[ RadSafe ] I-131 Patients and Taxi Driver

Michael, Joey L joey-michael at uiowa.edu
Mon Feb 18 16:53:08 CST 2008

These types of situations come up often.  I have been involved in cases
where the patient wanted to go to the hotel so they could follow the
rules for being an outpatient.  In one case the woman had small children
at home and only one bathroom.  Its fairly simple to run a calculation
and see that no one at the hotel would get much dose.  Reg Guide 8.39
has a simple method for doing this, and has guidance on calculating
internal dose due to contamination.  
The thing that makes me squirm is the what if question.  What if the
hotel finds out that the hospital released a patient that has now
contaminated their hotel room.  Its perfectly legal, but do you want to
answer those questions in the newspapers.
I also have a hard time reconciling the release level for removable
contamination (200 DPM/100 cm^2).  If its in our facility we have to
clean it to below that level, if its in the patient's home, car, taxi,
or hotel room, there is no contamination limit.
It makes it difficult to explain the room prep to inpatients.  I usually
tell them that by regulation, I have to make the room as though they
were never even here after they leave.  
Also, the calcs in 8.39 assume an average distance of 1 m, and 0.25
occupancy.  I ran some numbers for a school bus driver getting 10 mCi,
and made changed the distance to 1 ft, for 1.5 hrs/day.  It worked out
to a max dose of about 311 mrem.  Well below the 500 mrem limit, but
still surprisingly high.  
Joey Michael
Health Physicist Assistant 
Health Protection Office
The University of Iowa

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