Radiation dose uses different units depending on what you’re measuring: absorbed dose (energy deposited), equivalent dose (radiation type weighting), and effective dose (tissue weighting). Common units: Gray (Gy), Sievert (Sv), and older unit rem. In plain English  Gy = how much radiation energy got absorbed by material/tissue.  Sv = “how harmful it is” after adjusting for radiation type and tissue sensitivity.  rem = older “Sv-like” unit still seen in some contexts. Worked example 1 (unit conversion) Convert 250 mrem to Sv.  1 Sv = 100 rem, so 1 rem = 0.01 Sv  250 mrem = 0.250... Show more

Radiation dose uses different units depending on what you’re measuring: absorbed dose (energy deposited), equivalent dose (radiation type weighting), and effective dose (tissue weighting).

Common units: Gray (Gy), Sievert (Sv), and older unit rem.

In plain English
 Gy = how much radiation energy got absorbed by material/tissue.
 Sv = “how harmful it is” after adjusting for radiation type and tissue sensitivity.
 rem = older “Sv-like” unit still seen in some contexts.

Worked example 1 (unit conversion)
Convert 250 mrem to Sv.
 1 Sv = 100 rem, so 1 rem = 0.01 Sv
 250 mrem = 0.250 rem
 0.250 rem × 0.01 Sv/rem = 0.0025 Sv (which is 2.5 mSv)

Worked example 2 (Gy to rad)
A dose of 0.8 Gy absorbed dose equals how many rad?
 1 Gy = 100 rad
 0.8 Gy = 80 rad

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