Control of Dynamically Coupled Cavitation Bubbles in Shock Wave Lithotripsy

冲击波碎石术中动态耦合空化气泡的控制

• 批准号: 7615543
• 负责人: Mark F Hamilton
• 金额: $ 33.4万
• 依托单位: UNIVERSITY OF TEXAS AT AUSTIN
• 依托单位国家: 美国
• 财政年份: 2008
• 资助国家: 美国
• 起止时间: 2008-05-01 至 2012-04-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7615543
• 关键词: 3-Dimensional; Accounting; Adverse effects; Blood; Blood Vessels; Bowman' s space; Calculi; Clinical; Confined Spaces; Coupled; Coupling; Development; Electromagnetic Energy; Experimental Models; Extracorporeal Shockwave Lithotripsy; Feedback; Film; Frequencies; Goals; Growth; Hemorrhage; Image; In Vitro; Individual; Injury; Kidney; Kidney Calculi; Knowledge; Liquid substance; Lithotripsy; Measurement; Modeling; Monitor; Physiologic pulse; Play; Probability; Procedures; Process; Property; Protocols documentation; Public Health; Pulse Rates; Recommendation; Reporting; Research; Role; Safety; Shock; Solid; Speed; Stress; Surface; Testing; Tissues; Translations; Treatment Protocols; Tube; Ultrasonography; Ureter; Urinary tract; Width; base; clinically significant; cost; improved; in vivo; mathematical model; models and simulation; movie; novel; particle; polyvinylidene fluoride; pressure; research study; risk benefit ratio; sensor; simulation; theories; transmission process; urinary

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.

体外冲击波碎石术（Extracorporeal shock wave lithotripsy， SWL）是目前应用最广泛的尿路结石碎石术，但经过20多年的研究，其安全性和有效性非但没有提高，反而出现了下降的趋势。在一些报告中，临床上显著的肾脏出血增加了十倍，而成功治疗的可能性降低了一半。对公众健康的影响是风险/效益比和重复治疗的费用增加。体外和体内实验表明，空化在预期效果（结石粉碎）和不期望的副作用（组织损伤）中都起着重要作用，尽管粉碎过程中需要一些数量不明的气泡，但高冲击波传递率会产生更多的气泡，从而抑制粉碎。最近的高速摄像机图像表明，空化气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簇动力学。目前，在SWL中没有模型可以解释气泡之间或气泡与附近组织之间的动态耦合。该项目的目标及其与公共卫生的相关性是建立准确的分析模型，并得到实验的检验和支持，以增加我们对肾结石和组织附近空化簇的理解，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)建立气泡簇动力学的数学模型，并利用该模型来理解和预测与簇中单个空化气泡相关的生长、平移、坍塌和冲击波辐射，并估计这些影响对石头的集体影响。扩展模型以考虑气泡中散布的固体颗粒。计算并比较碎石团产生的压力和四个临床碎石机产生的冲击波。最终，确定参数并预测冲击波波形、冲击波传输速率和碎石机光束宽度的条件，以提高石料粉碎。(2)建立尿小管、血管和其他受组织限制的空间中的单个和群集气泡动力学模型。(3)利用压电传感器和两台高速摄像机获得簇内的压力测量和簇动力学的3D电影，与模型模拟进行比较。通过数值和实验量化岩石或血管壁上的压力对气泡数量的影响，从而确定SW输送速率。同时，在b超上表征抑制簇作为对临床医生的反馈。模型和实验结果可以共同指导监测、方案和碎石机的开发。