Thulium fiber laser lithotripsy:: An in vitro analysis of stone fragmentation using a modulated 110-watt thulium fiber laser at 1.94 μm

Background and Objectives: The high-power Thulium fiber laser has previously been shown to rapidly vaporize and coagulate soft urinary tissues (e.g., prostate). This is the first preliminary study of a high-power Thulium fiber laser for fragmentation of urinary stones. Study Design/Materials and Methods: A continuous-wave, high-power Thulium fiber laser operating at a wavelength of 1.94 pm, was modulated to operate in pulsed mode with an output pulse energy of 1J through a 300-mu m-core silica fiber at a 20 milliseconds pulse length and repetition rate of 10 Hz. The fragmentation time to reduce uric acid (UA) (n = 13) and calcium oxalate monohydrate (COM) (n - 6) stones into particles < 2 mm was measured. Results: Mean initial mass of the UA and COM stones measured 860 +/- 211 and 763 +/- 204 mg. Fragmentation rates measured 388 +/- 49 and 25 +/- 2 mg/minute. Average time needed to fragment the UA and COM stones into particles < 2 mm was 2.25 +/- 0.63 and 30.7 +/- 8.4 minutes, respectively. Conclusions: The high-power Thulium fiber laser, when operated in pulsed mode, is capable of fragmenting both soft (UA) and hard (COM) urinary stones. The Thulium fiber laser may be useful as a single laser system for use in multiple soft and hard tissue laser ablation applications in urology.