In vitro comparison of pulsed-Thulium:YAG, Holmium:YAG and Thulium Fiber Laser.

To characterize the pulse characteristics and risk of fiber fracture(ROF) of the pulsed-Thulium:YAG(p-Tm:YAG) Laser , and to compare its ablation volumes(AVs) against Holmium:YAG(Ho:YAG) and Thulium Fiber Lasers(TFL). p-Tm:YAG(100W-Thulio,DornierMedtech©,Germany) was characterized using single-use 272μm core-diameter-fibers(CDF). p-Tm:YAG characterization included pulse shape, duration and Peak Power (PP) studies. ROF was assessed after 5min continuous laser activation(CLA) at five decreasing fiber bend radii(1, 0.9, 0.75, 0.6, and 0.45cm). p-Tm:YAG, Ho:YAG (120W-Cyber-Ho,Quanta®,USA) and TFL (60W-TFLDrive(Coloplast®, Denmark)) AVs were compared using a 20mm linear CLA at 2mm/sec velocity in contact with 20mm cubic hard and soft stone phantoms(HSP and SSP, 15:3 and 15:5 water to powder ratio) fully submerged in saline solution at 0.5J-20Hz or 1J-10Hz. After CLA, phantoms underwent three-dimensional(3D) micro-scanning(computed tomography) and subsequent 3D segmentation to estimate the AVs, using 3DSlicer©. Each experiment was performed in triplicate. p-Tm:YAG presents a uniform pulse profile in all of the available pre-set modes. Peak Power(PP) ranged from 564 to 2199W depending on pulse mode. No Laser fiber(LF) fracture occurred at any bend radius. p-Tm:YAG achieved similar mean AVs to TFL and Ho:YAG for HSP(8.96±3.1 vs 9.78±1.1 vs 8.8±2.8mm3, p=0.67) but TFL was associated with higher AVs compared to p-Tm:YAG and Ho:YAG(12.86±1.85 vs 10.12±1.89 vs 7.56±2.21mm3, p=0.002) against SSP. AVs for HSP increased with pulse energy for p-Tm:YAG and Ho:YAG and (11.56±1.8 vs 6.36±0.84 mm3 and 11.27±1.98 vs 6.34±0.55mm3,p=0,03 and p=0,02), while AVs for SSP were similar across laser settings for all laser sources. AVs with TFL were similar across laser settings for both phantom types. p-Tm:YAG combines intermediate Peak Power between Ho:YAG and TFL, a uniform pulse profile, no risk of fiber fracture with increasing deflection and effective ablation rates. Further clinical studies are needed to confirm these in vitro results.