  High-intensity focused ultrasound (HIFU) is a promising treatment modality
for the non-invasive ablation of pathogenic tissue in many organs. Optimal
treatment planning strategies based on high-performance computing methods are
expected to form a vital component of a successful clinical outcome in which
healthy tissue is preserved and accurate focusing achieved. The practical
application of the algorithms informing these strategies depends on the ability
to produce fast and accurate full-wave patient-specific simulations, with
minimal computational overheads. For realistic clinical scenarios, all
simulation methods which employ volumetric meshes require several hours or days
to run on a computer cluster. The boundary element method (BEM) is an effective
approach for modelling the wave field because only the boundaries of the hard
and soft tissue regions require discretisation. A multiple-domain BEM
formulation with a novel preconditioner for solving the Helmholtz transmission
problem (HTP) is presented in this paper. Numerical experiments are performed
to solve HTP in multiple domains comprising: i) human ribs, an abdominal fat
layer and liver tissue, ii) a human kidney and a perinephric fat layer, exposed
to the acoustic field generated by a 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 rapid and accurate HIFU treatment planning.
