Computed Radiography (CR) Theory
1234563 – 12/12/94
2–11
CR Overview
Computed Radiography (CR) is the common term used when referring to the digital acquisition of projection radiographs. A number of operations is required in order
to capture the latent image stored in the storage phosphor screen and turn it into a digital image that can be viewed on a computer screen and printed out. These
operations. Each of these operations is performed by specialized components of the computed radiography system:
CR Operations and Components
Note
The table below outlines the operations and components common in computed radiographic systems.
These operations are described in the following subsections.
CR Operation
CR Component
Exposing the storage phosphor plate to X-ray photons.
• X-ray generator (not part of the CR system)
• Storage Phosphor Plate
Releasing the energy stored in the charged phosphors by stimulating the
phosphor (scanning).
• Stimulating light source (red laser beam)
• Scanning optics
– Deflector, such as the Galvo used in the CR 800 System.
– Beam-shaping components. The CR 800 uses a beam expander lens to adjust
the size of the laser spot.
Collecting and detecting the emitted blue light and converting it to an
analog signal.
• Light collector
• Filter
• Detector (Photomultiplier Tube, others are available but not as efficient)
• Analog Electronics
Converting the analog signal to a digital signal.
Analog to digital converter
Processing the digital signal to make it available for viewing.
Specialized software programs for assembling, correcting, and processing the image