The curie (symbol Ci) is a non-SI unit of radioactivity, named after Marie and Pierre Curie. It is defined as $1Ci = 3.7 \times 10^{10} decays\ per\ second$. Its continued use is discouraged. One Curie is roughly the activity of 1 gram of the radium isotope Ra, a substance studied by the Curies. The SI derived unit of radioactivity is the becquerel (Bq), which equates to one decay per second. Therefore: $1Ci = 3.7 \times 10^{10} Bq= 37 GBq$ and $1Bq \equiv 2.703 \times 10^{-11}Ci $.
Curie