Which of the following is equivalent to size distortion in radiography?

• A. Elongation
• B. Magnification
• C. Foreshortening
• D. Pixelation

Answer: (B)

Size distortion shows up when the image size does not match the actual object size due to geometric setup. Magnification directly describes this change in size: the image is larger than the object when there is distance between the object and the image receptor. The magnification factor, roughly image size divided by object size, increases as the object-to-image distance grows or as the source-to-object distance changes unfavorably, so the radiographic image becomes bigger than the real object. Elongation and foreshortening are about shape changes from angulation or alignment errors, not the overall size of the image, and pixelation relates to image resolution rather than true size distortion. So magnification is the concept that corresponds to size distortion.