A preliminary study on clinical application of Nd:YAG laser to the face and head

Preliminary experiments were carried out for use of the Nd:YAG laser therapy of malignant tumors of the head and face. Because bone and brain tissue lie under the soft tissues in the face and head, the authors prepared two experimental models and examined the thermal effects of laser irradiation using three irradiating methods, single-pulse, automatic running, and manual. In experiments using results from these models, a temperature rise inducing protein coagulation did not occur under the surface of the soft tissue under the bone in both models. With automatic running irradiation, the temperature rise in the surface of the soft tissue under the bone was about 5 degrees C at 60 W with a running speed of 4 mm/sec in model I. These conditions were considered to be sufficiently within safe limits. In the second model, it was estimated that no thermal effects would be exerted on the soft tissue under the bone at 60 W or less with a running speed of 8 mm/sec or less. Using manual irradiation, no thermal disturbance of the soft tissue under the bone was induced in the first model, but without a shortening of irradiation time or an increase in irradiation distance this method could cause thermal damage to the second model and must be taken into consideration.