12 October 2015 Efficacy and predictability of soft tissue ablation using a prototype Raman-shifted alexandrite laser
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Previous research showed that mid-infrared free-electron lasers could reproducibly ablate soft tissue with little collateral damage. The potential for surgical applications motivated searches for alternative tabletop lasers providing thermally confined pulses in the 6- to-7-μm wavelength range with sufficient pulse energy, stability, and reliability. Here, we evaluate a prototype Raman-shifted alexandrite laser. We measure ablation thresholds, etch rates, and collateral damage in gelatin and cornea as a function of laser wavelength (6.09, 6.27, or 6.43  μm), pulse energy (up to 3  mJ/pulse), and spot diameter (100 to 600  μm). We find modest wavelength dependence for ablation thresholds and collateral damage, with the lowest thresholds and least damage for 6.09  μm. We find a strong spot-size dependence for all metrics. When the beam is tightly focused (∼100-μm diameter), ablation requires more energy, is highly variable and less efficient, and can yield large zones of mechanical damage (for pulse energies >1  mJ). When the beam is softly focused (∼300-μm diameter), ablation proceeded at surgically relevant etch rates, with reasonable reproducibility (5% to 12% within a single sample), and little collateral damage. With improvements in pulse-energy stability, this prototype laser may have significant potential for soft-tissue surgical applications.
© 2015 Society of Photo-Optical Instrumentation Engineers (SPIE)
John A. Kozub, John A. Kozub, Jin-H. Shen, Jin-H. Shen, Karen M. Joos, Karen M. Joos, Ratna Prasad, Ratna Prasad, M. Shane Hutson, M. Shane Hutson, } "Efficacy and predictability of soft tissue ablation using a prototype Raman-shifted alexandrite laser," Journal of Biomedical Optics 20(10), 105004 (12 October 2015). https://doi.org/10.1117/1.JBO.20.10.105004 . Submission:

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