Interstitial laser photocoagulation: Nd:YAG 1064 nm optical fiber source compared to point heat source

Interstitial laser photocoagulation (ILP) was performed in vitro in lean bovine and chicken muscle by delivering 1.6 W of continuous‐wave Nd:YAG laser energy (1064 nm) from a 400‐μm core optical fiber for 300s. The resulting thermal coagulation lesion was consistently larger when the delivered energy was deposited into a small steel sphere than when it was delivered freely into the tissue. Mathematical modelling confirms this result. This preliminary study suggests that a point heat source produces a larger volume of thermal coagulation than a point optical source (1064 nm) delivering the same power. © 1992 Wiley‐Liss, Inc.