Cell viability of melanoma cells after treatment with DOX-liposomes (light gray bars), DOX-liposome-loaded microbubbles (dark gray bars), and DOX-liposome-loaded microbubbles that were first radiated with ultrasound. The debris of the radiated DOX-liposome-loaded microbubbles was applied to the cells (white bars). For higher doxorubicin concentrations, more doxorubicin liposomes were used, whereas the microbubble concentration was always 109 microbubbles per OptiCell unit. *P < 0.05. DOX, doxorubicin; USE, ultrasound exposure.