What is the standard source to image distance (SID) for most extremities in x-ray imaging?

The standard source to image distance (SID) for most extremities in x-ray imaging is typically 40 inches. This distance is chosen based on a balance between minimizing magnification and maximizing image clarity. At this SID, the images produced are less distorted and maintain enough detail for proper diagnosis while accommodating the specific needs of examining extremities. An appropriate SID is essential for achieving optimal image quality, particularly for structures that are relatively close to the imaging receptor, as is the case with extremities. Maintaining this standard distance helps ensure consistent imaging results across different patients and conditions.