What happens to exposure if the distance to the image receptor is decreased while maintaining mAs?

When the distance to the image receptor is decreased while maintaining the milliampere-seconds (mAs), the exposure to the receptor increases. This phenomenon is governed by the inverse square law, which states that the intensity of radiation is inversely proportional to the square of the distance from the source.

As the distance between the X-ray source and the image receptor decreases, the x-ray photons become denser, leading to a higher concentration of exposure at the receptor. Since the mAs is held constant, you may be emitting the same amount of radiation over time, but the closer proximity results in more of those photons reaching the receptor, thereby increasing the exposure.

This principle is crucial to understand in radiographic imaging, as it impacts image quality and patient safety. By maintaining a constant mAs while reducing distance, radiologists must be aware that exposure levels will increase significantly, which can affect both image appearance and dose to the patient.