Experimental Investigation of Excitation Strategies for Erosion by Cavitation Histotripsy

Cavitation histotripsy has been applied to the disintegration on the surface of soft tissue in a well-controlled manner. Its performance was assumed to be determined by the acoustic pressure alone. Long pulse duration with low pulse repetition frequency (PRF) can also successfully generate erosion. This study was designed to investigate the excitation strategies for cavitation histotripsy-induced erosion. The erosion area and volumes produced by cavitation histotripsy on the alginate gel phantom using single-frequency, dual-frequency, and two pulsed excitations at the same power output at the PRF of 1 Hz and 200 Hz were compared. Dual-frequency excitation can improve the erosion at all PRFs, while pulsed excitations decrease it at the PRF of 200 Hz. Using both pulsed and dual-frequency excitations has more erosion areas than using single-frequency at a PRF of 1 Hz. In comparison, although the induced erosion areas using the pulsed excitations are larger than those of single-frequency at the PRF of 200 Hz, the erosion volumes are much lower than that of dual-frequency excitation. It suggests that a sufficient long pulse duration is another important factor for the performance of cavitation histotripsy. Dual-frequency excitation or amplitude modulation by the low-frequency sinusoidal envelope can achieve more erosion than that produced by single-frequency excitation at the same power output in a wide range of PRFs.