组织表面附着水膜层对脉冲CO2激光骨硬组织消融的影响

Influence of an Applied Water Film on Bone Hard Tissue Ablationwith Pulsed CO_2 Laser

评估组织表面附着水膜层对激光骨硬组织消融效果的影响。以新鲜离体牛胫骨组织为实验样品，置于速度为12mm／s的一维电动平移台上，分别在有附着和无附着水膜层情况下使用脉冲CO2激光进行垂直照射，来回扫描5次。激光波长10．64μm，脉冲频率60Hz，能量密度范围18～84J／cm2，光斑直径400pm，水膜层厚度0．4mm。辐照后，利用体视显微镜和扫描电镜（SEM）观察消融凹槽表面形貌改变和微结构变化，利用光学相干层析成像（OCT）技术测量消融凹槽深度。结果表明，组织表面附着水膜层可减少激光骨消融过程产生的碳化和热损伤，有利于清洁消融凹槽，且辐射曝光量为50J／cm2和70J／cm2时附着水膜层可提高消融速率。

The influence of an applied water film on bone hard tissue ablation by pulsed C02 laser is evaluated. Fresh bovine shank bone in vitro used in the experiment is put on a PC-controlled motorized linear drive stage and is moved repeatedly with the speed of 12 mm/s through focused beam of laser. In each sample, two cuts are produced, one with water film and the other with not. The wavelength of pulsed CO2 laser is 10.64 μm, the pulse repetition rate is 60 Hz, the energy density is 18 ~ 84 J/cm2 , the beam diameter is about 400 μm and the water film tickness is 0.4 mm. The scanning number is five. The surface morphology and microstructure of ablation grooves are examined by steroscopic microscope and scanning electron microscope （SEM） respectively. The crater depth is measured with optical coherence tomography （OCT）. It shows that water film can not only reduce carbonization and thermal damage, clean the ablation groove, but also augment ablation rate at the radiant exposure of 50 and 70 J/cm2.