Radiation Exposure Converter — Roentgen (R), C/kg
Convert between 5 units of radiation exposure — coulomb per kilogram (C/kg), millicoulomb per kilogram (mC/kg), roentgen (R), milliroentgen (mR), and microroentgen (μR). 1 R = 2.58 × 10⁻⁴ C/kg. Background radiation at sea level is ~0.1 mR/h. The roentgen was named after Wilhelm Röntgen, discoverer of X-rays in 1895. Now largely superseded by absorbed dose (Gy) and effective dose (Sv) in modern radiological practice.
About the Radiation Exposure Converter
Radiation exposure historically measured the ability of X-rays or gamma rays to ionise air. The traditional unit is the roentgen (R), defined as the amount of radiation that produces a certain ionisation in dry air. The modern SI equivalent is coulombs per kilogram (C/kg) of air. Exposure is now largely superseded by absorbed dose (gray) and effective dose (sievert) in modern radiological practice, but the roentgen is still encountered in older equipment and literature.
- ›One roentgen corresponds to 2.58 × 10⁻⁴ C/kg of ionisation in dry air
- ›Background radiation exposure varies from ~0.1 mR/h at sea level to over 0.3 mR/h at altitude
- ›The roentgen was named after Wilhelm Röntgen, discoverer of X-rays in 1895
- ›Occupational dose limits for radiation workers are expressed as effective dose (mSv/year), not exposure