Plutonium Biokinetics in Human Body A. Luciani - Kit-Bibliothek - FZK

to be specified at a point but it is normally used to express the average dose absorbed by an organ or
a tissue:
where ε T is the average dose absorbed by the organ or tissue of m T.
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equation A.2
The probability of occurrence of stochastic effects depends linearly on the absorbed dose
over the low dose range. The dose response relationship is not linear for deterministic effects;
therefore the absorbed dose is not indicative of the severity of such effects, unless the dose is
uniformly absorbed over the organ or tissue of interest.
However the probability of stochastic effects depends not only on the absorbed dose, but
also on the type and energy of the radiation causing delivering the dose to the biological matter. In
order to take into account of this effect radiation weighting factors, w R, have been set up. The
radiation weighting factors are given in Table A.1.
Table A.1 Radiation weighting factors.
D T = T
m T
Type and energy range Radiation weighting factor, w R
Photons, all energies 1
Electrons and muons, all energies 1
Neutrons, energy E n < 10 keV 5
10 keV ≤ E n < 100 keV 10
100 keV ≤ E n < 2 MeV 20
2 MeV ≤ E n < 20 MeV 10
E n ≥ 20 MeV 5
Protons, other then recoil protons, energy > 2 MeV 5
Alpha particles, fission fragments, heavy nuclei 20
The absorbed dose weighted by the radiation weighting factors is called equivalent dose and
it is expressed as following:
HT = ∑wR
DT , R
R
equation A.3
where D T,R is the absorbed dose averaged over a tissue or organ T due to the radiation R and
w R is the relating radiation weighting factor. The summation is introduced in order to account of a
radiation field where particles of types and energy with different radiation weighting factors are