How does misplacement of AEC detectors affect patient dose and image quality?

• A. Misplacement results in overexposure, providing excess radiation to the patient
• B. Misplacement can lead to underexposure, requiring additional images and increasing patient dose
• C. It has no effect on radiation dose
• D. It improves image quality without dose change

Answer: (B)

Automatic exposure control relies on detectors beneath the patient to measure the transmitted radiation and stop the exposure once the desired signal is reached. When those detectors are placed correctly under the anatomy of interest, the measured signal reflects the attenuation of that specific area, producing a properly exposed image.

If the detectors are misplaced, the area they measure may not represent the part of interest. The device can then terminate the exposure too soon, giving an underexposed image with too little density and more image noise. To achieve adequate image quality, the technologist will often have to raise exposure factors or repeat the exam with the detectors correctly positioned, which increases the patient’s overall dose.