Radiation Heart Devices

[Michael Stabin <stabin@npd.ufpe.br>]

> Even if the panel backs the device and the agency approves it,
> analysts expect that many hospitals may wait to see the devices that
> J&J's rivals will put on the market. The machines from Novoste and
> Guidant use a different form of radiation, beta. Novoste's device
> takes only three to five minutes to use, and hospital personnel can
> stay in the room during the procedure. J&J's system, which uses a
> different type of radiation, takes longer to use, and medical
> technicians must leave the area.

> HEALTH PHYSICS
> Schedule of Contents
> Volume 79 No. 2,  August 2000
>
> On the cover: An oncologist, assisted by a medical physicist, is loading a
radioactive source(192Ir) during a gamma endovascular brachytherapy
procedure.

> Personnel Exposure During Gamma Endovascular
> Brachytherapy
> S. Balter, M. Oetgen, A. Hill, J. Dalton, A. Sacher, R.
> Lipsztein, M. Collins, and J. Moses     Page - 136

This is really a fascinating new technology, with several important
radiation safety concerns.  As noted, the gamma devices will have on the
order of 20-40 GBq of activity (500-1000 mCi), which can cause a significant
dose to other organs of the patient and the attending staff.  Beta sources
can work with more like 0.7-2.0 GBq (20-50 mCi), and deliver most of their
dose locally. Source centering is much more important for beta sources than
for gamma sources, but is important for both.  Centering can be improved
with the use of balloons filled with radioactive liquids, but there is a
small risk of a balloon rupture and all this activity entering the
bloodstream and irradiating other organs. Another approach uses radioactive
stents (wire mesh devices permanently left in the arteries), which can be of
lower activity still (kBq-MBq range), as they decay in situ and deliver dose
over a longer time (the temporary implants are usually left in the artery
for just a few minutes). Stents typically employ beta emitters.  There will
be a specific session on this at the HPS meeting, Mon 3:00-4:30 for those
interested. Clearly there will be interesting work ahead for HPs in
institutions that apply this technology.


Michael Stabin, PhD, CHP
Departamento de Energia Nuclear/UFPE
Av. Prof. Luiz Freire, 1000 - Cidade Universitaria
CEP 50740 - 540
Recife - PE
Brazil
Phone 55-81-271-8251 or 8252 or 8253
Fax  55-81-271-8250
E-mail stabin@npd.ufpe.br

"Quantum Mechanics: The dreams stuff is made of"
- Steven Wright


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