Re: I-123 study dose to unborn kid

[jtowson@nucmed.rpa.cs.nsw.gov.au (Jocelyn Towson)]

There is a table in a paper by E Watson from Oak Ridge in the Proceedings
of the 5th International Radiopharmaceutical Dosimetry Symposium (1991)
which I have copied here in full as it might be of interest to NucMed
radsafers. In Watson's model the highest concentration of iodide in the
fetal thyroid occurs at the 5th and 6th months of gestation.  The fetal
thyroid is said to begin concentrating iodide at about the 90 days after
conception.

Absorbed Dose in Fetal Thyroid from Radionuclides Administered to the
Pregnant Woman (mGy/MBq administered to Woman):

Gestational age (mo)    I-123   I-124   I-125   I-131
3                       2.7     24      290     230
4                       2.6     27      240     260
5                       6.4     76      280     580
6                       6.4     100     210     550
7                       4.1     96      160     390
8                       4.0     110     150     350
9                       2.9     99      120     270

For comparison, according to ICRP53, the dose to the mother's thyroid
assuming 15% euthyroid uptake should be about
                        1.9     130     140     210


Jocelyn Towson, RSO
Dept of Nuclear Medicine
Royal Prince Alfred Hospital
Sydney, NSW 2050
jtowson@nucmed.rpa.cs.nsw.gov.au