Focused ultrasound system with adaptive anatomical aperture shaping

• US 20060058671A1
• Filed: 08/11/2004
• Published: 03/16/2006
• Est. Priority Date: 08/11/2004
• Status: Active Grant

• Current Assignee: InSightec Ltd.
• Original Assignee: Insightec-Image-Guided Treatment Limited (InSightec Ltd.)
• Inventors: Vitek, Shuki, Vortman, Kobi
• Granted Patent: US 7,699,780 B2
• Time in Patent Office: Days
• US Class Current: 600/447
• CPC Class Codes: A61B 2017/00084 Temperature
• CPC Class Codes: A61B 90/04 Protection of tissue around surgical sites against effects of non-mechanical surgery, e.g. laser surgery protection of eyes against laser radiation A61F9/022
• CPC Class Codes: A61N 7/02 Localised ultrasound hyperthermia hyperthermia in general A61F7/00

Abstract

A method of treating tissue within a body includes directing an ultrasound transducer having a plurality of transducer elements towards target body tissue, and delivering ultrasound energy towards the target tissue from the transducer elements such that an energy intensity at the target tissue is at or above a prescribed treatment level, while an energy intensity at tissue to be protected in the ultrasound energy path of the transducer elements is at or below a prescribed safety level.

Claims

1. A method of treating body tissue using an ultrasound transducer, the ultrasound transducer comprising a plurality of transducer elements, the method comprising:

directing the ultrasound transducer towards target body tissue; and

delivering ultrasound energy from the transducer elements in an ultrasound energy path towards the target tissue such that an energy intensity at the target tissue is at or above a prescribed treatment level, while an energy intensity at tissue to be protected in the ultrasound energy delivery path outside of the target tissue is at or below a prescribed safety level.

2. The method of claim 1, wherein one or both of the prescribed treatment level and prescribed safety level comprise a temperature threshold or a thermal dose threshold.

3. The method of claim 1, wherein one or both of the prescribed treatment level and prescribed safety level comprise a tissue parameter that can be used to assess tissue viability.

4. The method of claim 1, wherein delivering ultrasound energy comprises controlling one or more of the transducer elements to create a limited energy density at the tissue to be protected in the ultrasound energy path.

5. The method of claim 1, wherein delivering ultrasound energy comprises controlling one or more of the transducer elements to provide a beam aperture having a size and a shape for protecting the tissue to be protected in the ultrasound energy path.

6. The method of claim 1, wherein one or more of the transducer elements are deactivated or not activated during the step of delivering ultrasound energy.

7. The method of claim 1, wherein one or more of the transducer elements delivers acoustic energy at an energy level that is lower than an acoustic energy level delivered by one or more other of the transducer elements during the step of delivering ultrasound energy.

8. The method of claim 1, wherein delivering ultrasound energy comprises controlling a positioner that is coupled to the transducer elements.

9. A focused ultrasound system, comprising:

an ultrasound transducer device having a plurality of transducer elements;

drive circuitry coupled to the transducer elements; and

a drive signal controller coupled to the drive circuitry, the drive signal controller configured to control acoustic energy delivered from the transducer elements in an ultrasound energy path towards the target tissue such that an energy intensity at the target tissue is at or above a prescribed treatment level, while an energy intensity at tissue to be protected in the ultrasound energy delivery path outside of the target tissue is at or below a prescribed safety level.

10. The system of claim 9, wherein one or both of the prescribed treatment level and prescribed safety level comprise a temperature threshold or a thermal dose threshold.

11. The system of claim 9, wherein one or both of the prescribed treatment level and prescribed safety level comprise a tissue parameter that can be used to assess tissue viability.

12. The system of claim 9, wherein the drive signal controller controls one or more of the transducer elements to create a limited energy density at the tissue to be protected in the ultrasound energy path.

13. The system of claim 9, wherein the drive signal controller controls one or more of the transducer elements to provide a beam aperture having a size and a shape for protecting the tissue to be protected in the ultrasound energy path.

14. The system of claim 9, wherein the drive signal controller does not activate or deactivates one or more of the transducer elements for protecting the tissue to be protected in the ultrasound energy path while delivering ultrasound energy.

15. The system of claim 9, wherein the drive signal controller causes one or more of the transducer elements to deliver acoustic energy at an energy level that is lower than an acoustic energy level delivered by one or more other of the transducer elements for protecting the tissue to be protected in the ultrasound energy path while delivering ultrasound energy.

