Curie

The curie (symbol Ci) is a unit of radioactivity, defined as

1 Ci = 3.7 × 1010 decays per second.

This is roughly the activity of 1 gram of the radium isotope 226Ra, a substance studied by the pioneers of radiology, Marie and Pierre Curie, for whom the unit was named.[1][2] In addition to the curie, activity can be measured using an SI derived unit, the becquerel (Bq), which equates to one decay per second. Therefore:

1 Ci = 3.7 × 1010 Bq = 37 GBq
(100 mCi = 3.7 GBq)

and

1 Bq = 2.703 × 10−11 Ci

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.

Another commonly used measure of radioactivity is the microcurie:

1 μCi = 3.7 × 104 disintegrations per second = 2.22 × 106 disintegrations per minute

The typical human body contains roughly 0.1 μCi of naturally occurring potassium-40.

References

  1. ^ curie - Britannica Online Encyclopedia
  2. ^ Paul W. Frame. "How the Curie Came to Be". http://www.orau.org/ptp/articlesstories/thecurie.htm. Retrieved 2008-04-30. 

See also