Atomic Pacemakers

[bgb3@mhg.edu]

To those individuals who were interested in the characteristics of atomic   
powered pacemakers I'll try to answer a few of the questions raised.
We are presently monitoring 10 active atomic pacemakers in patients.   
 There are approximately 70 being worn by patients in the U.S.  The two   
principal manufacturers of these pacemakers were  Cordis and Medtronic   
(Coratomic).  They are no longer involved with the monitoring.  Other   
companies have assumed that function.
Each pacemaker contains 175 mg plutonium-238 about 2.8 curies).  The   
plutonium is in the form of a sintered oxide( PuO2) pressed pellet.  It   
is first contained in a small can fabricated from Tantalum-10 percent   
tungsten.  The Ta-10W container is then placed in a superalloy can   
fabricated from Hostelloy-C276 ( a material much akin to stainless steel)   
which has a melting point of 2400 degrees F.  The Ta-10W cylinder has a   
melting point of over 5500 degrees F.  The entire assembly is oxidation   
and corrosion resistant.  It also has extremely high shock and impact   
resistance.  One test of the assembly was to fire a bullet from a high   
powered weapon point blank onto the container.  That test did not break   
the seal of the container.  It will certainly withstand any external   
challenges imaginable (certainly cremation will not affect it other than   
destroy the electronic pacing circuit components inside).  The container   
was extensively tested by the USAEC (USNRC now).  It withstood a crush   
test load of 1000 Kg. (Over 50 tests were performed with no unfavorable   
results).  Actual cremation testing was performed at 2400 degrees F for   
40 minutes with no damage to the inner liner.

I personally measured the radiation exposure levels from a patient   
wearing the Corotomic pacemaker.  At the skin surface just above the   
presumed pacer location (I didn't have an x-ray unit available- just   
found the max reading) the reading was 300 micro-R/hour and was 20 micro   
R/hour at 1 meter.  Reading on the back of the patient was 25   
micro-R/hour on surface, 60 micro-R/hour on the right arm, 10   
micro-R/hour on the left arm, and 30 micro-R/hour on the left chest   
surface.  The background for the micro-R meter was 10 micro-R/hr.

Sorry for being long winded, but there appeared to be considerable   
interest throughout RADSAFE, so, for whatever it's worth....

Bill

Billy G. Bass, PhD, Radiation Safety Spec.
Washington Hospital Center,  Washington, DC  20010

phone (202) 877-8025
e-male  bgb3@mhg.edu  

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