Thulium fiber laser ablation of kidney stones using a 50 -μm -core silica optical fiber

Richard L. Blackmon, Thomas C. Hutchens, Luke A. Hardy, Christopher R. Wilson, Pierce B. Irby, Nathaniel M. Fried

Research output: Contribution to journalArticle

Abstract

Our laboratory is currently studying the experimental thulium fiber laser (TFL) as a potential alternative laser lithotripter to the gold standard, clinical Holmium:YAG laser. We have previously demonstrated the efficient coupling of TFL energy into fibers as small as 100-μm-core-diameter without damage to the proximal end. Although smaller fibers have a greater tendency to degrade at the distal tip during lithotripsy, fiber diameters (≤200 μm) have been shown to increase the saline irrigation rates through the working channel of a flexible ureteroscope, to maximize the ureteroscope deflection, and to reduce the stone retropulsion during laser lithotripsy. In this study, a 50-μm-core-diameter, 85-μm-outer-diameter, low-OH silica fiber is characterized for TFL ablation of human calcium oxalate monohydrate urinary stones, ex vivo. The 50-μm-core fiber consumes approximately 30 times less cross-sectional area inside the single working channel of a ureteroscope than the standard 270-μm-core fiber currently used in the clinic. The ureteroscope working channel flow rate, including the 50-μm fiber, decreased by only 10% with no impairment of ureteroscope deflection. The fiber delivered up to 15.4 ± 5.9 Wunder extreme bending (5-mm-radius) conditions. The stone ablation rate measured 70 ± 22 μg/s for 35-mJ-pulse-energy, 500-μs-pulse-duration, and 50-Hz-pulse-rate. Stone retropulsion and fiber burnback averaged 201 ± 336 and 3000 ± 2600 μm, respectively, after 2 min. With further development, thulium fiber laser lithotripsy using ultra-small, 50-μm-core fibers may introduce new integration and miniaturization possibilities and potentially provide an alternative to conventional Holmium:YAG laser lithotripsy using larger fibers.

Original languageEnglish (US)
Article number011004
JournalOptical Engineering
Volume54
Issue number1
DOIs
StatePublished - 2015

Keywords

  • 50-μm fiber
  • ablation
  • burnback
  • kidney stones
  • lithotripsy
  • retropulsion
  • thulium

ASJC Scopus subject areas

  • Atomic and Molecular Physics, and Optics
  • Engineering(all)

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    Blackmon, R. L., Hutchens, T. C., Hardy, L. A., Wilson, C. R., Irby, P. B., & Fried, N. M. (2015). Thulium fiber laser ablation of kidney stones using a 50 -μm -core silica optical fiber. Optical Engineering, 54(1), [011004]. https://doi.org/10.1117/1.OE.54.1.011004