Sensitivity of effective dose to changes in tissue weighting factors

Effective dose E is the radiological protection quantity for stochastic health effects from whole-body exposure to ionising radiation. It is defined as a weighted sum of average absorbed doses in 15 selected tissues (organs), with weighting factors for radiation effectiveness and tissue sensitivity. This paper analyses the sensitivity of effective dose E with respect to the tissue weighting factors wT . It shows that a change of any single weighting factor by 100% results in relative changes of effective dose by a few percent for photons above an energy of 50 keV and for neutrons. Larger variations are observed for neutrons with an energy around 1 MeV and photons with low energies. The organs close to the body surface, breast and skin, are identified as the cause for these larger variations. Absolute changes of effective dose remain small, with exception for persons predominately exposed to low-energy photon radiation.