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Dr. Tsubokura's Radiation Lecture Vol.151

Author: Masaharu Tsubokura M.D., PhD.

Editors: Yudai Kaneda, Akihiko Ozaki M.D.,PhD.,

301  The unit "Sv" measures effects on the human body

October 24, 2021

If we compare radiation to sparklers, the tinder is the radioactive material, and the sparks are the radiation. The capability of emitting those sparks is radioactivity. If we compare radiation to a flashlight, the flashlight is the radioactive material, the light produced from it is the radiation, and the ability to produce light is the radioactivity.

 The units we use in radioprotection are the becquerel (Bq) and the sievert (Sv). The becquerel measures the capability of emitting radiation—simply the amount of radioactive material—and the sievert is a unit used to measure the effects on the human body. Therefore, the subject is always "things" when using the becquerel, while the subject of the sievert is "people" because it is a measurement for humans. It is expressed as in the following: this food has 〇〇 becquerels, this soil has 〇〇 becquerels, and so forth. In contrast, sieverts are expressed like this: eating this food has an effect of 〇〇 sieverts, or being in a certain place has an effect of 〇〇 sieverts.