Abstract: Methods and apparatus for producing synchronously pumped (SP) ultrasonic bursts which can be used to create ultrasound radiation pressure. The emission of an ultrasonic burst by a piezoelement is synchronized with the reflection of another ultrasonic burst by the same piezoelement to create a combined ultrasonic burst with increased amplitude. Repeated synchronized emissions and reflections of ultrasonic bursts lead to resonant growth of a burst amplitude to equal that of a standing wave, but without formation of a nodal structure. In some embodiments, the SP ultrasonic bursts generate shear waves. In some embodiments, the shear waves are resonant shear waves. In some embodiments, the shear waves are formed in a supersonic regime. Shear waves thus formed can be used for various treatments of biological tissues, with or without RF heating.

Abstract: Apparatus and methods for generating resonantly amplified ultrasound shear waves in biological tissue. The apparatus comprises a plurality of transducer elements and a controller for controlling the element excitation such as to cyclically generate the pattern of focal regions having associates shear waves and to create resonant amplification of the shear waves. Resonant amplification of the shear waves is obtained when shear waves generated at one focal region are superposed in phase on shear waves synchronously generated at an adjacent focal region. The generation may be done by burst or continuous wave excitation. In some embodiments, the shear waves are supersonic shear waves.

Abstract: A method of treating a region of tissue with ultrasound, the method comprising: generating a first ultrasound standing wave (USW) pattern at a first frequency in the region; and simultaneously generating a second USW pattern in the region spatially overlapping the first USW pattern at a second frequency different from the first frequency.