Deterministic effects

Last revised by Andrew Murphy on 29 Mar 2020

Deterministic effects describe a cause and effect relationship between ionizing radiation and certain side-effects. They are also known as non-stochastic effects to contrast them with chance-like stochastic effects (e.g. cancer induction).

These effects depend on dose, dose rate, dose fractionation, irradiated volume and type of radiation (linear energy transfer (LET)).

Deterministic effects have a threshold below which the effect does not occur. The threshold may be very low and may vary from person to person. However, once the threshold has been exceeded, the severity of an effect increases with dose.

There are practical threshold doses below which no significant changes are apparent and these thresholds should never be reached occupationally if sensible procedures are upheld.

Examples of deterministic effects (doses are given as absorbed doses and expressed in grays (Gy)):

  • skin erythema: 2-5 Gy
  • irreversible skin damage: 20-40 Gy
  • hair loss: 2-5 Gy
  • sterility: 2-3 Gy
  • cataracts: 0.5 Gy (NB: a significantly lowered threshold of 5Gy to 0.5Gy in the latest ICRP 118 1)
  • lethality (whole body): 3-5 Gy
  • fetal abnormality: 0.1-0.5 Gy

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