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The absorbed dose can be a poor indicator of the biological effect of radiation, as the biological effect can depend on many other factors, including the type of radiation, energy, and type of tissue. The relative biological effectiveness can help give a better measure of the biological effect of radiation.
The ICRP introduced and then officially adopted the rem in 1962 as the unit of equivalent dose to measure the way different types of radiation distribute energy in tissue and began recommending values of relative biological effectiveness (RBE) for various types of radiation. [22]
W R is the radiation weighting factor defined by regulation. Thus for example, an absorbed dose of 1 Gy by alpha particles will lead to an equivalent dose of 20 Sv, and an equivalent dose of radiation is estimated to have the same biological effect as an equal amount of absorbed dose of gamma rays, which is given a weighting factor of 1.
The Röntgen equivalent physical (rep), introduced by Herbert Parker in 1945, [12] was the absorbed energetic dose to tissue before factoring in relative biological effectiveness. The rep has variously been defined as 83 or 93 ergs per gram of tissue (8.3/9.3 mGy) [13] or per cc of tissue. [14]
Effective dose is a dose quantity in the International Commission on Radiological Protection (ICRP) system of radiological protection. [1]It is the tissue-weighted sum of the equivalent doses in all specified tissues and organs of the human body and represents the stochastic health risk to the whole body, which is the probability of cancer induction and genetic effects, of low levels of ...
This is due to the high relative biological effectiveness of alpha radiation to cause biological damage after alpha-emitting radioisotopes enter living cells. Ingested alpha emitter radioisotopes such as transuranics or actinides are an average of about 20 times more dangerous, and in some experiments up to 1000 times more dangerous than an ...
Many studies have attempted to relate linear energy transfer to the relative biological effectiveness (RBE) of radiation, with inconsistent results. The relationship varies widely depending on the nature of the biological material, and the choice of endpoint to define effectiveness.
Some have hypothesized that alpha's high relative biological effectiveness might be attributable to cell's tendency to absorb transuranic metals into the cellular nucleus where they would be in very close proximity to the genome, though an elevated effectiveness can also be observed for external alpha radiation in cellular studies.