to the area of interest.
  41. What is the MAIN purpose for automatic collimators?

    Select one:
    reduce patient exposure
  42. BRIEFLY explain 2 general problems with the collimator light.
    The two general problems with a collimator light is that the light can go out and the light field can be misaligned depending on the angle of the mirror.
  43. Which exposure factor should you change to compensate for increasing collimation?

    Select one:
    mAs
  44. An aperture diaphragm with an attached elongated tube is a(n):

    Select one:
    Cylinder
  45. Increasing collimation results in reduced patient exposure, increased field size, and reduced scatter production.

    Select one:
  46. The smaller the volume of tissue irradiated, the:

    Select one:
    Less the amount of scatter produced
  47. As collimation increases, contrast:

    Select one:
    increases
  48. Name 3 types of beam restriction devices.
    Three types of beam restricting devices are: aperture diaphragms, cones and cylinders, and collimators.
  49. Which beam restriction device can be cut to the size needed?

    Select one:
    An aperture diaphragm
  50. What effect does increasing collimation have on patient dose?

    Select one:
    decreases
  51. What does PBL stand for?

    Select one:

    positive beam limitation
  52. What is the best type of beam restriction device?

    Select one:
    collimator
  53. What purpose does positive beam limitation serve?

    Select one:
    To reduce patient exposure by limiting the exposure field to the same size as the image receptor in the Bucky tray
  54. What is another name for PBL?

    Select one:
    automatic collimation
  55. Why is scatter radiation bad?

    Select one:
    Decreases image quality
  56. Which of the following 2 factors would you use to help determine if you will use a grid for a particular exam?

    Select one:
    >60 kVp and >10 cm thick body part
  57. In a grid, what are the 2 types of orientation of the lead lines in relationship to one another? (Choose all that apply)

    Select one or more:
    • parallel
    • focused
  58. What is focal range and why does it matter?
    Focal range is the recommended SID range that the beam should be from a focused grid.  Focused grids are made with specific angles that can absorb and restrict the beam if placed at the wrong distance. This may make the image undiagnostic.
  59. A grid whose lead strips run perpendicular to the long axis of the grid is called a(n):

    Select one:
    Short dimension grid
  60. The recommended SIDs that can be used with a focused grid describes the:

    Select one:
    Focal range
  61. Which of the following statements is true?

    Select one:
    As grid ratio increases, the removal of scatter increases.
  62. What is the most common type of grid cutoff error?

    Select one:
    off-level
  63. Why is Aluminum used at interspace material in grids?
    Aluminum is used because it is strong enough to support the grid but is also easily penetrated by photons.
  64. Grid frequencies can range from:

    Select one:
    25 to 80 lines per centimeter
  65. An adult's knee measuring 14 cm should be done without a grid.

    Select one:
  66. Increasing grid ratio has what effect on density?

    Select one:
    decreases
  67. Who invented radiographic grids?



    Select one:
    Gustave Bucky
  68. What is the MOST effective means for limiting scatter that hits the IR?

    Select one:
    grids
  69. Patient dose increases when:
    1. Changing from a higher to a lower grid ratio
    2. Changing from a lower to a higher grid ratio
    3. A grid is used


    Select one:
    2 & 3 only
  70. If you have a good technique at 5 mAs with a 5:1 grid, what technique would you need to use when switching to a 16:1 grid? (Units in mAs)
    15 mAs
  71. Which grid design is manufactured to match the divergence of the x-ray beam?

    Select one:

    The focused grid
  72. What occurs when the x-ray beam is not properly aligned with the grid strips?

    Select one:
    Grid cutoff
  73. Briefly expain why scatter radation is bad.
    Scatter adds unwanted density without adding to patient information.  Scatter ruins image quality.
  74. Increasing grid ratio has what effect on contrast?

    Select one:
    increases
  75. The only type of grid cutoff that occurs with both focused and parallel grids is due to:

    Select one:

    Off-level misalignment
  76. Which type of grid pattern is the MOST popular?

    Select one:

    linear
  77. If you have a good technique at 10 mAs without a grid, what mAs would you need to use when switching to a 6:1 grid? (Units in mAs)
    30 mAs
  78. What is the focal range for a parallel grid?

    Select one:
    parallel grids have no focal range
  79. Explain how the air gap technique works in terms of scatter radiation.
    When OID is increased, scatter from the patient is less likely to reach the IR.  The greater the gap, the greater the reduction on scatter reaching the IR.  The smaller the gap, the greater chance scatter has to reach the IR to contaminate the image.  mAs needs to be manipulated depending on OID to retain image density.
  80. Grids that move during the exposure:

    Select one:
    A and C
  81. Due to increased potential grid cutoff, which would be the most challenging grid to use?

