MAPPING ULTRASOUND TRANSDUCERS

• US 20110094288A1
• Filed: 10/14/2010
• Published: 04/28/2011
• Est. Priority Date: 10/14/2009
• Status: Active Grant

• Current Assignee: InSightec Ltd.
• Original Assignee: InSightec Ltd.
• Inventors: Medan, Yoav, Hertzberg, Yoni, Maor, Dov
• Granted Patent: US 8,661,873 B2
• Time in Patent Office: Days
• US Class Current: 73/1.82
• CPC Class Codes: A61B 8/587 Calibration phantoms models for medical purposes G09B23/28
• CPC Class Codes: A61N 2007/0078 with multiple treatment transducers
• CPC Class Codes: A61N 2007/0095 by modifying an excitation signal
• CPC Class Codes: G01H 17/00 Measuring mechanical vibrations or ultrasonic, sonic or infrasonic waves, not provided for in the preceding groups see provisionally also G01H1/00
• CPC Class Codes: G01N 29/30 Arrangements for calibrating or comparing, e.g. with standard objects
• CPC Class Codes: G10K 11/346 using phase variation

Abstract

Ultrasound transducers may be mapped by varying a focus-affecting parameter and adjusting the parameter so as to improve focus quality. In some embodiments, mapping involves successively varying the phase of one transducer element, or group of elements, with respect to a constant phase of the other transducer elements, and determining the phase at which a tissue displacement in the ultrasound focus is maximized.

Claims

1. A method for improving the focus of an ultrasound transducer comprising a plurality of transducer elements, the method comprising:

(a) driving the plurality of transducer elements so as to generate an ultrasound focus;

(b) varying a focus-affecting parameter associated with at least one of the elements and measuring a resulting variation on a quality of the focus; and

(c) selecting a value of the parameter associated with a best focus quality.

2. The method of claim 1 wherein the quality measurement comprises scanning a profile of the focus.

3. The method of claim 1 wherein the quality measurement comprises measuring a size of a cross-section of the focus.

4. The method of claim 1 wherein the quality measurement comprises measuring an integral intensity of the focus.

5. The method of claim 1 wherein the quality measurement comprises measuring a peak intensity of the focus.

6. The method of claim 1 wherein the quality measurement comprises measuring a displacement associated with the focus.

7. The method of claim 6 wherein the displacement is measured using acoustic radiation force imaging.

8. The method of claim 7 wherein the acoustic radiation force imaging comprises applying a sequence of MR field gradients.

9. The method of claim 8 wherein the sequence of MR field gradients comprises repeated bipolar gradients.

10. The method of claim 8 wherein step (a) comprises generating an ultrasound pulse synchronized with the sequence of MR field gradients.

11. The method of claim 1 wherein the focus-affecting parameter comprises at least one of a phase or an amplitude of the at least one element.

12. The method of claim 1 wherein the focus-affecting parameter comprises at least one of a location or an orientation of the at least one element.

13. The method of claim 1 wherein the varying and measuring step comprises:

(i) driving a selected one of the transducer elements at a variable phase while driving the other transducer elements at a constant phase, thereby varying the focus quality;

(ii) determining a phase difference, if any, between the constant and variable phases where the focus quality is optimized; and

(iii) if the phase difference is non-zero, adjusting a relative phase of the selected transducer element based thereon.

14. The method of claim 13 further comprising repeating steps (i) through (iii) for the remaining transducer elements.

15. The method of claim 1 further comprising the step of providing a phantom, the driving step generating an ultrasound focus in the phantom and the measuring step measuring a focus quality in the phantom.

16. The method of claim 15 wherein the phantom comprises a material having low tensile strength.

17. The method of claim 16 wherein the phantom comprises a material having a small elastic modulus.

18. A method for mapping an ultrasound transducer comprising a plurality of transducer elements, the method comprising:

(a) driving the plurality of transducer elements so as to generate an ultrasound focus;

(b) using acoustic radiation force imaging, measuring a displacement associated with the focus;

(c) driving a selected one of the transducer elements at a variable phase while driving the other transducer elements at a constant phase, thereby varying the displacement;

(d) determining a phase difference, if any, between the constant and variable phases where the displacement is maximized; and

(e) if the phase difference is non-zero, adjusting a relative phase of the selected transducer element based thereon.

19. A method for controlling an ultrasound transducer comprising a plurality of transducer elements, the method comprising:

(a) mapping the ultrasound transducer by (i) driving the plurality of transducer elements so as to generate an ultrasound focus, (ii) varying a focus-affecting parameter associated with at least one of the elements and measuring a resulting variation on a quality of the focus, and (iii) selecting a value of the parameter associated with a best focus quality; and

(b) controlling the transducer based on the mapping step.

20. The method of claim 19 wherein controlling the transducer comprises driving the elements to produce outputs converging at a focus corresponding to a target treatment region.

21. The method of claim 19 wherein the mapping step comprises generating the ultrasound focus in a phantom and measuring the focus quality in the phantom.

22. The method of claim 19 further comprising, following step (b), repeating the mapping step.

23. The method of claim 19 wherein substep (ii) comprises, for each of the transducer elements, determining a relative phase associated with the transducer element by (1) driving the transducer element at a variable phase while driving the other transducer elements at a constant phase, thereby varying the focus quality, and (2) determining a phase difference, if any, between the constant and variable phases where the focus quality is optimized.

24. The method of claim 19, wherein the focus quality is measured using acoustic radiation force imaging to measure a displacement associated with the focus.

25. A method for mapping an ultrasound transducer comprising a plurality of transducer elements, the method comprising:

(a) driving the plurality of transducer elements so as to generate an ultrasound focus;

(b) using acoustic radiation force imaging, measuring a displacement associated with the focus;

(c) grouping the transducer elements;

(d) driving a selected group of transducer elements at a variable phase while driving the other groups of transducer elements at a constant phase, thereby varying the displacement;

(e) determining a phase difference, if any, between the constant and variable phases where the displacement is maximized; and

(f) if the phase difference is non-zero, adjusting a relative phase of the selected group of transducer elements based thereon.