In vitro comparative analysis of ablation volume and energy requirements for 1 mm³ stone ablation using ho: YAG,...

This study aimed to quantify the ablation volume per laser pulse (AVP, µm³) and the energy required to ablate 1 mm³ of stone material (RE, J/mm³) using the RevoLix HTL pulsed Thulium: YAG (p-Tm: YAG) laser (OmniGuide©, USA). Results were compared with those obtained using a Holmium: YAG (Ho: YAG) laser (MH1, Rocamed©, Monaco) and a Thulium Fiber Laser (TFL) system (IPG©, Russia). Experiments were conducted on pure human urinary stones composed of calcium oxalate monohydrate (COM), uric acid (UA), and cystine (CYS). Each sample was submerged in saline and lasered in contact mode with a 272-µm fiber. The p-Tm: YAG and TFL lasers were tested at 0.5, 0.8, and 1 J, while the Ho: YAG was evaluated at 0.6, 0.8, and 1 J, all using the shortest pulse setting available. After treatment, stone craters were imaged and segmented using 3D Slicer software to compute AVP, from which RE values were derived. All measurements were based on three repetitions per condition. Across multiple energy settings, Ho: YAG showed superior ablation performance in CYS and UA stones, particularly at 0.6 and 1 J, while no significant differences were noted among lasers for COM stones. TFL outperformed p-Tm: YAG in ablating UA stones at both 0.5 and 1 J. Regarding energy efficiency, Ho: YAG consumed less energy than TFL for CYS (at 0.8 and 1 J) and UA stones (all energies), and less than p-Tm: YAG for CYS (0.5 J) and UA (1 J). Conversely, both TFL and p-Tm: YAG were more efficient than Ho: YAG for COM stones. TFL also required significantly less energy than p-Tm: YAG at 0.5 J for COM and at 0.8 and 1 J for CYS stones. Our findings suggest that TFL and p-Tm: YAG may be less effective than Ho: YAG for cystine and uric acid stones. Stone composition should be carefully considered when selecting the laser source, as it may impact procedural efficiency and outcomes.