Equivalent amount

In Nuclear physics, the equivalent of amount is a physical Grandeur measuring the impact on the biological fabrics of an exposure to a Ionizing ray, in particular with a source of Radioactivité. It is defined as the absorptive Dose , namely the energy received by unit of Masse, corrected of a factor loading of the radiation, without dimension, which takes into account the relative dangerosity of the radiation considered. This factor is worth 1, by definition, for the X-rays.

The unit of the equivalent of amount is the Sievert (Sv), in the honor of the Physicien Rolf Sievert, and can be expressed in equivalent of Joule by Kilogram (J/kg). The old unit, the Rem, is worth 10 mSv (100 rem = 1 Sv).

Calculation

Equivalent amount

Knowing the amount S D R delivered by various types of radiations, the equivalent of amount H is

H = \ sum_ \ mathrm {R} w_ \ mathrm {R} D_ \ mathrm {R} \, .
where the W R are the factor loadings of the radiations (in the past: factors of quality).

Factor loading of the radiation

To take into account in a precise way the dangerosity of an amount of a type of radiation, a biological factor of effectiveness should take into account several parameters:
  • the type of radiations;
  • their energy;
  • the studied biological effect.

In order to simplify, the radiological International commission of protection put forth a recommendation on the calculation of a factor of quality or factor loading of the radiations, considering the factor of effectiveness biological. The values are listed below:

Use

The equivalent amount is a unit used in Radioprotection to predict the risks Stochastique S related to a chronic irradiation. It is not adapted to envisage the effects of a acute irradiation.

See too

Internal bonds

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