CT skin dose is typically on the order of which range?

• A. 0.5 rad
• B. 1 rad
• C. Five rad
• D. Ten rad

Answer: (C)

CT skin dose reflects the amount of radiation deposited where the beam enters the patient. Because a CT scan uses a rotating gantry and a relatively wide beam, the entrance point on the skin tends to receive a higher dose than a single radiographic view. For a typical diagnostic CT exam, the entrance-skin dose is in the order of a few rad, commonly around five rad (about 50 mGy). This rough range accounts for differences in body region, technique, and scanner design, and while actual values vary, five rad is a good general estimate. Values like 0.5 or 1 rad are generally too low for standard CT, and ten rad would be higher than typical modern CT skin doses, though optimization and protocol choice can influence the exact amount.