Effective dose meaning

In radiation law and practice, effective dose is the calculated whole‑body measure used by regulators and dutyholders to assess compliance with legal limits on exposure to ionising radiation and to compare different exposure situations. It is defined in UK and Irish radiation‑protection legislation (GB: Ionising Radiations Regulations 2017; NI: Ionising Radiations Regulations (Northern Ireland) 2017; Ireland: regulations implementing the EU Basic Safety Standards, 2013/59/Euratom), and its use is broadly consistent across England & Wales, Scotland, Northern Ireland and Ireland. Effective dose (unit: sievert, symbol Sv) is obtained by multiplying the equivalent dose received by each specified tissue or organ by the relevant tissue weighting factor and summing the results. The weighting factors reflect relative radiosensitivity. The measure represents the aggregate risk of stochastic health effects from non‑uniform internal and external exposures. In practice, effective dose underpins statutory dose limits for workers and the public, dose constraints, individual and workplace dosimetry, radiation risk assessments and optimisation (ALARP/ALARA). It is sometimes loosely shortened to “dose”, but other dose quantities exist; when citing legal thresholds or records, refer to “effective dose” to avoid ambiguity.