High-amplitude ultrasound waves, generated outside the body, can be focused deep within tissue onto a region about the size of a grain of rice. In that region, conversion of the mechanical energy carried by the ultrasound wave into heat can lead to cell death by thermal necrosis, whilst leaving tissue outside the HIFU focal region unaffected. The potential of this technique to destroy deep-seated tumours non-invasively is currently being explored in the Clinical HIFU Unit at the Churchill Hospital in Oxford. The research being carried out in the IBME is aimed at further improving the speed, resolution, targeting and real-time monitoring of HIFU treatments, as applied to cancer therapy and to a range of novel HIFU applications.