The efficacy of high-intensity focused ultrasound (HIFU) for the treatment of a range of different cancers including those of the liver, prostate and breast, has been demonstrated.

HIFU offers considerable advantages over techniques such as chemotherapy and surgical resection, in terms of its non-invasiveness and low risk of harmful side effects. Despite this, however, there are a number of signifi cant challenges which currently hinder its widespread clinical application.

One of these challenges is the need to transmit sufficient energy through the rib cage to induce tissue necrosis in the required volume whilst minimising the formation of side lobes. Multi-element random arrays are currently showing great promise in overcoming the limitations of single-element transducers.

Nevertheless, successful treatment of a patient with liver tumours requires a thorough understanding of the way in which the ultrasonic pressure field from
a HIFU array is scattered by the rib cage.