Characterization of a 50-um-core optical fiber for potential use in Thulium fiber laser lithotripsy

Richard L. Blackmon; Thomas C. Hutchens; Luke A. Hardy; Pierce B. Irby; Nathaniel M. Fried

doi:10.1117/12.2035556

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4 March 2014 Characterization of a 50-μm-core optical fiber for potential use in Thulium fiber laser lithotripsy

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

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Proceedings Volume 8926, Photonic Therapeutics and Diagnostics X; 89261F (2014) https://doi.org/10.1117/12.2035556
Event: SPIE BiOS, 2014, San Francisco, California, United States

Abstract

Our laboratory is currently studying the Thulium fiber laser (TFL) as a potential alternative laser lithotripter to the standard clinical Holmium:YAG laser. We have previously demonstrated efficient coupling of TFL energy into fibers as small as 100-μm-core-diameter without damage to the proximal end. Although smaller fibers have greater tendency to degrade at the distal tip during lithotripsy, fiber diameters (≤ 200 μm) have been shown to increase saline irrigation rates through the working channel of a flexible ureteroscope, maximize ureteroscope deflection, and reduce stone retropulsion during laser lithotripsy. In this study, a 50-μm-core-diameter, 85-μm-outer-diameter fiber is characterized for TFL ablation of human calcium oxalate monohydrate urinary stones, ex vivo. The stone ablation rate was measured to be 70 ± 22 μg/s for 35-mJ-pulse-energy, 500-μs-pulse-duration, and 50-Hz-pulse-rate. 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 W under extreme bending (5-mm-radius) conditions. Stone retropulsion and fiber burn-back averaged 201 ± 336 and 3000 ± 2600 μm, respectively, after 2 minutes. 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 alternatiμe to conventional Holmium:YAG laser lithotripsy using larger fibers.

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Richard L. Blackmon, Thomas C. Hutchens, Luke A. Hardy, Pierce B. Irby, and Nathaniel M. Fried "Characterization of a 50-μm-core optical fiber for potential use in Thulium fiber laser lithotripsy", Proc. SPIE 8926, Photonic Therapeutics and Diagnostics X, 89261F (4 March 2014); https://doi.org/10.1117/12.2035556

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