CoreFull access
Size distortion and magnification
Magnification grows with OID and shrinks with SID; magnification factor is SID divided by SOD.
The rule
Distortion is any misrepresentation of the true size or shape of anatomy. Size distortion is magnification: the image is larger than the object. Every radiograph has some, because the part always sits some distance above the receptor and x-rays diverge from the focal spot. Two distances control it, SID and OID. Shape distortion, meaning elongation and foreshortening, comes from alignment and angulation and is a separate topic.