What is the role of the photomultiplier tube (PMT) within the CR system?

• A. Collect light photons and convert them to a digital image
• B. Release the latent image from the IP
• C. Collect and multiply the light photons and convert them to electrons
• D. Convert the analog data to a digital signal

Answer: (C)

The photomultiplier tube serves to detect the light emitted from the photostimulable phosphor plate during readout and turn that light into a strong electrical signal. Light photons strike the PMT’s photocathode, releasing electrons. These electrons are then multiplied through a cascade of dynodes, producing an amplified current that is proportional to the original light intensity. That amplified electrical signal is what gets sent on to the digitizer to create the digital image. The PMT’s role is not to release the latent image or to digitize the signal itself; its job is light collection and amplification into electrons.