Occupational Intakes of Radionuclides Part 1 - ICRP

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DRAFT REPORT FOR CONSULTATION
For both sexes the equivalent dose rate H ( rT
, t)
in target tissue rT at time t after an
acute intake is expressed as
H ( r , t)
A(
r , t)
S ( r r ) (3)
T
r
S
S
where
A( rS
, t)
is the activity, Bq, of the radionuclide in source region rS at time t after
intake for the reference male or female; in this report series, only male
values are used;
S w ( rT
rS
) is the radiation-weighted S value (Bolch et al, 2009); i.e. the equivalent
dose in target tissue rT per nuclear transformation in source region rS,
Sv (Bq s) -1 , for the reference male or female.
(232) The first factor in equation (3) is derived with biokinetic models which
describe the uptake of activity into the body, its distribution and retention within body
regions, and its excretion from the body. The second factor is derived with dosimetric
models which are used to calculate the dose to target tissues arising from
transformations in source regions.
3.7.1 Dosimetric models
(233) The equivalent dose in target tissue rT per nuclear transformation in source
region rS, is calculated by:
where
E R,
i
Y R,
i
S
w
( r
T
r )
S
wR
E
R,
i
98
w
Y
R,
i
R i T
T
T
S
(
r r , E
M ( r )
is the energy of the i th nuclear transition of radiation type R, in Mev,
is the yield of i th radiation of type R per nuclear transformation, (Bq s) -
1 ,
w R is the radiation weighting factor for radiation type R, Table 1
r r , E ) is the absorbed fraction, defined as the fraction of energy ER,i of
( T S R,i
radiation type R emitted within the source region rS that is absorbed in
the target tissue rT,
M ( rT
) is the mass of target tissue rT, kg.
(234) The energies and yields of the emitted radiations, E and Y R,
i
R,
i , are taken
from Publication 107 (ICRP, 2008), which supersedes Publication 38 (ICRP, 1983).
For β radiation and neutrons accompanying spontaneous fission, the spectral data are
used in the calculation of Sw rather than mean values. The sex-dependent target tissue
S
R,
i
)
(4)