dose to the pancreas and certainly less than two times the dose to the
pancreas.
Now
we
previously
stated
that
we
would
evaluate
the
dose
to
the
salivary glands and the lactating breast from the ingestion of lIodine-131.
Both
of these tissues can concentrate
Stomach,
lactating
concentrating
breast,
mechanisms,
and
or
iodine.
certain
an
iodine
Serous
other
tissues
salivary glands,
possess
concentrating mechanism
iodine
that
is
comparable to that of the thyroid.
Next
viewgraph,
please
(LRA-14).
We
can
summarize
available data by examining the fluid-to-plasma ratio.
11
fluid-to-plasma
12
juice,
13
derived.
14
to a
15
rate.
16
inversely with the collection rate.
17
ratio
and milk;
and
the
range
of
values
for
the
readily
We list the average
saliva,
for
gastric
and these are the references from which the data were
In the case of the salivary glands, the fluid-to-plasma ratio are
large extent
In
the
independent of the plasma concentration and secretion
case
of
gastric
juice,
the
fluid-to-plasma
May I have the next viewgraph, please (LRA-15).
ratio
varies
So we made attempts
18
to estimate dose factors to extrathyroidal fodide concentrating tissues for
19
jodine-131 as follows:
20
assumed to be the rapidly turning-over component of the iodine retention
21
function
22
effective turnover rate of about two per day.
23
concentration in extracellular fluid is then 0.7, assuming that 0.7 of the
24
ingested ‘iodine
25
corresponds to the iodide space,
26
that we just examined above.
27
28
This
with
leads
a
The half-life of iodine in extracellular fluid is
half-life
goes
to
of 0.35
the
to a time
days;
extracellular
this
is equivalent to an
Now the time integral of the
fluid,
and
the
2.7 x
104 ml
and the two per day is the turnover rate
integral
cellular fluid of 1.3 x 10-5 d/1.
and
then of the concentration
in extra-
Now we assume that the equivalence of