When using AEC, which part of the patient's anatomy should be positioned over the active chamber?

When using Automatic Exposure Control (AEC), it is crucial to position the part of the patient's anatomy that is of primary interest directly over the active chamber of the AEC. This practice ensures that the system measures the appropriate exposure based on the density of the tissue being imaged. Positioning the structure of primary concern over the active chamber allows the AEC to accurately determine when enough radiation has been received to produce a diagnostic-quality image.

If a structure of least concern or less density is positioned over the chamber, the AEC might terminate the exposure too early or too late, resulting in underexposed or overexposed images. Similarly, placing the highest or lowest density structures over the chamber could mislead the AEC into making inappropriate adjustments for exposure, further compromising image quality. Therefore, placing the structure of primary concern over the active chamber aligns the exposure settings with the specific imaging requirements, leading to optimal radiographic outcomes.