Which radiographic exam typically uses a 72-inch target-to-film distance instead of the standard 40-inch distance?

• A. Chest radiography
• B. Abdomen radiography
• C. Skull radiography
• D. Pelvic radiography

Answer: (A)

Using a longer target-to-film distance for chest radiography helps minimize magnification of the heart and mediastinal structures and improves overall sharpness of the image. The chest is a large structure, and reducing magnification with a 72-inch SID (about 180 cm) allows for a more accurate assessment of heart size and contour, while also reducing geometric blur. In contrast, exams of the abdomen, skull, or pelvis are typically done at the standard 40-inch distance, where the magnification and distance-related blur are acceptable for those smaller or differently focused areas. So, the exam that usually uses the 72-inch distance is chest radiography.