[ RadSafe ] Xe-133 in negative pressure rooms

garyi at trinityphysics.com garyi at trinityphysics.com
Tue Jul 20 17:00:57 CDT 2010

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 

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 

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

This e-mail message (including any attachments) is for the sole use of
the intended recipient(s) and may contain confidential and privileged
information. If the reader of this message is not the intended
recipient, you are hereby notified that any dissemination, distribution
or copying of this message (including any attachments) is strictly

If you have received this message in error, please contact
the sender by reply e-mail message and destroy all copies of the
original message (including attachments).
You are currently subscribed to the RadSafe mailing list

Before posting a message to RadSafe be sure to have read and understood the RadSafe 
rules. These can be found at: http://health.phys.iit.edu/radsaferules.html

For information on how to subscribe or unsubscribe and other settings visit: 

More information about the RadSafe mailing list