Ultrasonic concentration of drug delivery capsules

Methods, compositions and apparatus for localized delivery of compounds are provided. In certain embodiments, radiation force is used to direct carriers to a target site, and additional radiation is used to fragment the localized carriers, releasing associate compounds. Ultrasound radiation is preferred as the source for radiation force and for fragmentation. Also encompassed are embodiments in which targeting and fragmentations are combined with imaging of the treatment site. Alternate embodiments are disclosed in which compounds are locally delivered without use of carriers.