sievert

sie·vert   (sē'vərt)    n.   Abbr. Sv The SI unit for the amount of ionizing radiation required to produce the same biological effect as one rad of high-penetration x-rays, equivalent to a gray for x-rays. [After Rolf Maximilian Sievert (1896-1966), Swedish radiologist.]

Main Entry: sie·vert
Pronunciation: 'sE-v&rt
Function: noun
: an SI unit for the dosage of ionizing radiation equal to 100 rems—abbreviation Sv
Sievert, Rolf Maximilian (1896–1966), Swedish physicist. Sievert was a pioneer in radiation physics and protection from radiation. He servedas head of the physics laboratory at Sweden's Radiumhemmet from 1924 to 1937, when he became head of the department of radiation physics at the Karolinska Institute. He played a pioneering role in themeasurement of doses of radiation especially in its use in the diagnosis and treatment of cancer. In later years he focused his research on the biological effects of repeated exposure to low doses ofradiation. In 1964 he founded the International Radiation Protection Association, serving for a time as its chairman. He also chaired the United Nations Scientific Committee on the Effects of AtomicRadiation. In 1979 a scientific conference named a unit for the dosage of ionizing radiation in his honor.

sievert sie·vert (sē'vərt)
n.

Abbr. Sv A unit of ionizing radiation absorbed dose equivalent in the International System of Units, obtained as a product of the absorbed dose measure in grays and a dimensionless factor, stipulated by the International Commission on Radiological Protection, and indicating the biological effectiveness of the radiation.

sievert   (sē'vərt)  Pronunciation Key  The SI derived unit used to measure the amount of radiation necessary to produce the same effect on living tissue as one gray of high-penetration x-rays. The sievert is named after Swedish physicist Rolf Sievert (1896-1966).

sievert

unit of radiation absorption in the International System of Units (SI). The sievert has been recommended by the International Commission on Radiation Units and Measurements (ICRU) as a substitute for the rem, the long-standing special unit for measuring biological absorption of radiation. Like the rem, the sievert takes into account the relative biologic effectiveness (RBE) of ionizing radiation, since each form of such radiation-e.g., X rays, gamma rays, neutrons-has a slightly different effect on living tissue. Accordingly, one sievert is generally defined as the amount of radiation roughly equivalent in biologic effectiveness to one gray (or 100 rads) of gamma radiation. The sievert is inconveniently large for various applications, and so the millisievert (mSv), which equals 11,000 sievert, is frequently used instead. One millisievert corresponds to 10 ergs of energy of gamma radiation transferred to one gram of living tissue.

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