ee ee erent aeSth
SESSION Hl
133
the thyroid cells that remain with thyroid-stimulating hormone. So
{ would suppose that the adenomas would go through a maximum at
sore point. In addition to that, if with radioiodine, as you have said,
Leo, the irradiation of the thyroid is not homogeneous so that the outer
l' yer gets less of a dose than the internal part, there might reinain a
reservoir of cells or the periphery which would be stimulated by the
pituitary response to hypothyroidism.
CONARD: But we had two cases, remember, with ablation and
with practically no thyroid function. These glands are gone.
DUNHAM:
hypothyroid.
What's your evidence that there is ablation?
How hypo were they?
You said
CONARD: Their PBI's dropped to below 2 micrograms percent,
their glands were no longer paipable, and -heir iodine uptake was
nil. Ido not see how you could account for this ablation on the basis
of the increased whole-body radiation since, if the whole-body exposure had been increased by even a factor of two, we would have
seen considerably lower white counts than we did.
BUSTAD:If you look back on these two boys can you really separate
out the blood picture from, say, 150 r versus 250 r exposure?
CONARD: I think so. I think if they had had 250 rad we would have
seen signs of infection or bleeding in these kids.
AYRES: You said a while ago that the thyroids of these young children would absorb about the same amountof iodine as an adult but
the glands were smaller. Is that taken into account in the internal
dosage calculation?
_ CONARD: Yes.
This is what brings the child's dose up so much
higher than the adult dose.
AYRES: I just didn't notice.
BUSTAD: A factor of ten.
BRUES:
In fact, the ratio is better estimated than the absolute dose.
CONARD:
Perhaps! [Laughter]