The Bq or becquerel is the modern unit of activity. One becquerel equals one disintegration per second. This is an extremely small unit. His many are kilobecquerel (kBq), the megabequerel (kBq), the gigabecquerel (GBq), the terabequerel (TBq) which represent respectively, a thousand, a million, a billion a trillion becquerels. The Becquerel now replaces the historical activity unit, Becquerel unit replaces, the curie or Ci. One curie is 37 billion becquerels, the activity of 1 gram of radium.