# Comparative evaluation of temperature generation during laser lithotripsy: thulium fiber laser, pulsed thulium: YAG, and holmium: YAG with pulse modulation in an ex vivo porcine kidney model

## TL;DR

This study compares heat generation from three laser systems used in kidney stone removal, finding that the thulium fiber laser produces the most heat but stays within safe limits.

## Contribution

The first comparative evaluation of temperature generation among three modern laser lithotripsy systems in an ex vivo model.

## Key findings

- The thulium fiber laser (TFL) caused the highest temperature rise compared to other systems.
- All systems remained below the 43°C thermal safety threshold during testing.
- Temperature increase per energy unit was significantly higher for TFL than for the other lasers.

## Abstract

Ureteroscopic laser lithotripsy results in heat generation, raising concern for thermal injury. As laser platforms evolve, comparative assessment of their thermal profiles is increasingly important. This study presents the first comparative evaluation of temperature generation using three contemporary systems: pulsed thulium: YAG (Tm: YAG; Dornier Thulio), thulium fiber laser (TFL; Olympus SOLTIVE), holmium: YAG with pulse modulation (MOSES 2.0; Boston Scientific MOSES 2.0) using manufacturer-recommended dusting settings in an ex vivo porcine kidney model. Eighteen porcine kidney–ureter units were implanted with renal pelvic temperature probes and Bego stones. Specimens were randomized to one of three lithotripsy systems (n = 6 per group; one MOSES specimen excluded). A flexible ureteroscope was introduced via a 35 cm 10/12Fr ureteral access sheath, followed by 10 min of near-continuous dusting using 200 μm fibers (0.3 J/50Hz for TFL and Tm: YAG; 0.3 J/60 Hz for MOSES 2.0). Pressurized irrigation was maintained at 100-150mmHg. Outcomes included absolute temperature change, total energy delivered, and temperature increase normalized to energy (°C/kJ). The greatest mean temperature rise was observed with TFL (8.13 ± 1.96 °C), followed by pulsed Tm: YAG (4.12 ± 1.26 °C) and MOSES 2.0 (3.32 ± 1.84 °C). TFL demonstrated significantly greater heat generation than Tm: YAG (p = 0.0031) and MOSES 2.0 (p = 0.0010). When temperature was adjusted for energy delivery, TFL (1.09 ± 0.30 °C/kJ) surpassed both Tm: YAG (0.47 ± 0.14 °C/kJ; p = 0.0007) and MOSES 2.0 (0.31 ± 0.18 °C/kJ; p = 0.0001). No specimen exceeded temperatures of 43 °C. In this ex vivo setting, TFL was associated with higher heat generation relative to both pulsed Tm: YAG and MOSES 2.0; however, all systems remained below accepted thermal safety thresholds under the tested conditions (43 °C).