What is the recommended SID for lateral projection of the sinus?

What is the recommended SID for lateral projection of the sinus?

• A. 34 inches
• B. 40 inches
• C. 60 inches
• D. 72 inches

Answer: (B)

SID, or source-to-image distance, directly influences magnification and sharpness in radiography. For a lateral projection of the paranasal sinuses, a moderate SID of about 40 inches is used because it minimizes geometric magnification of the small sinus structures while still providing sufficient beam intensity for a clean image. A shorter distance would exaggerate magnification and blur fine details; a much longer distance would reduce image brightness and require higher exposure to maintain image quality. So, 40 inches (roughly 102 cm) is the standard, giving a good balance of image sharpness and practical exposure for this view.

SID, or source-to-image distance, directly influences magnification and sharpness in radiography. For a lateral projection of the paranasal sinuses, a moderate SID of about 40 inches is used because it minimizes geometric magnification of the small sinus structures while still providing sufficient beam intensity for a clean image. A shorter distance would exaggerate magnification and blur fine details; a much longer distance would reduce image brightness and require higher exposure to maintain image quality. So, 40 inches (roughly 102 cm) is the standard, giving a good balance of image sharpness and practical exposure for this view.