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Effective Dose and Tissue Weighting Factors
Effective dose adds up each organ's equivalent dose times its tissue weighting factor, so partial-body exams can be compared by whole-body risk.
Three steps
Effective dose is built in three steps. First, absorbed dose (D, in gray) is the energy deposited per kilogram in an organ. Second, equivalent dose (H, in sievert) adjusts for the type of radiation: H = D × wR, where wR is the radiation weighting factor. Third, effective dose (E, in sievert) adjusts for how sensitive each organ is: E = Σ (wT × HT), the sum over every exposed tissue of its tissue weighting factor times its equivalent dose. The result is the uniform whole-body dose that would carry the same overall stochastic risk, meaning cancer and heritable effects.