Nd:YAG laser-induced interstitial hyperthermia using a long frosted contact probe

The heating potential of a closed loop interstitial hyperthermia system employing 1,064 nm laser light in conjunction with a long frosted contact probe was investigated in hind limb muscle of anesthetized dogs. The laser system was an Nd:YAG surgical laser modified with a single channel thermometry unit, a computer, a printer, and a computer-controlled laser exposure shutter. The long frosted laser probe was implanted into the muscle, and 3.12-5.00 Watts of laser power was delivered interstitially. Temperature distribution was measured in three dimensions around the frosted probe. The temperature distributions generated by this technique were satisfactory for producing desired hyperthermia temperatures in an approximately 3.5 cm3 cylindrical tissue volume. A multiple laser delivery system is needed to induce interstitial hyperthermia in large tumors. A significant potential for the long frosted contact probe may be its use in combining interstitial hyperthermia and interstitial photodynamic therapy. Using this technique, both modalities may be delivered while employing the same treatment setup.