We recently found that chemical agents such as hematoporphyrin can be
activated by ultrasound, producing significant antitumor effects. This
was demonstrated with plane wave insonation at 2 MHz in experiments o
f killing isolated tumor cells. The efficacy of focal ultrasound at 75
0 kHz to localize sonochemical reactions was also demonstrated in inso
nation of a specially developed agarose gel phantom and in treatments
of inoculated experimental tumors.