[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

Re: RADSAFE digest 3593/Mock I-125

We use I-129 button and rod check sources to mimick I-125 on a regular basis.  According to Kocher's Radioactive Decay Data Tables, I-129 emits the following photons, (in addition to auger and conversion electrons, and a 152 keV (max) beta-):

X-ray	4.1 keV 		(8.2%)
"	29.5 keV 	(20%)
"	29.8 keV	(37%)
"	33.6 keV	(13.2%)
gamma 39.6 keV	(7.5%)

Our company used to make these commercially, but just recently got out of the sealed/reference sources business.

One interesting phenomenon I have encountered very occasionally when doing check source checks on NaI probes (the "low energy" type probes such as Ludlum model 44-3) hooked up to count rate meters is that a check source check with a Cs-137 button source can look fine, (or maybe a little lower than expected), but a check with an I-129 check source, which normally would give a healthy response, actually gives no response at all.  Usually an increase in the voltage fixes the situation, but we have had to rethink our calibration and daily meter check procedures due to this.

Regards,

John R. Laferriere, CHP
DuPont Pharmaceuticals Co.
Medical Imaging Division
john.r.laferriere@dupontpharma.com
(978) 671-8316   fax (978) 671-8149
************************************************************************
The RADSAFE Frequently Asked Questions list, archives and subscription
information can be accessed at http://www.ehs.uiuc.edu/~rad/radsafe.html