不同离焦条件对骨硬组织激光消融的影响

Influence of Different Defocus Conditions on Bone Hard Tissue Ablation with Pulsed CO_2 Laser

评估了不同离焦辐照条件对脉冲COz激光骨硬组织消融的影响。实验样品为新鲜离体牛胫骨组织，置于由计算机自动控制的一维电动平移台上。调节工作距离，分别在光束聚焦平面前后光斑尺寸约为510μm处进行非接触式垂直照射。脉冲CO2激光波长为10．64μm，脉冲频率为60Hz，能量密度范围5～45J／cm^2。平移台移动速度为20mm／s，重复扫描6次。肉眼和显微镜观察组织样品形态学变化，常规组织病理切片处理，苏木精-伊红（HE）染色，共焦扫描显微镜观察并摄取图像。运用测量软件测量骨样品消融凹陷的几何尺寸，获得切口宽度、深度和切口截面积随辐射曝光量的变化关系。结果表明，脉冲CO2激光可以应用于骨头等硬组织的切割，不同的离焦辐照条件对组织消融效果具有重要影响；在临床上，为获得窄且深的消融切口和高的消融率，可以稍微将光束聚焦在组织表面下方。

This paper evaluates the influence of different defocus irradiation conditions on bone hard tissue ablation by pulsed COz laser. Bovine shank bones in vitro were used in this experiment which were put on a PC-controlled motorized linear drive stage and moved repeatedly through the focused beam. Work distance was adjusted to obtain a beam spot size of about 510 μm on tissue sample before and after focus plane respectively. The wavelength of pulse CO2 laser was 10.64 μm, pulse repetition rate was 60 Hz, and the energy density is 5-45 J/cm^2. The moving speed of the stage was 20 mm/s, scanning times was 6. After irradiation, the incision morphology was observed by naked eye and confocal microscopy. The geometry measurement of the incision was also taken. It was showed that pulsed CO2 laser can be used to cut hard bone tissue, and the defocus irradiation condition has an important influence on ablation effect. In order to obtain a narrow-and-deep incision and high ablation rate, one can locate the beam focus slightly under the bone surface.