Holmium:YAG vs. Thulium fiber laser for high-power vaporization of canine prostate tissue

Abstract

Direct studies comparing different lasers for treatment of BPH are lacking. This preliminary study compares continuous-wave (CW) vs. pulsed prostate tissue vaporization for the Thulium fiber laser and Holmium:YAG laser, both operating near the 1940 nm water absorption peak in tissue. A 50-W Thulium fiber laser (&lambda;= 1908 nm) delivered CW laser radiation through a 600-&mu;m silica fiber in non-contact mode with a 5-mm-diameter spot at the tissue surface. A Holmium:YAG laser (&lambda;= 2120 nm) operated with an energy of 2 J, pulse rate of 25 Hz, and average power of 50 W, and delivered pulsed laser radiation through a 600-&mu;m silica fiber with a 5-mm-diameter laser spot to achieve similar irradiances at the tissue surface. Tissue vaporization was performed in air with the prostate kept hydrated in saline. Tissue vaporization efficiency of both lasers was compared (n = 10 canine prostates for each laser group). Mean vaporization efficiency measured 5.30 &plusmn; 0.48 kJ/g vs. 4.13 &plusmn; 0.46 kJ/g for Thulium fiber and Holmium lasers (P < 0.05). Tissue vaporization rates measured 0.57 &plusmn; 0.05 g/min vs. 0.73 &plusmn; 0.07 g/min (P < 0.05). The Holmium:YAG laser vaporizes prostate tissue at a higher rate than the Thulium fiber laser, for the same average power delivered to the tissue. Both the Thulium fiber laser and Holmium:YAG lasers are capable of vaporizing prostate tissue at a rate > 1 g/min if operated at the high powers (100-W) typically used in the clinic.