Ultrasound transducers for imaging and therapy

• US 6,719,694 B2
• Filed: 12/22/2000
• Issued: 04/13/2004
• Est. Priority Date: 12/23/1999
• Status: Expired due to Fees

• Current Assignee: Otsuka Medical Devices Co., Ltd. (Otsuka Holdings Company Limited)
• Original Assignee: Therus Corp. (Boston Scientific Corporation)
• Inventors: Zhang, Jimin, Perozek, David M., Weng, Lee
• Primary Examiner(s): Ruhl, Dennis W.
• Assistant Examiner(s): Lin, Jeoyuh
• Application Number:
  US09/747,310
• Publication Number:
  US 20010031922A1
• Time in Patent Office: 1,208 Days
• Field of Search: 600/439, 600/444, 600/459, 601/2, 310/336
• US Class Current: 600/439
• CPC Class Codes: A61B 17/0057 Implements for plugging an opening in the wall of a hollow or tubular organ, e.g. for sealing a vessel puncture or closing a cardiac septal defect sutures A61B17/04; closing rectum or urethra near body surface A61F2/0009
• CPC Class Codes: A61B 2017/00504 Tissue welding
• CPC Class Codes: A61B 2017/00907 for light
• CPC Class Codes: A61B 2090/062 penetration depth
• CPC Class Codes: A61B 2090/378 using ultrasound
• CPC Class Codes: A61B 2090/3904 specially adapted for marking specified tissue
• CPC Class Codes: A61B 2090/3937 Visible markers
• CPC Class Codes: A61B 2562/164 the sensor is mounted in or on a conformable substrate or carrier
• CPC Class Codes: A61B 8/12 in body cavities or body tracts, e.g. by using catheters catheters per se A61M25/00
• CPC Class Codes: A61B 8/445 Details of catheter construction
• CPC Class Codes: A61B 8/4461 Features of the scanning mechanism, e.g. for moving the transducer within the housing of the probe
• CPC Class Codes: A61H 23/0245 with ultrasonic transducers, e.g. piezoelectric
• CPC Class Codes: A61N 2007/0052 using the same transducer for therapy and imaging
• CPC Class Codes: A61N 2007/0065 Concave transducers
• CPC Class Codes: A61N 2007/0078 with multiple treatment transducers
• CPC Class Codes: A61N 7/02 Localised ultrasound hyperthermia hyperthermia in general A61F7/00
• CPC Class Codes: G10K 11/32 characterised by the shape of the source
• CPC Class Codes: G10K 11/346 using phase variation

Abstract

Ultrasound applicators able to both image a treatment site and administer ultrasound therapy include an array of transducer elements that can be focused. In several embodiments, an electronically phased array is used for controlling the focal point of an ultrasound beam. The ultrasound beam produced thereby can also be electronically steered. To reduce the quality factor or Q of the array when the array is used for imaging, an electronic switch is selectively closed, placing a resistance in parallel with each of the array elements. A flexible array is employed in several embodiments and is selectively bent or flexed to vary its radius of curvature and thus control the focal point and/or a direction of focus of the array. In another embodiment, each of the transducer elements comprising the array are individually mechanically pivotable to steer the ultrasonic beam produced by the transducer elements.

Claims

1. An ultrasound applicator that is capable of both ultrasound imaging and administering ultrasound therapy to a site, comprising:

(a) a plurality of ultrasound transducer elements configured in an array and mounted in a housing;

(b) a plurality of conductors adapted to couple a control system to the plurality of ultrasound transducer elements, for conveying signals that energize the plurality of ultrasound transducer elements in one of an imaging mode and a therapy mode; and

(c) a quality factor circuit adapted to couple to the control system and connected to the plurality of ultrasound transducer elements, said quality factor circuit including a switch movable between a first position and a second position, the switch being selectively actuated into one of the first position and the second position to select a quality factor associated with the plurality of ultrasound transducer elements based upon whether the plurality of ultrasound transducer elements are operated in the imaging mode or the therapy mode, such that when the switch is in the first position, a bandwidth of each energized transducer is wider relative to a bandwidth of the energized transducer when the switch is in the second position.

2. The ultrasound applicator of claim 1, wherein the plurality of ultrasound transducer elements are configured in a concave array.

3. The ultrasound applicator of claim 2, wherein a focal point of the plurality of ultrasound transducer elements is determined by phase differences of the signals applied to energize the plurality of ultrasound transducer elements, said phase differences being controlled to achieve a desired focal point.

4. The ultrasound applicator of claim 2, wherein an ultrasound beam produced by the plurality of ultrasound transducer elements is steered in a desired direction based upon phase differences in the signals applied to energize the plurality of ultrasound transducer elements.

