What SID is recommended for cervical spine radiographs to control magnification?

What SID is recommended for cervical spine radiographs to control magnification?

• A. 40 inches
• B. 60 inches
• C. 72 inches
• D. 80 inches

Answer: (C)

Longer source-to-image distance reduces magnification and distortion of the cervical spine, helping the vertebral anatomy appear closer to its true size. For cervical spine radiographs, a SID of 72 inches (about 183 cm) is the standard choice because it provides the best balance between image sharpness and practical exposure. Shorter distances would magnify the vertebrae more, compromising measurements and alignment, while a much longer distance isn’t routinely needed and can affect exposure consistency. Therefore, the recommended SID is 72 inches.

Longer source-to-image distance reduces magnification and distortion of the cervical spine, helping the vertebral anatomy appear closer to its true size. For cervical spine radiographs, a SID of 72 inches (about 183 cm) is the standard choice because it provides the best balance between image sharpness and practical exposure. Shorter distances would magnify the vertebrae more, compromising measurements and alignment, while a much longer distance isn’t routinely needed and can affect exposure consistency. Therefore, the recommended SID is 72 inches.