Which exposure control option is used when AEC is unsuitable or precise timing is required?

• A. Manual timer
• B. Synchronous timer
• C. Auto exposure control
• D. Dose-limiting timer

Answer: (A)

When you need direct control over how long the x-ray tube is energized, a manual timer is used. Automatic exposure control relies on detectors to terminate the exposure when the desired amount of radiation has been detected. But if the detectors can’t reliably sense the exposure—due to anatomy, positioning, or certain projection setups—or if you require a very specific, fixed exposure time for consistency or dosimetry, you set and run the exposure with a manual timer. This gives you exact control over the duration of the exposure, independent of detector response, ensuring the technique is reproduced exactly as planned.