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Minerva Urologica e Nefrologica 2004 March;56(1):49-63

Copyright © 2004 EDIZIONI MINERVA MEDICA

language: English

Calculus fragmentation in laser lithotripsy

Welch A. J. ¹, Kang H. W. ², Lee H. ³, Teichman J. M. H. ⁴

¹ Department of Biomedical Engineering University of Texas at Austin, Austin, TX,USA 2 Department of Mechanical Engineering University of Texas at Austin, Austin, TX,USA 3 Wellman Laboratories of Photomedicine Harvard Medical School, Boston, MA,USA 4 Division of Urology Providence Healthcare and University of British Columbia, Vancouver, BC, Canada

The intracorporeal treatment of urinary calculi with lasers is presented, which describes laser-calculus interactions associated with lithotripsy. Reliable fragmentation of calculi with diverse compositions and minimal collateral tissue damage are primarily contingent upon laser parameters (wavelength, pulse duration, and pulse energy) and physical properties of calculi (optical, mechanical, and chemical). The pulse duration governs the dominant mechanism in calculi fragmentation, which is either photothermal or photoacoustical/photomechanical. Lasers with long pulse durations (i.e. > tens of µs) induce a temperature rise in the laser-affected zone with minimal acoustic waves; material is removed by means of vaporization, melting, mechanical stress, and/or chemical decomposition. Short-pulsed laser ablation (i.e. < 10 μs), on the other hand, produces shock waves, and the resultant mechanical energy fragments calculi. Work continues throughout the world to evaluate the feasibility of advanced lasers in lithotripsy and to optimize laser parameters and light delivery systems pertinent to efficient fragmentation of calculi.