Nonlinear Acoustics in Calibration/Metrology of High Intensity Focused Ultrasound

高强度聚焦超声校准/计量中的非线性声学

• 批准号: 7686775
• 负责人: Vera Khokhlova
• 金额: $ 49.12万
• 依托单位: UNIVERSITY OF WASHINGTON
• 依托单位国家: 美国
• 财政年份: 2008
• 资助国家: 美国
• 起止时间: 2008-09-15 至 2012-06-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7686775
• 关键词: Acoustics; Address; Adoption; Algorithms; Animals; Calibration; Clinic; Clinical; Communities; Data; Development; Devices; Evaluation; Experimental Models; Face; Fiber Optics; Focused Ultrasound Therapy; Frequencies; Furuncles; Heat-Shock Response; Heating; Heterogeneity; Holography; Hot Spot; Industry; Laboratories; Lesion; Manufacturer Name; Measurement; Measures; Methods; Metric; Microbubbles; Modeling; Monitor; Morphologic artifacts; Non-linear Models; Operative Surgical Procedures; Output; Photography; Procedures; Public Health; Radiation; Recommendation; Reporting; Research; Role; Safety; Shock; Source; Speed; System; Techniques; Temperature; Testing; Therapeutic; Therapeutic Studies; Therapeutic Uses; Thermometry; Time; Tissue Sample; Tissues; Transducers; Ultrasonic Therapy; Ultrasonic Transducer; Ultrasonography; Uncertainty; Water; Work; absorption; attenuation; base; clinically relevant; improved; in vivo; metrology; millisecond; minimally invasive; patient population; pressure; public health relevance; research study; response; simulation; sound; tissue phantom; tool; transduction efficiency; vapor

DESCRIPTION (provided by applicant): High Intensity Focused Ultrasound (HIFU) is used to perform surgical procedures non-invasively by using high amplitude focused sound waves to induce irreversible tissue damage within a mm-size focal `hot spot.' HIFU is rapidly gaining widespread clinical use and is poised to reach even broader patient populations. However, there has been a rising concern within all parts of the HIFU community that no standards exist for measuring or reporting of HIFU fields. It has been also realized that the relation between HIFU output and the produced bioeffects is poorly understood. This lack of standards and relations of acoustics to bioeffects is a major impediment to broad clinical adoption of HIFU. The proposal addresses this current gap in development of such standards as well as understanding the bioeffect mechanisms. Nonlinear acoustics is the study of high amplitude sound. Nonlinear acoustic propagation leads to shocks, discontinuities in the acoustic wave, which encompass a very broad range of frequencies. Shock formation and strong focusing distinguish HIFU from other medical ultrasound approaches and combine to make accurate measurements difficult. Also, since ultrasound energy losses that create heating are frequency dependent, the relatively high absorption in tissue counteracts nonlinear propagation, which means that no simple way exists to extrapolate water measurements directly to tissue. Since the broadest frequency content is in the shocks, absorption at the shocks is the critical mechanism of tissue heating. The specific aims of this proposed project are: (1) Use combined simulations and measurements to determine the high amplitude acoustic output of HIFU sources in water. (2) Determine the fields in tissue phantoms and tissue and define methods to derate water measurements to tissue. (3) Quantify the mechanism of enhanced tissue heating due to nonlinear acoustics and corresponding bioeffects in ex-vivo tissue and in vivo animal studies (4) Synthesize results of Aims 1-3 into practical recommendations for characterization of HIFU devices to improve regulatory oversight, understanding bioeffects, and efficacy and safety of clinically relevant HIFU therapeutic devices. Our method is a combined approach of numerical simulation and experimental measurement. Our model includes nonlinear acoustic propagation effects, diffraction, absorption, and tissue heterogeneities. Our acoustic measurements tools include small broad bandwidth hydrophones and a new step-shock source to calibrate the hydrophones. Our thermal measurement techniques involve the noninvasive observation of boiling with high speed photography and active and passive acoustic transducers. Tissue phantoms, excised and in vivo tissue will be used in experiments and modeling. This proposed work will benefit public health by providing tools and recommendations to help regulate and control HIFU exposures, which will improve efficacy and safety and facilitate a more rapid clinical acceptance of this promising therapy. PUBLIC HEALTH RELEVANCE: High Intensity Ultrasound (HIFU) is gaining wider acceptance in the clinic as a form of noninvasive or minimally invasive surgery. However, no agreed system for calibration of HIFU output currently exists today. This proposed work will benefit public health by providing tools and recommendations to help regulate and control HIFU exposures which will improve efficacy and safety and facilitate a more rapid clinical acceptance of this promising therapy.

描述（由申请人提供）：高强度聚焦超声（HIFU）用于通过使用高振幅集中的声波来非侵入性地进行手术程序，从而在MM大小的焦点“热点”中诱导不可逆的组织损伤。 HIFU正在迅速获得广泛的临床用途，并有望达到更广泛的患者人群。但是，在HIFU社区的各个地区，人们一直在关注不存在用于衡量或报告HIFU领域的标准。还已经意识到，HIFU输出与生物效应之间的关系知之甚少。声学与生物效应的标准缺乏和关系是广泛采用HIFU的主要障碍。该提案解决了此类标准的发展以及了解生物效应机制的当前差距。非线性声学是对高振幅声音的研究。非线性声学传播导致冲击，声波中的不连续性，其中包括非常广泛的频率。冲击形成和强烈的焦点将HIFU与其他医学超声方法区分开，并结合使用以使准确的测量变得困难。同样，由于产生加热的超声能量损失是频率依赖性的，因此组织中相对较高的吸收可以抵消非线性传播，这意味着没有简单的方法可以直接推断水测量到组织。由于最广泛的频率含量是在冲击中，因此减震是组织加热的关键机制。该提出的项目的具体目的是：（1）使用合并的模拟和测量来确定水中HIFU源的高幅度声音输出。 （2）确定组织幻象和组织中的场，并定义将水测量置于组织的方法。 (3) Quantify the mechanism of enhanced tissue heating due to nonlinear acoustics and corresponding bioeffects in ex-vivo tissue and in vivo animal studies (4) Synthesize results of Aims 1-3 into practical recommendations for characterization of HIFU devices to improve regulatory oversight, understanding bioeffects, and efficacy and safety of clinically relevant HIFU therapeutic devices.我们的方法是数值模拟和实验测量的组合方法。我们的模型包括非线性声学传播效应，衍射，吸收和组织异质性。我们的声学测量工具包括小的宽带宽带言语和一个新的台阶源以校准言语。我们的热测量技术涉及对高速摄影以及主动和被动声音传感器沸腾的无创观测。组织幻像，切除和体内组织将用于实验和建模。这项拟议的工作将通过提供工具和建议来帮助调节和控制HIFU暴露，这将提高功效和安全性，并促进对这种有希望的治疗的临床接受，从而使公共卫生受益。公共卫生相关性：高强度超声（HIFU）在诊所中以一种无创或微创手术的形式获得更广泛的接受。但是，目前尚无商定的HIFU输出校准系统。这项拟议的工作将通过提供工具和建议来帮助调节和控制HIFU暴露，从而提高功效和安全性，并促进对这种有希望的治疗的临床接受，从而使公共卫生受益。