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That model calculates an effective radiation dose, measured in units of rem, which is more representative of the stochastic risk than the absorbed dose in rad. In most power plant scenarios, where the radiation environment is dominated by X-or gamma rays applied uniformly to the whole body, 1 rad of absorbed dose gives 1 rem of effective dose. [5]
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.
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).
In 1953 the International Commission on Radiation Units and Measurements (ICRU) recommended the rad, equal to 100 erg/g, as the unit of measure of the new radiation quantity absorbed dose. The rad was expressed in coherent cgs units. [5] In 1975 the unit gray was named as the SI unit of absorbed dose. One gray is equal to 1 J/kg (i.e. 100 rad).
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.
The International Committee for Weights and Measures states: "In order to avoid any risk of confusion between the absorbed dose D and the dose equivalent H, the special names for the respective units should be used, that is, the name gray should be used instead of joules per kilogram for the unit of absorbed dose D and the name sievert instead ...
The fundamental quantity is the absorbed dose (D), which is defined as the mean energy imparted [by ionising radiation] (dE) per unit mass (dm) of material (D = dE/dm) [8] The SI unit of absorbed dose is the gray (Gy) defined as one joule per kilogram. Absorbed dose, as a point measurement, is suitable for describing localised (i.e. partial ...
A dose rate is quantity of radiation absorbed or delivered per unit time. It is often indicated in micrograys per hour (μGy/h) [ 1 ] or as an equivalent dose rate Ḣ T in rems per hour (rem/hr) or sieverts per hour (Sv/h).