Effective Dose
A radiation protection quantity representing the overall stochastic health risk to the whole body by weighting organ equivalent doses by tissue sensitivity factors w_T.
Governing formula
E = ∑ H_T × w_T = ∑ D_T × w_R × w_T
SI unit
mSv (Millisieverts)
In depth
Organ weighting factors w_T account for varying radiation radiosensitivity (e.g. bone marrow and gonads w_T = 0.12 vs skin w_T = 0.01), allowing comparison of risk across different diagnostic procedures.
Examples in the real world
A chest X-ray delivering an effective dose of ~0.1 mSv compared to annual background radiation of ~3 mSv.