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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.
A 0.05 Gy dose will increase death due to cancer 10 fold, from the normal 0.5 per 1000 birth rate to a rate of 5 per 1,000. [ citation needed ] An antenatal dose of 1 Gy in the first trimester causes the lifetime risk of fatal cancer sometime in the child's life to increase from c. 25% in non-exposed humans to 100% in the first trimester after ...
Geiger-Müller counter with dual counts/dose rate display measuring a "point source". The dose per count is known for this specific instrument by calibration. The count rates of cps and cpm are generally accepted and convenient practical rate measurements. They are not SI units, but are de facto radiological units of measure in widespread use.
For such purposes, doses should be evaluated in terms of absorbed dose (in gray, Gy), and where high-LET radiations (e.g., neutrons or alpha particles) are involved, an absorbed dose, weighted with an appropriate RBE, should be used" Radiation weighting factors are largely based on the RBE of radiation for stochastic health risks. However, for ...
A dose of 100 to 200 rad delivered to the entire body in less than a day may cause acute radiation syndrome (ARS), but is usually not fatal. Doses of 200 to 1,000 rad delivered in a few hours will cause serious illness, with poor prognosis at the upper end of the range.
Neutron radiation is a form of ionizing radiation that presents as free neutrons.Typical phenomena are nuclear fission or nuclear fusion causing the release of free neutrons, which then react with nuclei of other atoms to form new nuclides—which, in turn, may trigger further neutron radiation.
This included a proposal to discontinue use of equivalent dose as a separate protection quantity. This would avoid confusion between equivalent dose, effective dose and dose equivalent, and to use absorbed dose in Gy as a more appropriate quantity for limiting deterministic effects to the eye lens, skin, hands & feet. [10]
The definition of the BRET unit is apparently unstandardized, and depends on what value is used for the average annual background radiation dose, which varies greatly across time and location. The 2000 UNSCEAR estimate for worldwide average natural background radiation dose is 2.4 mSv (240 mrem), with a range from 1 to 13 mSv. A small area in ...