Zhong P, Tong H L, Cocks F H, Preminger G M
Department of Mechanical Engineering and Materials Science, Duke University Medical Center, Durham, NC, USA.
J Endourol. 1997 Feb;11(1):55-61. doi: 10.1089/end.1997.11.55.
Using high-speed photography and acoustic emission measurements, we studied the dynamics of a transient cavitation bubble near a stone surface and the concomitant shockwaves generated during electrohydraulic lithotripsy (EHL). At each spark discharge, a vapor plasma and subsequently a cavitation bubble oscillating around the tip of an EHL probe are produced. Simultaneously, three distinctive shockwave pulses are generated. The first shockwave is produced by the rapid expansion of the vapor plasma, while the second and third waves are produced by rebounds of the cavitation bubble. Depending on the proximity of the probe to the stone surface, the collapse of the cavitation bubble may be symmetric, resulting in a strong shockwave emission; or asymmetric, leading to the formation of a liquid jet. For the Nortech AUTOLITH lithotripter with a 1.9F probe that was used in this study, maximum shockwave emission is produced when the probe is about 1 mm from the stone surface, whereas the maximum jet velocity is produced when the probe tip is at distance equivalent to the maximum bubble radius of about 3 mm. These findings are consistent with clinical experience, which suggests that for optimal treatment results, the EHL probe should be placed close to the stone surface.
我们使用高速摄影和声发射测量技术，研究了电液压碎石术（EHL）过程中结石表面附近瞬态空化泡的动力学以及伴随产生的冲击波。每次火花放电时，会产生一个蒸汽等离子体，随后在EHL探头尖端周围会产生一个振荡的空化泡。同时，会产生三个不同的冲击波脉冲。第一个冲击波由蒸汽等离子体的快速膨胀产生，而第二个和第三个波由空化泡的反弹产生。根据探头与结石表面的距离，空化泡的坍塌可能是对称的，从而产生强烈的冲击波发射；也可能是非对称的，导致形成液体射流。对于本研究中使用的配备1.9F探头的Nortech AUTOLITH碎石机，当探头距结石表面约1mm时产生最大冲击波发射，而当探头尖端距离等于约3mm的最大泡半径时产生最大射流速度。这些发现与临床经验一致，临床经验表明，为获得最佳治疗效果，EHL探头应靠近结石表面放置。
