Alternative acoustic pulse echo immersion measurement system development for nonporous tissue mimicking materials

Abstract

Acoustic properties are important to evaluate the compatibility of tested samples as tissue mimicking materials (TMMs). Common acoustic measurement systems require distilled water as the propagation medium. However, their accuracies are affected by the small change in the medium density and the inaccurate measurement of water temperature. An alternative acoustic pulse echo immersion measurement system for nonporous TMMs is developed in this study. It is developed based on the alternative pulse echo immersion technique (aPEIT) to improve the previous developed system for the noncontact pulse echo immersion technique (PEIT) and specifically designed for the step-shaped nonporous sample. It consists of a pulser/receiver generator, an unfocused transducer, a digital oscilloscope, a temperature controller and a personal computer which are installed with the custom-developed computer program to determine the longitudinal velocity, acoustic impedance, phase velocity and attenuation coefficient of the sample. The precision and accuracy of the developed system are tested for different thickness of sample, temperature of medium, density of medium and center frequency of transducer. The study indicates that developed system for the aPEIT produces the comparable results within 1.16% differences as the previous developed system for the noncontact PEIT, precise results within 6.38% from the average values and accurate results within 0.62% error compared to the reference values. The developed system for the aPEIT offers comparable but more precise results compared to the previous developed system for the noncontact PEIT in measuring the acoustic properties of nonporous TMMs. It can be operated using online and offline analysis modes to measure and differentiate the acoustic properties of specific types of human tissues and TMMs.