Which SID is recommended for erect cervical spine radiographs?

• A. 72 inches
• B. 40 inches
• C. 60 inches
• D. 84 inches

Answer: (A)

For erect cervical spine radiographs, the distance between the X-ray tube and the image receptor is chosen to minimize magnification and distortion while still capturing the entire cervical region in one upright view. Using a 72-inch SID achieves that balance: it reduces the apparent size of the vertebrae compared with shorter distances, so alignment and spacing between vertebrae can be assessed more accurately. It also provides enough field to include from the skull base down to the upper thoracic region without moving the patient.

A shorter distance, like 40 inches, would make the cervical vertebrae appear larger and more magnified, compromising measurement accuracy and surgical planning if needed. A longer distance, such as 84 inches, would further reduce magnification but is often impractical in typical radiography rooms and would require higher exposure to maintain image brightness. The 72-inch distance is the standard, widely used practice for erect cervical spine imaging.