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22 May 1995 Holmium laser ablation of cartilage: effects of cavitation bubbles
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The ablation of fresh harvested porcine femur patellar groove cartilage by a 2.12 micrometers Cr:Tm:Ho:YAG laser in clinically used irradiation conditions was studied. Laser pulses were delivered via a 600 micrometers diameter fiber in isotonic saline. Ablation was investigated as a function of the angle of incidence of the delivery fiber with respect to the cartilage surface (0-90 degrees) and of radiant exposure. Laser pulses with energies of 0.5, 1.0 and 1.5 J and a duration of 250 microseconds were used. A constant fiber tip-tissue distance of 1 mm was maintained for all experiments. The dynamics of the induced vapor bubble and of the ablation process was monitored by time resolved flash videography with a 1 microseconds illumination. Acoustic transients were measured with a piezoelectric PVDF needle probe hydrophone. Bubble attachment to the cartilage surface during the collapse phase, leading to the direct exposition of the cartilage surface to the maximal pressure generated, was observed in all investigated irradiation conditions. Maximal pressure transients of up to 200 bars (at 1 mm distance from the collapse center) were measured at the bubble collapse at irradiation angles >= 60 degrees. No significant pressure variation was observed in perpendicular irradiation conditions as a function of radiant exposure. A significant reduction of the induced pressure for irradiation angles
© (1995) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Thomas Asshauer, Thomas Jansen, Thorsten Oberthur, Guy P. Delacretaz, and Bruno E. Gerber "Holmium laser ablation of cartilage: effects of cavitation bubbles", Proc. SPIE 2391, Laser-Tissue Interaction VI, (22 May 1995);

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