Dependence of calculus retropulsion on pulse duration during HO: YAG laser lithotripsy

Kang, Hyun Wook; Lee, Ho; Teichman, Joel M.H.; Oh, Junghwan; Kim, Jihoon; Welch, Ashley J.

doi:10.1002/lsm.20376

Cited by 88 publications

(55 citation statements)

References 40 publications

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“…[19][20][21][22][23][24] The bubbles are larger than the fiber diameter and can extend from the fiber tip up to ∼2 mm depending on pulse rate and energy. The mechanical shockwaves created by the cavitation bubbles are not a major contributor to stone fragmentation at the 500-μs pulse duration used in this study, because the ablation mechanism is predominantly photothermal.…”

Section: Retropulsion and Flow Velocimetrymentioning

confidence: 99%

Hollow steel tips for reducing distal fiber burn-back during thulium fiber laser lithotripsy

et al. 2013

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Abstract. The use of thulium fiber laser (TFL) as a potential alternative laser lithotripter to the clinical holmium:YAG laser is being studied. The TFL's Gaussian spatial beam profile provides efficient coupling of higher laser power into smaller core fibers without proximal fiber tip degradation. Smaller fiber diameters are more desirable, because they free up space in the single working channel of the ureteroscope for increased saline irrigation rates and allow maximum ureteroscope deflection. However, distal fiber tip degradation and "burn-back" increase as fiber diameter decreases due to both excessive temperatures and mechanical stress experienced during stone ablation. To eliminate fiber tip burn-back, the distal tip of a 150-μm core silica fiber was glued inside 1-cm-long steel tubing with fiber tip recessed 100, 250, 500, 1000, or 2000 μm inside the steel tubing to create the hollow-tip fiber. TFL pulse energy of 34 mJ with 500-μs pulse duration and 150-Hz pulse rate was delivered through the hollow-tip fibers in contact with human calcium oxalate monohydrate urinary stones during ex vivo studies. Significant fiber tip burn-back and degradation was observed for bare 150-μm core-diameter fibers. However, hollow steel tip fibers experienced minimal fiber burn-back without compromising stone ablation rates. A simple, robust, compact, and inexpensive hollow fiber tip design was characterized for minimizing distal fiber burn-back during the TFL lithotripsy. Although an increase in stone retropulsion was observed, potential integration of the hollow fiber tip into a stone basket may provide rapid stone vaporization, while minimizing retropulsion. © The Authors.Published by SPIE under a Creative Commons Attribution 3.0 Unported License. Distribution or reproduction of this work in whole or in part requires full attribution of the original publication, including its DOI.

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Section: Retropulsion and Flow Velocimetrymentioning

confidence: 99%

Hollow steel tips for reducing distal fiber burn-back during thulium fiber laser lithotripsy

et al. 2013

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“…8,12,16,[20][21][22] Some of these reports have shown images of small residual effects of the bubble collapse behind the fiber tip. 12,19 This is presumably due to a collapsing bubble-induced pressure wave propagating in the axial direction of the fiber, both toward and away from the fiber tip. Although this pressure wave has been observed to be too weak to induce photomechanical ablation of urinary stones, it has been shown to be sufficiently strong to push stones away from the fiber tip.…”

Section: Discussionmentioning

confidence: 99%

“…Previous investigators have also used PoP stone phantoms to model urinary stones because of their comparable tensile strength. 11,12 Each stone was dried for at least 24 h and weighed using an analytical balance (AB54-S, Mettler-Toledo, Switzerland). The stones were monitored throughout the suction experiments, and any damaged stone was removed and replaced.…”

Section: Stone Suction Experimentsmentioning

confidence: 99%

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Fiber-optic manipulation of urinary stone phantoms using holmium:YAG and thulium fiber lasers

et al. 2013

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Abstract. Fiber-optic attraction of urinary stones during laser lithotripsy may be exploited to manipulate stone fragments inside the urinary tract without mechanical grasping tools, saving the urologist time and space in the ureteroscope working channel. We compare thulium fiber laser (TFL) high pulse rate/low pulse energy operation to conventional holmium:YAG low pulse rate/high pulse energy operation for fiber-optic suctioning of plaster-ofparis (PoP) stone phantoms. A TFL (wavelength of 1908 nm, pulse energy of 35 mJ, pulse duration of 500 μs, and pulse rate of 10 to 350 Hz) and a holmium laser (wavelength of 2120 nm, pulse energy of 35 to 360 mJ, pulse duration of 300 μs, and pulse rate of 20 Hz) were tested using 270-μm-core optical fibers. A peak drag speed of ∼2.5 mm∕s was measured for both TFL (35 mJ and 150 to 250 Hz) and holmium laser (210 mJ and 20 Hz). Particle image velocimetry and thermal imaging were used to track water flow for all parameters. Fiber-optic suctioning of urinary stone phantoms is feasible. TFL operation at high pulse rates/low pulse energies is preferable to holmium operation at low pulse rates/high pulse energies for rapid and smooth stone pulling. With further development, this novel technique may be useful for manipulating stone fragments in the urinary tract. © The Authors. Published by SPIE under a Creative Commons Attribution 3.0 Unported License. Distribution or reproduction of this work in whole or in part requires full attribution of the original publication, including its DOI.

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“…Previous Ho:YAG laser lithotripsy retropulsion studies also have reported that the use of lower pulse energies, longer pulse durations, higher pulse rates, and smaller optical fiber diameters is the optimal combination of laser parameters for minimizing stone retropulsion. [17][18][19][20][21][22] The TFL technology is ideally suited for operation with this combination of laser parameters.…”

Section: Stone Phantom Retropulsion Studiesmentioning

confidence: 99%

Enhanced thulium fiber laser lithotripsy using micro-pulse train modulation

2012

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Abstract. 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 parameters (e.g., pulse rate, pulse duration, and duty cycle) for studying the influence of pulse train mode on stone ablation rates. The TFL under study was operated at 1908 nm, 35-mJ pulse energy, and 500-μs pulse duration, in a train 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 monohydrate (COM) stones. Mass removal rates, optical coherence tomography, and light microscopy were used to analyze the ablation craters. Stone retropulsion and fiber tip degradation studies also were conducted for these laser parameters. TFL operation in micro-pulse train (MPT) mode resulted in a factor of two increase in the ablation rate of 414 AE 94 μg∕s and 122 AE 24 μg∕s for the UA and COM stones, respectively, compared to 182 AE 69 μg∕s and 60 AE 14 μg∕s with standard pulse trains delivered at 50 Hz (P < 0.05). Stone retropulsion remained minimal (<2 mm after 1200 pulses) for both pulse modes. Fiber burnback was significant for both pulse modes and was higher for COM stones than UA stones. TFL operation in MPT mode results in increased stone ablation rates which, with further optimization, may approach levels comparable to Ho:YAG laser lithotripsy in the clinic.

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Dependence of calculus retropulsion on pulse duration during HO: YAG laser lithotripsy

Abstract: Less retropulsion and equivalent fragmentation occurred when Ho:YAG pulse duration increased.

Cited by 88 publications

References 40 publications

Hollow steel tips for reducing distal fiber burn-back during thulium fiber laser lithotripsy

Hollow steel tips for reducing distal fiber burn-back during thulium fiber laser lithotripsy

Fiber-optic manipulation of urinary stone phantoms using holmium:YAG and thulium fiber lasers

Enhanced thulium fiber laser lithotripsy using micro-pulse train modulation

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