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聚焦声波在毫米大小的焦点“热点”内引起不可逆的组织损伤来执行非侵入性外科手术。 HIFU 正在迅速获得广泛的临床应用，并有望覆盖更广泛的患者群体。然而，HIFU 社区的各个部分越来越担心没有测量或报告 HIFU 场的标准。人们还认识到，人们对 HIFU 输出与产生的生物效应之间的关系知之甚少。缺乏声学与生物效应的标准和关系是 HIFU 广泛临床应用的主要障碍。该提案解决了目前在制定此类标准以及了解生物效应机制方面的差距。非线性声学是对高振幅声音的研究。非线性声学传播会导致声波的冲击和不连续性，其频率范围非常广泛。冲击形成和强聚焦将 HIFU 与其他医学超声方法区分开来，两者结合起来使精确测量变得困难。此外，由于产生热量的超声能量损失与频率相关，组织中相对较高的吸收抵消了非线性传播，这意味着不存在将水测量结果直接推断到组织的简单方法。由于最宽的频率内容存在于冲击中，因此冲击吸收是组织加热的关键机制。该项目的具体目标是： (1) 结合模拟和测量来确定水中 HIFU 源的高振幅声输出。 (2) 确定组织模型和组织中的场，并定义降低组织水测量值的方法。 (3) 量化离体组织和体内动物研究中非线性声学和相应生物效应导致的增强组织加热的机制 (4) 将目标 1-3 的结果综合为 HIFU 设备表征的实际建议，以改善监管监督，了解临床相关 HIFU 治疗装置的生物效应、功效和安全性。我们的方法是数值模拟和实验测量的结合方法。我们的模型包括非线性声传播效应、衍射、吸收和组织异质性。我们的声学测量工具包括小型宽带水听器和用于校准水听器的新阶跃冲击源。我们的热测量技术涉及通过高速摄影以及主动和被动声换能器对沸腾进行无创观察。组织模型、切除的组织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，从而有益于公众健康，这将提高疗效和安全性，并促进临床更快地接受这种有前景的疗法。公共健康相关性：高强度超声 (HIFU) 作为一种无创或微创手术形式在临床上得到了更广泛的接受。然而，目前还没有一致同意的 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，从而有益于公众健康，这将提高疗效和安全性，并促进临床更快地接受这种有前景的疗法。