What does kilocurie mean?
A kilocurie is a unit used to express radioactivity, particularly the activity of radioactive substances used in medicine, industry, research, and the production of energy. It equals 1,000 curies; one curie corresponds to 3.7 × 10^10 nuclear disintegrations per second, making one kilocurie equal to 3.7 × 10^13 disintegrations per second. The unit combines the metric prefix kilo-, meaning one thousand, with the curie, a non-SI unit named after the physicists Pierre and Marie Curie. Although the becquerel has replaced the curie in formal scientific measurement, kilocuries remain familiar in technical and historical descriptions of radiotherapy, isotope sources, and radiological engineering. The term should therefore be understood as a conventional unit of radioactivity rather than a separate physical process or an SI standard.
nounA unit of radioactivity equal to 1,000 curies, used especially in medicine, industry, and the description of radioactive sources. It is a non-SI unit and has largely been replaced by the becquerel.
- A non-SI unit of radioactivity equal to 1,000 curies.
"The treatment contained a measured dose of several kilocuries of radioactive material."
"The laboratory used a kilocurie source for its radiation experiments."
"The medicine is administered in carefully calculated kilocuries under specialist supervision."
The plural is formed by adding -s to the entire unit name.
"The source emitted several kilocuries of radiation each hour."
A kilocurie carries both a metric prefix and the name of the Curie family in its story: thousand plus the unit named in honor of Pierre and Marie Curie.
Reviewed by Deb Chak, Editor. AI-assisted content curated by RJS Tech Solutions LLP.
Where does kilocurie come from?
The word is formed from the prefix kilo-, derived from the Greek chilioi, meaning “thousand,” and the curie, the unit named in honor of Pierre and Marie Curie. Kilocurie was adopted in the early 20th century as the larger unit needed for describing substantial radioactive activity. The kilo- element is shared by modern metric terms such as kilogram, kilometer, and kilowatt.
How kilocurie is actually used
The kilocurie remains common in specialized medical, industrial, and historical contexts, but the becquerel is preferred in modern scientific usage. Its abbreviation is kCi.
Easily confused with kilocurie
A curie is the base unit of radioactivity, whereas a kilocurie equals 1,000 curies.
The becquerel is the SI unit of radioactivity, while the kilocurie is an older, non-SI unit.