Acoustic measurements in a tissue mimicking liquid

Area of Science:

• Biomedical Engineering
• Ultrasound Physics
• Acoustics

Background:

• Accurate ultrasound safety assessments require reliable tissue-mimicking materials.
• Current methods for derating ultrasound exposure in water may not fully represent in vivo conditions.

Purpose of the Study:

• To develop and evaluate a novel liquid that mimics soft tissue properties for ultrasound applications.
• To assess the effectiveness of attenuation derating methods using this new tissue-mimicking liquid.

Main Methods:

• A liquid was formulated to match soft tissue's acoustic properties (propagation speed, attenuation, nonlinearity parameter B/A).
• A clinical ultrasound system was used to measure acoustic outputs in the liquid and in water.
• Pulse intensity integral and rarefactional pressure were computed and compared between the liquid and derated water measurements.

Main Results:

• The developed liquid exhibits consistent attenuation slopes up to 18 MHz, suitable for derating assessment.
• Measurements in the liquid showed that linear derating in water is not always a conservative approach for modeling in vivo exposure.
• Discrepancies were observed in pulse intensity integral and rarefactional pressure estimations.

Conclusions:

• The novel tissue-mimicking liquid provides a valuable tool for evaluating ultrasound safety protocols.
• Current in vivo exposure modeling using linearly derated water measurements may underestimate actual acoustic bioeffects.
• Further research is needed to refine ultrasound safety assessment methodologies.