mystery brachytherapy source

["Moroney, Roger W" <Roger.Moroney@mkg.com>]

I have a coworker who has asked me about some radioactive implants he
received as an infant. I have been unable to ID the original isotope and I
have a pretty limited knowledge of brachytherapy so I turn to the
accumulated wisdom of Radsafe in hopes of enlightenment. Here goes.

This person received these implants at the age of two weeks for treatment of
hematomas. This was 42 years ago and was performed at a hospital in New York
City. The sources are just below the surface of the skin and are
approximately 1/2 inch (1.3 cm) long and about 3/32 inch (0.24 cm) in
diameter. The sources are located in many parts of the body including one
near the right eye. Several have been removed over the years as they broke
through the skin. He said they are a gold color. Unfortunately, he can no
longer locate the ones which were removed.

A scintillation probe (Ludlum model 44-21) gives 3500 - 4000 cpm on contact
with a source in his wrist. We managed to get this one positioned near a Ge
detector. Lines were found at 66.9 keV (area = 1663), 68.7 keV (area =
3205), 77.7 keV (area = 2009) and 79.9 keV (area = 843). This was for a ten
minute count. These lines seem to correspond to Hg-194 for energy and
intensity. The half life for Hg-194 is given as >15 years in Erdtmann &
Soyka and as 520 years in the 14th edition of the GE Chart of the Nuclides
(which also says there are no gammas). There was also a nice bremsstrahlung
spectrum present which appeared to extend to about 500 keV.

I'm guessing the Hg-194 is a contaminant of the original isotope? Would the
original isotope have been Au-???. If anyone could help out it would be
appreciated. I'll have to admit to being a little surprised at the amount of
activity still present after 4 plus years.

********************************************************
********************************************************
Roger Moroney
Technical Director - External Dosimetry Program
Health Physicist
Mallinckrodt
roger.moroney@mkg.com
314.654.7457 voice
314.654.7571 fax
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