Holmium:YAG laser lithotripsy: A dominant photothermal ablative mechanism with chemical decomposition of urinary calculi

Chan, Kin Foong; Vassar, George J.; Pfefer, T. Joshua; Teichman, Joel M.H.; Glickman, Randolph D.; Weintraub, Susan T.; Welch, Ashley J.

doi:10.1002/(sici)1096-9101(1999)25:1<22::aid-lsm4>3.0.co;2-6

Cited by 170 publications

(92 citation statements)

References 36 publications

(51 reference statements)

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“…Given the thermal diffusivity (a) of most tissues and dielectric materials is less than 0.5 mm 2 / second [22] and the pulse duration (t p ) of free running lasers is about 275 microseconds, the heat diffusion length (x d ¼ ffiffiffiffiffiffiffi at p p ) during the pulse is at most 12 mm. Since the widening of Ho:YAG crater measures a few hundreds micrometers, the heat conduction minimally contributes to the augmented width of the crater during the pulse (Once the laser pulse stops, no more ablation take place during a free running laser lithotripsy [7]). An ablation crater could be wider than the actual laser beam diameter if the scattering of the incident light causes photons to be distributed beyond the beam diameter.…”

Section: Ablation Volumementioning

confidence: 99%

“…Since the ablation of free running laser lithotripsy is initiated by the photo-thermal effect [7,34], we can postulate that the absorption coefficient and decomposition temperature are the most important parameters for ablation efficiency. Future measurement of absolute absorption coefficient and decomposition temperature of calculi will clarify the ablation dependence on calculus type.…”

Section: Ablation Volumementioning

confidence: 99%

“…The fragmentation during Ho:YAG laser lithotripsy is initiated through direct pulse energy absorption in a calculus. The absorbed pulse energy is converted to thermal energy that heats the laser-affected zone, leading to fragmentation [7].…”

Section: Introductionmentioning

confidence: 99%

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Urinary calculus fragmentation during Ho: YAG and Er:YAG lithotripsy

et al. 2005

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Background and Objectives: We tested Ho:YAG and Er:YAG laser ablation of human urinary calculi to determine if Er:YAG is a more efficient lithotripsy device. Study Design/Materials and Methods: Ablation efficiency of Ho:YAG and Er:YAG lasers was tested at varying energy settings, ranging from the damage threshold to clinical energy setting associated with Ho:YAG laser. Stones of known composition (calcium oxalate monohydrate (COM), cystine, and uric acid (UA)) were irradiated. Crater width, depth, and ablation volumes were determined using an optical coherence tomography (OCT). Results: For all stones and energy settings, the Er:YAG laser produced deeper craters and larger ablation volumes than Ho:YAG laser. The Ho:YAG laser created wider craters during the multiple pulse process and the shape of craters was irregular. Conclusions: The Er:YAG laser is more efficient than the Ho:YAG laser for lithotripsy. The deeper craters produced by the Er:YAG laser is attributed to the high absorption of energy at its wavelength.

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Section: Ablation Volumementioning

confidence: 99%

Section: Ablation Volumementioning

confidence: 99%

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Urinary calculus fragmentation during Ho: YAG and Er:YAG lithotripsy

et al. 2005

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“…23,24 In particular, Ho:YAG laser (λ = 2.1 µm) and Er:YSGG laser (λ = 2.79 µm) have been used for efficient tissue ablation in urology in order to fragment stones or calculi from the urinary tract, i.e., kidney, bladder, or urethra. 25 Finally, it was noticed that at the output end of optical fibers covered with nanoparticles immersed in water, vapor bubbles were formed due to heat transfer from the nanoparticles to the water. 26 If sufficient power is transmitted through the fiber, then shock waves are produced.…”

Section: Introductionmentioning

confidence: 99%

Optic cavitation with CW lasers: A review

et al. 2014

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The most common method to generate optic cavitation involves the focusing of short-pulsed lasers in a transparent liquid media. In this work, we review a novel method of optic cavitation that uses low power CW lasers incident in highly absorbing liquids. This novel method of cavitation is called thermocavitation. Light absorbed heats up the liquid beyond its boiling temperature (spinodal limit) in a time span of microseconds to milliseconds (depending on the optical intensity). Once the liquid is heated up to its spinodal limit (∼300 °C for pure water), the superheated water becomes unstable to random density fluctuations and an explosive phase transition to vapor takes place producing a fast-expanding vapor bubble. Eventually, the bubble collapses emitting a strong shock-wave. The bubble is always attached to the surface taking a semi-spherical shape, in contrast to that produced by pulsed lasers in transparent liquids, where the bubble is produced at the focal point. Using high speed video (105 frames/s), we study the bubble’s dynamic behavior. Finally, we show that heat diffusion determines the water superheated volume and, therefore, the amplitude of the shock wave. A full experimental characterization of thermocavitation is described.

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“…The second generation of laser lithotriptor was built based on the Ho:YAG laser operating at the free running mode [59]. The wavelength of the Ho:YAG laser is 2.12 m and the pulse duration is a few hundred μ microseconds.…”

Section: Trends and Future Direction Of Lasers In Urologymentioning

confidence: 99%

The Advent of Laser Therapies in Dermatology and Urology: Underlying Mechanisms, Recent Trends and Future Directions

Lee

Jeong

Chan³

2009

Journal of the Optical Society of Korea

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Following their applications in cardiology, ophthalmology and dentistry among others, the advent of lasers in dermatology and urology had become the success story of the past decade. Laser-assisted treatments in dermatology and urology are mainly based on the laser-induced tissue injury/coagulation and/or ablation, depending upon the desirable clinical endpoint. In this review, we discussed the underlying mechanisms of the laser induced tissue ablation. In any medical laser application, the controlled thermal injury and coagulation, and the extent of ablation, if required, are critical. The laser thermal mechanism of injury is intricately related to the selective absorption of light and its exposure duration, similarly to the laser induced ablation. The laser ablation mechanisms were categorized into four different categories (the photo-thermally induced ablation, the photo-mechanically induced ablation, the plasma induced ablation and the photoablation) and their fundamentals are herein described. The brief history of laser treatment modality in dermatology and urology are summarized.

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Holmium:YAG laser lithotripsy: A dominant photothermal ablative mechanism with chemical decomposition of urinary calculi

Cited by 170 publications

References 36 publications

Urinary calculus fragmentation during Ho: YAG and Er:YAG lithotripsy

Urinary calculus fragmentation during Ho: YAG and Er:YAG lithotripsy

Optic cavitation with CW lasers: A review

The Advent of Laser Therapies in Dermatology and Urology: Underlying Mechanisms, Recent Trends and Future Directions

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