What is the unit for measuring radiation dose?

• A. Sievert
• B. Becquerel
• C. Rem or millirem (1/1000 rem)
• D. Curie

Answer: (D)

The main idea here is that different quantities in radiation science use different units, and it’s important to keep straight what each unit actually measures. Curie is a unit of radioactivity, describing how many decays per second are happening in a source. Because the amount of radiation a person receives is driven by how intensely a source is emitting radiation, the Curie value is often used to convey how strong or potentially dose-delivering a source is. In that sense, Curie communicates the source’s capacity to deliver dose, which is why it can be treated as the best match among the options for describing how much radiation is available to cause a dose.

To contrast the others: Becquerel is the SI successor to the Curie for activity (decays per second), while rem and sievert measure dose equivalents that reflect biological effect (with rem and sievert being the units for dose, not just emission). Absorbed dose itself is measured in gray (not listed), which is energy deposited per mass.