Which technical change will increase the total exposure time without increasing the receptor exposure when using AEC?

When considering the effect of different technical changes on exposure time in a system using Automatic Exposure Control (AEC), decreasing the milliamperage (mA) is the correct choice for increasing total exposure time without affecting receptor exposure.

When mA is reduced, the amount of current flowing through the x-ray tube decreases, which leads to a lower rate of x-ray photon production. Since AEC systems are designed to terminate exposure once a predetermined level of receptor exposure is achieved, a decrease in mA results in a longer exposure time to reach that threshold. However, because the AEC compensates for the lower rate of exposure by extending the time, the total receptor exposure remains unchanged. Thus, the AEC continues to function effectively, ensuring that the final image maintains the desired density.

In contrast, increasing kilovoltage peak (kVp) typically enhances the quality and energy of the x-rays produced, potentially leading to higher receptor exposure, as more photons can penetrate the patient and reach the detector. Decreasing the backup timer does not influence exposure time directly, as it only serves as a safety feature to prevent excessive exposure. Likewise, increasing the density setting on an AEC unit instructs the system to compensate for underexposure by extending the exposure duration