Where should the CR be centered for AP cervical spine and what should be included in the collimation?

Where should the CR be centered for AP cervical spine and what should be included in the collimation?

• A. Centered at C4; include skull base through upper thoracic inlet and both atlantoaxial joints
• B. Centered at C3; include entire head
• C. Centered at C6; include from skull base to T1
• D. Centered at C1; include from occipital bone to C7

Answer: (A)

Centering the CR at about the level of the laryngeal prominence (C4) places the midline of the cervical spine in the center of the image, giving a balanced projection of all seven cervical vertebrae and ensuring the upper cervical region is well demonstrated. The exposure field should extend from the skull base down to the upper thoracic inlet so that C1 through T1 are included, which allows a complete view of the craniocervical junction and both atlantoaxial joints. This coverage is essential for assessing alignment and potential instability at the atlas–axis level as well as the transition to the lower cervical spine. Centering too high or too low would crop out parts of the necessary anatomy, and focusing only on the head or on just the lower cervical region would miss critical joints and vertebral relationships.

Centering the CR at about the level of the laryngeal prominence (C4) places the midline of the cervical spine in the center of the image, giving a balanced projection of all seven cervical vertebrae and ensuring the upper cervical region is well demonstrated. The exposure field should extend from the skull base down to the upper thoracic inlet so that C1 through T1 are included, which allows a complete view of the craniocervical junction and both atlantoaxial joints. This coverage is essential for assessing alignment and potential instability at the atlas–axis level as well as the transition to the lower cervical spine. Centering too high or too low would crop out parts of the necessary anatomy, and focusing only on the head or on just the lower cervical region would miss critical joints and vertebral relationships.