Photothermal ablation is the primary mechanism in Holmium: YAG laser lithotripsy of urinary calculi

Randolph D. Glickman, Joel M H Teichman, Nicole S. Corbin, George J. Vassar, Susan E. Weintraub, Kin Foong Chan, Ashley J. Welch

Research output: Chapter in Book/Report/Conference proceedingConference contribution

2 Scopus citations

Abstract

Because of the ≥250 μs pulsewidth emitted by the Ho:YAG laser used in clinical lithotripsy, it is unlikely that stress confinement occurs within the irradiated stones. Experimental data supports a thermal mechanism for Ho:YAG laser stone ablation. Previous work has shown that stone fragmentation occurs soon after the onset of the laser pulse, is uncorrelated to cavitation bubble formation or collapse, and is associated with low pressures. Moreover, lithotripsy proceeds fastest with desiccated stones in air (data based on laser ablation of calcium oxalate monohydrate stones), indicating that direct absorption of the laser radiation by the stone material is required for the most efficient ablation. Lowering the initial temperature of calculi reduces the stone mass-loss following 20 J of delivered laser energy: 2.2 ± 1.1 mg vs 5.2 ± 1.6 mg for calcium oxalate monohydrate (COM) stones (-80 vs 23°C), and 0.8 ± 0.4 mg vs 2.2 ± 1.1 mg for cystine stones (-80 vs 23°C), p≤.05. In all of the stone compositions examined, thermal breakdown products have been detected, e.g. CaCO 3 from COM; free sulfur and cysteine from cystine; Ca 2O 7P 2 from calcium hydrogen phosphate dihydrate, and cyanide and alloxan from uric acid. All of these observations are most consistent with a photothermal breakdown process induced by Ho:YAG laser lithotripsy.

Original languageEnglish (US)
Title of host publicationProceedings of SPIE - The International Society for Optical Engineering
PublisherSociety of Photo-Optical Instrumentation Engineers
Pages376-384
Number of pages9
Volume3863
StatePublished - 1999
EventProceedings of the 1999 International Conference on Biomedical Optics (BMO'99) - Wuhan, China
Duration: Oct 25 1999Oct 27 1999

Other

OtherProceedings of the 1999 International Conference on Biomedical Optics (BMO'99)
CityWuhan, China
Period10/25/9910/27/99

ASJC Scopus subject areas

  • Electrical and Electronic Engineering
  • Condensed Matter Physics

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