We investigated the use of a new Nd:YAG laser irradiation method, 'balloon
laserthermia' I involving use of a balloon filled with a light diffusing substance
attached to the end of a quartz fiber. This balloon laserthermia technique, using
a 3cm diameter balloon containing 0.25% Intralipid solution, was tested on a
Meth-A sarcoma in Balb-C mice. A 20 minute irradiation at 20 watts resulted in the
following necrosis rates: control group -4%; 40.0-40.5°C. 35%; 42.5-62%; 50.0 -50.5°C. - 97%.
When the balloon size was reduced from 3 to 2cm, the optimum values for
hypertherinia were a 0.5% Intralipid solution density and a laser power output of
10 watts.
As previous use of balloon laserthermia has generally involved use of quartz
fibers with a standard 8° angle of light emission, these experiments included
trials of a fiber with a 40°light emission angle, along with various combinations
of solution densities and laser output conditions. When used with 0.25% Intralipid
I the wide-angle fiber provided a power density distribution around the
balloon equivalent to that of the standard fiber, but with only half the laser
output for hyperthermia, about 10 watts.
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