Medical noninvasive operations using focused modulated high power ultrasound

Noninvasive surgical apparatus comprising an ultrasound transmitter, including:

• a source of a high frequency ultrasound signal,
• a source of a low frequency ultrasound signal, said low frequency ultrasound signal having an amplitude below a cavitation threshold of a medical target region in order to enhance bubble growth during vaporous cavitation and
• means for superimposing the high frequency signal and the low frequency signal in order to produce a modulated, multifrequency signal;
• and
• means for focusing the multifrequency signal into the medical target region in order to produce vaporous cavitation therein.

A method for performing noninvasive surgery using modulated high powered ultrasound, said method comprising the steps of:

• inducing a low frequency ultrasound signal at an amplitude below a cavitation threshold of a medical target region in order to control growth of cavitation microbubbles in the target region;
• superimposing a high frequency signal onto the low frequency signal in order to produce a modulated signal having an amplitude that exceeds said cavitation threshold, said modulated signal having a focal zone of a size determined by the high frequency signal;
• and
• positioning the focal zone of the modulated signal into the medical target region in order to cause vaporous cavitation therein.