Module 10 - Week 15 Flashcards
What is the main function of AEC?
Automatically stops exposure when enough radiation reaches the image receptor.
What components make up an AEC system?
Ionization chambers, amplifier, and exposure control circuit.
How does AEC measure exposure?
Measures exit radiation using ionization chambers that detect photon energy.
What triggers exposure termination in AEC?
A preset voltage threshold reached by the ionization chamber’s signal.
What does AEC NOT measure?
Image quality, anatomy, or density outside the active chamber area.
Benefits of AEC for technologists?
Reduces guesswork, saves time, lowers repeat rates.
Benefits of AEC for patients?
Personalized exposure, lower dose, consistent image quality.
Benefits of AEC for equipment?
Longer tube life due to lower mA, prevents overheating.
What are key AEC limitations?
Positioning errors, wrong chamber use, prosthetics, contrast media, or poor collimation.
What causes AEC exposure errors?
Miscentering, incorrect chamber selection, lead over chamber, or excess scatter.
What is a backup timer?
Safety feature that stops exposure if AEC fails. Set to 150% of expected mAs.
What are signs of AEC misuse?
Repeats, over/underexposure, inconsistent image quality.
When should you avoid AEC?
With implants, gas-filled bowels, barium, or oblique views.
What does the technologist need to do for correct AEC use?
Center anatomy over chamber, select correct factors, use proper collimation.
What is APR in radiography?
Anatomically Programmed Radiography – selects technique settings automatically using presets.
Can APR override AEC settings?
Yes, the technologist can adjust or override if needed.
Why check the mAs readout after exposure?
Helps with future manual settings and repeat imaging accuracy.
