What is the approximate patient skin dose for CT examinations?

What is the approximate patient skin dose for CT examinations?

• A. ten to fifty rem
• B. one to several rem
• C. one to several mrem
• D. fifty to one hundred rem

Answer: (B)

CT exams deliver more radiation to the skin than standard X-rays because the beam rotates around the patient and the exposure accumulates over the imaged volume as multiple slices are acquired. The entrance skin dose from a typical CT study is on the order of tens of milligray, which translates to roughly 1 to 5 rem when converted to dose equivalent. That’s why the best estimate for CT skin dose is about one to several rem. Values higher than this (tens to hundreds of rem) would reflect unusually high or outdated protocols, while doses in the millirem range would be too low for a complete CT study.

CT exams deliver more radiation to the skin than standard X-rays because the beam rotates around the patient and the exposure accumulates over the imaged volume as multiple slices are acquired. The entrance skin dose from a typical CT study is on the order of tens of milligray, which translates to roughly 1 to 5 rem when converted to dose equivalent. That’s why the best estimate for CT skin dose is about one to several rem. Values higher than this (tens to hundreds of rem) would reflect unusually high or outdated protocols, while doses in the millirem range would be too low for a complete CT study.