Digital 4, 5 and6

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Digital 4, 5 and6
2010-09-30 18:35:35
PACS Chapter

PACS Chapter 4, 5 and 6
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  1. In CR, the radiographic image is recorded on a thin sheet of plastic known as the:
    imaging plate
  2. The imaging plate consists of the following layers:
    Protective layer, phosphor layer, reflective layer, color layer, support layer, and backing layer
  3. The protective layer of the imaging plate is responsible for:
    protecting the phosphor layer
  4. The phosphor layer of the imaging plate is a layer of ______ that traps electrons during exposure.
    photostimulable phosphor
  5. Phosphors in the phosphor layer are usually made of phosphors from the:
    barium fluorohalide family
  6. The CR cassette consists of a durable and lightweight ____ material backed by a thin sheet of ____ that absorbs x-rays.
    plastic, aluminum
  7. Instead of an intensifying screen inside, the CR cassette has a ____ _____ that protects against ___ ____ buildup, dust collection, and mechanical damage.
    antistatic material, static electricity
  8. The layer of the imaging plate that sends light in a forward direction when released in the cassette reader:
    reflective layer
  9. The layer of the imaging plate that absorbs and reduces static electricity:
    conductive layer
  10. Newer imaging plates may contain a color layer, located between the active layer and the support, which:
    absorbs the stimulating light but reflects emitted light
  11. The support layer in the imaging plate consists of:
    a semirigid material that gives the imaging sheet some strength
  12. Soft polymer that protects the back of the cassette:
    Backing layer
  13. In CR, the remnant beam interacts with:
    electrons in the barium fluorohalide crystals contained within the imaging plate
  14. When electrons in the imaging plate are stimulated by the remnant beam, they enter the ____ _____ where they are trapped in an area of the crystal known as the ____ _____.
    conductive layer, color or phosphor center.
  15. After exposure, the cassette is fed into a reader that:
    removes the imaging plate and scans it with a laser to release the stored electrons
  16. What does “laser” stand for?
    Light Amplification by Stimulated Emission of Radiation
  17. A laser is a device that creates and amplifies a:
    narrow, intense beam of coherent light
  18. The laser beam passes through ___ ____ to an ___ ____ that directs the laser beam to the surface of the imaging plate
    beam-shaping optics, optical mirror
  19. Two types of lasers used to scan imaging plates:
    helium laser beam and solid-state laser diodes
  20. The laser beam is about ____ wide with a wavelength of ___ and scans the plate with a red laser light in a _____ pattern and gives energy to the trapped electrons.
    100 micrometers 633 nm, raster
  21. The plate movement through the scanner is known as:
  22. Digitizing a signal, such as the light signal from the photomultiplier, is:
    assigning a numeric value to each light photon
  23. An entire analog image is divided into a matrix of pixels with a unique brightness value based on the:
    energy stored on the phosphor
  24. Typical matrix sizes are:
    512x512, 1024x1024, or 2500x2500
  25. The number of bits per pixel is known as:
    bit depth
  26. The number of gray tones a pixel can produce is ___ to the power of the ____.
    2, bit depth
  27. The amount of detail in any image is known as it’s:
    spatial resolution
  28. What determines spatial resolution in CR?
    phosphor layer thickness and pixel size
  29. The thinner the phosphor layer, the ____ the resolution.
  30. Which has better spatial resolution: CR or film/screen? Why?
    film screen has 10lines/mm as opposed to 2.5-5 lines/mm
  31. The loss of spatial resolution in CR is made up for by:
    increased contrast resolution due to the dynamic range or number of recorded densities
  32. Dynamic range is:
    the number of recorded densities
  33. In conventional radiography, speed is determined by:
    size and layers of crystals in the film and the screen
  34. The speed class in CR is a reflection of the amount of:
    light emitted by the plate during the reading process
  35. The amount of light emitted by the plate during the reading process in CR is related to:
    the level of exposure received by the receptor
  36. The phosphors in the imaging pate emit light according to the ___ and ____ of the laser beam as it scans the plate.
    width and intensity
  37. Imaging plates should be erased at least:
    once a week to remove background radiation and scatter
  38. Systems automatically erase the plate by:
    flooding it with light to remove any electrons still trapped after initial reading
  39. It is not recommended that kVp values less than ___ or more than ___ be used.
    45, 120
  40. Optimum exposure ranges:
    60-110 kVp
  41. The mAs is selected according to the:
    number of photons needed for a particular part
  42. When insufficient light is produced, the image is grainy, a condition known as:
    quantum mottle or quantum noise
  43. Two important factors to be considered when selecting the CR imaging cassette:
    type and size
  44. Two types of imaging plates:
    standard and high resolution
  45. Typically, high resolution imaging plates are limited to size range and most often used for:
    extremities, mammography, and other examinations requiring increased spatial resolution
  46. The CR reader scans the imaging plate at a frequency of about
    2000x2000 pixels
  47. Grid line artifact also known as:
    moire’ pattern
  48. Grid selection factors:
    frequency, ratio, and focus
  49. Why is the use of a grid device more critical in CR than in conventional?
    Because CR imaging plates are more sensitive to scatter
  50. Grid frequency refers to the:
    number of grid lines per centimeter or lines per inch
  51. Typical grid frequency is between:
    80 and 152 lines per inch
  52. The higher the frequency of the grid, the:
    less interference with the image, but greater risk for cut-off
  53. The grid ratio is the relationship between the:
    height of the lead strips to the space between them
  54. Recommended grid ratios are ____ for mobile and ____ for departmental.
    6:1, 12:1
  55. Regarding grid focus, most grids chosen by the department are:
    parallel and focused
  56. Parallel beams are less critical to ____ but should not be used with distances less than ___.
    beam centering, 48”
  57. Focused grids consist of lead strips angled to coincide with the:
    divergence of the x-ray beam.
  58. Focused grids must be used with ___ ____ and using a precisely ____ ____.
    specific distances, centered beam
  59. A black background that can be added around the original collimation to improve viewing but is not a replacement for proper pre-exposure collimation:
  60. The amount of light given off by the imaging plate is converted into a signal that is used to calculate the:
    exposure indicator number
  61. Companies that use the “S” or Sensitivity Number as the exposure indicator:
    Fuji, Phillips, and Konica
  62. The “S” number is the amount of ____ emitted at 1 mR at ___kVp and has a value of ___.
    luminescence, 80, 200
  63. The higher the “S” number, the _____ the exposure.
  64. The base exposure indicator number for all systems designates the:
    middle of the detector operating range
  65. Kodak uses what as the exposure indicator?
    Exposure Index (EI)
  66. EI plus ___ is equal to doubling exposure while an EI minus ___ is equal to halving exposure.
  67. The higher the EI, the ____ the exposure.
  68. the exposure indicator in an Agfa system is the:
    lgM, or logarithm of the median exposure
  69. For lgM, each step of .3 above or below 2.6 equals an exposure factor of:
  70. X-ray photons are absorbed by the coating material and immediately converted into an electrical signal.
    Direct Conversion
  71. Two types of flat panel detectors:
    Direct conversion and indirect conversion
  72. The DR plate has a radiation conversion material or photoconductor usually made of ____ ____. This material absorbs x-rays and converts them to electrons which are stored in the ____.
    Amorphous Selenium, TFT detectors