roentgen

Legacy unit of measurement for the kerma of X-rays and gamma rays up to 3 MeV; equals 0.258 mC/kg

Entityunit of exposure UCUM derived unitQ321017

Also known as R · röntgen

Instance of: unit of exposure
, UCUM derived unit

Overview

From Wikipedia, the free encyclopedia · Read full article · Text CC BY-SA 4.0

The roentgen or röntgen is a legacy unit of measurement for the exposure of X-rays and gamma rays, and is defined as the electric charge freed by such radiation in a specified volume of air divided by the mass of that air . In 1928, it was adopted as the first international measurement quantity for ionizing radiation to be defined for radiation protection, as it was then the most easily replicated method of measuring air ionization by using ion chambers. It is named after the German physicist Wilhelm Röntgen, who discovered X-rays and was awarded the first Nobel Prize in Physics for the discovery.

Overview

All data

26 statements · 8% with external sources · numbers in brackets are citations

Named after: Wilhelm Röntgen
Measured physical quantity: exposure
ion dose
Unit symbol: R
Conversion to SI unit: 0.000258 coulomb per kilogram
Different from: Roentgen equivalent man

On other databases

18 identifiers linking roentgen across the web's reference databases

Data quality

statements

externally sourced

Source last edited October 26, 2026. AIDb refreshes this page daily.

Suggest a fact or correction

Links

Use this data

curl https://aidb.si/api/v1/entities/Q321017

API docs, limits & keys

Cite this page

AIDb. (2026). roentgen (Q321017). Retrieved from https://aidb.si/e/roentgen-Q321017