Image: SI Radiation dose units

Description: Graphic showing ICRU protection dose quantities in SI units. See the following explanation of the evolution of this sometimes confusing set of quantities. From: "Radiological protection issues arising during and after the Fukushima nuclear reactor accident Abel J Gonzalez et al. Journal of Radiological Protection vol 33 (2013) 497–571 2.3.2. The changing names of the radiological protection quantities. The names used for the radiological protection quantities have evolved. ICRP Publication 26 (ICRP 1976) and its amendment issued by the ICRP’s 1978 Stockholm statement introduced and defined the quantities ‘organ or tissue dose equivalent’ and ‘effective dose equivalent’. ICRP Publication 60 (ICRP 1991) changed the terms to ‘equivalent dose in a tissue or organ’ and ‘effective dose’. The reason for the change was that ‘the weighted dose equivalent (a doubly weighted absorbed dose) has previously been called the effective dose equivalent but this name is unnecessarily cumbersome, especially in more complex combinations such as collective committed effective dose equivalent’. ICRP Publication 60 also states that ‘the Commission has decided to revert to the earlier name of equivalent dose in a tissue or organ’. However, searching for the name ‘equivalent dose’ in previous ICRP reports failed to find clear evidence for this statement. For example, in ICRP Publication 2 (ICRP 1959) the name ‘RBE dose’ was used and in ICRP Publications 6 (ICRP 1962) and 9 (ICRP 1965) the name ‘dose equivalent’ was used. Therefore, the coexistence of the names of equivalent dose and dose equivalent appears to be due to changes introduced by the ICRP in Publication 60. The coexistence of the two different names for the same quantity has added confusion and misunderstanding within an already complex dosimetric system for radiological protection. Finally, ICRP Publication 103 (ICRP2007a) uses equivalent dose without the specification ‘in a tissue or organ’ which can add to misunderstanding with effective dose if the quantity is not clearly specified since the unit, sievert (Sv), is the same.
Title: SI Radiation dose units
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Author: Doug Sim
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