HESI Radiologic Technologist Practice Exam 2026 – Your All-in-One Guide to Certification Success!

Increasing object-to-image distance changes the geometry of projection so the object's shadow on the receptor becomes larger. When the distance between the object and the image receptor increases (with the source-to-image distance held constant), the distance from the source to the object effectively shrinks, raising the magnification factor (M = SID / SOD). In practical terms, rays spread out more before hitting the receptor, producing a larger image of the object on the film. Density, contrast, and noise are governed mainly by exposure factors and beam properties, not by OID, so they don’t primarily change with increased OID.