What SID is recommended for a cross-table lateral cervical spine radiograph with a horizontal beam when using a wall Bucky?

• A. 60 inches
• B. 72 inches
• C. 84 inches
• D. 90 inches

Answer: (B)

For a lateral cervical spine radiograph with a horizontal beam using a wall Bucky, the distance from the x-ray tube to the image receptor (SID) directly affects magnification and sharpness. A 72-inch SID provides the best balance, minimizing magnification of the cervical vertebrae while keeping the entire region in the field and allowing the grid to reduce scatter effectively. Using a shorter distance, like 60 inches, would exaggerate magnification and blur fine details. A longer distance, such as 84 or 90 inches, offers less magnification but can increase penumbra and complicate proper field coverage and exposure. Therefore, 72 inches is the recommended SID for this setup.