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Proceedings Paper

Basic ablation phenomena during laser thrombolysis
Author(s): Ujwal S. Sathyam; Alan Shearin; Scott A. Prahl
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Paper Abstract

This paper presents studies of microsecond ablation phenomena that take place during laser thrombolysis. The main goals were to optimize laser parameters for efficient ablation, and to investigate the ablation mechanism. Gelatin containing an absorbing dye was used as the clot model. A parametric study was performed to identify the optimal wavelength, spot size, pulse energies, and repetition rate for maximum material removal. The minimum radiant exposures to achieve ablation at any wavelength were measured. The results suggest that most visible wavelengths were equally efficient at removing material at radiant exposures above threshold. Ablation was initiated at surface temperatures just above 100 degrees Celsius. A vapor bubble was formed during ablation. Less than 5% of the total pulse energy is coupled into the bubble energy. A large part of the delivered energy is unaccounted for and is likely released partly as acoustic transients from the vapor expansion and partly wasted as heat. The current laser and delivery systems may not be able to completely remove large clot burden that is sometimes encountered in heart attacks. However, laser thrombolysis may emerge as a favored treatment for strokes where the occlusion is generally smaller and rapid recanalization is of paramount importance. A final hypothesis is that laser thrombolysis should be done at radiant exposures close to threshold to minimize any damaging effects of the bubble dynamics on the vessel wall.

Paper Details

Date Published: 22 May 1997
PDF: 9 pages
Proc. SPIE 2970, Lasers in Surgery: Advanced Characterization, Therapeutics, and Systems VII, (22 May 1997); doi: 10.1117/12.275038
Show Author Affiliations
Ujwal S. Sathyam, Oregon Graduate Institute and Oregon Medical Laser Ctr. (United States)
Alan Shearin, Oregon Medical Laser Ctr. and Palomar Medical Technologies (United States)
Scott A. Prahl, Oregon Graduate Institute and Oregon Medical Laser Ctr. (United States)


Published in SPIE Proceedings Vol. 2970:
Lasers in Surgery: Advanced Characterization, Therapeutics, and Systems VII
R. Rox Anderson; Harvey Lui; Michail M. Pankratov; Kenneth Eugene Bartels; Gerhard J. Mueller; Graham M. Watson; Reza S. Malek; Lawrence S. Bass; Lloyd P. Tate; Hans-Dieter Reidenbach; Kenneth Eugene Bartels; R. Rox Anderson; Lawrence S. Bass; Aaron P. Perlmutter; Kenton W. Gregory; David M. Harris; David M. Harris; Harvey Lui; Reza S. Malek; Gerhard J. Mueller; Michail M. Pankratov; Aaron P. Perlmutter; Hans-Dieter Reidenbach; Lloyd P. Tate; Graham M. Watson, Editor(s)

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