Degree of pulse nonlinearity for 10 µs HCT pulses

Determine the degree of acoustic pulse nonlinearity for 10 µs, 6.1 MHz pulses generated by the radially polarized hollow cylindrical piezoelectric transducer (2.5/3.3 mm inner/outer diameter, 2.5 mm length) operated in the thickness-mode bandwidth, to quantitatively establish their placement within the shock scattering histotripsy classification.

Background

The paper used 10 µs pulses that, by duration, align with the shock scattering histotripsy regime; however, the authors note that the actual degree of pulse nonlinearity has not been quantified. Clarifying the nonlinearity would confirm whether the pulses truly operate under shock scattering conditions, which has implications for cloud formation dynamics and lesion characteristics.

Quantifying nonlinearity in this intravascular-scale, thickness-mode HCT context would also inform how pulse waveform steepening, shock content, and harmonic generation contribute to cavitation initiation and growth in the constrained lumen environment.