Which statement best describes how ionization chambers function in AEC?

• A. They sense transmitted radiation and terminate exposure at preset charge.
• B. They measure patient dose after exposure.
• C. They adjust kVp during exposure.
• D. They are used to calibrate the monitor brightness.

Answer: (A)

Ionization chambers in AEC work by detecting the amount of radiation that reaches the detector after it passes through the patient. When X-rays reach the chamber, the gas inside becomes ionized, creating a small current. The system integrates this charge, and once a preset value is reached, the exposure is automatically terminated. This ensures a consistent image receptor exposure by adjusting exposure time to account for patient size and tissue variation, rather than altering kVp during the shot. It’s not measuring dose after the exposure, nor changing kVp mid-exposure, nor used to calibrate monitor brightness.