What is the centimeter equivalent of the 40 inch SID used for calcaneus radiographs?

What is the centimeter equivalent of the 40 inch SID used for calcaneus radiographs?

• A. 90 cm
• B. 76 cm
• C. 102 cm
• D. 120 cm

Answer: (D)

Converting inches to centimeters uses the factor 1 inch = 2.54 cm. So a 40-inch SID is 40 × 2.54 = 101.6 cm, which rounds to about 102 cm. This is the centimeter equivalent used for calcaneus radiographs. For context, the other numbers correspond to shorter or longer distances: 90 cm is about 35.4 inches, 76 cm is about 29.9 inches, and 120 cm is about 47.2 inches. In clinical practice, 40 inches is a common SID for calcaneus imaging to balance image sharpness and magnification. So the centimeter equivalent is about 102 cm.

Converting inches to centimeters uses the factor 1 inch = 2.54 cm. So a 40-inch SID is 40 × 2.54 = 101.6 cm, which rounds to about 102 cm. This is the centimeter equivalent used for calcaneus radiographs.

For context, the other numbers correspond to shorter or longer distances: 90 cm is about 35.4 inches, 76 cm is about 29.9 inches, and 120 cm is about 47.2 inches. In clinical practice, 40 inches is a common SID for calcaneus imaging to balance image sharpness and magnification. So the centimeter equivalent is about 102 cm.