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The absorbed dose, measured in rad, is a better indicator of ARS. [3]: 592–593 A rem is a large dose of radiation, so the millirem (mrem), which is one thousandth of a rem, is often used for the dosages commonly encountered, such as the amount of radiation received from medical x-rays and background sources.
The rad is a unit of absorbed radiation dose, defined as 1 rad = 0.01 Gy = 0.01 J/kg. [1] It was originally defined in CGS units in 1953 as the dose causing 100 ergs of energy to be absorbed by one gram of matter. The material absorbing the radiation can be human tissue, air, water, or any other substance.
The roentgen or röntgen (/ ˈ r ɛ n t ɡ ə n,-dʒ ə n, ˈ r ʌ n t-/; [2] symbol R) 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 (statcoulomb per kilogram).
Recognized effects of higher acute radiation doses are described in more detail in the article on radiation poisoning.Although the International System of Units (SI) defines the sievert (Sv) as the unit of radiation dose equivalent, chronic radiation levels and standards are still often given in units of millirems (mrem), where 1 mrem equals 1/1,000 of a rem and 1 rem equals 0.01 Sv.
Absorbed dose is a dose quantity which is the measure of the energy deposited in matter by ionizing radiation per unit mass.Absorbed dose is used in the calculation of dose uptake in living tissue in both radiation protection (reduction of harmful effects), and radiology (potential beneficial effects, for example in cancer treatment).
the rad (radiation absorbed dose), now replaced by the gray; and; the rem (Röntgen equivalent man), now replaced by the sievert. [25] The rad and rem are essentially equivalent for almost all nuclear medicine procedures, and only alpha radiation will produce a higher Rem or Sv value, due to its much higher Relative Biological Effectiveness ...
To help avoid confusion between these quantities, absorbed dose is measured in units of grays (in SI, unit symbol Gy) or rad (in CGS), while the others are measured in sieverts (in SI, unit symbol Sv) or rem (in CGS). 1 rad = 0.01 Gy and 1 rem = 0.01 Sv. [37]
External dose quantities used in radiation protection and dosimetry. To enable consideration of stochastic health risk, calculations are performed to convert the physical quantity absorbed dose into equivalent dose, the details of which depend on the radiation type.