Control of Dynamically Coupled Cavitation Bubbles in Shock Wave Lithotripsy

描述(申请人提供)体外冲击波碎石术(SWL)是最广泛使用的尿路结石粉碎方法，但经过20年的SWL，安全性和效率似乎在下降，而不是提高。在一些报告中，临床上肾脏内的重大出血增加了十倍，成功治疗的可能性降低了一半。对公众健康的影响是增加了重复治疗的风险/收益比和成本。体外和体内实验表明，空化在期望的碎石效果和不良的副作用组织损伤中都发挥着重要作用，虽然粉碎过程中需要一些数量不确定的气泡，但由于高冲击波传送率可以产生更多的气泡，从而抑制粉碎。最近的高速摄像机图像表明，空化泡团可以生长到包裹石头，并且现有的理论无法预测单个孤立气泡的团簇动力学。目前，SWL中还没有一个模型能够解释气泡之间或附近组织之间的动态耦合。该项目及其与公众健康的相关性的目标是开发经过实验验证和支持的准确分析模型，以增加我们对肾结石和组织附近的空泡团的了解，并为提高SWL的疗效和安全性提供指导。该项目有三个具体目标。(1)建立气泡团动力学的数学模型，并利用该模型来理解和预测气泡团中单个空化气泡的生长、平移、坍塌和冲击波辐射，并估计这些效应对石头的集体影响。展开模型以考虑散布在气泡中的固体粒子。计算并比较该碎石器产生的压力和四种临床碎石机产生的冲击波。最终，确定能改善碎石效果的冲击波波形、冲击波传输率和碎石机束宽的参数和预测条件。(2)建立了尿小管、血管和其他受组织限制的空间中单个和聚集的气泡动力学模型。(3)使用压电式传感器和两个高速摄像机获得团簇内的压力测量和团簇动力学的3D电影，以与模型模拟进行比较。从数值和实验上量化气泡数对石材或血管壁上的压力的影响，从而得出短波传送率的影响。同时，对B超上的抑制簇进行表征，作为对临床医生的反馈。同时，模型和实验结果可以指导监测、方案和碎石机的开发。

DESCRIPTION (provided by applicant) Extracorporeal shock wave lithotripsy (SWL) is the most widely used procedure for comminution of urinary tract calculi, but after two decades of SWL, safety and efficiency appear to be declining, not improving. In some reports, clinically significant hemorrhaging within the kidney has increased tenfold, and the probability of successful treatment has been reduced by half. The effect on public health has been an increased risk/benefit ratio and cost of repeated treatments. In vitro and in vivo experimentation have shown that cavitation plays an important role in both the desired effect, stone comminution, and the undesired side effect, tissue injury, and that whereas some undefined number of bubbles is necessary in comminution, more bubbles, as can be produced by high shock wave delivery rates, inhibit comminution. Recent high-speed camera images indicate that the cavitation bubble cluster can grow to envelop the stone and that the cluster dynamics cannot be predicted by existing theories for single, isolated bubbles. Currently no model in SWL accounts for the dynamic coupling of bubbles to one another or to nearby tissue. The goal of this project and its relevance to public health is to develop accurate analytical models, tested and supported by experiment, to increase our understanding of cavitation clusters near kidney stones and tissue, and to provide guidance for improving the efficacy and safety of SWL. The project has three specific aims. (1) Develop a mathematical model for bubble cluster dynamics and use this model to understand and predict the growth, translation, collapse, and shock wave radiation associated with individual cavitation bubbles in the cluster, and to estimate the collective impact of these effects on the stone. Expand the model to account for solid particles interspersed among the bubbles. Calculate and compare pressures produced by the cluster and the shock wave produced by four clinical lithotripters. Ultimately, determine parameters and predict conditions for shock waveform, shock wave delivery rate, and lithotripter beam width that improve stone comminution. (2) Develop a model for individual and clustered bubble dynamics in urinary tubules, blood vessels, and other spaces confined by tissue. (3) Obtain pressure measurements within the cluster and 3D movies of cluster dynamics using piezoelectric sensors and two high speed cameras to compare to model simulations. Quantify numerically and experimentally the pressure on a stone or vessel wall as an effect of bubble number and therefore SW delivery rate. Simultaneously, characterize inhibitory clusters on B-mode ultrasound as a feedback to clinicians. Together, the model and experimental results may then guide monitoring, protocol, and lithotripter development.