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Proceedings Paper

Comparison of urinary calculus fragmentation during Ho:YAG and Er:YAG lithotripsy
Author(s): Hyun Wook Kang; Ho Lee; Joel H. Teichman; A. J. Welch
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Paper Abstract

We compared urinary calculus fragmentation with long pulsed Ho:YAG (λ= 2.12 μm) versus Er:YAG (λ = 2.94 μm) lasers. We measured the ablation width, depth, volume and efficiency as a function of pulse energy from calculus threshold energy to clinical energy typically used for Ho:YAG laser lithotripsy. Ablation effects were evaluated for three types of urinary calculi (calcium oxalate monohydrate, cystine, and uric acid), for single and multiple pulses applied at various optical energy levels. By means of comparing laser-induced crater topography and ablation volume for each stone type, the feasibility of Er:YAG laser lithotripsy was appraised. The Er:YAG laser pulse energy generated deeper and narrower crater shapes with relatively smooth contours whereas the Ho:YAG laser produced shallower and wider craters with irregular shapes. In terms of multiple pulses ablation, the Er:YAG produced larger ablation volume than Ho:YAG. The deeper crater induced by the Er:YAG was attributed to the higher absorption coefficient of stones at the 2.94 μm wavelength, and widening of crater by Ho:YAG was perhaps caused by lateral expansion of ablated material. Comparing the ablation efficiency, Er:YAG was superior to Ho:YAG for both single and five-pulses.

Paper Details

Date Published: 25 April 2005
PDF: 12 pages
Proc. SPIE 5686, Photonic Therapeutics and Diagnostics, (25 April 2005); doi: 10.1117/12.589455
Show Author Affiliations
Hyun Wook Kang, Univ. of Texas at Austin (United States)
Ho Lee, Wellman Labs. of Photomedicine, Harvard Medical School (United States)
Joel H. Teichman, Providence Healthcare and Univ. of British Columbia (United States)
A. J. Welch, Univ. of Texas at Austin (United States)

Published in SPIE Proceedings Vol. 5686:
Photonic Therapeutics and Diagnostics
Brian Jet-Fei Wong M.D.; Eugene A. Trowers M.D.; Kenton W. Gregory M.D.; Abraham Katzir; Nikiforos Kollias; Reza S. Malek M.D.; Henry Hirschberg M.D.; Kenneth Eugene Bartels D.V.M.; Steen J. Madsen; Lloyd P. Tate V.D.M.; Lawrence S. Bass M.D.; Werner T. W. de Riese; Karen M. McNally-Heintzelman, Editor(s)

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