22 May 1995 Surface characteristics of argon laser ablated bone in the presence and absence of an initiator
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Abstract
Argon lasers are widely used in neurotologic surgery for hard tissue ablation. They are used in stapes bone surgery to treat surgically correctable hearing loss. While the Argon laser has been shown to be effective in performing the stapedotomy operation, few studies exist which focus on the deleterious effects of this laser in a model that is relevant to clinical practice and laser-tissue interactions. This study focuses on surface temperature changes in otic capsule and cortical bone in the presence and absence of an initiator. For tissues which are poor absorbers at visible wavelengths, such as bone, an initiator can be applied to the surface. It then absorbs the applied laser energy and initiates ablation by creating a carbonized surface over the tissue in question. Clinically, blood or burnt tissue is used to initiate ablation over bone in ear surgery. In this study black ink was used as the initiator substance. We also studied the effect of multiple lasers pulses on these bone tissues. Fresh porcine otic capsule and cortical bone was machined to a uniform thickness of 0.8 mm. A coherent 920 Argon laser was used with a focusing lens as a delivery system (200 micrometers spot size, 100 msec pulse duration, 514 nm). A Hg-Cd-Te thermal camera system was used to measure surface temperature. Hot spot temperatures were recorded along with the full width-half maximum (FWHM) of the spatial thermal disturbance at that time. The time for the hot spot to return to ambient temperature was also measured. Minimal surface temperature elevation was recorded in the absence of an initiator. No surface modification was observed by light microscopy. In contrast, the addition of an initiator resulted in marked temperature elevations and significant surface carbonization. Surface changes were studied with scanning EM and an interferometric surface analyzer. The role of an initiator, mechanisms of tissue destruction, and clinical relevance of these findings will be discussed.
© (1995) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Brian Jet-Fei Wong, Mark Russell Dickinson, Belinda Simonian, Michael W. Berns, Joseph Neev, "Surface characteristics of argon laser ablated bone in the presence and absence of an initiator", Proc. SPIE 2391, Laser-Tissue Interaction VI, (22 May 1995); doi: 10.1117/12.209904; https://doi.org/10.1117/12.209904
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