Which factors influence image distortion?

• A. 1 and 3
• B. 1 and 2
• C. 2 and 3
• D. 1, 2, and 3

Answer: (D)

Distortion in radiography comes from how the X-ray projection maps the three-dimensional anatomy onto a two-dimensional image receptor. Size distortion (magnification) occurs when the part is at different distances from the receptor—closer to the receptor reduces magnification, farther away increases it. Shape distortion (elongation or foreshortening) happens when the beam is not perpendicular to the part or when the part is not parallel to the receptor, causing the projected image of the anatomy to be stretched or compressed. Alignment also matters: if the central ray isn’t properly aimed at the part and receptor, the projection shifts and distorts the anatomy’s appearance.

Because all three aspects—distance relationships (OID and SID), beam angle relative to the part, and proper alignment between the part and the image receptor—can influence distortion, every contributing factor plays a role. Therefore, all of them affect distortion.