Self-adaptive time reversal cavity for ultrasound therapy through the ribcage

Ultrasound therapy requires focusing high pressures in confined focal spots, to ablate tissues. For organs like the heart, the treatment is challenging, as the US beam must cross the ribs. Part of the energy is reflected by the bones, leading to potential injuries at tissue — bone interface and a pressure drop on target. With usual therapy devices — large transducers on spherical shells — an adaptive US beam propagating in the intercostal space is hard to build without losing power. Time reversal cavities (TRC) have shown promising results for shockwave therapy [1], and have been used as compact emitter-receivers [2]. We present here a dual mode TRC that can perform shock wave therapy in large regions and image the ribs. The image is then use to form a therapy beam propagating selectively through the ribs [3].