Therapeutic ultrasound is a promising non-invasive method for inducing various beneficial biological effects in the human body. In cancer treatment applications, high-power ultrasound is focused at a target tissue volume to ablate the malignant tumour. The success of the procedure depends on the ability to accurately focus ultrasound and destroy the target tissue volume through coagulative necrosis whilst preserving the surrounding healthy tissue. Patient-specific treatment planning strategies are therefore being developed to increase the efficacy of such therapies, while reducing any damage to healthy tissue. These strategies require to use high-performance computing methods to solve ultrasound wave propagation in the body quickly and accurately. For realistic clinical scenarios, all numerical methods which employ volumetric meshes require several hours or days to solve the full-wave propagation on a computer cluster. The boundary element method (BEM) is an efficient approach for modelling the wave field because only the boundaries of the hard and soft tissue regions require discretisation. This paper presents a multiple-domain BEM formulation with a novel preconditioner for solving the Helmholtz transmission problem (HTP). This new formulation is efficient at high-frequencies and where high-contrast materials are present. Numerical experiments are performed to solve the HTP in multiple domains comprising: (i) human ribs, an idealised abdominal fat layer and liver tissue, (ii) a human kidney with a perinephric fat layer, exposed to the acoustic field generated by a high-intensity focused ultrasound (HIFU) array transducer. The time required to solve the equations associated with these problems on a single workstation is of the order of minutes. These results demonstrate the great potential of this new BEM formulation for accurately and quickly solving ultrasound wave propagation problems in large anatomical domains which is essential for developing treatment planning strategies.

中文翻译：

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一种用于计算体内超声传播的快速全波求解器

治疗性超声是一种很有前途的非侵入性方法，可在人体中诱导各种有益的生物效应。在癌症治疗应用中，高功率超声聚焦于目标组织体积以消融恶性肿瘤。该程序的成功取决于准确聚焦超声并通过凝固性坏死破坏目标组织体积同时保留周围健康组织的能力。因此，正在开发针对患者的治疗计划策略，以提高此类治疗的功效，同时减少对健康组织的任何损害。这些策略需要使用高性能计算方法来快速准确地解决超声波在体内的传播问题。对于现实的临床场景，所有采用体积网格的数值方法都需要数小时或数天才能在计算机集群上求解全波传播。边界元法 (BEM) 是一种对波场建模的有效方法，因为只有硬组织和软组织区域的边界需要离散化。本文提出了一种多域 BEM 公式，其中包含用于解决亥姆霍兹传输问题 (HTP) 的新型预处理器。这种新配方在高频和存在高对比度材料的情况下非常有效。进行数值实验以解决多个域中的 HTP，包括：(i) 人体肋骨、理想化的腹部脂肪层和肝脏组织，(ii) 具有肾周脂肪层的人体肾脏，暴露于高频产生的声场中。强度聚焦超声 (HIFU) 阵列换能器。在单个工作站上求解与这些问题相关的方程所需的时间为数分钟。这些结果证明了这种新的 BEM 公式在准确、快速地解决大型解剖学域中的超声波传播问题方面的巨大潜力，这对于制定治疗计划策略至关重要。