The effect of free-electron laser pulse structure on mid-infrared soft-tissue ablation: biological effects
The effect of free-electron laser pulse structure on mid-infrared soft-tissue ablation: biological effects
复制标题
DOI：
10.1088/0031-9155/50/8/017
复制
发表时间：
2005-04-21
影响因子：
3.5
通讯作者：
Jansen, ED
中科院分区：
文献类型：
--
作者：
Mackanos, MA;Kozub, JA;Jansen, ED
以往的研究表明，改变脉冲结构的自由电子激光（FEL）从1到200 ps，从而减少200倍的微脉冲的峰值辐照度有很小或没有影响的烧蚀阈值辐射曝光和烧蚀坑深度为一个定义的辐射曝光。这项研究的重点是在6.1和6.45 μ m的烧蚀机制，强调自由电子激光脉冲结构的作用。进行了三个不同的实验来深入了解这种机制。首先是一个分析的烧蚀羽动力学观察到的1 ps微脉冲相比，通过明场分析看到的200 ps微脉冲。由于该成像，在消融的尺寸上观察到可忽略的差异，但在消融的动力学上没有观察到差异。第二个实验是角膜和皮肤组织的组织学分析，以确定是否有较少的热损伤与一个微脉冲持续时间相比，另一个。对于在任一波长下研究的微脉冲持续时间，在犬角膜或小鼠真皮上的热损伤程度上没有观察到显著差异。最后一组实验涉及使用质谱法来确定是否酰胺键断裂可能发生在存在于组织中的蛋白质中，作为中红外光直接反射到酰胺I和酰胺II吸收带的结果。该分析表明，在蛋白质上没有由于6.45 μ m的辐射而导致的酰胺键断裂。
Previous studies have shown that changing the pulse structure of the free electron laser (FEL) from 1 to 200 ps and thus reducing the peak irradiance of the micropulse by 200 times had little or no effect on both the ablation threshold radiant exposure and the ablated crater depth for a defined radiant exposure. This study focuses on the ablation mechanism at 6.1 and 6.45 mu m with an emphasis on the role of the FEL pulse structure. Three different experiments were performed to gain insight into this mechanism. The first was an analysis of the ablation plume dynamics observed for a 1 ps micropulse compared with a 200 ps micropulse as seen through bright-field analysis. Negligible differences are seen in the size, but not the dynamics of ablation, as a result of this imaging. The second experiment was a histological analysis of corneal and dermal tissue to determine whether there is less thermal damage associated with one micropulse duration versus another. No significant difference was seen in the extent of thermal damage on either canine cornea or mouse dermis for the micropulse durations studied at either wavelength. The final set of experiments involved the use of mass spectrometry to determine whether amide bond breakage could occur in the proteins present in tissue as a result of direct absorptions of mid-infrared light into the amide I and amide II absorption bands. This analysis showed that there was no amide bond breakage due to irradiation at 6.45 mu m on protein.