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Liu Ghang-Shan
NEW
CANCERTHERAPY
TECHNIQUE:
PH0T0N
KNIFE
The
Photon Knife
is
a
new
technique
of
cancertreat-
ment
that was being
devel-
oped
in
the
90s-a high
irradia-
tion
dose is delivered to the
target but without damaging
surrounding normal tissues.
This
is especially relevant
if
the target
is
adjoining
critical
structures.
CT
scan
slices
are
required
at
the
treatment
plan-
ning system (TPS) and
doc-
tors delineate the target
and
critical
structures.
After
choosing
the
best treatment
plan devised
by
the
medical
physicist with
the
sophisti-
cated
TPS software,
the
treat-
ment plan
is
implemented
through precise isocenter
po-
sitioning devices instead
of
drawing gentian violet
lines
directly on
the
patient's
skin
as
in
the past. With such pre-
cision treatment, the smaller
the
target, the
better
would
be
the effect
of
treatment.
Originally, Photon Knife
was
for
benign
lesions; with
appro-
priate modifications,
the
tech-
nique
is
now applicable
to
brain,
nasopharyngeal
or
nose
cancer and even
lung
cancer. Such 3-D conformal
irradiation techniques would
have wider and
wider
applications.
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