For AP axial projections of the cervical spine, which statement describes how the X-ray beam is centered to the part?

• A. The MSP should be centered to the middle of the IR
• B. The CR should be at the glabella
• C. The MSP should be centered to the SID
• D. The center of the image should be at C4

Answer: (B)

For AP axial cervical spine projections, you want the central ray to enter along the midline of the head and neck in a reproducible location so the cervical vertebrae are imaged without excessive overlying structures. Centering the beam at the glabella provides a stable, midline facial landmark that aligns with the midline of the cervical spine when the head is positioned for this view. A cephalad angle is used to open the intervertebral spaces and project the lower cervical vertebrae without the mandible or occipital bone obscuring the anatomy.

Centering to the glabella ensures the image is symmetrical and the beam travels through the intended portion of the neck. Centering the MSP to the middle of the IR, or placing the image center at C4, does not specify a consistent entry point for a cervical axial projection, and pointing at the SID isn’t a valid method for beam localization.