Re: I-125 Seed Implant Safety - Part 2

[Chris Alston <alstonc@odrge.odr.georgetown.edu>]

In re the question of fluoroscopy: I avoided mention of it because it's not
peculiar to seed implants. Strict issues of radiation protection aside, many
(most?) states have regulatory language that effectively mandates the use of
lead aprons, whenever fluoro is done (some states exempt the mini-C-arms),
without regard to the actual amount of exposure that may be incurred. Note
that last-image-hold can be used very effectively; this is generally true of
surgical fluoro. Also note that the fluoro exposure can be estimated from
the collar badge reading (as well as by real-time survey). One very active
seed implant team, of which I have knowledge, does about a minute of fluoro
at the beginning of the procedure, and about a minute at the end, at which
times everyone present dons and doffs aprons.

It seems to me that there are some significant questions that medical RSO's
could be asking themselves, bearing on the wearing of aprons in the OR. For
one thing, are 0.5mm equivalents needed, given the short beam-times? Then,
does everyone in the room really need to wear aprons, regardless of their
location (again, regulatory positions may make this a moot question)? Also,
I still worry about possible infection control problems (clearly, the latter
are not problems that the RSO should consider all by her/his lonesome self).
Finally, if one has a concern about extremity exposures, I suggest issuing
ring badges, for a provisional period (this is always useful for negative
documentation, too). I'd be very surprised if anyone were to receive ring
doses anywhere near 50 mSv (5000 mrem), in a year, or even doses above the
minimum detectable, which, for monthly rings, from one major supplier, is
3.6 mSv (360 mrem)/year.

P.S. If you do use rings, make sure that your dosimetric vendor knows the E
of interest.

chris alston
alstonc@odrge.odr.georgetown.edu
The opinions above are not given in representation of those of my employer.
Chris Alston
alstonc@odrge.odr.georgetown.edu
I am not here a representative of my employer.

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