水冷却Er: YAGレーザ骨きりでの低熱侵襲のための照射重複数最適化

Abstract

Lasers have the capability to remove or cut bone precisely without large reaction forces. However, surgeons have had many difficulties with using lasers during operations because of the thermal damage. In this paper, we propose an optimization the overlapping ratio, using water cooling; for the efficiency of laser bone ablations per unit time without thermal damages for operational application. A water-cooling Er: YAG laser (18.5 J/cm2, λ=2.94μm, 20Hz, 200μs) using optical fiber was operated at 0.5-3.0mm/s moving velocities and repetitions. We focused specifically on the overlapping irradiated area and the interval time between the laser irradiations. Swine scapulae were ablated and its rate and performance were evaluated. The water-cooling Er: YAG laser obtained optimal ablation results when the moving velocity was set at 2.0mm/s; the overlapping ratio is 0.89, and the ablated area along the troughs per unit time was optimized to 0.50mm2/s. Carbonization was not evident at this velocity. Controlling of the laser's moving velocity, we can optimize the ablation ability to 0.50mm2/s at 2.0 mm/s. At this velocity, the mass removal efficiency was at 208 μg/J. This result was almost same with previously conducted results accomplished by free running without water cooling.