Abstract: A method for sensing a disturbance in a transmission path of a converging ultrasound energy beam transmitted by a transducer in a focussed ultrasound system comprises transmitting a burst of ultrasound energy from the transducer, detecting whether a reflected portion of the ultrasound energy burst is received at the transducer within a certain time period following transmission of the burst, and, if so, analyzing the received reflected portion to determine a characteristic of the disturbance.

Abstract: Systems and methods for testing the performance of a focused ultrasound transducer array include transmitting ultrasonic energy from the transducer array towards an acoustic reflector, such as a planar air mirror, and receiving ultrasonic energy reflected off of the acoustic reflector using a sensing element. A characteristic of the reflected ultrasonic energy, such as amplitude and phase, is measured by processing circuitry, for example, by comparing the characteristic of the received ultrasonic energy to a corresponding characteristic of the transmitted ultrasonic energy to obtain an actual gain and phase shift for the received ultrasonic energy. A controller compares the actual gain and phase shift of the received ultrasonic energy to an expected gain and phase shift of the received ultrasonic energy. This information is used to calibrate the transducer array and/or to declare a system failure if the comparison indicates an error.

Abstract: A focused ultrasound system includes a plurality of transducer elements disposed about and having an angular position with a central axis. Drive signals drive respective transducer elements that include phase shift values based upon the angular position of each respective transducer element. The phase shift values are based upon an oscillation function that oscillates about the central axis between minimal and maximal phase shift values such that a first on-axis focal zone and a second off-axis focal zone are created. An amplitude and frequency of the oscillation function are controlled to adjust relative acoustic energy levels of the first and second focal zones, and to adjust a radius of the second focal zone, respectively. In addition, the drive signals include an additional predetermined phase shift based upon a radial position of each respective transducer element to adjust a focal distance of the focal zones.

Abstract: Systems and methods for controlling the phase and amplitude of individual drive sinus waves of a phased-array focused ultrasound transducer employ digitally controlled components to scale the amplitude of three or more bases sinuses into component sinus vectors. The component sinus vectors are linearly combined to generate the respective sinus of a selected phase and amplitude. The use of digitally controlled controlled components allows for digitally controlled switching between various distances, shapes and orientations (“characteristics”) of the focal zone of the transducer. The respective input parameters for any number of possible focal zone characteristics may be stored in a comprehensive table or memory for readily switching between focal zone characteristics in &mgr; seconds. Changes in the output frequency are accomplished without impacting on the specific focal zone characteristics of the transducer output.

Abstract: Systems and methods for performing a focused ultrasound procedure monitored using magnetic resonance imaging (MRI) is provided. An MRI system uses a timing sequence for transmitting radio frequency (RF) signals and detecting magnetic resonance (MR) response signals from a patient's body in response to the RF pulse sequences. A piezoelectric transducer is driven with drive signals such that the transducer emits acoustic energy towards a target tissue region within the patient's body. Parameters of the drive signals are changed at times during the timing sequence that minimize interference with the MRI system detecting MR response signals, e.g., during transmission of RF signals by the MRI system.

Abstract: System and methods for performing a therapeutic procedure using focused ultrasound include providing a piezoelectric transducer including a plurality of transducer elements, such as a concave concentric ring array or a liner array of transducer elements. Drive circuitry is coupled to the transducer for providing drive signals to the transducer elements at one of a plurality of discrete RF frequencies. A controller is coupled to the drive circuitry for periodically changing a frequency of the drive signals to one of the plurality of discrete frequencies, while controlling a phase component of the drive signals to maintain the focus of the transducer at a primary focal zone during a single sonication.

Abstract: Cells are destroyed within a subcutaneous tissue region using a transducer disposed externally adjacent to a patient's skin. The transducer emits acoustic energy that is focused at a linear focal zone within the tissue region, the acoustic energy having sufficient intensity to rupture cells within the focal zone while minimizing heating. The transducer may include one or more transducer elements having a partial cylindrical shape, a single planar transducer element coupled to an acoustic lens, or a plurality of linear transducer elements disposed adjacent one another in an arcuate or planar configuration. The transducer may include detectors for sensing cavitation occurring with the focal zone, which is correlated to the extent of cell destruction. A frame may be provided for controlling movement of the transducer along the patient's skin, e.g., in response to the extent of cell destruction caused by the transducer.

Abstract: Cells are destroyed within a subcutaneous tissue region using a transducer disposed externally adjacent to a patient's skin. The transducer emits acoustic energy that is focused at a linear focal zone within the tissue region, the acoustic energy having sufficient intensity to rupture cells within the focal zone while minimizing heating. The transducer may include one or more transducer elements having a partial cylindrical shape, a single planar transducer element coupled to an acoustic lens, or a plurality of linear transducer elements disposed adjacent one another in an arcuate or planar configuration. The transducer may include detectors for sensing cavitation occurring with the focal zone, which is correlated to the extent of cell destruction. A frame may be provided for controlling movement of the transducer along the patient's skin, e.g., in response to the extent of cell destruction caused by the transducer.