16. The system of claim 9, further comprising a positioner coupled to one or more of the transducer elements.

17. A method for creating a treatment plan for treating a patient using a focused ultrasound system, the focused ultrasound system comprising a transducer having a plurality of transducer elements, the method comprising:

identifying target tissue to be treated;

prescribing a treatment energy level for treating the target tissue by directing ultrasound energy from the transducer elements at the target tissue in an ultrasound energy path;

identifying tissue to be protected in the ultrasound energy path outside of the target tissue;

prescribing a safety energy level for protecting the tissue to be protected; and

determining operational parameters for controlling the transducer elements to deliver ultrasound energy in the ultrasound energy path such that an energy intensity at the target tissue is at or above the prescribed treatment level, while an energy intensity at the tissue to be protected is at or below the prescribed safety level.

18. The method of claim 17, wherein the identifying steps comprise:

obtaining an image of tissue in the ultrasound energy path; and

identifying the target tissue and the tissue to be protected in the image.

19. The method of claim 17, wherein the operational parameters are determined by performing an acoustic wave simulation.

20. The method of claim 19, wherein performing an acoustic wave simulation comprises

determining relative positions between the target tissue and respective transducer elements;

determining relative positions between the tissue to be protected and the respective transducer elements; and

calculating the energy intensity at one or more locations in the target tissue and the energy intensity at one or more locations in the tissue to be protected based at least in part on the determined relative positions.

21. The method of claim 19, wherein performing an acoustic wave simulation comprises creating a ray model.

22. The method of claim 17, wherein the operational parameters are determined, at least in part, by using the focused ultrasound system to deliver diagnostic energy towards an object.

23. The method of claim 22, wherein the object comprises a phantom.

24. The method of claim 22, wherein the object comprises the target tissue.

25. The method of claim 17, wherein the operational parameters are selected from the group consisting of a phase, an amplitude, a frequency, a power, a duration, and a position of one or more of the transducer elements.

26. A method for creating a treatment plan for treating a patient using a focused ultrasound system, the focused ultrasound system comprising a transducer having a plurality of transducer elements, the method comprising:

creating a model representing energies to be delivered by respective transducer elements of the transducer;

calculating an energy density based on the model at a tissue region in an ultrasound energy path of the transducer elements, the tissue region associated with patient body tissue to be protected from ultrasound energy treatment; and

determining whether the calculated energy density at the tissue region to be protected exceeds a prescribed safety threshold.

27. The method of claim 26, wherein the model comprises a plurality of rays extending from respective representations of surfaces of the respective transducer elements.

28. The method of claim 27, wherein the rays are created at respective resolutions that are comparable to wavelengths of energies output by the respective transducer elements.

29. The method of claim 26, further comprising adjusting the model if the calculated energy density at the tissue region to be protected is determined to exceed the prescribed safety threshold.

30. The method of claim 29, wherein the adjusting comprises reducing one or more respective transducer element energies.

31. The method of claim 26, wherein the prescribed safety threshold comprises a thermal dose threshold or a temperature threshold.

32. The method of claim 26, wherein the prescribed safety threshold comprises a tissue parameter value.

33. A method for creating a treatment plan for using a focused ultrasound system, the focused ultrasound system comprising a transducer having a plurality of transducer elements, the method comprising:

directing the ultrasound transducer towards a first region of a subject;

delivering a sub-lethal ultrasound energy from the transducer elements towards the first region;

obtaining an energy density associated with the delivered ultrasound energy at a second region of the subject;

determining whether the energy density at the second region exceeds a prescribed safety threshold; and

reducing the delivered ultrasound energy from one or more of the transducer elements if the determined energy density at the second region is above the prescribed safety threshold.

34. The method of claim 33, wherein the subject comprises a phantom.

35. The method of claim 33, wherein the subject comprises a body of a patient.

36. The method of claim 35, wherein the first region comprises a region of target tissue, and the second region comprises a region of tissue to be protected in an ultrasound energy path of the transducer elements outside of the target tissue region.

37. The method of claim 33, wherein the energy density at the second region is determined by obtaining a temperature or a thermal dose at the second region.

38. The method of claim 33 wherein the energy density at the second region is determined by obtaining a measurement of a tissue parameter related to tissue viability at the second region.

39. The method of claim 33, wherein the delivered ultrasound energy is reduced by changing a phase, an amplitude, or both, of a drive signal of the one of the transducer elements.

40. The method of claim 33, wherein the delivered ultrasound energy is reduced by not activating one of the transducer elements.