In CT imaging, the patient skin dose is typically on the order of which unit?

In CT imaging, the patient skin dose is typically on the order of which unit?

• A. one to several RADS
• B. one to several mrems
• C. one to several Gy-SV
• D. 10 to 20 rems

Answer: (A)

The key idea is that the entrance skin dose from a typical CT exam is described in absorbed dose units and falls in the range of a few rads. In CT, energy is deposited along the beam path and at the skin surface during the rotation, so the skin receives about 1 to a few rad per exam. Since 1 rad equals 0.01 Gy, that corresponds to roughly 0.01 to 0.05 Gy. Other options reflect either much smaller doses (millirems) or different concepts (dose equivalents like rem or Gy-SV) that aren’t as representative for the actual skin absorption in a standard CT scan. A 10 to 20 rem range would imply a far higher exposure than typical CT skin dose. So the entrance skin dose in CT is best described as about one to several RADS.

The key idea is that the entrance skin dose from a typical CT exam is described in absorbed dose units and falls in the range of a few rads. In CT, energy is deposited along the beam path and at the skin surface during the rotation, so the skin receives about 1 to a few rad per exam. Since 1 rad equals 0.01 Gy, that corresponds to roughly 0.01 to 0.05 Gy. Other options reflect either much smaller doses (millirems) or different concepts (dose equivalents like rem or Gy-SV) that aren’t as representative for the actual skin absorption in a standard CT scan. A 10 to 20 rem range would imply a far higher exposure than typical CT skin dose. So the entrance skin dose in CT is best described as about one to several RADS.