Which arrangement yields elongation when the anatomy is parallel to the image receptor and the beam is angled?

Which arrangement yields elongation when the anatomy is parallel to the image receptor and the beam is angled?

• A. Beam perpendicular to anatomy and the IR.
• B. Anatomy parallel to the image receptor and the beam angled.
• C. Beam perpendicular to anatomy and beam angled.
• D. Anatomy perpendicular to the image receptor and the beam perpendicular.

Answer: (B)

Elongation happens when the structure lies flat against the image receptor and the X-ray beam is angled. When the anatomy is parallel to the receptor, tilting the beam causes the shadows to stretch along the plane of the film. In this setup, rays skim along the length of the structure rather than cutting across it head-on, so the projected length on the image is longer than the actual length. If the beam is perpendicular to the anatomy (or the anatomy is perpendicular to the receptor), you get true length with no distortion from angle. And if the anatomy is not parallel to the receptor, the projection tends to foreshorten rather than elongate.

Elongation happens when the structure lies flat against the image receptor and the X-ray beam is angled. When the anatomy is parallel to the receptor, tilting the beam causes the shadows to stretch along the plane of the film. In this setup, rays skim along the length of the structure rather than cutting across it head-on, so the projected length on the image is longer than the actual length.

If the beam is perpendicular to the anatomy (or the anatomy is perpendicular to the receptor), you get true length with no distortion from angle. And if the anatomy is not parallel to the receptor, the projection tends to foreshorten rather than elongate.