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Roentgen (R) Unit Definition
The roentgen or röntgen is a legacy unit of measurement for radiation exposure. It measures the radiation 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. It is equivalent to the statcoulomb (statC) per kilogram (kg) or statC/kg. The roentgen is represented by the symbol R.
In 1928, the roentgen was adopted as the first international measurement quantity for ionizing radiation to be defined for radiation protection. At the time it was 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 his discovery.
SI Multiples
A table of various radiation exposure roentgen derived from SI multiples:
Submultiples |
Multiples |
||||||
Scientific Notation |
Value |
Prefix |
Name |
Scientific Notation |
Value |
Prefix |
Name |
10-1 R |
0.1 R |
Deci (d) | Deciroentgen (dR) | 101 R |
10 R |
Deca (da) | Decaroentgen (daR) |
10-2 R |
0.01 R |
Centi (c) | Centiroentgen (cR) | 102 R |
100 R |
Hecto (h) | Hectoroentgen (hR) |
10-3 R |
0.001 R |
Milli (m) | Milliroentgen (mR) | 103 R |
1000 R |
Kilo (k) | Kiloroentgen (kR) |
10-6 R |
0.000001 R |
Micro (µ) | Microroentgen (µR) | 106 R |
1000000 R |
Mega (M) | Megaroentgen (MR) |
10-9 R |
0.000000001 R |
Nano (n) | Nanoroentgen (nR) | 109 R |
1000000000 R |
Giga (G) | Gigaroentgen (GR) |
10-12 R |
0.000000000001 R |
Pico (p) | Picoroentgen (pR) | 1012 R |
1000000000000 R |
Tera (T) | Teraroentgen (TR) |
10-15 R |
0.000000000000001 R |
Femto (f) | Femtoroentgen (fR) | 1015 R |
1000000000000000 R |
Peta (P) | Petaroentgen (PR) |
10-18 R |
0.000000000000000001 R |
Atto (a) | Attoroentgen (aR) | 1018 R |
1000000000000000000 R |
Exa (E) | Exaroentgen (ER) |
10-21 R |
0.000000000000000000001 R |
Zepto (z) | Zeptoroentgen (zR) | 1021 R |
1000000000000000000000 R |
Zetta (Z) | Zettaroentgen (ZR) |
10-24 R |
0.000000000000000000000001 R |
Yocto (y) | Yoctoroentgen (yR) | 1024 R |
1000000000000000000000000 R |
Yotta (Y) | Yottaroentgen (YR) |
10-27 R |
0.000000000000000000000000001 R |
Ronto (r) | Rontoroentgen (rR) | 1027 R |
1000000000000000000000000000 R |
Ronna (R) | Ronnaroentgen (RR) |
10-30 R |
0.000000000000000000000000000001 R |
Quecto (q) | Quectoroentgen (qR) | 1030 R |
1000000000000000000000000000000 R |
Quetta (Q) | Quettaroentgen (QR) |
Other Radiation Exposure Unit Definitions
Abcoulomb (abC)
- Attocoulomb (aC)
- Attoparker (aparker)
- Attorep (arep)
- Attoroentgen (aR)
- Centicoulomb (cC)
- Centiparker (cparker)
- Centirep (crep)
- Centiroentgen (cR)
- Coulomb (C)
Coulomb International (C)
- Decacoulomb (daC)
- Decaparker (daparker)
- Decarep (darep)
- Decaroentgen (daR)
- Decicoulomb (dC)
- Deciparker (dparker)
- Decirep (drep)
- Deciroentgen (dR)
- Dekacoulomb (daC)
- Dekaparker (daparker)
- Dekarep (darep)
- Dekaroentgen (daR)
Electronic Charge (q)
- Exacoulomb (EC)
- Exaparker (Eparker)
- Exarep (Erep)
- Exaroentgen (ER)
Faraday Constant (F)
- Femtocoulomb (fC)
- Femtoparker (fparker)
- Femtorep (frep)
- Femtoroentgen (fR)
Franklin (Fr)
- Gigacoulomb (GC)
- Gigaparker (Gparker)
- Gigarep (Grep)
- Gigaroentgen (GR)
- Hectocoulomb (hC)
- Hectoparker (hparker)
- Hectorep (hrep)
- Hectoroentgen (hR)
- Kilocoulomb (kC)
- Kiloparker (kparker)
- Kilorep (krep)
- Kiloroentgen (kR)
- Megacoulomb (MC)
- Megaparker (Mparker)
- Megarep (Mrep)
- Megaroentgen (MR)
- Microcoulomb (μC)
- Microparker (µparker)
- Microrep (µrep)
- Microroentgen (µR)
- Millicoulomb (mC)
- Milliparker (mparker)
- Millirep (mrep)
- Milliroentgen (mR)
- Nanocoulomb (nC)
- Nanoparker (nparker)
- Nanorep (nrep)
- Nanoroentgen (nR)
- Parker (parker)
- Petacoulomb (PC)
- Petaparker (Pparker)
- Petarep (Prep)
- Petaroentgen (PR)
- Picocoulomb (pC)
- Picoparker (pparker)
- Picorep (prep)
- Picoroentgen (pR)
- Quectocoulomb (qC)
- Quectoparker (qparker)
- Quectorep (qrep)
- Quectoroentgen (qR)
- Quettacoulomb (QC)
- Quettaparker (Qparker)
- Quettarep (Qrep)
- Quettaroentgen (QR)
- Rep (rep)
- Roentgen (R)
- Ronnacoulomb (RC)
- Ronnaparker (Rparker)
- Ronnarep (Rrep)
- Ronnaroentgen (RR)
- Rontocoulomb (rC)
- Rontoparker (rparker)
- Rontorep (rrep)
- Rontoroentgen (rR)
Statcoulomb (statC)
- Teracoulomb (TC)
- Teraparker (Tparker)
- Terarep (Trep)
- Teraroentgen (TR)
Tissue Roentgen (R)
- Yoctocoulomb (yC)
- Yoctoparker (yparker)
- Yoctorep (yrep)
- Yoctoroentgen (yR)
- Yottacoulomb (YC)
- Yottaparker (Yparker)
- Yottarep (Yrep)
- Yottaroentgen (YR)
- Zeptocoulomb (zC)
- Zeptoparker (zparker)
- Zeptorep (zrep)
- Zeptoroentgen (zR)
- Zettacoulomb (ZC)
- Zettaparker (Zparker)
- Zettarep (Zrep)
- Zettaroentgen (ZR)
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Related Definitions
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Sources
“Roentgen (Unit).” Wikipedia, Wikimedia Foundation, 4 Sept. 2023, en.wikipedia.org/wiki/Roentgen_(unit).