What term is used to describe the strength of a radiation source?

The term that describes the strength of a radiation source is referred to as "Activity." In the context of radiation, activity specifically quantifies the number of decay events that occur in a radioactive substance over a specific time period, usually expressed in units such as Becquerels (Bq) or Curie (Ci). This measure is fundamentally tied to the inherent properties of the radioactive material itself, and it reflects how much radiation is being emitted from the source.

Understanding activity is crucial in radiation safety and health physics as it helps assess the potential dose that workers, patients, or the public might receive from exposure to a radioactive source. This concept is preferred over vague terms like intensity or output, which may infer different meanings depending on the context, such as radiation beam intensity in radiotherapy rather than the inherent strength of the radioactive material itself. Concentration, while relevant in some contexts, does not specifically denote the inherent rate of radioactive decay. Thus, "Activity" is the most accurate term for describing the strength of the radiation source.