What effect does increasing the distance between the x-ray tube and the image receptor have on radiographic density?

Increasing the distance between the x-ray tube and the image receptor results in a decrease in radiographic density. This phenomenon is explained by the inverse square law, which states that the intensity of radiation (and therefore the exposure reaching the image receptor) decreases with the square of the distance from the source of the radiation. As the distance from the x-ray tube increases, the amount of x-ray photons that ultimately reach the image receptor diminishes, leading to a lighter image or reduced density.

In practice, if the distance is increased without any compensatory adjustments (such as increasing the exposure time or the x-ray tube output), the image will have less overall exposure, resulting in lower density. This concept is crucial for radiographic technique, as radiographers must consider the appropriate distance to achieve the desired image quality.