What device reads the latent image from a CR IP by scanning with a laser in a raster pattern?

• A. The energy trap
• B. A laser scanning device
• C. The cassette transport
• D. The readout detector

Answer: (B)

In computed radiography, the latent image is stored in the phosphor layer of the imaging plate as trapped electrons. To read that information, the plate is scanned with a laser that moves across it in a raster pattern. As the laser hits the plate, it stimulates the trapped electrons to release their energy as light. This emitted light is then detected by a readout detector (usually a photomultiplier tube) inside the scanner and converted into a digital signal that becomes the image. The device that performs this stimulation and sequential readout in a raster fashion is the laser scanning device, making it the correct choice. The energy trap describes the storage sites in the phosphor, the cassette transport is just the physical handling of the plate, and the readout detector is a component within the system but does not define the scanning mechanism itself.