RE: I-129 Sources

[Dave Derenzo <dave@uic.edu>]

To all,

David North is correct about I-129.  When used as a mock I-125 standard, a 
little Am-241 is sometimes mixed in to better emulate the I-125 
spectrum.  There is an NRC license exemption that reflects 
this.  Auto-gamma counter manufacturers usually supply mock I-125 standards 
in small test tubes that are similar in size, shape, and counting geometry 
to the RIA samples that will be analyzed.  Commercial suppliers like 
Amersham used to sell these also.  Regarding Franz's comment about Ba-133, 
it is sometimes used as a mock I-131 source, and Co-57 is used to mock 
Tc-99m.    All of these are common sources used in nuclear medicine (dose 
calibrator testing, gamma camera peaking, etc) and radioimmunoassay (RIA) 
labs.  RIA is rapidly being replaced by other techniques.  Here at UIC, 
what used to be our RIA lab is now called the ligand immunoassay lab and 
they no longer use radioactive materials.  The only RIA test that is still 
done uses Co-57 and is sent out to a commercial lab.

Dave Derenzo

At 08:21 AM 1/11/01, you wrote:
>According to NCRP Report No. 58, I-129 is indeed a gamma-emitter, but the
>emission is relatively weak (7.5%). Most of the useful photons are x-rays
>following the prevalent internal conversion after beta-minus decay.
>
>David L. North, Sc.M. DABR
>Associate Physicist
>Department of Medical Physics
>Rhode Island Hospital
>593 Eddy St.
>Providence, RI 02903
>ph: (401)444-5961
>fax: (401)444-4446
>dnorth@lifespan.org
>
>
> > ----------
> > From:         Franz Schoenhofer
> > Reply To:     radsafe@romulus.ehs.uiuc.edu
> > Sent:         Wednesday, January 10, 2001 18:27
> > To:   Multiple recipients of list
> > Subject:      Re: I-129 Sources
> >
> >
> > -----Ursprüngliche Nachricht-----
> > Von: Perrero, Daren <Perrero@idns.state.il.us>
> > An: Multiple recipients of list <radsafe@romulus.ehs.uiuc.edu>
> > Datum: Mittwoch, 10. Jänner 2001 23:05
> > Betreff: RE: I-129 Sources
> >
> >
> > >I believe what you are referring to is commonly called "a mock iodine"
> > >source.  The I-129 is configured in such a way that the emitted spectrum
> > >mimics that of I-125 but has the obvious advantage of the extended half
> > life
> > >of I-129.  Most gamma counter equipment vendors would be happy to link
> > you
> > >up with direct vendors or may even be able to provide such sources
> > >themselves.
> >
> >
> > "Mock Iodine" is not I-129, it cannot be, because I-129 is not a
> > gamma-emitter. Somewhere deeply buried in my brain the information is
> > stored, maybe it was Ba-133. Daren is right - the vendors can answer this
> > questions.
> >
> > Franz
> >
> >
> >
> >
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> >
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Dave Derenzo, MPH  (dave@uic.edu)
Associate Director for Radiation Safety
University of Illinois at Chicago
Radiation Safety Section, MC932
820 S. Wood St., Chicago, IL 60612-7314
Voice:(312)996-7429  Fax:(312)996-8776
URL:  http://www.uic.edu/depts/envh

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information can be accessed at http://www.ehs.uiuc.edu/~rad/radsafe.html