Abstract: An ultrasound system and method for performing relatively non-invasive cardiac ablation on a patient. The system of the present invention includes a plurality of ultrasound transducers forming a phased array that is to be located externally of the patient. The array a focused beam of sufficient energy to ablate a predetermined cardiac tissue volume. The system is capable of refocusing the beam so that acoustical aberrations encountered by the beam, as it is transmitted through inhomogeneous body tissues between the array and the treatment volume, are taken into account and will not impede operation of the system. To refocus the beam, the system includes a senor which senses the phase distribution caused by the aberrations allowing a controller to calculate a compensating driving phase distribution and accordingly drive the array. The system also allows for real time correction of the beam's position enabling the beam to follow a moving myocardial target volume.

Abstract: Herein disclosed is a system for irradiating sound waves to be converged into an annular focal zone having a desired size. This system uses a transducer which is composed of a plurality of elements divided at least in a circumferential direction of the face of the transducer so that the phases of drive signals may be changed according to the respective circumferential positions of the oscillating elements to rotate the phases of the drive signals n rotations in the circumferential direction. As a result, the annular focal zone of having a desired radius is formed, and integrated values of sound waves in the circumferential direction may be substantially zero on the focal plane so that an unnecessary secondary focal zone is prevented from being formed.

Abstract: The disclosed apparatus of the invention operates to generate and direct ultrasound over predetermined regions of a body, such as a programmed sequence of target points. A plurality of side-by-side tapered piezoelectric transducer elements are provided. Means are provided for energizing the transducer elements with electrical energy having a variable frequency. The frequency of the electrical energy is varied to change the direction of the ultrasound produced by the transducer elements. In the preferred embodiment of the invention, a processor is responsive to a coordinate of an input target point for controlling the variation of frequency. In one form of the invention, means are provided for varying the relative phases of the electrical energy applied to the transducer elements. In this form of the invention, the processor means is also responsive to at least another coordinate of the input target point for controlling the variation of the relative phases.

Abstract: A rotating electric field is generated in the vicinity of a rotating member, the electric field having an axis of rotation coinciding with the axis of rotation of the member. An electric-field sensing or reading device is positioned at the rotational axis of the electric field and associated therewith for detecting variations therein as the electric field passes the rotating member, and creates an electrical output whose relative phase is dependent upon the angular orientation of the rotating member.