The difference between Curies, Roentgen, RAD, REM, Sieverts, grays…

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The difference between Curies, Roentgen, RAD, REM, Sieverts, grays…

In: Physics

Curie measures the radioactivity or radioactive decay of a material and is outdated as a unit (modern unit is the becquerel).

Roentgen (named after the German physicist who identified xrays) is another outdated unit used to measure radiation exposure levels in air or other material. The modern unit is coulombs per kilogram.

Rad is a measure of absorbed dose (typically in tissue), but the modern unit is the Gray.

Rem is a measure of effective dose, or the potential for the radiation to do damage to biological tissue based on tissue type, quantity of exposure etc. One would use the effective dose multiplied by the tissue weighting factor (different tissues have different levels of radiosensitivity) to calculate the equivalent dose, measured in Sieverts. Both Rem and sievert are still used today: 100 rem = 1 sievert (Sv).

Radiation workers in the US like xray techs, nuclear medicine techs, radiologists, etc have annual dose limits of 50 mSv and most of us do not even reach 10% of that in a year.

Thank you
Tried to search this out after the Chernobyl docudrama and could find an easy answer.