In DR, what is the function of automatic exposure control (AEC)?

• A. It determines kVp
• B. It terminates exposure automatically to achieve target detector exposure
• C. It reduces exposure time but not dose
• D. It schedules exams

Answer: (B)

Automatic exposure control in digital radiography is about ending the X-ray exposure once the detector has received the amount of radiation it needs to produce a proper image. It uses sensors (ionization chambers) placed under or near the patient to gauge the exposure. When the sensor value reaches the preset target, the system automatically terminates the exposure, helping deliver consistent receptor exposure across patients and reducing the need for repeats. The radiographer still sets the technique factors such as kVp and mA, but AEC mainly controls exposure time to reach that detector target. It also relies on a backup timer for safety in case the sensors fail. It does not schedule exams.