Systems and methods for creating longer necrosed volumes using a phased array focused ultrasound system

A system for performing a therapeutic procedure in a target tissue region of a patient using focused ultrasound, comprising:

• a transducer array comprising a plurality of “n” transducer elements;
• drive circuitry coupled to the transducer elements, the drive circuitry configured for providing sets of respective drive signals to each of the transducer elements;
• and
• a controller coupled to the drive circuitry, the controller configured for alternatively focusing ultrasonic energy from a plurality of sets of the transducer elements at a target tissue region within a patient being treated during a single sonication, each set of transducer elements including a plurality of “m” transducer elements, with “m” being less than “n,”
• wherein the controller is further configured for dividing the transducer array into “p” sets of transducer elements during the single sonication, “p” being greater than one, each set of transducer elements having an overall surface area “a,” where “a” equals “A/p,” A being an aperture area of the entire transducer array, such that an f-number of each set is substantially greater than an f-number of the entire transducer array the f-number being a ratio of a radius of curvature of the transducer array to a cross-sectional dimension of the transducer array.

A method for performing a therapeutic procedure in a target tissue region of a patient using focused ultrasound, the method comprising:

• providing a transducer array comprising a plurality of sets of transducer elements, the plurality of gets including all of the transducer elements of the transducer array;
• and
• alternatively driving each of the sets of transducer elements with a set of respective drive signals for a predetermined duration during a single sonication, while substantially continuously focusing ultrasonic energy produced by the transducer elements of each set at a desired focal zone,
• wherein the predetermined duration for which each set of transducer elements is alternatively driven is not more than about one second.

A system for performing a therapeutic procedure in a target tissue region of a patient using focused ultrasound, comprising:

• a transducer having a surface area “A” and an f-number, the transducer being configured for emitting ultrasonic energy towards a focal zone, the f-number being a ratio of a radius of curvature of the transducer to a cross-sectional dimension of the transducer;
• drive circuitry coupled to the transducer, the drive circuitry configured for providing drive signals to the transducer to cause the transducer to emit ultrasonic energy;
• and
• a shutter device disposed between the transducer and the focal zone, the shutter device being configured for exposing the focal zone to alternative surface areas “a” of the transducer, “a” being less than “A.”

A method for performing a therapeutic procedure in a target tissue region of a patient using focused ultrasound, the method comprising:

• providing a transducer configured for emitting ultrasonic energy having a surface area “A;”
• driving the transducer with drive signals for a predetermined duration during a single sonication, while substantially focusing ultrasonic energy produced by the transducer at the target tissue region;
• and
• alternatively directing ultrasonic energy from a plurality of surface areas “a” of the transducer, “a” being less than “A,” during the single sonication while substantially focusing the ultrasonic energy at the target tissue region.

A method for performing a therapeutic procedure in a target tissue region of a patient using focused ultrasound, the method comprising:

• providing a transducer configured for emitting ultrasonic energy having a surface area “A;”
• driving the transducer with drive signals for a predetermined duration during a sonication, while substantially focusing ultrasonic energy produced by the transducer at the target tissue region;
• and
• alternatively directing ultrasonic energy from surface areas “a” of the transducer, “a” being less than “A,” during the sonication towards the target tissue region;
• wherein a shutter device is disposed between the transducer and the patient, and wherein the step of alternatively directing ultrasonic energy comprises controlling the shutter device to expose at the patient to surface areas “a” of the transducer through the shutter device.