ICRU Report No. 51 supersedes Part B of ICRU Report 33 entitled “Quantities and Units for Use in Radiation Protection”. Since that report was published in 1980, much discussion has taken place on this subject. This led to the introduction of operational quantities for the specification of dose equivalents for area and individual monitoring for external radiations, as discussed in ICRU Reports 39 (1985), 43 (1988) and 47 (1992).
The determination of quantities relevant to radiation protection often entails significant uncertainties, and approximations will need to be introduced. However, it is essential that the quantities employed be unambiguously defined, and that the approximations be clearly identified. ICRU Report 51 aims to provide, in a revised format, a single clear presentation of a coherent system of quantities and units for use in radiation protection dosimetry. It is intended for purposes of measurement and calculation in the assessment of compliance with dose limitations. Thus, the report is divided into two parts. Part I deals with the quantities and units defined for use in measurements and calculations, whereas Part II relates to quantities based on mean values which are used for limitation purposes.