Analysis of bubble cavitation in ultrasound therapy by wavelet technique

Bubble cavitation is one of the major mechanisms for ultrasound treatment. To understand its characteristics, cavitation signals were picked up using passive cavitation detection and then analysed by wavelet transform. Although the Fast Fourier Transform (FFT) has been used widely in signal analysis, the absence of temporal information is one of its limitations. The inertial cavitation strength detected by wavelet method was ∼60 folds higher than that using FFT. Furthermore, the relationship of waveform profile and acoustic pressure with the corresponding bubble cavitation were investigated. All together, wavelet approach could be new tool for studying bubble cavitation.