Importance

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Abstract

A system for detecting gas bubbles in a specimen utilizes a transducer which produces pulses, illustratively of ultrasonic acoustic energy, having predetermined frequency characteristics. A first pulse has an increasing frequency with time, and a second pulse has a decreasing frequency with time. Imaging arrangements, which may be formed of ultrasonic transducers, produce images of the region within the specimen after exposure to each such pulse. In one embodiment, a growth transducer array is utilized for dramatically increasing the size of the bubbles, which array is formed of a plurality of transducers which are moved with respect to the specimen and which have respective frequency characteristics over different frequency ranges. Thus, bubble radius is successively increased as each bubble is exposed to the acoustic energy from each such transducer within the growth transducer array. The present invention can be used to reduce the cavitation threshold of bubbles, particularly in the vicinity of tumors, or to increase the temperature in the bubble-containing region.

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First Claim