Fast Numerical Modeling Of Medical Ultrasound For Therapy And Imaging

摘要： 医学超声的许多重要发展都是由大规模的超声模拟实现的，这些模拟是 对新设备和应用的设计、评估和优化至关重要。尽管无处不在 医学超声中的计算机模拟，诊断和治疗超声中的许多问题 仍然没有解决，预计更好的数值模式将在解决这些问题方面发挥关键作用 有问题。特别是，现有的冲击模拟软件需要进行显著的改进 组织电切换能器产生的电波有助于肝脏、前列腺和大脑的有效非侵入性治疗 肿瘤。需要更好、更有效的模拟软件来改进横波成像 肝脏fiBROSI、甲状腺肿瘤和乳腺肿瘤，以及增强的软件工具需要用于模拟 超快成像和其他动态超声成像序列。改进的模型和方法是 对于软组织中的瞬变纵波和横波的衰减也是必要的，这是显著的fi不能 用于横波成像、超声显微镜、定量超声和超声断层扫描。主 该计划的目标是创建有价值的新软件资源，以实现以下基本解决方案 从三个专业fic目标的完成看医学超声存在的问题。在目标1中，我们建议创建新的 用不连续伽辽金(DG)方法进行组织摩擦的瞬时非线性全波超声模拟。 与fiNite差分、fiNite元素、伪谱和k空间方法不同，间断Galerkin方法 是在高性能计算系统上评估的冲击波的全波模型的理想选择。这事很重要 因为所有现有的医学超声非线性全波建模工具都是基于这些其他的 方法试图为组织摩擦学建立高度非线性的压力fifi区模型时，遇到了显著的困难。 在目标2中，我们建议使用不连续Galerkin来创建横波的瞬时全波模拟 方法，当应用于横波模拟时，具有类似的优点。我们还将讨论另一个 在现有横波模拟中增加分数阶横波模拟的局限性 描述软组织中剪切波衰减和色散的微积分模型。在目标3中，我们建议 为图形处理单元和计算集群创建新程序，进一步加速所有 在现有的聚焦程序中，实现了‘快速面向对象的C++超声模拟器’，以方便有效 超快成像和其他超声成像序列的数值模拟。AIM 3还将整合一个 新的数值技术成为焦点，它模拟了由几个因素描述的指数衰减和色散 为医学超声开发了不同的时间分数和空间分数模型。总体而言，我们预计 由提议的努力产生的模拟软件具有巨大的潜力来实现即时和 医学超声对整个fi领域的长期影响，特别是对组织摩擦、剪切术的应用 波弹性成像，以及其他治疗和诊断超声应用。

Abstract: Many important developments in medical ultrasound are enabled by large-scale ultrasound simulations, which are essential for the design, evaluation, and optimization of new devices and applications. Despite the pervasiveness of computer simulations in medical ultrasound, numerous problems in diagnostic and therapeutic ultrasound remain unsolved, where better numerical models are expected to play a crucial role in the solution to these problems. In particular, significant improvements are needed in the available software for simulations of shock waves produced by histotripsy transducers to facilitate effective noninvasive treatments of liver, prostate, and brain tumors. Better, more effective simulation software is required to enable improvements in shear wave imaging of liver fibrosis, thyroid tumors, and breast tumors, and enhanced software tools are needed for simulations of ultrafast imaging and of other dynamic ultrasound imaging sequences. Improved models and methods are also needed for the attenuation of transient compressional and shear waves in soft tissues, which is significant for shear wave imaging, ultrasound microscopy, quantitative ultrasound, and ultrasound tomography. The main goal of this proposal is to create valuable new software resources that will enable new solutions of fundamental problems in medical ultrasound through the completion of three specific aims. In Aim 1, we propose to create new transient nonlinear full-wave ultrasound simulations for histotripsy using the discontinuous Galerkin (DG) method. Unlike finite difference, finite element, pseudo-spectral, and k-space methods, the discontinuous Galerkin method is ideal for full-wave models of shock waves evaluated on high performance computing systems. This is important because all of the existing nonlinear full-wave modeling tools for medical ultrasound that are based on these other methods encounter significant difficulties when attempting to model highly nonlinear pressure fields for histotripsy. In Aim 2, we propose to create transient full-wave simulations of shear waves with the discontinuous Galerkin method, which has similar advantages when applied to simulations of shear waves. We will also address another limitation of present shear wave simulations by augmenting the proposed shear wave simulations with a fractional calculus model that describes the attenuation and dispersion of shear waves in soft tissue. In Aim 3, we propose to create new programs for graphics processing units and compute clusters that further accelerate all of the existing programs in FOCUS, the `Fast Object-oriented C++ Ultrasound Simulator,' in order to facilitate effective numerical modeling of ultrafast imaging and other ultrasound imaging sequences. Aim 3 will also integrate a new numerical technique into FOCUS that models the power law attenuation and dispersion described by several different time-fractional and space-fractional models developed for medical ultrasound. Overall, we anticipate that the simulation software produced by the proposed effort has great potential to achieve both immediate and long-term impact across the entire field of medical ultrasound, particularly for applications of histotripsy, shear wave elasticity imaging, and other therapeutic and diagnostic ultrasound applications.