roentgen

also rönt·gen (rĕnt'gən, -jən, rŭnt'-)
n. (Abbr. R or r)
A unit of radiation exposure equal to the quantity of ionizing radiation that will produce one electrostatic unit of electricity in one cubic centimeter of dry air at 0°C and standard atmospheric pressure.

[After Wilhelm Konrad ROENTGEN.]

roentgen roent'gen adj.

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The former unit of dose equivalent (see radiation units). It is named after the discoverer of X-rays, W. K. Roentgen (1845–1923).

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[Etymology: W. K. Röntgen; Germany 1845-1923] radiation physics Symbol R, röntgen. An obsolescent unit of ionizing electromagnetic radiation, being the quantity of x-rays or gamma rays that, through ionization, produces 2.58 × 10^-4 coulombs of electricity per kilogram of dry air at s.t.p.

The roentgen was originated relative only to x-rays, being agreed in 1928 as the amount that would produce 1 electrostatic unit of electric charge from 1 cubic centimetre of standard dry air. In 1937, for practical reasons, mass replaced volume for the reference amount of air, making the amount 1.293~ mg of air. The 1978 decision of the CIPM considering it acceptable to continue to use the roentgen with the SI still stands.

Such ionization displaces electrons from individual atoms to produce negatively charged free electrons and matching positively charged ions; 1 roentgen produces 1.61~ × 10¹⁵ of each per kilogram. The energy required for such displacing is 8.69~ mJ·kg^-1 or 11.2~ mJ·m^-3.

Using this energy figure of 8.69~ mJ·kg^-1, the roentgen was extended to apply to materials other than air, and to the particulate radiation of alpha and beta rays. In this extended form it was called the tissue roentgen or, much more usually, the roentgen equivalent physical, abbreviated to and universally called the rep. However, the roentgen itself was often so used; until 1956 it was used in a radiological context not only as a measure of exposure (which it correctly is) but also as a measure of absorbed dose; the rad took over the latter role.

Until 1952 the British authorities used a version about 8% less.

[ܒrentgǝn; ܒrǝnt-; -jǝn]

ˈrentgǝn; ˈrǝnt-; -jǝn n.a unit of exposure dose of gamma (or X) radiation. One roentgen is essentially equal to one rad.

See the Introduction, Abbreviations and Pronunciation for further details.

(DOD, NATO) A unit of exposure dose of gamma (or X-) radiation. In field dosimetry, one roentgen is essentially equal to one rad.

IN BRIEF: n. - German physicist who discovered x-rays and developed x-ray photography (1845-1923).

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or roentgen

symbol R; the unit of exposure (def. 3) to X- or gamma radiation, expressed in terms of the amount of ionization caused in air. Defined originally (1928, 1937) as that quantity of radiation having a corpuscular emission per 0.001293 gram of air (equivalent of 1 cm³ of dry air at stp) producing, in air, ions carrying one electrostatic unit quantity of electricity of either sign. Expressed in SI units, 1 R causes the production in air of ions (of one sign) carrying a charge of 2.58 × 10⁴ C kg⁻¹; this corresponds to the formation of 1.61 × 10¹⁵ ion-pairs per kg of air and to an absorption of energy by air equal to 0.00869 J kg⁻¹. The energy absorption by water or tissue from 1 R of x- or gamma-radiation is about 0.0096 J kg⁻¹. Prior to 1956, the röntgen was used in clinical work to express both exposure and absorbed dose. See also rad (def. 2), rem, rep. [After Wilhelm Konrad von Röntgen (1845 — 1923), German physicist, discoverer of X-rays.]

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A superseded international unit of x- or γ-radiation; it is the quantity of x- or γ-radiation such that the associated corpuscular emission per 0.001293 g of air produces, in air, ions carrying 1 electrostatic unit of electrical charge of either sign. Abbreviated R. Now replaced by coulomb/kg (C/kg); see coulomb. 1 R = 2.58 × 10⁻⁴ C/kg; 1 C/kg = 3876 R.

• r. equivalent man (rem) — see rem.
• r. equivalent physical (rep) — see rep.
• r. ray — x-ray.

(rent′gən)
n
r

An international unit based on the ability of radiation to ionize air. The exposure to x or gamma radiation such that the associated corpuscular emission per 0.001293 Gm of air produces, in air, ions carrying 1 esu of quantity of electricity of either sign (2.083 billion ion pairs).

For a list of words related to roentgen, see:

• Nuclear and Particle Physics - roentgen: standard unit that measures ionizing radiation from X-rays or gamma rays

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See words rhyming with "roentgen."

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Dansk (Danish)
n. - røntgen

idioms:

• roentgen rays    røntgenstråler

Nederlands (Dutch)
röntgen

Français (French)
n. - Röntgen

idioms:

• roentgen rays    rayons Röntgen

Deutsch (German)
n. - Röntgen

idioms:

• roentgen rays    Röntgenstrahlen

Ελληνική (Greek)
n. - ακτίνες Χ, ακτίνες Ραίντγκεν

idioms:

• roentgen rays    ακτίνες Ραίντγκεν

Italiano (Italian)
idioms:

• roentgen rays    raggi X

Português (Portuguese)
idioms:

• roentgen rays    raio x

Русский (Russian)
рентген

idioms:

• roentgen rays    рентгеновские лучи

Español (Spanish)
n. - rayos roentgen

idioms:

• roentgen rays    rayos X

Svenska (Swedish)
n. - (fys) Röntgen (enhet)

中文（简体）(Chinese (Simplified))
伦琴

idioms:

• roentgen rays    X光射线

中文（繁體）(Chinese (Traditional))
n. - 倫琴

idioms:

• roentgen rays    X光射線

한국어 (Korean)
n. - 뢴트겐

日本語 (Japanese)
n. - レントゲン
adj. - レントゲンの

idioms:

• roentgen rays    レントゲン線

العربيه (Arabic)
‏(الاسم) الوحدة الدوليه لأشعه إكس‏

עברית (Hebrew)
n. - ‮צילום או שיקוף בקרני רנטגן‬

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