[ RadSafe ] Xe-133 in negative pressure rooms

[garyi at trinityphysics.com]

I don't know, but I can speculate.

The calculations for room clearance times in case of "spill" and for acceptable air 
concentrations sometimes come up with very short times and concentrations only a little over 
limit.  That amounts to Xe-133 sometimes being a rather trivial risk even for people inside the 
imaging room.  If that is true, it follows that some fractional leakage to surrounding spaces is 
probably not dangerous.

I don't know of any facilities around Houston that do not check for negative pressure 
annually.

I just checked the most recent state regs I have here.  It is different from what I remember, 
which is negative pressure and venting to a remote exterior location.  Now there is just a not-
to-specific " When venting of radioactive gases is required, a hood shall exhaust to the 
exterior."

I guess if the resulting air concentration is reasonably low, I don't feel very alarmed about a 
bit of positive pressure.

-Gary Isenhower



On 20 Jul 2010 at 15:39, Grimm, Steven wrote:


Didn't there used to be requirements in 10CFR35 that Xe-133 had to be used in a negative 
pressure room?
Does anyone know why they aren't there anymore?
Does your medical facility still maintain that requirement?


Steve Grimm, MS, CHP
Deputy Radiation Safety Officer
Emory University Hospital Midtown
404-686-1426


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