What occurs when the tube or the image receptor is not properly aligned?

When the tube or the image receptor is not properly aligned, elongation occurs. This distortion happens because the object being radiographed is not perpendicular to the central ray, leading to an exaggerated lengthening of structures in the image. For instance, if the x-ray beam is angled more than necessary, parts of the object which are not parallel to the receptor will appear stretched. This can result in an inaccurate representation of the actual anatomy, which complicates the interpretation of the radiographs.

Proper alignment is crucial for radiographic accuracy because it ensures that the anatomy is captured in its true form. When there is misalignment, a technician must recognize the potential for elongation so they can correct the positioning in future images to obtain the desired detail and clarity.

The other terms relate to different forms of image distortion. Foreshortening describes the phenomenon where an object appears shorter than its actual length due to improper alignment. Overlap can occur when structures are superimposed on each other, making it hard to differentiate them. Distortion is a broader term that encompasses both elongation and foreshortening but in the context of the question, elongation specifically is the result mentioned when alignment issues occur with the tube or image receptor.