Enhanced thulium fiber laser lithotripsy using micro-pulse train modulation

Richard L. Blackmon, Pierce B. Irby, Nathaniel M. Fried

Research output: Contribution to journalArticlepeer-review

30 Scopus citations


The thulium fiber laser (TFL) is currently being studied as an alternative to the conventional holmium:YAG (Ho:YAG) laser for lithotripsy. The diode-pumped TFL may be electronically modulated to operate with variable arameters (e.g., pulse rate, pulse duration, and duty cycle) for studying the influence of pulse train mode on stone blation rates. The TFL under study was operated at 1908 nm, 35-mJ pulse energy, and 500-μs pulse duration, in a rain of 5 micro-pulses, with macro-pulse rates of 10 Hz, compared with conventional TFL operation at 10 to 50 Hz. TFL energy was delivered through 100-μm-core fibers in contact with human uric acid (UA) and calcium oxalate onohydrate (COM) stones. Mass removal rates, optical coherence tomography, and light microscopy were used to nalyze the ablation craters. Stone retropulsion and fiber tip degradation studies also were conducted for these laser arameters. TFL operation in micro-pulse train (MPT) mode resulted in a factor of two increase in the ablation rate of 414± 94 μg/s and 122± 24 μg/s for the UA and COM stones, respectively, compared to 182± 69 μg/s and 60± 4 μg/s with standard pulse trains delivered at 50 Hz (P <0.05). Stone retropulsion remained minimal (μ2 mm after 200 pulses) for both pulse modes. Fiber burnback was significant for both pulse modes and was higher for COM tones than UA stones. TFL operation in MPT mode results in increased stone ablation rates which, with further ptimization, may approach levels comparable to Ho:YAG laser lithotripsy in the clinic.

Original languageEnglish (US)
Article number028002
JournalJournal of Biomedical Optics
Issue number2
StatePublished - Feb 2012


  • Ablation
  • Burst mode
  • Lithotripsy
  • Pulse trains
  • Thulium fiber laser
  • Urinary stones

ASJC Scopus subject areas

  • Biomedical Engineering
  • Biomaterials
  • Electronic, Optical and Magnetic Materials
  • Atomic and Molecular Physics, and Optics


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