What is the SID for plantodorsal axial calcaneus radiographs?

What is the SID for plantodorsal axial calcaneus radiographs?

• A. 48 inches (122 cm)
• B. 30 inches (76 cm)
• C. 72 inches (183 cm)
• D. 40 inches (102 cm)

Answer: (D)

The main idea here is that the distance from the X-ray tube to the image receptor (SID) affects how large the calcaneus appears and how sharp the image will be. For the plantodorsal axial projection of the calcaneus, standard practice uses 40 inches (102 cm) SID. This distance provides a good balance between image sharpness and practical exposure for this small, angled view. Using a much shorter SID would magnify the calcaneus more and degrade detail, while a much longer SID isn’t the typical setting for this projection and can complicate positioning and exposure. So 40 inches is the conventional and best choice for this radiograph.

The main idea here is that the distance from the X-ray tube to the image receptor (SID) affects how large the calcaneus appears and how sharp the image will be. For the plantodorsal axial projection of the calcaneus, standard practice uses 40 inches (102 cm) SID. This distance provides a good balance between image sharpness and practical exposure for this small, angled view. Using a much shorter SID would magnify the calcaneus more and degrade detail, while a much longer SID isn’t the typical setting for this projection and can complicate positioning and exposure. So 40 inches is the conventional and best choice for this radiograph.