&lt;title&gt;Dual-wavelength-alexandrite laser lithotripsy: in-vitro results of urinary calculi fragmentation&lt;/title&gt;

Steiger, Erwin; Geisel, Gunter

doi:10.1117/12.175037

Cited by 3 publications

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“…Consequently, a strong Shockwave emission, a high- speed microjet, or both are generated on bubble collapse, which have been found to be the primary mechanisms of stone fragmentation.5 Similar physical processes occur for the alexandrite laser because of its short pulse duration and a wavelength (755 nm) that is absorbed by most stone materials. 6,7 In contrast, the holmium laser (at a wavelength of 2100 nm), although absorbed by all stone materials, is most strongly absorbed by water. Thus, the incident laser pulse will vaporize water immediately after its release, leading to the formation of a cavitation bubble at the tip of the optical fiber.…”

Section: Stone Fragmentationmentioning

confidence: 92%

Transient Cavitation and Acoustic Emission Produced by Different Laser Lithotripters

Zhong

Tong

Cocks

et al. 1998

Journal of Endourology

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Transient cavitation and shockwave generation produced by pulsed-dye and holmium:YAG laser lithotripters were studied using high-speed photography and acoustic emission measurements. In addition, stone phantoms were used to compare the fragmentation efficiency of various laser and electrohydraulic lithotripters. The pulsed-dye laser, with a wavelength (504 nm) strongly absorbed by most stone materials but not by water, and a short pulse duration of approximately 1 microsec, induces plasma formation on the surface of the target calculi. Subsequently, the rapid expansion of the plasma forms a cavitation bubble, which expands spherically to a maximum size and then collapses violently, leading to strong shockwave generation and microjet impingement, which comprises the primary mechanism for stone fragmentation with short-pulse lasers. In contrast, the holmium laser, with a wavelength (2100 nm) most strongly absorbed by water as well as by all stone materials and a long pulse duration of 250 to 350 microsec, produces an elongated, pear-shaped cavitation bubble at the tip of the optical fiber that forms a vapor channel to conduct the ensuing laser energy to the target stone (Moss effect). The expansion and subsequent collapse of the elongated bubble is asymmetric, resulting in weak shockwave generation and microjet impingement. Thus, stone fragmentation in holmium laser lithotripsy is caused primarily by thermal ablation (drilling effect).

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Section: Stone Fragmentationmentioning

confidence: 92%

Transient Cavitation and Acoustic Emission Produced by Different Laser Lithotripters

Zhong

Tong

Cocks

et al. 1998

Journal of Endourology

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“…Another approach to improve the energy deposition at the stone surface is the use of two wavelengths from a frequency-doubled alexandrite laser. At 375 nm the threshold for plasma formation is considerably lower than at the fundamental wavelength of 750 nm (Steiger and Geisel 1994). If both wavelengths are used simultaneously, the UV component starts the plasma formation, and the first harmonic provides the energy for further heating of the plasma.…”

Section: Optimization Strategiesmentioning

confidence: 99%

Nonlinear absorption: intraocular microsurgery and laser lithotripsy

Vogel

1997

Phys. Med. Biol.

115

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A Perspective on Laser Lithotripsy: The Fragmentation Processes

Chan¹,

Pfefer

Teichman

et al. 2001

Journal of Endourology

129

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This paper describes in simple terms the physics of laser-calculus interactions and introduces a method with which physicians can understand or evaluate the application of any new laser technique for use in lithotripsy or other medical fields. Tissue optical properties and laser parameters govern the mechanism(s) of fragmentation of urinary or biliary calculi. Laser pulse energies for clinical lithotripsy range from Q0 = 20 mJ to 2 J for short-pulsed lasers to long-pulsed lasers, respectively. Lasers with short pulse durations (i.e., less than a few microseconds) fragment calculi by means of shockwaves following optical breakdown and plasma expansion of ionized water or calculus compositions or by cavitation collapse, thus manifesting a photoacoustical effect. Laser-tissue interactions involving dominant photomechanical or photoacoustical effects are usually stress confined. Long-pulsed lasers (i.e., >100 microsec), on the other hand, generate minimal acoustic waves, and calculi are fragmented by temperatures beyond the thresholds for vaporization of calculus constituents, melting, or chemical decomposition.

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<title>Dual-wavelength-alexandrite laser lithotripsy: in-vitro results of urinary calculi fragmentation</title>

Cited by 3 publications

References 0 publications

Transient Cavitation and Acoustic Emission Produced by Different Laser Lithotripters

Transient Cavitation and Acoustic Emission Produced by Different Laser Lithotripters

Nonlinear absorption: intraocular microsurgery and laser lithotripsy

A Perspective on Laser Lithotripsy: The Fragmentation Processes

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