[ RadSafe ] Fwd: Stolen cobalt-60 found in Mexico; curious thieves likely doomed

[dlawrencenewyork at aol.com]

The teletherapy machine was being decommissioned due to obsolescence and not necessisarily insufficient activity "the material was used in obsolete radiation therapy equipment that is being replaced throughout Mexico's public health system" according to news sources. Likely this was being replaced with a low energy Linac which does not have these very source management and replacement issues as with the Co-60  machines. 


Additionally the IAEA reported that the source contained somewhere under 40 grams of material with a reported activity of 3000 Ci. Obviously it is not 100% pure Co-60 as a back of the napkin calculation would indicate 44000 Ci which implies only 6.8% Co-60. Some earlier reports had it listed as a 14000 Ci source so perhaps this 3000 Ci number is a decay corrected activity.


Best Regards,
David



-----Original Message-----
From: Chris Alston <achris1999 at gmail.com>
To: The International Radiation Protection (Health Physics) Mailing List <radsafe at health.phys.iit.edu>
Sent: Thu, Dec 5, 2013 3:49 pm
Subject: [ RadSafe ] Fwd:  Stolen cobalt-60 found in Mexico; curious thieves likely doomed


Dan

I think that you are thinking of a radiocesium machine, like an
irradiator.  Cobalt sources in teletherapeutic machines are usually
changed at < 1 t1/2 (5 y).  You want to treat a pt as fast as
possible, for a number of reasons, including minimizing pt motion and
discomfort, and the number of pts you can treat in a day.  Going from,
e.g., delivery of a daily treatment fraction that takes 0.5 h to one
which takes 1.0 h is a big deal in a busy clinic.

Of course, the clinic might have shut down many years ago, and the
machine is only now being "decommissioned".  That is basically how a
number of ugly incidents have occurred.

Cheers
cja
---------- Forwarded message ----------
From: Dan McCarn <hotgreenchile at gmail.com>
Date: Thu, Dec 5, 2013 at 3:03 PM
Subject: Re: [ RadSafe ] Stolen cobalt-60 found in Mexico; curious
thieves likely doomed
To: "The International Radiation Protection (Health Physics) Mailing
List" <radsafe at health.phys.iit.edu>Dear Group:
If this is an old radio teletherapy source heading toward disposal, then
the actual activity (assuming about 30 years of use) would be less than 1/6
the labeled activity - so perhaps 500 Ci might be more accurate.
Thoughts?
Dan ii
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