Re: sentinel node biopsy; radiation safety

<< Previous Message | Next Message >> (by way of Marvin Hanna)
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This topic of radiation safety with sentinel node biopsy specimens has been
discussed here on Histonet several times. Somebody ought to put it on a Web
site - I hesitate to do that myself because I have no experience with the

Sentinel node biopsy is presently used to evaluate metastasis of breast
cancer and melanoma. The tumor area is injected with a mixture of a blue dye
and a radioactive colloid, both of which drain into the nearest lymph node
(the "sentinel node") where they are detected either visually or with a gamma
counter. If the sentinel node is negative, it is unlikely that the lymph
nodes above it contain cancer. The technique is somewhat arduous for the
surgeon, and it takes every surgeon a while to learn it, and stresses may be
high during the learning period.

The radioactive colloid is labelled with technetium 99m, which has a half
life of six hours, emitting a gamma particle and becoming technetium 99,
which is also radioactive but with a half life so long that its radioactivity
is negligible.

According to radiation safety people I have talked with, and that others on
Histonet have talked with, no special handling of the specimen at all is
required, and rubber gloves give quite adequate protection from the small
amount of radiation received.

Frozen section examination is medically inadvisable, but is not
contraindicated because of the radioactivity.

Bob Richmond
Samurai Pathologist
Knoxville TN

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