Radiation Dose Measurement

While reading about ionizing radiation you may notice a few, if not MANY, ways to measure the amount of radiation present, exposed to, or absorbed.  This week's Word of the Week is many words! Here are some of the measurements and their definitions you may come across during your reading.

Absorbed Radiation

When the human body comes close to a radioactive source, exposure occurs. The hazards of such exposure are measured as absorbed dose. Different units of measurement are used to quantify the absorbed dose by biological tissue. 

Radiation Absorbed Dose (RAD)

A single rad is equivalent to 100 ergs of energy absorbed by 1 gram of tissue. 1 erg is about one-ten-millionth of a Joule. 

Gray (Gy)

Gray is the standard international unit for measuring radiation doses. 1 Gy is equal to 100 rad.

Roentgen Equivalent Man (REM)

The REM takes into account different sources of ionizing radiation, and their relative effectiveness. Rem can be measured by multiplying RAD with a Quality Factor (Q).  Q is taken to be as 1 for beta and gamma radiation, 10 for neutrons, and 20 for alpha radiation. 

Curie (Ci)

As a traditional measurement of radioactivity, Curie is equivalent to the radioactivity of one gram of pure radium-226.

 Sievert (Sv)

Is a derived unit used in measuring equivalent/effective/committed dose equivalent of low level ionizing radiation to an absorbed dose. 1 Sievert is equal to 100 rem.