Laser-Forschungslabor, LIFE Centre, Ludwig-Maximilians-University Munich, Marchioninistrasse 23, 81377, Munich, Germany.
Lasers Med Sci. 2012 May;27(3):637-43. doi: 10.1007/s10103-011-0992-0. Epub 2011 Oct 20.
Ureteroscopic laser lithotripsy is a commonly used technique to treat ureteral calculi.The type of energy source used is one of the main influences of retrograd calculi propulsion. Using a momentum pendulum under-water set-up the induced momentum and the initial velocity were investigated. Pulsed laser light from three different clinically available laser systems, including a Ho:YAG laser, a frequency-doubled double-pulse (second harmonic generation, SHG) Nd:YAG laser and a flash-lamp pumped dye (FLPD) laser, were transmitted via flexible fibres of different core diameter to the front of the pendulum sinker. Single pulses at variable pulse energy, according to the clinical laser parameter settings, were applied to the target sinker, thus causing a repulsion-induced deflection which was documented by video recording. The maximum deflection was determined. Solving the differential equation of a pendulum gives the initial velocity, the laser-induced momentum and the efficiency of momentum transfer. The induced deflection as well as the starting velocity of the two short-duration pulsed laser systems (SHG Nd:YAG, FLPD) were similar (s (max) = 2-3.6 cm and v (0) = 150-200 mm/s, respectively), whereas both values were lower using the Ho:YAG laser with a long pulse duration (s (max) = 0.9--1.6 cm and v (0) = 60-105 mm/s, respectively). The momentum I induced by the Ho:YAG laser was only 50% and its transfer efficacy η (Repuls) was reduced to less than 5% of the values of the two short-pulsed laser systems. This investigation clearly showed the variable parts and amounts of repulsion using different pulsed lasers in an objective and reproducible manner. The momentum transfer efficiency could be determined without any physical friction problems. Further investigations are needed to compare stone fragmentation techniques with respect to laser repulsion and its clinical impact.
输尿管镜激光碎石术是治疗输尿管结石的常用技术。所使用的能量源类型是影响逆行结石推进的主要因素之一。使用水下动量摆装置研究了感应动量和初始速度。三种不同临床可用的激光系统的脉冲激光光，包括 Ho:YAG 激光、双脉冲倍频（二次谐波产生，SHG）Nd:YAG 激光和闪光灯泵浦染料（FLPD）激光，通过不同芯径的柔性光纤传输到摆锤沉子的前端。根据临床激光参数设置，将可变脉冲能量的单个脉冲施加到目标沉子上，从而导致由于排斥力引起的偏转，通过视频记录进行记录。确定最大偏转。解一个摆的微分方程得到初始速度、激光诱导动量和动量传递效率。感应偏转以及两个短脉冲激光系统（SHG Nd:YAG、FLPD）的起始速度相似（s(max)=2-3.6 cm 和 v(0)=150-200 mm/s，分别），而使用具有长脉冲持续时间的 Ho:YAG 激光时，这两个值较低（s(max)=0.9--1.6 cm 和 v(0)=60-105 mm/s，分别）。Ho:YAG 激光诱导的动量仅为 50%，其传递效率η（Repuls）降低到两个短脉冲激光系统的 5%以下。这项研究清楚地以客观和可重复的方式显示了不同脉冲激光的可变部分和排斥量。可以在没有任何物理摩擦问题的情况下确定动量传递效率。需要进一步的研究来比较结石破碎技术相对于激光排斥及其临床影响。
