How are radionuclide source activities expressed?

Radionuclide source activities are expressed in curies (Ci) or becquerels (Bq) because these units specifically measure the rate at which radioactive decay occurs. The curie is a traditional unit that represents a certain amount of radioactive material producing a specific number of decays per second, which is equivalent to approximately 37 billion disintegrations per second. On the other hand, the becquerel is the SI unit for measuring radioactivity, defined as one disintegration per second.

These units are directly related to the activity of radionuclides and provide essential information for radiation safety and management practices, crucial for personnel working in industrial radiography and other fields involving radioactive materials.

In contrast, the other units listed do not measure radioactivity itself. Volts (V) measure electric potential, millirems (mrem) measure radiation dose to tissue, and grays (Gy) measure absorbed dose of radiation in matter. Therefore, only curies and becquerels accurately represent the activity levels of radionuclide sources.