What is the required tube angulation direction for the AP axial projection of the sacrum?

• A. 10° caudal
• B. 15° cephalic
• C. 20° caudal
• D. 25° cephalic

Answer: (B)

For the AP axial projection of the sacrum, a 15° cephalic tube angulation is optimal. This angulation is necessary to project the sacrum away from the pelvic inlet and to minimize superimposition of the sacral curve onto the lumbar spine. The cephalic angle helps to align the sacrum within the imaging receptor and ensures that the structure can be visualized clearly and accurately, allowing for an effective assessment of any pathologies or anatomical anomalies.

In this projection, the caudal angulation options are not appropriate as they would direct the X-ray beam in the opposite direction needed to obtain a proper view of the sacrum. The correct angulation ensures that the sacrum is centered and well depicted in the radiograph while minimizing the distortion of surrounding structures. Using a 15° cephalic angle accurately reflects the typical anatomical curvatures and enhances the visibility of the sacrum for both diagnostic purposes and anatomical assessments.