What is the function of automatic exposure control (AEC) in radiology?

The correct answer highlights that the primary function of automatic exposure control (AEC) in radiology is to terminate the exposure when the appropriate radiographic density is achieved. AEC systems are designed to autonomously adjust the duration of the x-ray exposure based on the amount of radiation that reaches the image receptor. This ensures that consistently optimal image quality is obtained without the need for manual adjustments by the technologist.

By measuring the radiation that passes through the patient and reaches the detector, AEC can ensure that the resultant image has the desired level of contrast and detail, thereby reducing the likelihood of underexposure or overexposure. This capability is particularly beneficial in maintaining patient safety by minimizing the amount of ionizing radiation exposure.

Other options do not accurately describe AEC's function. While regulating x-ray tube temperature is important for equipment safety and functionality, it is not within the scope of what AEC does. Adjusting image brightness is typically a post-processing feature rather than an inherent capability of AEC during the exposure phase. Controlling radiation exposure time, while an essential concept related to image acquisition, is more accurately described as a function of AEC’s ability to terminate exposure based on achieved density rather than merely controlling the time itself.