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Tissue-mimicking liquid for use in exposimetry
Timothy A Stiles1, Ernest L Madsen, Gary R Frank
1Medical Physics Department, University of Wisconsin-Madison, 1300 University Ave, Room 1530, Madison, WI 53706, USA. tastiles@wisc.edu
Summary
Researchers developed a stable, tissue-mimicking liquid using concentrated fat-free milk for accurate diagnostic ultrasound exposimetry. This new method improves the determination of ultrasound exposure parameters for better safety and efficacy.
Area of Science:
- Acoustics
- Biophysics
- Medical Imaging
Background:
- Current diagnostic ultrasound exposure parameter measurements use water, which lacks tissue-like attenuation and nonlinear propagation properties.
- A linear derating factor is applied to approximate soft tissue attenuation, but this does not fully account for nonlinear propagation effects.
- Accurate ultrasound exposimetry requires a liquid medium that mimics soft tissue properties, including nonlinearity parameter B/A.
Purpose of the Study:
- To develop a stable, tissue-mimicking liquid for accurate diagnostic ultrasound exposure parameter determination.
- To identify a liquid with stable acoustic properties, including speed of sound, attenuation, and nonlinearity parameter B/A, representative of soft tissues.
- To provide a practical laboratory tool for ultrasound exposimetry that avoids frequent sample preparation.
Main Methods:
- Fifty-two samples of fat-free milk were concentrated by ultrafiltration and preserved using various methods.
- Acoustic properties, including speed of sound, attenuation, and nonlinearity parameter B/A, were measured using narrowband through-transmission techniques.
- Samples were monitored over 22 months for stability of ultrasonic properties at room temperature.
Main Results:
- Six of the 52 prepared milk samples maintained liquid form and stable acoustic properties for over 22 months.
- The stable samples exhibited acoustic properties suitable for mimicking soft tissue in ultrasound applications.
- Concentrated and preserved fat-free milk demonstrated consistent performance for laboratory exposimetry.
Conclusions:
- Fat-free milk, concentrated and preserved, serves as a stable, tissue-mimicking liquid for ultrasound exposimetry.
- This milk-based liquid offers a practical and reliable alternative to water for calibrating diagnostic ultrasound equipment.
- The developed liquid facilitates more accurate determination of ultrasound exposure parameters, enhancing safety and efficacy in medical imaging.