Nonlinear Bubble Dynamics and Medical Ultrasound

非线性气泡动力学和医学超声

• 批准号: 9712179
• 负责人: Andrew Szeri
• 金额: $ 19.06万
• 依托单位: University of California-Berkeley
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 1998
• 资助国家: 美国
• 起止时间: 1998-01-01 至 2001-12-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=9712179&HistoricalAwards=false
• 关键词: Nonlinear; Bubble; Dynamics; Medical; Ultrasound

9712179 Szeri High frequency sound waves, known as ultrasound, are used in an increasing number of diagnostic and therapeutic modes in medicine. The beneficial effects of ultrasound can often be increased when microbubbles are present; these may either be produced by the sound field itself or injected into the patient. Hence, the nonlinear dynamics and control of volume oscillations of microbubbles is of great importance in a variety of medical applications of ultrasound. In medical imaging, microbubbles are valuable as contrast agents. Owing to their compressibility relative to surrounding tissue, bubbles return a stronger echo from an incident sound field that can be used to construct an image useful to physicians. The echo from bubbles can be enhanced by exploiting the nonlinear oscillations of bubbles which return an echo at a simple fraction or multiple of the incident frequency, further differentiating the bubbles from the surrounding tissue. In a second application known as sonodynamic therapy, ultrasound interacting with microbubbles drives chemical reactions that release radicals from injected reagents to destroy tumor tissue. The rate-limiting step is the slow growth of microbubbles to useful size by uptake of dissolved gases from the surrounding liquid. When the slowly growing bubbles become large enough, violent collapses initiate the therapeutic effect. The importance of nonlinear dynamics to these developing applications is clear, yet much is unknown about the physics of bubbles undergoing nonlinear oscillations at medically-relevant conditions. Therefore, research is proposed into nonlinear dynamics of resonances, damping, ultrasound-induced bubble growth, effects of encapsulation, and control of bubble oscillations. New control capabilities are under development that involve a novel technique for optimizing bubble dynamics by alteration of the driving acoustic waveform from a simple sine wave. The optimization can be constructed so a s to increase the echo from microbubbles used in imaging, or to increase the rate of ultrasound-induced growth of bubbles used in sonodynamic therapy. These enhancements do not require more intense ultrasound, but rather alterations in the acoustic waveform, and so can be obtained without additional risk to the patient. ***

9712179 Szeri高频声波，即超声，在医学中越来越多地用于诊断和治疗模式。 当存在微泡时，超声的有益效果通常可以增加;这些微泡可以由声场本身产生或注入患者体内。 因此，微泡体积振荡的非线性动力学和控制在超声的各种医学应用中具有重要意义。 在医学成像中，微泡作为造影剂是有价值的。 由于它们相对于周围组织的可压缩性，气泡从入射声场返回更强的回波，其可用于构建对医生有用的图像。 来自气泡的回波可以通过利用气泡的非线性振荡来增强，气泡的非线性振荡以入射频率的简单分数或倍数返回回波，从而进一步区分气泡与周围组织。 在第二种被称为声动力疗法的应用中，超声与微泡相互作用驱动化学反应，从注射的试剂中释放自由基以破坏肿瘤组织。 速率限制步骤是通过从周围液体中吸收溶解的气体使微泡缓慢生长到有用的尺寸。 当缓慢增长的气泡变得足够大时，剧烈的崩溃就会引发治疗效果。 非线性动力学的重要性，这些发展中的应用是显而易见的，但很多是未知的物理泡沫经历非线性振荡在医疗相关的条件。 因此，研究提出了非线性动力学的共振，阻尼，超声诱导的气泡生长，封装的影响，和控制气泡振荡。 新的控制能力正在开发中，涉及一种新的技术，用于通过从简单的正弦波改变驱动声波波形来优化气泡动力学。 可以构建优化，以便增加来自成像中使用的微泡的回波，或者增加声动力学治疗中使用的超声诱导的气泡生长的速率。 这些增强不需要更强的超声波，而是改变声波波形，因此可以在不给患者带来额外风险的情况下获得。 ***