Gijsbers G H, van den Broecke D G, Sprangers R L, van Gemert M J
Laser Center, Academic Medical Center, Amsterdam, The Netherlands.
Lasers Surg Med. 1992;12(6):576-84. doi: 10.1002/lsm.1900120603.
The effect of force applied to a 430 micron single fiber, delivering 60 pulses of 308 nm XeCl laser radiation at 20 Hz, on the ablation depth in porcine aortic tissue under saline has been investigated. Energy densities of 8, 15, 25, 28, 31, 37, and 45 mJ/mm2 were used. Force was applied by adding weights from 0 to 10 grams to the fiber. The fiber penetration was monitored by means of a position transducer. At 0 grams, the ablation depth increased linearly with incident energy density, but the fiber did not penetrate the tissue; with any weight added, the fiber penetrated the tissue at energy densities above 15 mJ/mm2. The fiber did not penetrate during the first several pulses, possibly due to gas trapped under the fiber. After these first pulses, a smooth linear advancement of the fiber began, which lasted until the pulse train stopped. The ablation depth increased with increasing energy densities and weights. This effect was largest above 25 mJ/mm2 where the ablation efficiencies (unit mm3/J), with weights added to the fiber, were substantially larger than values found in 308 nm ablation experiments described in the literature, which were conducted with either a focused laser beam or a fiber without additional force. The results imply that in 308 nm excimer laser angioplasty, force must be applied to the beam delivery catheter for efficient recanalization, and that experiments performed with a focused beam or without actual penetration of the fiber do not represent the situation encountered in excimer laser angioplasty.
研究了在20Hz频率下，对一根430微米的单纤维施加力，并使其传输60个脉冲的308nm XeCl激光辐射，对猪主动脉组织在盐水中的消融深度的影响。使用了8、15、25、28、31、37和45mJ/mm²的能量密度。通过向纤维上添加0至10克的重物来施加力。通过位置传感器监测纤维的穿透情况。在0克时，消融深度随入射能量密度线性增加，但纤维未穿透组织；添加任何重量后，纤维在能量密度高于15mJ/mm²时穿透组织。在最初的几个脉冲期间，纤维未穿透，可能是由于纤维下方 trapped气体。在这些最初的脉冲之后，纤维开始平稳线性推进，一直持续到脉冲序列停止。消融深度随能量密度和重量的增加而增加。在高于25mJ/mm²时，这种效应最大，此时向纤维添加重量后的消融效率（单位为mm³/J）明显大于文献中描述的308nm消融实验的值，那些实验是用聚焦激光束或没有额外力的纤维进行的。结果表明，在308nm准分子激光血管成形术中，必须对光束传输导管施加力才能实现有效的再通，并且用聚焦光束或纤维未实际穿透进行的实验不能代表准分子激光血管成形术中遇到的情况。
