TABLE 3.1 Selected Quantities and Units for Radiation Exposure and Dose

Quantity Old Unit SI Unit or
Its Special
Name
Between Units
Relationship
Field of
Application
Reference
Exposure R C kg-1 1 R = 2.58 10-4
C kg-1
Monitoring NCRP
(2007)
Absorbed dose rad Gy 1 rad = 0.01 Gy Research ICRP
(2007b)
Dose equivalenta rem Sv 1 rem = 0.01 Sv Radiation Protection ICRP
(1977)
Equivalent dosea rem Sv 1 rem = 0.01 Sv Radiation protection ICRP
(1991)
Effective dose
equivalentb
rem Sv 1 rem = 0.01 Sv Radiation protection ICRP
(1991)
Effective doseb rem Sv 1 rem = 0.01 Sv Radiation protection ICRP
(1991)
Committed effective
dose equivalentc (CEDE)
rem Sv 1 rem = 0.01 Sv Radiation protection ICRP
(1991)
Collective dose
equivalent
person-rem person-Sv 1 person-rem =
0.01 person-Sv
Radiation protection ICRP
(1991)

aDose equivalent and equivalent dose are conceptually similar. However, dose equivalent makes use of quality factors (QFs), which were replaced with radiation-weighting factors (wR) for the calculation of equivalent doses.

bEffective dose equivalent and effective dose are conceptually similar. Effective dose equivalent is the weighted sum of the dose equivalents over all organs and tissues of the body, using tissue-weighting factors (wT), whereas effective dose is the weighted sum of the equivalent doses over all organs and tissues of the body. An additional difference is that different wT values are used in the calculation of effective dose equivalent and effective dose.

cCommitted effective dose equivalent is the time integral of the effective dose equivalent from the time of the activity intake until the age of 70 y.

unit mass at a point of interest. The unit of absorbed dose is J/kg, and its special name is the gray (Gy) (ICRU, 2011). Although defined as a point quantity, absorbed dose usually represents an average over some finite volume or mass, such as the mass of the thyroid or the volume of red bone marrow distributed in the entire body. When the absorbed dose has approximately the same value for all organs and tissues of the body, as is the



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