Gray and Sievert

• Gray The IS unit for the energy absorbed from ionizing radiation, equal to one joule per kilogram. An absorbed dose of one gray is equal to the absorption of one joule of radiation energy by one kilogram of matter.The gray is the correct unit to use when you wish to monitor energy absorbed per unit mass.
• Sievert The IS unit for the amount of ionizing radiation required to produce the same biological effect as one rad of high-penetration x-rays, equivalent to a gray for x-rays. It measures the radioactive dose equivalent. One sievert is equal to one gray multiplied by a relative biological effective factor, Q, and a factor that takes into account the distribution of the radiation energy, N. The sievert is the correct unit to use when you wish to monitor the biological danger of radiation.

1 rad = 10 milligray (mGy)

1 sievert (Sv) = 1,000 millisieverts (mSv) = 1,000,000 microsieverts

1 sievert = 100 rem

1 becquerel (Bq) = 1 count per second (cps)

1 curie = 37,000,000,000 becquerel = 37 Gigabecquerels (GBq)

For x-rays and gamma rays, 1 rad = 1 rem = 10 mSv

For neutrons, 1 rad = 5 to 20 rem (depending on energy level) = 50-200 mSv

For alpha radiation (helium-4 nuclei), 1 rad = 20 rem = 200 mSv