Compare the CR (PSP) workflow with the DR workflow.

• A. CR uses a photostimulable phosphor plate scanned by a laser to read the latent image; DR uses direct-detection flat-panel detectors for immediate digital output.
• B. CR is direct capture with a panel; DR uses cassette with film.
• C. CR and DR are identical workflows.
• D. CR uses radioactive phosphor; DR uses phosphor plate.

Answer: (A)

The main difference is how the image is captured and read out. In computed radiography, exposure occurs on a reusable photostimulable phosphor plate inside a cassette. After exposure, the plate is removed and read by a laser in a separate reader; the laser stimulates the stored image and the emitted light is captured and digitized. This means the digital image only appears after scanning the plate, and the plate must be reused for the next exam. In direct radiography, the detector is a flat-panel unit built into the imaging system. It converts x-ray energy directly (or via a scintillator) into an electronic signal with no intermediate cassette or plate, giving an immediate digital image. So CR uses a cassette with a readout step, while DR provides instantaneous digital output from an integrated detector. The ideas that CR is direct capture with a panel, or that CR uses a radioactive phosphor, or that CR and DR are identical workflows, don’t fit because they misstate how the image is captured or read.