5. The ultrasound applicator of claim 2, wherein the plurality of ultrasound transducer elements comprise a flexible array mounted within the housing so that a radius of curvature of the flexible array is selectively variable to control a focal point of the flexible array.

6. The ultrasound applicator of claim 5, further comprising a movable shaft that is coupled to one end of the flexible array, said movable shaft being moved to vary the radius of curvature of the flexible array.

7. The ultrasound applicator of claim 5, further comprising a prime mover that is drivingly coupled to the movable shaft, said prime mover being selectively energized to move the movable shaft and thereby vary the radius of curvature of the flexible array and thus, vary the focal point of the flexible array.

8. The ultrasound applicator of claim 2, wherein the plurality of ultrasound transducer elements comprise a flexible array mounted within the housing, further comprising a movable link coupled to one end of the flexible array, said movable link being movable to control a curvature shape of the flexible array and thereby to control a direction in which an ultrasound beam is emitted by the flexible array.

9. The ultrasound applicator of claim 8, further comprising a limit that controls and limits the curvature shape assumed by the flexible array as the movable link is moved.

10. The ultrasound applicator of claim 1, wherein each of the plurality of ultrasound transducer elements comprises a composite mixture that includes a piezo-ceramic, an adhesive binder, and thermally conductive particles.

11. The ultrasound applicator of claim 1, further comprising a dampening network, such that when the switch is in the first position, the dampening network is coupled to each transducer, the dampening network providing a lower resistance that increases the bandwidth of each transducer.

12. The ultrasound applicator of claim 1, further comprising:

(a) an imaging network that when coupled to each transducer achieves an impedance matched, highly damped transducer configuration, the imaging network being coupled to each transducer when the switch is in the first position; and

(b) a therapy network that when coupled to each transducer achieves an impedance matched, weakly damped transducer configuration, the therapy network being coupled to each transducer when the switch is in the second position.

13. An ultrasound applicator that is capable of both ultrasound imaging and administering ultrasound therapy to a site, comprising:

(a) a ultrasound transducer mounted in a housing;

(b) a plurality of conductors adapted to couple a control system to the ultrasound transducer, for conveying signals that energize the ultrasound transducer in one of an imaging mode and a therapy mode; and

(c) a quality factor circuit adapted to couple to the control system and connected to the ultrasound transducer, said quality factor circuit including a switch movable between a first position and a second position, the switch being selectively actuated in one of the first position and the second position to select a quality factor associated with the ultrasound transducer based upon whether the ultrasound transducer is operated in the imaging mode or the therapy mode, such that when the switch is in the first position, a bandwidth of the energized transducer is wider relative to a bandwidth of the transducer when the switch is in the second position.

14. The ultrasound applicator of claim 13, wherein the ultrasound transducer is configured in a concave curved shape.

15. The ultrasound applicator of claim 13, wherein the ultrasound transducer comprises a composite mixture that is flexible and includes a piezo-ceramic, an adhesive binder, and thermally conductive particles.

16. The ultrasound applicator of claim 15, wherein the ultrasound transducer is mounted within the housing so that a radius of curvature of the ultrasound transducer is selectively variable to control a focal point of ultrasound transducer.

17. The ultrasound applicator of claim 16, further comprising a movable shaft that is coupled to one end of the ultrasound transducer, said movable shaft being moved to vary the radius of curvature of the ultrasound transducer.

18. The ultrasound applicator of claim 17, further comprising a prime mover that is drivingly coupled to the movable shaft, said prime mover being selectively energized to move the movable shaft and thereby vary the radius of curvature of the ultrasound transducer and thus, vary the focal point of the ultrasound transducer.

19. The ultrasound applicator of claim 16, further comprising a movable link coupled to one end of the ultrasound transducer, said movable link being movable to control a curvature shape of the ultrasound transducer and thereby, to control a direction in which an ultrasound beam is emitted.

20. The ultrasound applicator of claim 19, further comprising a limit that controls and limits the curvature shape assumed by the ultrasound transducer as the movable link is moved.

21. The ultrasound applicator of claim 13, further comprising a dampening network, such that when the switch is in the first position the dampening network is coupled to the transducer, the dampening network providing a lower resistance that increases the bandwidth of the transducer.

22. The ultrasound applicator of claim 13, further comprising:

(a) an imaging network that when coupled to the transducer achieves an impedance matched, highly damped transducer configuration, the imaging network being coupled to the transducer when the switch is in the first position; and

(b) a therapy network that when coupled to the transducer achieves an impedance matched, weakly damped transducer configuration, the therapy network being coupled to the transducer when the switch is in the second position.