ASSESSMENT OF CAVITATION FROM DIAGNOSTIC ULTRASOUND

通过超声诊断评估空化

• 批准号: 3178262
• 负责人: ROBERT E APFEL
• 金额: $ 19.59万
• 依托单位: YALE UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 1985
• 资助国家: 美国
• 起止时间: 1985-09-01 至 1992-03-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/3178262
• 关键词: biomedical equipment safety; lithotripsy; luminescence; radiation hazard; ultrasonography; ultrasound biological effect; visible light

Cavitation at the cellular scale - or microcavitation - has been implicated as a potential biological risk to the patient, analogous to low level ionizing radiation. Cavitation can be caused by acoustic waves of relatively low energy density which can create a small, but very high concentration of energy in the form of a collapsing bubble. The energy of a single bubble collapse has been estimated to be, in the units of ionizing radiation, on the order of 300 million electron volts, deposited in a region the size of the cell nucleus. Theoretical estimates of the acoustic conditions to produce such bubbles fall in the range of some diagnostic ultrasound equipment, yet clinical confirmation of this possibility has been absent, either because experimental methods have been too insensitive to cellular activity on a spatial scale of one micron and on a temporal scale of a microsecond, or because the theoretical estimates include assumptions that do not obtain in vivo. The work outlined in this proposal continues our earlier experimental and theoretical work, extending it to a) more sensitive systems of cavitation detection, b) more clinically relevant fluids (e.g. blood, amniotic fluid, aqueous and vitreous humor - which have a range of viscosities), c) more comprehensive theoretical models for bubble inception and action, d) a closer look at the interaction of ultrasound with biological membranes - in the presence and absence of free radical scavengers, and e) to high pulse amplitude systems (such as in Extracorporal Shock Wave Lithotripters) that can induce cavitation in vivo. Our quantitative results with active and passive cavitation detection reveal a new and valuable perspective with regard to the likelihood of deleterious effects from cavitation induced by diagnostic ultrasound: In particular, the preoccupation with the question of whether cavitation occurs is replaced with the more realistic questions of how often it occurs and with what consequences. Moreover, the size of cavitation nuclei appears to be of relatively small importance compared to the number and concentration of nuclei, which appears to be an extremely small fraction of the "particles" that are exposed to the diagnostic ultrasound beam. Whereas gas saturation effects also appear of relatively small importance, the visco-elastic characteristics of the biological environment play a much greater role in determining the potential location, inception, and violence of cavitation. The extension of this work to biological fluids and clinical instrumentation should provide definitive evidence on these questions and thus provide a basis on which to assess quantitatively the risk from diagnostic ultrasound.

在细胞尺度上的空化 - 或微浪费 - 对患者的潜在生物学风险暗示 至低水平的电离辐射。 空化可能是由 能量密度相对较低的声波，可以产生 以A形式的小但很高的能量浓度 崩溃的气泡。 单个气泡崩溃的能量​​已经 估计在电离辐射的单位上估计为 3亿电子伏特，存放在一个大小的区域 细胞核。 声学条件的理论估计 产生这种气泡在某些诊断范围内 超声设备，但对这种可能性的临床确认 缺乏，要么是因为实验方法也已经 在一个微米的空间尺度上对细胞活性不敏感 并在微秒的时间范围内，或者是因为 理论估计包括未获得的假设 体内。 该提案中概述的工作继续我们 实验和理论工作，将其扩展到a）更多 敏感的空化检测系统，b）更临床 相关的液体（例如血液，羊水，水性和玻璃体 幽默 - 具有一系列粘度），c）更全面 气泡成立和动作的理论模型，d）更接近 查看超声与生物膜的相互作用 - 在存在和不存在自由基清除仪的情况下，e） 高脉冲振幅系统（例如在体外冲击波中 岩性磨牙）可以在体内诱导空气。 我们的定量结果通过主动和被动的空化 检测揭示了关于 由于诱导的空化作用的可能性 诊断超声：尤其是对 是否发生空化的问题被更多 关于频率发生的频率和什么的现实问题 结果。 此外，空气核的大小似乎 与数字相比，重要性相对较小 核的浓度似乎很小 暴露于诊断的“颗粒”的一部分 超声梁。 而气体饱和效应也出现 相对较小的重要性，即粘弹性特征 生物环境在确定中起着更大的作用 潜在的位置，建立和气蚀暴力。 这 将这项工作扩展到生物流体和临床 仪器应就这些提供明确的证据 问题，因此提供了评估的基础 定量诊断超声的风险。