The curie is a unit used to measure a radioactivity. One curie is the amount of radioactivity in one gram of the element first discovered by Madame Curie, Radium. It is also the quantity of a radioactive material that will have 37,000,000,000 transformations in one second. Often radioactivity is expressed in smaller units like: thousandths (mCi), one millionths (uCi) or even billionths (nCi) of a curie. The relationship between Becquerel and curie is: 3.7 x 1010 Bq in one curie.