In vitro comparison of laser induced lithotripsy on artificial stones by means of different laser systems

Objectives: In this study, clinically available pulsed laser systems emitting either in the infrared (IR) - or visible (VIS) spectral region were compared in a standardized manner with respect to their impact on phantom stones in an underwater laboratory set-up. Methods: There were three pulsed laser systems emitting light either in the IR (λ=2100nm: Ho: YAG-laser) or VIS (λ=532nm/1064nm: FREDDY-laser and 598nm: FLPD-laser) spectral range available for this investigation. After determination of the ablation threshold different fragmentation rates were determined in relation to the fluence (depending on pulse energy and fiber diameter) using artificial stones. Results: The threshold value of the laser pulse energy to induce an ablation of artificial stones induced by the different laser systems showed that even the lowest laser settings induced significant ablation with no regards to the repetition rate and fiber diameter. The VIS-lasers showed higher fragmentation rates than the IR-lasers. Conclusions: VIS-lasers are solely useful for laser induced shockwave lithotripsy, while IR-lasers are also in use for other clinical applications (e.g. coagulation and ablation). Investigations on artificial stone fragmentation are useful to compare clinical laser parameter settings but can partially be transferred to clinically urinary stone fragmentation.