Læknablaðið - 15.12.1997, Side 52

836
LÆKNABLAÐIÐ 1997; 83
Nýr doktor í læknisfræði
Þann 17. maí 1997 varði Páll Helgi Möller
læknir doktorsritgerð við Háskólann í Lundi.
Ritgerðin nefnist Interstitial Laser Thermo-
therapy of Liver Tumours. Methodology and
Application. Ágrip úr ritgerðinni fer hér á eft-
ir.
Interstitial laser thermotherapy (ILT) offers
the possibility of precise and selective heating
of malignant tumours. The initial technique for
delivering laser light into tissue - continuous
energy delivery with bare fibre and without
feedback control - carries a risk of carbon-
isation and danrage to the fibre end. Present
limitations of ILT are limited volume effect
and lack of real-time monitoring of the tissue
damage. Full advantage of the technique will
be realised only with improvements in control
of energy delivery, volume effect and imaging
techniques.
In this work, a laser thermotherapy system
based on continuous temperature control of
the energy delivery by rneans of a computeris-
ed feedback system was developed. Tempera-
ture control was excellent in experiments with-
out carbonisation and only a moderate de-
crease in light penetration, wheras tempera-
ture oscillations were large and light
penetration was impaired in experiments with
carbonisation. Both the laser thermotherapy
system and sapphire probe seemed to lower
the risk of carbonisation.
Using the bare fibre, carbonisation was seen
in almost all (30/32 or 94%) experiments in
vitro, regardless of output power (1-4 W) but
only occasionally in vivo using 2 W. Using the
sapphire probe (1-4 W), representing a diffuser
tip, carbonisation was absent in all but two
experiments in vitro at 1-2 W (2/16 or 87%), in
half of the experiments at 3 W (4/8 or 50%)
and in one experiment at 4 W (1/8 or 13%). In
vivo, carbonisation was seldom observed with
the sapphire probe at output powers of 3 W.
The bare fibre gave a steeper temperature gra-
dient than the sapphire probe. It seems likely
that the sapphire probe and the absence of
carbonisation allow a larger lesion size to be
created because a higher output power is re-
quired to reach coagulation temperatures.
ILT was used to treat patients with tumours
in the pancreas, abdominal wall, thoracic wall
and perineum whereas ILP was used in pa-
tients with liver tumours. No carbonisation
was observed and temperature control was
good. The volume effect was limited with a
single fibre. Ultrasound (liver) was not ideal
for real-time monitoring because of treatment
artefacts. Assessment of the outcome was
impossible as the number of patients was small
and all patients had irresectable tumours at the
time of treatment.
In normal pig liver, occlusion of the blood