Microcurie

Another commonly used measure of radioactivity, the microcurie: $1 \micro Ci = 3.7 \times 10 disintegrations per second = 2.22 \times 10 disintegrations per minute$. A radiotherapy machine may have roughly 1000 Ci of a radioisotope such as caesium-137 or cobalt-60. This quantity of radioactivity can produce serious health effects with only a few minutes of close-range, un-shielded exposure. The typical human body contains roughly $0.1\micro Ci$ of naturally occurring potassium-40.