NSF/FDA Scholar-in-Residence at FDA: Nonlinear Derating in Pre-Clinical Testing of High-Intensity Focused Ultrasound Systems

这项研究的长期目标是改进HIFU换能器的表征方法。这项应用的目的是测试一种能够预测高功率HIFU光束热效应的非线性降额方法。这项研究的中心假设是，通过在水中进行测量并使用非线性降级方法来量化组织中的生物效应，可以估计组织内焦点体积内的温度上升。他们计划验证这一假设，并通过追求两个具体目标来实现这一目标：1)推导出在给定水中压力模式幅度的情况下，评估组织中压力模式幅度的算法。工作假设是，用于将组织中的压力模式幅度从水转换为幅度的折算算法将是准确的，并且当插入到温度模式的表达式中时，将能够评估组织模体中的温度升高；以及2)利用热电偶在组织模体中使用逆传热法来评估折算方法。工作假设是，在组织模体中进行测量，结合逆方法，可以验证降级算法。这项研究的预期结果是一种独特的方法，用于确定设备的热效率和安全性，该方法准确、低成本，并适用于临床相关功率。预计该方法将产生重要的积极影响，提供一种工具，加快新HIFU系统的临床前测试，使超声设备行业和FDA审查人员都受益。

1041508BanerjeeThe long-term goal of this research is to improve characterization methods for HIFU transducers. The objective of this application is to test a nonlinear derating method that can predict the thermal effects of HIFU beams at high powers. The central hypothesis of this research is that temperature rise within the focal volume in tissues can be estimated by performing measurements in water and using a nonlinear derating method to quantify bioeffects in tissues. They plan to test the hypothesis and accomplish the objective by pursuing the two specific aims: 1) To derive algorithms for assessing the amplitudes of pressure modes in tissue, given the amplitudes in water. The working hypothesis is that a derating algorithm for converting pressure mode amplitudes from water to amplitudes in tissue will be accurate and that, when inserted into the expression for temperature modes, will enable assessment of temperature rise in a tissue phantom; and 2) To evaluate the derating approach with inverse heat-transfer method in tissue phantoms using thermocouples. The working hypothesis is that measurements in tissue phantoms, combined with inverse method, can validate the derating algorithm. The expected outcome of this study is a unique method for establishing the thermal efficacy and safety of the devices that is accurate, low-cost, and applicable at clinically relevant powers. The method is expected to have an important positive impact by providing a tool that will expedite the preclinical testing of new HIFU systems, benefitting both the ultrasound device industry and FDA reviewers.