Which unit is used to measure the quantity of radioactive material?

The unit used to measure the quantity of radioactive material is the Curie. This unit quantifies the amount of radioactive decay occurring in a substance. Specifically, one Curie is defined as the activity of a sample containing one gram of radium-226, which undergoes approximately 37 billion disintegrations per second.

In the context of radiology and radiation physics, understanding the quantity of radioactive material is crucial for assessing exposure risks and determining appropriate safety protocols. The Curie provides a straightforward measurement that indicates how much radiation a material emits, making it essential for both medical applications and safety regulations in environments where radioactive materials are used.

The other units mentioned are related to different aspects of radiation measurement: Gray is a unit of absorbed dose, Rad is an older unit of absorbed dose, and Rem is a unit that accounts for the biological effect of radiation. Each of these plays a different role in radiation physics but does not directly measure the quantity of radioactive material itself.