Ionizing radiation units

Ionizing radiation units

Radiation Measurement Units - International System (SI)

Activity of an isotope or material

conventional unit: 1 curie = 37 billion disintegrations per second.

SI unit: 1 becquerel = 1 disintegration per second


1 curie (Ci) = 37 gigabecquerel (GBq)

1 gigabecquerel (GBq) = 27 millicurie (mCi)

Radiation Absorbed Dose (rad)

conventional units: A dose of 1 Rad means the absorption of 100 ergs of radiation energy per gram of material

SI units: A dose of 1 Gray means the absorption of 1 joule of radiation energy per kilogram of material


1 Gray = 100 Rads

1 Rad = 0.01 Gray

A unit of exposure to ionizing radiation. Only used by well trained personnel.

The amount of gamma or x-rays required to produce ions carrying 1 electrostatic unit of electrical charge (either positive or negative) in 1 cc of dry air under standard conditions.

1 roentgen (R) = 258 microcoulomb/kg (mC/kg)

1 millicoulomb/kg mC/kg = 3876 milliroentgen (mR)

dose equivalent

The dose equivalent is a measure of biological effect for whole body irradiation. The dose equivalent is equal to the product of the aborbed dose and the Quality Factor.

The Quality Factor(Q) depends on the type of radiation:

x, gamma, or beta radiation: Q = 1

alpha paraticles: Q = 20

neutrons of unknown energy: Q = 10 (If the neutron energy is known, see more specific Q values at 10 CFR 20.1004, at

conventional units: dose equivalent(Rems) is the product of dose (Rads) and Q

SI units: dose equivalent (Sieverts) is the product of dose (Grays) and Q


1 Sievert = 100 Rems

1 Rem = 0.01 Sievert

"C"ounts "P"er "M"inute (CPM)

Used for alpha particles, beta particles or mixed gamma/beta, gamma/alpha, alpha/beta actual counts per minute. Counts per minute can also be useful when detector efficiency is in question. Like when a scintillator is designed to detect the 0.013 mev photons from 238U and one is measuring the 1.146 mev photons from 40K, The units cannot be easyly converted to roentgen's so CPM is a more appropriate unit under these conditions.

"R"oentgen "E"quivalent "P"hysical (rep)

An obsolete unit of absorbed dose of any ionizing radiation with a magnitude of 93 ergs per gram. It has been superseded by the rad.


Rad pro calculator.

Metric units and conversion charts, A metrication handbook for engineers, technologist, and scientist. By Theodore Wildi. ISBN 0-7803-1050-0, IEEE order Number: PP4044.

Code of Federal (US) Regulations, Title 10, Chapter 20, "Standards For Protection Against Radiation"

ee also

* Counts per minute
* Curie
* Becquerel
* Rad (unit)
* Gray (unit)
* Roentgen
* Röntgen equivalent man
* Sievert
* Alpha particles
* Scintillation counter
* Geiger counter
* Radon gas
* Lucas cell
* Photomultiplier

Wikimedia Foundation. 2010.

Look at other dictionaries:

  • Ionizing radiation — consists of highly energetic particles or waves that can detach (ionize) at least one electron from an atom or molecule. Ionizing ability depends on the energy of the impinging individual particles or waves, and not on their number. A large flood …   Wikipedia

  • Radiation therapy — Radiation (medicine) redirects here. It is not to be confused with Radiation (pain) or Radiology. Radiation therapy Intervention ICD 10 PCS D ICD 9 CM …   Wikipedia

  • Radiation poisoning — Radiation poisoning, also called radiation sickness or a creeping dose , is a form of damage to organ tissue due to excessive exposure to ionizing radiation. The term is generally used to refer to acute problems caused by a large dosage of… …   Wikipedia

  • radiation — radiational, adj. /ray dee ay sheuhn/, n. 1. Physics. a. the process in which energy is emitted as particles or waves. b. the complete process in which energy is emitted by one body, transmitted through an intervening medium or space, and… …   Universalium

  • radiation measurement — ▪ technology Introduction       technique for detecting the intensity and characteristics of ionizing radiation, such as alpha, beta, and gamma rays or neutrons, for the purpose of measurement.       The term ionizing radiation refers to those… …   Universalium

  • Nuclear and radiation accidents — This article is about nuclear and radiation accidents in general. For a list of military nuclear accidents, see List of military nuclear accidents. For a list of civilian nuclear accidents, see List of civilian nuclear accidents. For a discussion …   Wikipedia

  • Stopping power (particle radiation) — In passing through matter, fast charged particles ionize the atoms or molecules which they encounter. Thus, the fast particles gradually lose energy in many small steps. Stopping power is defined as the average energy loss of the particle per… …   Wikipedia

  • List of civilian radiation accidents — This article lists notable civilian accidents involving radioactive materials or involving ionizing radiation from artificial sources such as x ray tubes and particle accelerators. Accidents related to nuclear power that involve fissile materials …   Wikipedia

  • Electromagnetic radiation and health — Electromagnetic radiation can be classified into ionizing radiation and non ionizing radiation, based on whether it is capable of ionizing atoms and breaking chemical bonds. Ultraviolet and higher frequencies, such as X rays or gamma rays are… …   Wikipedia

  • Acute radiation syndrome — Classification and external resources A Japanese girl recovering from the effects of radiation sickness ICD 10 T …   Wikipedia