The automatic exposure control (AEC) system communicates with which part of the x-ray circuit when optimal exposure is achieved?

The automatic exposure control (AEC) system is designed to terminate the x-ray exposure once the desired level of radiation has been reached. This typically involves measuring the amount of radiation that has passed through the patient and reaching the image receptor. When the AEC detects sufficient radiation, it communicates this information to the exposure timer to halt the x-ray production.

The exposure timer is crucial in this communication because it’s responsible for controlling the total time that the x-ray beam is active, thus directly influencing the duration of exposure. Upon reaching the selected exposure threshold set by the AEC, the timer assists in cutting off the exposure, ensuring that the radiograph is neither underexposed nor overexposed.

In contrast, the other components mentioned serve different functions within the x-ray circuit. The filament circuit primarily handles the heating of the cathode's filament to produce electrons, while the autotransformer adjusts the voltage supplied to the x-ray tube. The milliampere (mA) selector regulates the current and thus influences the quantity of x-rays produced but does not directly terminate the exposure based on the AEC's findings.