What is the source-to-image distance (SID) for a lateral projection of the sacrum?

The source-to-image distance (SID) for a lateral projection of the sacrum is commonly set at 40 inches. This distance is significant because it balances factors such as image quality and the amount of radiation exposure to the patient. A 40-inch SID is typically used to provide an optimal level of detail for imaging the sacrum, which is essential for accurate diagnosis.

In radiographic practice, specific SIDs are established based on anatomical region and projection type. For the lateral view of the sacrum, using a distance of 40 inches helps ensure that the image is adequately magnified while minimizing distortion and maintaining acceptable levels of radiation exposure.

Utilizing other distances, such as 36, 44, or 48 inches, could lead to either insufficient image quality or unnecessary radiation exposure that exceeds standard protocols. Therefore, the choice of 40 inches is well-founded within the context of achieving high-quality radiographs of the sacrum.