Acoustic shock generation by ultrasonic imaging equipment

Area of Science:

• Acoustics
• Biomedical Engineering
• Non-linear Wave Propagation

Background:

• Ultrasonic imaging pulses are typically modeled as damped sine waves with minimal waveform change.
• Existing models assume linear acoustic propagation laws, neglecting non-linear effects.

Purpose of the Study:

• To investigate the validity of linear propagation assumptions for ultrasonic imaging pulses.
• To experimentally demonstrate waveform distortion and acoustic shock formation in water.

Main Methods:

• Experimental measurements of pulse waveforms using a calibrated broad-band polymer hydrophone.
• Analysis of pulse propagation in water under conditions generated by commercial pulse-echo imaging equipment.

Main Results:

• Observed formation of acoustic shocks in water within centimeters of the source.
• Demonstrated significant pulse distortion and shock formation due to the non-linear nature of the propagation medium.
• Experimental evidence invalidates the assumption of linear propagation at typical commercial equipment pressures.

Conclusions:

• Non-linearity of the propagation medium significantly impacts ultrasonic pulse waveforms, leading to shock formation.
• Findings necessitate re-evaluation of pulse-echo equipment calibration procedures.
• Further research is needed to assess biological effects of acoustic shocks during clinical ultrasound procedures.