Figure 3. Drawing illustrates a CR system based on storage-phosphor image plates. Image generation is separated into two steps. First, the image plate (IP) is exposed to x-ray energy, part of which is stored within the detective layer of the plate. Second, the image plate is scanned with a laser beam, so that the stored energy is set free and light is emitted. An array of photomultipliers collects the light, which is converted into electrical charges by an analog-to-digital (A/D) converter.