RE: Iodine Seed Implants

[Craig Reed <CReed@novoste.com>]

Second try: 

Depending upon the desired indications for use, you may not need an IDE
for a 510(k) device. (So clearence for use would be based on arguments
of "equivalence" with existing brachytherapy sources not necessarily any
studies.)

To respond to the dose part of your question, many of the body burdens
for a permissible continuous dose rate in critical organs are on the
order of 1's to 1000's of microCuries (alpha emitters being the
exception - 1/100'ths).  If you assumed that in the treated tumor the
worst "non-leaking" (i.e., undamaged) source released no more than 185Bq
every 4hrs (a passing ISO leak test value - granted very different
temp/chemistry conditions from use) then over a year you would have
released less than ~400,000 Bq to the body (less decay!).  (Note: I'm
absolutely not saying that seeds release activity this way, it's only an
example!)  That's about 10 microCi "released" per seed which is in the
range of continuous allowable body burden for many isotopes.  

I think you'd have to suspect a gross encapsulation failure (noticed
upon insertion?) to initiate any successful monitoring (but for what
"useful" medical purpose, I'm not sure.) Purpose of the seed is to avoid
surgery. 

Craig Reed
Novoste Corporation
creed@novoste.com


-----Original Message-----
From: Chris Alston [mailto:alstonc@odrge.odr.georgetown.edu]
Sent: Wednesday, December 15, 1999 6:16 PM
To: Multiple recipients of list
Subject: Iodine Seed Implants


Does anyone know of actual studies of patients who'd received permanent
implants, to document that the seeds did not leak? I mean, either in
vivo
thyroid monitoring, or urine collection, within the first few
half-lives. I
would have thought that some such work would have been a part of the
original Phase 1 IDE, but maybe the FDA thought that it was sufficient
to
demonstrate their extracorporeal integrity, and presume that the same
would
obtain post-implantation. Also, maybe some early users thought it the
better part of valor, or worth a decent paper, to do the studies.

Thanks, again, in advance.

cja

P.S. Does anyone know where I might find one or more HP10/11/15C
calculators, hopefully in at least VG condition? Of course, please
respond
to me directly, not to the list. Thanks much.
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