When AEC is used, increasing the kVp has which effect?

• A. Increases The Exposure Time
• B. Increases The Image Contrast
• C. Decreases The Exposure Time
• D. Has No Effect On Image Quality

Answer: (D)

When AEC is used, the system aims to reach a set detector exposure by terminating the x-ray beam once the preset signal is obtained. Increasing kVp raises the beam’s penetrating power and the number of photons reaching the detector per unit time. Because the AEC stops the exposure as soon as the desired detector exposure is reached, the exposure time becomes shorter as kVp increases. So the primary effect is a decrease in exposure time. It’s also true that higher kVp lowers image contrast (more beam penetration and scatter), so there is a change in image quality, not a “no effect.”