Chemical decomposition of urinary stones during Holmium-laser lithotripsy. Part II: Evidence for photothermal breakdown

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

Research output: Chapter in Book/Report/Conference proceedingChapter

1 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. 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 (cf. part I). The mass-loss of desiccated calcium oxalate monohydrate (COM) stones exposed to 150 J from the Ho:YAG laser in air was 40±12 mg (mean±1 s.d.); for hydrated stones in air was 25±9 mg; and for hydrated stones in water was 17±3 mg, p<.001. These differences indicate that direct absorption of the laser radiation by the stone is required for the most efficient ablation. Lowering the initial temperature of COM or cystine stones also reduced the stone mass-loss following 20 J of delivered laser energy: 2.2±1.1 mg vs 5.2±1.6 mg for 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. Finally, chemical analysis of the laser-induced stone fragments revealed the presence of thermal breakdown products: CaCO 3from COM; free sulfur and cysteine from cystine; Ca 2O 7P 2 from calcium hydrogen phosphate dihydrate, and cyanide from uric acid.

Original languageEnglish (US)
Title of host publicationProceedings of SPIE - The International Society for Optical Engineering
PublisherSociety of Photo-Optical Instrumentation Engineers
Pages369-376
Number of pages8
Volume3601
StatePublished - 1999
EventProceedings of the 1999 Laser-Tissue Interaction X: Photochemical, Photothermal, and Photomechanical - San Jose, CA, USA
Duration: Jan 24 1999Jan 27 1999

Other

OtherProceedings of the 1999 Laser-Tissue Interaction X: Photochemical, Photothermal, and Photomechanical
CitySan Jose, CA, USA
Period1/24/991/27/99

ASJC Scopus subject areas

  • Electrical and Electronic Engineering
  • Condensed Matter Physics

Fingerprint Dive into the research topics of 'Chemical decomposition of urinary stones during Holmium-laser lithotripsy. Part II: Evidence for photothermal breakdown'. Together they form a unique fingerprint.

  • Cite this

    Glickman, R. D., Teichman, J. M. H., Vassar, G. J., Weintraub, S. E., Chan, K. F., Pfefer, T. J., & Welch, A. J. (1999). Chemical decomposition of urinary stones during Holmium-laser lithotripsy. Part II: Evidence for photothermal breakdown. In Proceedings of SPIE - The International Society for Optical Engineering (Vol. 3601, pp. 369-376). Society of Photo-Optical Instrumentation Engineers.