Occupational Intakes of Radionuclides Part 1 - ICRP

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DRAFT REPORT FOR CONSULTATION
suppose the liver is depicted in the parent’s model as two compartments and also in
the progeny radionuclide’s model as two compartments. If the compartments
represent the same physically identifiable portions of the liver in both models, e.g.,
hepatocytes and Kuppfer cells, then decays of the parent in the two liver
compartments in the parent’s model would be assigned to the corresponding liver
compartments in the progeny radionuclide’s model. However, if the compartments are
defined on a kinetic basis in both models and have no obvious physical interpretation,
it will generally not be evident how the progeny atoms produced in the parent’s liver
compartments should be divided between the progeny’s liver compartments. In such
cases the convention used here is to assign all of the progeny atoms to the
compartment with the highest turnover rate, and assume that the progeny radionuclide
is removed from that compartment to the central blood compartment at that rate.
3.6 Medical Intervention
(229) If medical treatment to prevent uptake or enhance excretion is administered,
then the data provided in the models summarised above cannot be used directly to
assess committed effective doses from monitoring information (NCRP, 1980; Gerber
and Thomas 1992; IAEA 1996). In such circumstances a programme of special
monitoring (Section 5.5) should be undertaken to follow the retention of the particular
contaminant in the person, and these data should be used to make a specific
assessment of committed dose.
3.7 Methodology for dose calculations
(230) The general method of dose calculation described here is similar as in earlier
ICRP Publications (ICRP, 1979, 1994b), but some changes were introduced to accord
with ICRP Publications (ICRP, , 2008) which used MIRD terminology for
radiopharmaceutical dosimetry. In order to provide a consistent internal dosimetry
framework for both radiation protection and nuclear medicine, the standardised
nomenclature and symbols of MIRD Pamphlet No. 21 (Bolch et al 2009) used for
protection quantities, and their conventions are followed in this section.
(231) The Commission defines effective dose, E, for adults as:
E
Male
Female
H(
r
T , 50)
H(
rT
, 50)
wT
2
T
where wT is the tissue weighting factor (Table 2) for the target tissue rT and
H(rT,50) Male and H(rT,50) Female are the committed equivalent doses for the target tissue
rT for the reference male and female, respectively, integrated over 50 years. The
committed equivalent dose in the target tissue for the reference male or female is:
50
( r , 50)
H
( r , t)
dt (2)
H T
T
0
97
(1)