Effect of ultrasonic exposure time and burst frequency on the enhancement of chemotherapy by low-level ultrasound

Using previous methods, the ultrasonic potentiation of CHO cell killing by adriamycin at 2 μg/ml as a function of ultrasound exposure or burst frequency was investigated. The duty cycle is fixed at 1:10. At a burst frequency of 1000 Hz, potentiation increases over exposure times from 2 to 60 min. In separate burst treatments of 30 min and burst frequencies from 16 to 5000 Hz, the frequencies around 60 and 1000 Hz are most effective