Occupational Intakes of Radionuclides Part 1 - ICRP

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DRAFT REPORT FOR CONSULTATION
quantity, evaluated after a particular measurement in order to decide whether
the result of the measurement is significant. The decision threshold is also
referred as the critical level or the minimum significant activity.
Direct measurement
Generic term for any kind of in vivo measurement of incorporated
radionuclides (i.e. whole body counting, lung counting, thyroid counting, etc.).
Excretion function.
See ‘Bioassay function’.
Excretion rate
In general, the excretion rate is the amount of activity which is excreted via
urine or faeces during a 24 hour period, with the decay of the radionuclide
having been corrected for the end of the 24 hour sampling period.
Investigation level
A pre-set level above which the cause or the implications of an intake should
be examined (ICRP, 1997b). Investigation levels can be set for any operational
parameter related to the individual or to the working environment. For
individual monitoring of exposure to intakes of radionuclides, they are most
likely to relate to a measured body or organ/tissue content, an activity level in
excreta, or an air concentration measured by a personal air sampler.
Measured quantity (M)
Primary result of incorporation monitoring; the measured quantity represents
in the case of in vivo measurements the whole body, organ or tissue activity
(Bq) and in the case of in vitro measurements the daily excretion rate (Bq d -1 ,
Bq l -1 , or Bq kg -1 ).
Minimum Detectable Amount (MDA)
The smallest true value of a measured quantity that is detectable by the
measuring method. The MDA is the smallest true value that is associated with
the statistical test and hypothesis in accordance with the Decision Threshold,
as follows: if in reality the true value is equal to or exceeds the MDA, the
probability of wrongly not rejecting the hypothesis (Type II error) is at most
equal to a given value, β. The MDA is an a priori quantity, evaluated for a
particular measurement method in advance of the performance of a
measurement. The MDA is also referred as the detection limit or the lower
limit of detection; the term ‘MDA’ is also used as an abbreviation for
minimum detectable activity.
Recording level
A pre-set level above which a result should be recorded, lower values being
ignored.
Retention function.
See ‘Bioassay function’.
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