An ultrasonic apparatus for thereapeutical use, especially for remedying a malignant tumor, through activation of a drug at a desired local portion inside of a living body by sequentially irradiating a plurality kinds of convergent ultrasonic waves having different focal positions of different acoustic...http://www.google.fr/patents/US5158071?utm_source=gb-gplus-shareBrevet US5158071 - Ultrasonic apparatus for therapeutical use
