Ultrasound transducer and cooling thereof

Abstract

An ultrasonic transducer device for producing ultrasonic beams comprises a body vibratable at ultrasonic frequencies and an extensive surface for beam emanation, the device configured to produce an unfocused, or alternatively a focused, power beam for tissue ablation, the power beam being produced by vibration over the body of the transducer and emanating from the extent of the surface, whereby the extensive surface becomes subject to convective cooling when immersed in a fluid by a chimney effect set up by said unfocused beam.

Description

RELATIONSHIP TO EXISTING APPLICATIONS[0001]This application claims the benefit of priority under 35 USC 119(e) of U.S. Provisional Patent Application No. 61 / 393,947 filed Oct. 18, 2010, the contents of which are incorporated herein by reference in their entirety.FIELD AND BACKGROUND OF THE INVENTION[0002]The present invention relates to an ultrasound transducer device and cooling thereof and, more particularly, but not exclusively to the cooling of such a transducer device within a small vessel which may be filled with fluid, such as a blood vessel or other body lumen.[0003]Sverdlik et al, in PCT / IL2008 / 000234, filed Feb. 21, 2008 disclose a method of using ultrasonic energy for surgical procedures. In a procedure for stabilizing blood vessel wall abnormality, ultrasonic heating is carried out of at least a portion of the blood vessel wall having the abnormality. A parameter is monitored relating to a property of at least a portion of the heated portion of the blood vessel wall; and...

AI Technical Summary

Benefits of technology

[0007]The present embodiments may provide a transducer which carries out tissue ablation using an unfocused beam from an extended surface of the transducer. The beam heats surrounding fluid and sets up a chimney effect which then serves to cool the transducer surface.

[0008]The use of higher frequencies, in excess of 8 Megahertz, allows for thinner transducers to be used, which reduces the likelihood that large heat differentials will form or cause cracking. The thicknesses used are between 100-200 microns, and higher energies result from the higher frequencies used. The ultrasonic energy may be focused or unfocussed.

[0025]In an embodiment, said power beam is provided at a frequency of at least 8 Megahertz, and said vibratable body has a thickness not exceeding 0.3 millimeters, thereby to increase heat transfer from the element.

[0030]A distancing device may distance the transducers from a vessel wall, to allow liquid flow in between the device and wall, both for cooling the device and the wall. In this way the vessel wall is not damaged by the ultrasound beam.

[0032]The device may have a thickness below 0.3 millimeters or a thickness of 0.15 millimeters, thereby to increase heat transfer from the element.

Problems solved by technology

However the transformation of electrical energy into ultrasound is inefficient and considerable heat is generated at the transducer.

The heat needs to be safely dissipated without causing damage to the blood vessel itself, and standard heat sink structures cannot be used in blood flow because heat exchange fins can damage platelets and cause clotting.

Ceramics have low thermal conductivity and thus operation at high power causes relatively large heat differentials across the transducer which often causes cracking.

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