The following was received via E-mail:
On September 30, 2009 the licensee's radiation safety officer contacted the Agency [Illinois EMA] to advise that a dose to an embryo likely to have exceeded 5 Rem occurred as a result of an administration of I-131 to a mother under going thyroid treatment. Twenty five milliCi of I-131 was administered on September 21, 2009. As per hospital protocol, the patient had undergone [pregnancy] screening consisting of interviews and a urine based pregnancy test with negative results. Eight days subsequent to the administration, the patient missed an expected [menstrual] cycle and conducted a home based [pregnancy] test with positive results. Those test results were confirmed with a positive serum based test on that same day administered by her physician.
The authorized user estimates the embryo would potentially have progressed as much as 3 weeks at that time. TEDE estimates are roughly 6.7 Rem to the embryo, with no thyroid likely to have developed at this stage of pregnancy. The confirmed presence or absence of permanent functional damage is unknown, but the expectation is that there would no effect on the embryo. The patient was advised of this information the same day and further advised that a spontaneous termination was still a potential due to the early developmental stage involved although the radionuclide would not likely play a role in that outcome.
As a matter of practice, the radiation safety office is investigating details regarding this specific event to ensure all expected procedures were followed. Based on the initial report, no apparent violations are noted, nor any failures made that would have prevented the event from occurring. A formal report will be submitted within the required 15 days. At this time, no general corrective measures are anticipated but the event will be used as an opportunity for refresher training and a risk audit.
Illinois Report #: IL-0900074.