Re: radioisotopes and pregnancy

[Karin Gordon <kgordon@cc.UManitoba.CA>]

Dear Agnes

What type of nuclear medicine procedures are you concerned about - diagnostic or 
therapeutic?  Generally speaking, for either sex, there should be no radiation 
dose-related reason for delaying conception after diagnostic nuclear medicine 
procedures. The effective dose to the majority of patients undergoing nuclear medicine 
imaging procedures ranges from 5 to 20 mSv - similar to the dose that might be received 
while undergoing a CT scan or lumbar spine x-ray. 

The same does not necessarily hold true for radionuclide therapy, depending on the 
radionuclide, pharmaceutical and activity administered, and whether the therapy is 
delivered to a local site (i.e. P-32 injected into a joint space for a radiation 
synovectomy) or systemically (i.e. I-131 to treat Graves disease or thyroid cancer). 
It really depends on what is being treated.

Occasionally, a second treatment may be necessary because of inadequate response by the 
tissue being treated- usually this is not known until several months have elapsed after 
the initial therapy.  We normally counsel female patients undergoing radioiodine therapy 
for hyperthyroidism to avoid pregnancy for about 6 months.  The same goes for patients 
undergoing I-131 therapy for thyroid cancer or I-131 MIBG therapy for other 
malignancies.  A pregnancy certainly will seriously complicate any further course of 
treatment for these conditions - be it surgery, hormone therapy, chemotherapy or 
radiation (external beam, sealed source brachytherapy or radionuclide therapy). 

I hope this is helpful.

Karin Gordon
Radiation Safety Officer 
Health Sciences Centre
GC-214, 820 Sherbrook St.
Winnipeg, MB. Canada R3A 1R9
voice 	(204) 787-2903
fax	(204) 787-1313
e-mail	KGordon@cc.umanitoba.ca





Barlow, Agnes E. wrote:
> 
> In the last year, I recall reading recommendations on a length of time after
> Nuclear Medicine procedures [I don't recall if it was diagnostic or
> therapeutic levels] for which one should delay conception [??  2 months for
> women; one month for men ???]
> Now that I want to reread it, I can't recall where I saw it.  Does anyone
> know a good reference on the subject?  I am particularly interested in
> I-131.  Thanks for any input.
> 
> Aggie
> 
> Agnes.Barlow@Yale.edu
> 203 737-2142
> 203 785-7588 [fax]
> standard disclaimer