Systems and methods for controlling a phased array focused ultrasound system

• US 6,506,154 B1
• Filed: 11/28/2000
• Issued: 01/14/2003
• Est. Priority Date: 11/28/2000
• Status: Expired due to Term

• Current Assignee: InSightec Ltd.
• Original Assignee: Insightec Txsonics Ltd.
• Inventors: Izzydor, Kolisher, Vitek, Shuki, Ezion, Avner
• Primary Examiner(s): Lateef, Marvin M.
• Assistant Examiner(s): Imam, Ali M.
• Application Number:
  US09/724,611
• Time in Patent Office: 777 Days
• Field of Search: 600/407, 600/437, 600/439-447, 600/459, 367/7, 367/11, 367/138, 367/103
• US Class Current: 600/437
• CPC Class Codes: G10K 11/341 Circuits therefor

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 μ seconds. Changes in the output frequency are accomplished without impacting on the specific focal zone characteristics of the transducer output. Sequential changes in the transducer focal zone characteristics are implemented in the form of sequential sets of digital control signals transmitted from the central controller to respective control channels for generating the individual sinus waves. The digital control signals may be changed in accordance with a time-domain function as part of a single thermal dose.

Claims

1. A focused ultrasound system, comprising:

a sinus source configured to generate a sinus signal;

a phazor generator coupled to said sinus source and configured to generate a plurality of base waves in response to the sinus signal;

a plurality of control channels coupled to said phazor generator and configure to generate a plurality of drive signals in response to the plurality of base waves, each of said plurality of control channels controlling a relative phase shift, an amplitude, or both, of a corresponding one of the plurality of drive signals; and

a transducer array having a plurality of transducer elements coupled to said plurality of control channels and configured to emit an acoustic energy beam in response to the plurality of drive signals.

2. The system of claim 1, further comprising a controller coupled to said plurality of control channels for providing input parameters to control the relative phase shift, the amplitude, or both, of each of the plurality of drive signals for determining a distance, shape, orientation, or any combination thereof, of a focal zone of the acoustic energy beam.

3. The system of claim 1, further comprising a controller coupled to said plurality of control channels for providing input parameters corresponding to a set of expected phase shifts, amplitudes, or both, during a sonication, monitoring a set of actual phase shifts, amplitudes, or both, during the sonication, and comparing the set of actual phase shifts, amplitudes, or both to the set of expected phase shifts, amplitudes, or both.

4. The system of claim 3, wherein the controller is further configured to shut down one or more of the plurality of drive signals in response to the set of actual phase shifts, amplitudes, or both, sufficiently varying from the set of expected phase shifts, amplitudes, or both.

5. The system of claim 1, wherein each of said plurality of control channels comprises:

a digital controller; and

a plurality of digital potentiometers, each having a first input coupled to said digital controller, a second input coupled to said phazor generator, and an output coupled to said transducer array.

6. The system of claim 5, wherein each of said plurality of control channels further comprises a sampling amplifier coupled between said plurality of digital potentiometers and said transducer array.

7. The system of claim 5, wherein each of said plurality of control channels further comprises a cross point switch array coupled between said phazor generator and said plurality of digital potentiometers.

8. The system of claim 5, wherein said plurality of digital potentiometers scale the plurality of base waves in response to a control signal from said digital controller.

9. The system of claim 5, wherein said digital controller is configured to provide a plurality of successive sonication parameters to vary a distance, shape, orientation, or any combination thereof, of a focal zone of the acoustic energy beam.

10. The system of claim 9, wherein a frequency of the plurality of drive signals is determined in accordance with the plurality of successive sonication parameters provided to the sinus source.

11. The system of claim 1, wherein said phazor generator produces four base waves having relative phases of approximately 0°

, 90°

, 180°

, and 270°

.

12. The system of claim 1, wherein said phazor generator produces three base waves having relative phases of approximately 0°

, 120°

, and 240°

.

13. The system of claim 1, wherein said phazor generator produces six base waves having relative phases of approximately 0°

, 60°

, 120°

, 180°

, 240°

, and 300°

.

14. The system of claim 1, wherein said phazor generator produces eight base waves having relative phases of approximately 0°

, 45°

, 90°

, 135°

, 180°

, 225°

, 270°

, and 315°

.

15. A focused ultrasound system, comprising:

a transducer having a plurality of transducer elements for emitting acoustic energy;

a sinus generator for producing a source sinus wave;

phazor generation circuitry for producing a plurality of base sinus waves from the source sinus wave, the base sinus waves being offset in phase from one another; and

a plurality of control channels, each control channel associated with a respective transducer element, each control channel receiving as inputs the base sinus waves, each control channel having a plurality of digitally controlled elements configured for scaling selected ones of the input base sinus waves, each control channel having summing circuitry for summing the respective scaled input base sinus waves to produce a drive sinus wave for driving the respective transducer element.

16. The system of claim 15, further comprising a controller providing control parameters to the respective control channels to thereby control a relative phase shift, amplitude, or both, of the respective drive sinus waves in order to determine a distance, shape, orientation, or any combination thereof, of a focal zone of acoustic energy emitted by the transducer elements.

17. The system of claim 16, wherein the sinus generator is configured to change the frequency of the source sinus, thereby changing the frequency of the respective drive sinus waves, based on input parameters received from the controller.

18. The system of claim 15, wherein the phazor generation circuitry produces four base sinus waves from the source sinus wave, the base sinus waves having relative phases of approximately 0°

, 90°

, 180°

, and 270°

.

19. The system of claim 18, wherein the phazor generation circuitry produces eight base sinus waves from the source sinus wave, the base sinus waves having relative phases of approximately 0°

, 45°

, 90°

, 135°

, 180°

, 225°

, 270° and

315°

.

20. The system of claim 15, wherein the phazor generation circuitry produces three base sinus waves from the source sinus wave, the base sinus waves having relative phases of approximately 0°

, 120° and

240°

.

21. The system of claim 15, wherein the phazor generation circuitry produces six base sinus waves from the source sinus wave, the base sinus waves having relative phases of approximately 0°

, 60°

, 120°

, 180°

, 240° and

300°

.

22. In a focused ultrasound system having a plurality of transducer elements driven by a corresponding plurality of sinus drive signals to thereby emit acoustic energy, a method for generating respective sinus drive signals having a relative phase shift, amplitude, or both, comprising:

providing a source sinus wave;

generating a plurality of base sinus waves from the source sinus wave, the base sinus waves being offset in phase from one another;

scaling the amplitude of a first base sinus wave to produce a first scaled sinus wave;

scaling the amplitude of a second base sinus wave to produce a second scaled sinus wave; and

summing the first and second scaled sinus waves to generate a respective drive signal.

23. The method of claim 22, wherein the first and second base sinus waves are scaled using digitally controlled elements.

24. The method of claim 22, further comprising

comparing an expected phase shift, amplitude, or both, of a transducer element driven by the respective drive signal to an actual phase shift, amplitude, or both, of the transducer element during a sonication.

25. The method of claim 24, further comprising turning off the drive signal if the actual phase shift, amplitude, or both, of the transducer element sufficiently varies from the expected phase shift, amplitude, or both.