Re: internal doses monitoring in Nuclear Medicine

[Wes Van Pelt <VanPeltW@mail.idt.net>]

Richard Wu wrote:
> 
> Dear Radsafe:
> 
> I wonder how to document the internal dose in a
> Nuclear Medicine Department. Specificly, how to do the
> bioassay to monitor the Tc-99m intake. Thanks for any
> advise.
> 
> -------------------------------------
> Name: Richard Wu,MS,DABR,DABSNM
>       Radiation Safety Officer/Diagnostic Physicist
>       United/Unity/Mercy Hospital
>       St. Paul, MN 55102
> 
> E-mail: Richard Wu <wu@allina.com>
> Date: 1/22/97
> Time: 10:49:04 AM
> 
> This message was sent by Chameleon
> -------------------------------------

Richard,

Tc-99m is almost non-toxic.  With an ALI of 200 mCi, it would be pretty
difficult to have anyone overexposed.  I am sure a GM (or better yet, a
NaI crystal probe) frisk of the body would detect less than 1 mCi in a
person.

While this would not assay for internal dose, it would probably be
sufficient to demonstrate compliance with occupational dose limits if
everyone did such a frisk twice per day.

You could do a rough calibration by putting 0.1 or 1 mCi of Tc-99m in a
1- or 2-gallon bottle of water and noting the survey instrument
response.  But be careful, this could violate the conditions of your NRC
license.  That is, if your licensed use is for human diagnostic
procedures, using material for calibration may be a violation.

Cheers, Wes

-- 
Wesley R. Van Pelt, Ph.D., CIH, CHP                   KF2LG
President, Van Pelt Assoc., Inc.      vanpeltw@mail.idt.net
Consulting in radiological health and safety.
"TIME, its what keeps everything from happening at once."