Abstract
Previous studies of mid-infrared ablation of tissue showed blast damage to adjacent tissue in the form of large fissures extending from the crater wall. We hypothesized that these fissures are due to the forceful expansion of a water vapour bubble within tissue. Time resolved flash photography documented an expanding vapour bubble within the tissue by the elevation of the tissue surface. The aim of this study was to determine the relation between the intensity of holmiumrYSGG laser irradiation and bubble dimension in saline and in tissue. The influence of the spatial distribution of the intensity was determined by delivering 200 to 500 mJ laser pulses through a 320 μm and 600 tun diameter bare fiber, which was in light contact with porcine aorta. A holmiumrYSGG laser pulse is a superposition (500 /as long) of microsecond pulses. The first part of the laser pulse contains the most intens spikes. To determine the influence of the high peak power spikes on bubble formation, the first part of a 650 mJ laser pulse was absorbed. The modified laser pulse (400 mJ) was smoother and 75 fis shorter than the original 400 mJ laser pulse. Results: Increasing the fiber tip area by a factor of 3.5 (600 μm vs. 320 μn diameter) resulted in a decrease in the diameter of tissue elevation by only a factor of 1.25, indicating that the delivered energy determined the extent of tissue elevation. Elimination of the high peak power of the first part of the laser pulse did not decrease the dimension of the bubble in saline and of the tissue elevation. Therefore we anticipate that the extent of the blast damage in tissue cannot be reduced substantially by either reducing the fluence or by quenching high peak power spikes of the laser pulse.
Original language | English |
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Title of host publication | Laser-Tissue Interaction III |
Editors | Steven L. Jacques |
Publisher | SPIE |
Pages | 307-314 |
Number of pages | 8 |
ISBN (Electronic) | 9780819407924 |
DOIs | |
Publication status | Published - 7 Aug 1992 |
Externally published | Yes |
Event | 3rd Laser-Tissue Interaction Conference 1992 - Los Angeles, United States Duration: 19 Jan 1992 → 24 Jan 1992 Conference number: 3 |
Publication series
Name | Proceedings of SPIE - The International Society for Optical Engineering |
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Volume | 1646 |
ISSN (Print) | 0277-786X |
ISSN (Electronic) | 1996-756X |
Conference
Conference | 3rd Laser-Tissue Interaction Conference 1992 |
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Country/Territory | United States |
City | Los Angeles |
Period | 19/01/92 → 24/01/92 |