The phosphor layer of the CR IP is composed of which materials?

• A. Ba fluorohalides and amorphous selenium
• B. amorphous silicon and europium activators
• C. Ba fluorohalides and europium activators
• D. amorphous silicon and cesium iodide

Answer: (C)

In a computed radiography imaging plate, the phosphor layer is a host lattice of Ba fluorohalides doped with europium. The europium activator provides trap centers that store energy when the plate is exposed to X-rays. When the plate is later scanned with a laser, the trapped energy is released as visible light from the europium centers, and that light is detected to form the image. This is why the phosphor layer is described as Ba fluorohalides with europium activators.

Other materials like amorphous silicon or amorphous selenium are used in different detector technologies, not in the CR imaging plate phosphor layer.