Sievert, unit defined

The former (non-SI) unit of dose equivalent was the roentgen equivalent man (rem), which was defined in the same way as the sievert but with the absorbed dose in rad thus, 1 rem = 10 2 Sv. 

Dose Equivalent (DE)—A quantity used in radiation safety practice to account for the relative biological effectiveness of the several types of radiation. It expresses all radiations on a common scale for calculating the effective absorbed dose. It is defined as the product of the absorbed dose in rad and certain modifying factors. (The unit of dose equivalent is the rem. In SI units, the dose equivalent is the sievert, which equals 100 rem.)... 

SI Units—The International System of Units as defined by the General Conference of Weights and Measures in 1960. These units are generally based on the meter/kilogram/second units, with special quantities for radiation including the becquerel, gray, and sievert. 

Sievert (Sv) It is a more modem unit that substitutes the rem, as it reflects the biological effect of radiation. It is defined as the absorbed dose in Gy multiplied by a somewhat complicated factor that takes into account for example the quality factor defined above, the part of the body irradiated and the time and volume of exposure. 1 Sv = 100 rems. 

For radiation protection purposes, several theoretical dosimetric quantities have been created that attempt to normalize the responses of different tissues and organs of the body from irradiation by different types of ionizing radiation so that uniform radiation protection guidelines can be promulgated that are insensitive to the particulars of any given irradiation scenario. The traditionally used quantity has been the dose equivalent (DE), which is defined as the absorbed dose (D) multiplied by the quality factor Q. The unit of dose equivalent has been the rem, which is dimensionally the same as the rad the SI unit is the Sievert (Sv). Recently, the DE has been replaced by a similar concept called the equivalent dose. The equivalent dose depends on the relative biological effectiveness rather than on Q. 

The sievert (Sv) is the SI unit of equivalent dose, which is defined as the absorbed dose multiplied by a weighting factor that expresses the long-term biological risk from low-level chronic exposure to a specified type of radiation. The Sv is another special name for J/kg. 

The rad is a unit of absorbed radiation dose in terms of energy actually deposited in the tissue. The rad is defined as an absorbed dose of 0.01 joules of energy per kilogram of tissue. The rem (radiation equivalent man) is the unit of human exposure and is a dose equivalent (DE). The international or SI unit for human exposure is the sievert, which is defined as equal to 100 rem [2]. It takes into account the biological effective of different types of radiation. The biologically effective dose in rems, is the radiation dose in rads multiplied by a quality factor, which is an assessment of the effectiveness of that particular type and energy of radiation. 

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