decay
The curie Ci is one measure of the rate of decay named after Pierre and Marie Curie . One curie is equivalent to 3.7 10 10 disintegrations per second. Since this is obviously a large and unwieldy number, radiation is often expressed in millicuries or microcuries still very large numbers . Another measure is the becquerel Bq , named after Henri Becquerel. The becquerel is defined as an activity of one disintegration/second. Both of these units are concerned with the disintegration rate of the radioactive isotope and give no indication of dosage to the target material.