Increasing the source-to-image distance (SID) generally results in what effect on image quality?

Increasing the source-to-image distance (SID) improves image quality by enhancing image sharpness. This is largely due to the geometric principles of radiography, where greater SID results in less magnification of the subject and reduces the penumbra effect, which is the blurring that occurs around the edges of images.

As the distance between the x-ray source and the image receptor increases, the x-ray beam spreads out more, leading to a reduction in the effective size of the focal spot. This effect contributes to the production of clearer and sharper images because the rays are more parallel by the time they reach the image receptor, which means that the detail of the structure being imaged is better represented without the ambiguity introduced by blurring.

Although other factors such as exposure technique and the quality of the imaging system also play important roles, the principle of increased SID leading to greater sharpness is well established in radiographic practice.