Re: Sewer Releases: Nuclear Medicine Patients

["Dale E. Boyce" <dale@radpro.uchicago.edu>]

Sue,

We don't have hard number on release of patient excreta, but to
give you a ballpark figure I'll give you some estimates.  Our
hospital gets around 3 Curies of I-131 per year for patient use,
a guess is that about 70% of this winds up in excreta.   We get
about 10 Curies of Gallium 67 each year.  It is eliminated by the kidneys 
during the first 24 hours and in the stool from then on.   Ten to twenty five
percent is excreted in urine during the first 24 hours, and ten to fifteen
percent is eliminated in the stool.  We use some In-111, but not nearly
as much as Ga-67.  I don't have numbers on In-111 excretion.
Tl-201 is pretty tightly held in the body so not too much of it
goes out.  We obtain over 100 Curies of Mo-99 each year in Tc-99m
generators.  I don't know exactly how many Tc-99m scans are done or
the distribution od doses and imaging agents.  Let's guess that our
Nuc. Med. would get unit doses unless they were using at least several
doses per day.  I'll bet we would be far off saying twenty per day,
five days a week. So about five-thousand per year.  Each dose can vary
from a few up to about 25 mCi.  I'll take ten as an average for a
total of 50 Ci per year.  Depending on the pharmaceutical ten to fifty
percent is excreted.

Hope this helps.  

Dale E. Boyce
dale@radpro.uchicago.edu