the time integrals in fluids concentrated from extracellular fluid, and in
the tissues from which these fluids are derived, so we have then for the
time
integral
of
the
concentrations
in
the concentrated fluids,
10°5 x R, where R is the fluid-to-plasma ratio.
1.25 x
Now R is a poor choice
inasmuch as it also represents Roentgens, but, nonetheless, R is meant to
béthe fluid-to-plasma ratio.
Thedose factor then for extrathyroidal iodide concentrating tissues,
is this 1.25 <fes R d/g x 0.2 MeV, corresponding to the energy from the
disintegration-of7iodine-131 times the conversion factor of 51.2 rad per
(uCi-d/g)-MeV,
and!this
is
then
the resulting
expression
for
the
dose
factor for extrathytértdal iodide concentrating tissues.
ee
ia
Next viewgraph, please: (LRA-16).
We also made an attempt to estimate
a dose factor for iodine-13i-to_the lactating breast by making note of the
recoveries of, well,
jodine-131> or of the dietary iodide in milk.
Now
0.03 - 26.8% of I-131 administered to..women at the conclusion of the last
breast feeding, resulted in the recovery of this range of values of the
isotope in milk.
In the case of dietary stable iodide, ten percent or less
of the daily ingested iodide is secreted in milk.
And this varies
inversely with the dietary intake of iodine=So the transfer coefficient
and time integral then of the concentrationin milk following a single
intake of iodide, assuming a milk secretion rateof one liter per day, and
22
this seems to be a reasonable value for nursing mothers, leads to, well, a
23
transfer coefficient, or time integral of 0.1 of a dayper liter, and this
24
is equivalent to 10-4 d/ml.
25
time integrals in milk and lactating breast, so we have 10-4 d/g for the
26
time integral
27
times the 0.2 MeV times the conversion factor, and we get about 1.0 x 10-3
28
rad/uCci.
Now again we assume the. equivalence of the
in the lactating breast.
17
Dose factor then-is this number