The safety device that automatically terminates exposure if the main timer fails is the:

The safety device that automatically terminates exposure if the main timer fails is the:

• A. Back-up timer
• B. AEC
• C. Collimator
• D. Filter

Answer: (A)

A safety mechanism that stops the exposure if the main timer fails. The back-up timer is built into X-ray systems to terminate an exposure after a preset maximum time, providing a failsafe if the primary timer or the automatic exposure control (AEC) malfunctions. This protects the patient from accidental overexposure even when the main timing system has faults. AEC itself stops exposure when the detectors reach the required dose, but it isn’t a guaranteed safeguard against timer failure. The collimator merely narrows the beam, and the filter reduces dose by absorbing low-energy photons; neither controls exposure duration.

A safety mechanism that stops the exposure if the main timer fails. The back-up timer is built into X-ray systems to terminate an exposure after a preset maximum time, providing a failsafe if the primary timer or the automatic exposure control (AEC) malfunctions. This protects the patient from accidental overexposure even when the main timing system has faults.

AEC itself stops exposure when the detectors reach the required dose, but it isn’t a guaranteed safeguard against timer failure. The collimator merely narrows the beam, and the filter reduces dose by absorbing low-energy photons; neither controls exposure duration.