Thermo-controlled device for inducing deep coagulation in the liver with the Nd:YAG laser.
OBJECTIVE
To increase the effectiveness of laser-induced interstitial thermotherapy (LITT), a new thermo-controlled application system for minimal invasive intervention was designed. Our system consists of a laser applicator of 2.5 mm in diameter, insertion equipment, and a Nd:YAG-laser source.


METHODS
A cylindrical light emitting fiber (1-6 cm in length) was placed in the center of the applicator. The surrounding tissue was irradiated through a Duran window at the distal end of the applicator. The power of the laser source was controlled dynamically by thermosensors in a water-cooling system of the laser applicator. The temperature at the surface of the Duran window was kept constant at approximately 60 degrees C, without charring the surrounding tissue.


CONCLUSIONS
We obtained homogeneous coagulation zones. In in vitro experiments with pig livers, we reached ellipsoid coagulation volumes of 3 and 5 cm in diameter within 10 minutes, corresponding to a volume of approximately 25 cm3.
Orth
K
K
Department of General Surgery, University of Ulm, Germany.
Russ
D
D
Duerr
J
J
Hibst
R
R
Steiner
R
R
Beger
H G
HG
D000818:Animals; D006979:Hyperthermia, Induced; D017075:Laser Coagulation / Q000295:instrumentation*; D053685:Laser Therapy / Q000295:instrumentation*; D008099:Liver / Q000033:anatomy & histology / Q000601:surgery*; D008114:Liver Neoplasms, Experimental / Q000601:surgery; D013552:Swine