Definitions of units for radiation

gray

SI Unit of absorbed dose (symbol Gy) due to an ionizing radiation. 1 gray means 1 joule of energy from radiation deposited in 1 kilogram of some material. 1 gray is equivalent to 1 joule/kilogram.

rad

Old unit of absorbed dose, acronym for Radiation Absorbed Dose (rad), still commonly used. 1 rad means 100 ergs of energy from an ionizing radiation deposited in 1 gram of some material.

joule/kilogram

For safeguarding the human health, gray is admitted as SI unit for the quantity of adsorbed dose rather than joule/kilogram based on its definition.

rep

An obsolete unit of absorbed dose, acronym for Roentgen Equivalent Physical (rep). 1 rep of absorbed dose means any ionizing radiation with a magnitude of 93 ergs per gram or 9.3 milligrays (mGy). It has been superseded by the rad. The definition was made because a dose of 1 rep of beta rays was considered biologically equivalent to a dose of 1 roentgen of X rays.

erg per gram

1 erg/g means 1 erg of energy from an ionizing radiation deposited in 1 gram of some material. It is equivalent to 0.0001 gray.

sievert

Different radiation would be much more different biologically damaging to human body. Sievert (symbol Sv), SI derived unit of dose equivalent, is a measure of dose on the biological effects of the different radiations. which means 1 joule per kilogram of energy loss of body from an ionizing x-ray or gamma radiation. 1 sievert is equivalent to 1 joule/kilogram.

rem

A unit of dose equivalent, acronym for röntgen equivalent in man (rem), is a measure of dose deposited in body tissue. It is derived by multiplying Absorbed Dose (in Rads ) by a Quality Factor . For gamma rays and beta particles, 1 rad of exposure results in 1 rem of dose. One rem is equivalent to 0.01 sievert.

curie

The original unit used to describe the intensity of radioactivity (symbol Ci). The unit is named for a French physicist, Antoine-Henri Becquerel (1852-1908), the discoverer of radioactivity. One curie equals thirty-seven billion disintegrations per second (becquerel), or approximately the radioactivity of one gram of radium.

becquerel

A special name given as ths SI derived unit of radioactivity (symbol Bq). Radioactivity is caused when atoms disintegrate, ejecting energetic particles. One becquerel is the radiation caused by one disintegration per second. It is equivalent to about 27.0270 picocuries (pCi).

disintegration per second

One becquerel is the radiation caused by one disintegration per second, which is expressed in the SI unit as s-1. Both the becquerel and the hertz are basically defined as one event per second, yet they measure different things. The hertz is used to measure the rates of events that happen periodically in a fixed and definite cycle. The becquerel is used to measure the rates of events that happen sporadically and unpredictably, not in a definite cycle.

rutherford

An obsolete unit of radioactivity (symbol rd). It was defined as the activity of a quantity of radioactive material in which one million nuclei decay per second, which is equivalent to 1 MBq.

coulomb per kilogram

SI unit for radiation exposure (symbol C/kg).

Röntgen

The röntgen or roentgen (symbol R) is a unit of measurement for ionizing radiation exposure (such as X-ray and gamma rays) in the air. It is named after the German physicist Wilhelm Röntgen. 1 R is the amount of radiation required to liberate positive and negative charges of one electrostatic unit of charge in 1 cm³ of air at standard temperature and pressure (STP). In a standard atmosphere the air density is 1.293 kg/m³). Hence, one roentgen is equal to depositing in dry air enough energy to cause 2.58 x 10-4 coulombs per kg.