CRDR

• Computed Radiography Cassette


  • Made of durable, lightweight plastic material
  • Backed by a thin sheet of aluminum that absorbs x-rays
  • Contains antistatic material to prevent static electricity buildup, dust collection, and mechanical damage
• Layers of Computed Radiography Imaging Plate

  • Protective layer
  • Phosphor or active layer
  • Reflective layer
  • Conductive layer
  • Color layer
  • Support layer
  • Backing layer
• Protective layer


  Protects the phosphor layer
• Phosphor or active layer


  Traps electrons during exposure
• Reflective layer


  Sends light forward when released in the reader
• Conductive layer


  Absorbs and reduces static electricity
• Color layer


  Absorbs stimulating light but reflects emitted light
• Support layer


  Gives strength to the imaging sheet
• Backing layer


  Protects the back of the cassette
• Photostimulation in the Imaging Plate

  1. Remnant x-ray beam interacts with electrons in barium fluorohalide crystals, stimulating electrons

  2. Stimulated electrons enter the conductive layer and are trapped in the phosphor center

  3. Trapped electrons emit visible blue light as they relax into lower energy levels
• Laser


  Creates and amplifies a narrow, intense beam of coherent light
• Laser Beam Formation


  1. Excited atoms or molecules emit secondary photons in the same frequency as the bombarding atoms

  2. The atoms discharge simultaneously, producing a burst of coherent light
• Reading the Imaging Plate

  1. Imaging plate is extracted from the cassette and scanned with a laser beam

  2. Laser beam stimulates trapped electrons, causing them to emit visible blue light

  3. Photomultiplier amplifies the light, sending it to a signal digitizer

  4. Digitizer assigns numerical values to pixels based on brightness and position
• Image Erasure from the Imaging Plate

  1. Reading the image returns most but not all electrons to a lower energy state, effectively removing the image

  2. Imaging plates are sensitive to scatter radiation and should be erased to prevent background signal buildup

  3. CR readers have an erasure mode that floods the plate with light to remove any remaining trapped electrons
• Backing layer


  • Protects the back of the cassette
• Barcode label


  Allows identification of the cassette or imaging plate and links it with the patient examination
• Barium fluorohalide


  Crystals in the imaging plate that release light energy during exposure
• Cassette


  Holds the imaging plate and protects it during exposure
• Color layer


  Absorbs stimulating light but reflects emitted light in newer plates
• Conductive layer


  Absorbs and reduces static electricity
• Imaging plate


  Thin sheet of plastic where the radiographic image is recorded
• Laser


  Emits a narrow, intense beam of coherent light to scan the imaging plate
• Phosphor center


  Area within the phosphor layer where electrons are trapped during exposure
• Phosphor layer


  Layer of photostimulable phosphor that traps electrons during exposure
• Photomultiplier


  Amplifies the light emitted by the imaging plate during scanning
• Photostimulable phosphor


  Material in the phosphor layer that traps electrons during exposure
• Photostimulable luminescence (PSL)


  Light emitted by the imaging plate when stimulated by the laser
• Protective layer


  Thin, tough, clear plastic layer that protects the phosphor layer
• Raster


  Pattern in which the laser scans the imaging plate during reading
• Reflective layer


  Sends light forward when released in the reader
• Speed


  Relative measure of how quickly the imaging plate can capture and store radiation
• Support layer


  Provides structural support to the imaging sheet