Non-linear Wave Propagation and Safety Standards for Diagnostic Ultrasound Devices

Area of Science:

• Medical Imaging
• Acoustics
• Biophysics

Background:

• Established safety standards for diagnostic ultrasound (1-10 MHz) assumed negligible non-linear wave propagation effects.
• Modern ultrasound equipment operates at higher frequencies, potentially increasing the significance of these non-linear effects.
• Current standards may not adequately address risks associated with advanced high-frequency ultrasound devices.

Purpose of the Study:

• To review the impact of neglecting non-linear wave propagation on measurements and calculations for diagnostic ultrasound safety standards.
• To evaluate potential errors in exposure quantities defined by current standards at low and high frequencies.
• To propose necessary modifications for assessing risks in modern high-frequency ultrasound systems.

Main Methods:

• Literature review of published research on non-linear acoustic effects in diagnostic ultrasound.
• Analysis of existing safety standards and U.S. Food and Drug Administration (FDA) guidance.
• Evaluation of the adequacy of current methods for assessing thermal heating and cavitation risks.

Main Results:

• Neglecting non-linear wave propagation can lead to significant errors in exposure quantity calculations, particularly at higher frequencies.
• Current safety standards provide inadequate coverage of non-linear effects for modern high-frequency ultrasound equipment.
• Existing methods for cavitation risk assessment may be adaptable with modifications, but thermal heating assessment requires a new approach.

Conclusions:

• A new approach is necessary to incorporate non-linear effects for accurate thermal heating assessment in high-frequency diagnostic ultrasound.
• Existing safety standards require updates to address the impact of non-linear acoustics in advanced ultrasound devices.
• Further research is needed to refine risk assessment methodologies for modern clinical ultrasound technology.