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Proceedings Paper

Investigation of stone retropulsion as a function of Ho:YAG laser pulse duration
Author(s): Hyun Wook Kang; Ho Lee; Jason Petersen; J. H. Teichman; A. J. Welch
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Paper Abstract

Stone retropulsion during Ho:YAG (λ = 2.12 μm) laser lithotripsy with various pulse durations (τp: 250 ~ 495 μsec) was investigated. Depending on pulse energy, optical pulse durations were divided into two regimes: short pulse (250~350 μsec) and long pulse (315~495 μsec). Retropulsion distance was measured as a function of pulse energy from 0.4 J to 1.2 J. Calculus phantoms made from plaster of Paris were ablated with a free running Ho:YAG laser using various optical fibers (200, 400, 600 μm) in water. In order to examine the ablation efficiency of two different pulse durations, a single pulse was applied, and the dynamics of the recoil action of a calculus phantom was monitored using a high-speed camera. The correlation among laser-induced topography, ablation volume, and retropulsion was evaluated. Higher pulse energy and larger fibers resulted in larger ablation volume and retropulsion. At a given pulse energy, optical pulses with different durations yielded comparable ablation volumes. The shorter duration pulses induced more retropulsion than longer pulses did at the same pulse energy. Larger retropulsion with the shorter pulse is thought to be induced by higher temperature at the vapor-solid interface, subsequently resulting in faster plume ejection with higher recoil momentum. The results suggest that a longer pulse could minimize retropulsion of the stone during lithotripsy.

Paper Details

Date Published: 22 February 2006
PDF: 11 pages
Proc. SPIE 6078, Photonic Therapeutics and Diagnostics II, 607815 (22 February 2006); doi: 10.1117/12.646513
Show Author Affiliations
Hyun Wook Kang, Univ. of Texas at Austin (United States)
Ho Lee, Wellman Labs. of Photomedicine, Harvard Medical School (United States)
Jason Petersen, Convergent Laser Technologies (United States)
J. H. Teichman, Providence Health Care (United States)
Univ. of British Columbia (Canada)
A. J. Welch, Univ. of Texas at Austin (United States)

Published in SPIE Proceedings Vol. 6078:
Photonic Therapeutics and Diagnostics II
Kenton W. Gregory; Nikiforos Kollias; Reza S. Malek; Michael D. Lucroy; Henry Hirschberg; Brian Jet-Fei Wong; Eugene A. Trowers; Werner T.W. de Riese; Justus F. R. Ilgner; Steen J. Madsen; Lloyd P. Tate; Haishan Zeng; Guillermo J. Tearney; Bernard Choi, Editor(s)

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