    Select one:
    Cross-hatched grid
  82. Which of the following is not a way to reduce the production of scatter radiation?

    Select one:
    Increase the grid ratio.
  83. Changing from an 8:1 grid to a 12:1 grid, along with making the appropriate adjustments, will result in:
    1. Increased patient dose
    2. An image with increased contrast
    3. Using more mAs

    Select one:
    1, 2, & 3
  84. If the height of the grid strip is 16 mm, the distance between the strips is 2 mm, and the strip is 0.3 mm thick, what is the grid ratio?

    Select one:
    8:1
  85. What type of grid error results in appropriate exposure to the middle of the IR and marked underexposure along the sides of the IR?

    Select one:

    Upside-down focused grid
  86. What is grid ratio?

    Select one:

    ratio of the height of the lead strips to the distance between them
  87. Off-focus grid cutoff only occurs when the SID exceeds the focal range.

    Select one:
    False
  88. What is grid frequency?

    Select one:
    number of lead lines per unit of length
  89. What is the grid conversion factor for a 12:1 ratio grid?

    Select one:

    5x
  90. An optimal AP abdomen radiograph can be produced using 40 mAs, 75 kVp, and a 12:1 grid. How much mAs would be needed if the only grid available is a 6:1 ratio grid? (Units in mAs)
    24 mAs
  91. Which of the following influences the amount of scatter radiation striking the image receptor but not the production of scatter radiation?

    Select one:
    Increase the grid ratio.
  92. Which type of grid cutoff error is shown in this image?



    Select one:
    off-center
  93. Which type of grid error is shown in this radiograph?


    Select one:
    upside-down focused
  94. If an excellent knee radiograph is produced using 10 mAs and an 8:1 ratio grid, how much mAs will be needed if no grid is available?

    Select one:
    2.5 mAs
  95. Which of the following statements is true?

    Select one:
    If the height of the lead strips increases and the space between the grid strips decreases, the grid will be more effective at scatter removal.
  96. Inherent filtration
    • Glass envelope
    • Oil around tube
    • mirror
  97. Total filtration
    Inherent filtration + Added filtration
  98. Half-value layer
    • The amount of filtration that reduces the intensity of the beam to 1/2 its original value.
    • Indirect measure of total filtration.
  99. Hardening the beam
    is filtration
  100. What are the three types of generators?
    • Single-phase (voltage ripple = 100%)
    • Three-phase ( 6 phase = 13%, 12 phase = 4%)
    • High frequency (<1%)
  101. Filtration
    Process whereby the average energy of a heterogeneous radiation beam in increased by passing it through an absorber.
  102. What are the two purposes of beam restriction?
    • limit patient exposure
    • reduce scatter
  103. What are 2 problems with the collimator light?
    • light goes out
    • light field (mirror) is misaligned
  104. When were grids invented?
    1913
  105. Grid frequency
    • The number of lead lines per unit of length.
    • Range = 25 to 45 lines/cm, or 60 to 110 lines/inch.
  106. Grid ratio
    • The ratio of the height of the lead strips over the distance between them.
    • GR = h/D.
  107. Grid ratio ranges:
    • 5:1     2×mAs
    • 6:1     3×mAs
    • 8:1     4×mAs
    • 12:1   5×mAs
    • 16:1   6×mAs
  108. Grid patterns
    • Linear (lead lines run in one direction, most popular, allows tube angulation)
    • Crossed (crossed-hatched, lead lines run in 2 directions, removes more scatter, doesn't allow angulation)
  109. Grid focus
    • Refers to the orientation of the lead lines to one another.
    • Parallel or non-focused grid - mostly use in fluoro and mobile imaging.
    • Focused grid - allows more photons to hit IR.
  110. Convergent Point
    Imaginary line drawn from each of the lead lines.
  111. Convergent Line
    Points of convergence connected along the length of a linear focused grid.
  112. Focal distance
    distance between the grid and the convergent line or point.
  113. Focal Range
    recommended range of SIDs that can be used with a focused grid.
  114. Focal range at 40" focal distance?
    36" to 42"
  115. Focal range at 72" focal distance?
    66" to 74"
  116. Wafer Grid
    matches size of cassette, placed on top of IR, usually taped.
  117. Grid Cassette
    IR with a permanently built-in grid mounted to its surface.
  118. Grid cap
    Permanently mounted grid that allows an IR to slide in behind it.
  119. A short dimension grid has lead strips running perpendicular to the long axis of the grid.
  120. A long dimension grid has lead strips running parallel to the long axis of the grid.
  121. Grid cutoff
    a decrease in the number of transmitted photons that reach the image receptor because of some misalignment of the grid.
  122. 4 types of grid cut-off
    • Upside-down focused
    • Off-level
    • Off-center
    • Off-Focused

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