Which of the following is NOT a primary contributor to shape distortion due to misalignment?

• A. SID
• B. X-ray tube
• C. Anatomy being imaged
• D. Image receptor (IR)

Answer: (A)

Shape distortion arises when the projection geometry is off because the beam, the patient, and the image receptor aren’t aligned properly. The angle of the x‑ray tube can tilt the projection, causing structures to appear foreshortened or elongated. If the anatomy isn’t parallel to the receptor, or if the receptor itself is rotated relative to the anatomy, similar distortion occurs. The source‑to‑image distance mainly affects magnification and sharpness, not the directional distortion produced by misalignment. So, SID isn’t a primary factor in shape distortion from misalignment; the distortion comes from how the tube, anatomy, and receptor are aligned to each other.