In this study, pretreating prostate and skin cancer cells with ultrasound (20 kHz, 2 W cm-2, 60 s), then giving Quercetin (50 M) selectively induced cytotoxicity in skin and prostate cancer cells, while having minimal effect on corresponding normal cell lines. About 90% of the viable skin cancer cell population was lost within 48 h. Ultrasound reduced the LC50 of quercetin for skin cancer cells by almost 80-fold, while showing no effect on LC50 for nonmalignant skin cells.
 
In other words, ultrasound made Quercetin toxic to the cancer cells at a dose that is not toxic to normal cells.
 
British Journal of Cancer (2005) 92, 499-502.