Measuring Radiation

Three common measurements of radiation are the amount of radioactivity, ambient radiation levels, and radiation dose. But, to get accurate and reliable measurements, we need to have both the right instrument and a trained operator. It is important to maintain radiation detection equipment to ensure it is working properly.

It’s All About the Energy!

Radiation energy being emitted from trefoil symbol
  • When working with radiation, we are concerned about the amount of energy the material is emitting. The size, weight, and volume of the material do not necessarily matter.
  • A small amount of material may give off a lot of radiation.
  • On the other hand, a large amount of radioactive material may give off a small amount of radiation.

Learn more about measuring radiation

Measuring the Amount of Radioactivity

Image of geiger counter with pancake probe
  • We measure the amount of radioactivity by finding out how many radioactive atoms decay every second. These atoms may be giving off alpha particles, beta particles, and/or gamma rays.
  • The amount of radioactivity is reported in Becquerel (Bq), which is the international unit, or the Curie (Ci), which is the unit used in the United States.
  • Geiger counters are commonly used to measure the amount of radioactivity, but there are other types of detectors that may be used.

Learn more about measuring the amount of radioactivity

Measuring Ambient Radiation Levels

illustration of ambient radiation level = amount of radiation in the environment around us
  • Ambient radiation levels measure how much radiation is in the environment around us.
  • Ambient radiation levels are reported in Gray per hour (Gy/h) or Sievert per hour (Sv/h), which are the international units. In the United States, we use Roentgen per hour (R/h) or rem per hour (rem/h).
  • Instruments called pressurized ionization chambers are best suited for measuring ambient radiation levels.

Learn more about measuring ambient radiation levels

Measuring Radiation Dose

image of man with alarming dosimeter
  • Radiation dose is the amount of radiation absorbed by the body.
  • Radiation doses are reported in Gray (Gy) or Sievert (Sv), which are international units. In the U.S., we use rad or rem
  • Alarming dosimeters can be used by first responders and safety officers to monitor dose in real time. There are also specialized instruments used by hospitals and laboratories that can measure dose.

Learn more about measuring radiation dose

Page last reviewed: December 7, 2015