Ultrasound transducers for imaging and therapy

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.

1 . An ultrasound applicator, comprising: 
 a plurality of ultrasound transducer elements configured in an array;    a control system configured to energize the transducer elements; and    a first damping network configured to be electrically coupled to the transducer elements during use of the transducer elements for ultrasound imaging and configured to be electrically decoupled from the transducer elements during use of the transducer elements for ultrasound therapy.    
   
   
       2 . The ultrasound applicator of  claim 1 , comprising an electronic switch configured to selectively electrically couple or decouple the damping network to the transducer elements.  
   
   
       3 . The ultrasound applicator of  claim 1 , wherein the damping network is configured such that the transducer elements have a substantially greater quality factor when the damping network is electrically coupled to the transducer elements than when the damping network is electrically decoupled from the transducer elements.  
   
   
       4 . The ultrasound applicator of  claim 1 , wherein the control system is configured to provide a signal to at least one of the transducer elements that has a different phase than a signal provided to at least one other of the transducer elements.  
   
   
       5 . The ultrasound applicator of  claim 1 , wherein the plurality of ultrasound transducer elements are configured in a concave array.  
   
   
       6 . The ultrasound applicator of  claim 1 , wherein when the damping network is electrically coupled to the transducer elements, the applicator comprises an impedance matched, highly damped transducer configuration.  
   
   
       7 . The ultrasound applicator of  claim 1 , comprising a second damping network configured to be electrically coupled to the transducer elements during use of the transducer elements for ultrasound therapy and configured to be electrically decoupled from the transducer elements during use of the transducer elements for ultrasound imaging.  
   
   
       8 . The ultrasound applicator of  claim 7 , comprising an electronic switch configured to selectively electrically couple either the first damping network or the second damping network to the transducer elements.  
   
   
       9 . The ultrasound applicator of  claim 7 , wherein the first and second damping networks are configured such that the transducer elements have a substantially greater quality factor when the first damping network is electrically coupled to the transducer elements than when the second damping network is electrically coupled to the transducer elements.  
   
   
       10 . The ultrasound applicator of  claim 7 , wherein when the second damping network is electrically coupled to the transducer elements, the applicator comprises an impedance matched, weakly damped transducer configuration.  
   
   
       11 . An ultrasound applicator, comprising: 
 a flexible array of ultrasound transducer elements comprising a plurality of ultrasound transducer elements supported by a thermally and electrically conductive layer, each transducer element separated from adjacent elements by a kerf that is filled with a deformable material, wherein the flexible array is deformed into a concave shape; and    a control system configured to energize at least one of the transducer elements with a different phase than at least one other of the transducer elements.    
   
   
       12 . The ultrasound applicator of  claim 11 , further comprising a housing in which the flexible array is mounted.  
   
   
       13 . The ultrasound applicator of  claim 11 , 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.  
   
   
       14 . An ultrasound applicator, comprising: 
 means for generating ultrasonic energy have a first quality factor; and    means for reducing the first quality factor to generate ultrasonic energy having a second quality factor.    
   
   
       15 . The ultrasound applicator of  claim 14 , wherein the generating means comprises at least on ultrasound transducer.  
   
   
       16 . The ultrasound applicator of  claim 14 , wherein the reducing means comprises a damping network.