About. The Source-to-Image Distance (SID) is the distance measured between the focal spot target on an x-ray tube to the image receptor of a x-ray cassette.

What is source image receptor distance?

The source image receptor distance (SID), is the distance of the tube from the image receptor, affecting magnification. The greater the SID, the less magnification the image will suffer.

What is Sid and OID in radiography?

Three terms are used to describe positioning: source-object distance (SOD, where the object represents the patient); object-image distance (OID, where the image is the detector); and source-image distance (SID). … Magnification measures how much bigger the picture appears on the detector, x2 / x1 = SID / SOD.