An efficient boundary element solver for trans-abdominal high-intensity focused ultrasound treatment planning

Abstract

High-intensity focused ultrasound (HIFU) is a promising treatment modality for the non-invasive ablation of pathological tissue in many organs, including the liver. Since many patients are not suitable candidates for liver surgery, the possibility to locally deposit thermal energy in a non-invasive way would bear significant clinical impact. Optimal treatment planning strategies based on high-performance computing numerical methods are expected to form a vital component of a successful clinical outcome in which healthy tissue is preserved and optimal focusing achieved, thus compensating for soft tissue heterogeneity and the presence of ribs. The boundary element method (BEM) is an effective approach for this purpose because only the boundaries of the ribs and soft tissue regions require discretization, as opposed to standard approaches which require the entire volume around the ribcage to be meshed. A Galerkin discretized Burton-Miller formulation used in combination with preconditioning and matrix compression techniques was applied to compute the acoustic field generated by a focused array transducer in the presence of a layer of abdominal fat, a human ribcage model and liver tissue. The results demonstrate the effectiveness of this dedicated BEM algorithm for trans-abdominal HIFU treatment planning.