Relationship between peak density and acoustic scattering in high-frequency ultrasound wave propagation

Ultrasound wave propagation in materials has been used in different manners to determine the characteristics of materials including detecting defects, understanding the microstructure, thickness, density, elastic modulus, etc. Each of these parameters can be characterized using one or more ultrasound characteristics. Acoustic scattering is one of the key features of ultrasound that can be used to evaluate microstructural features. Peak density of the receiving signal in a pitch-catch mode is an ultrasound parameter that can be a characteristic of acoustic scattering and an indicative of microstructural features. The objective of this study was to establish a relationship between peak density and acoustic scattering while varying microstructural parameters like scatterer size, number of scatterer, and propagation path of ultrasound. Frequency range from 18 to 41 MHz was used as high-frequency ultrasound analysis. The focus was to demonstrate the pitch-catch technique during peak evaluation. Peak density obtained from the frequency spectrum of phantoms with different microstructures was compared to detect a pattern in microstructural change. An analytical study was conducted to measure peak density from various scatterer sizes and propagation distances. Multiple scattering was evaluated in computational simulation with varying scatterer size, number, and travel distance. The results were compared and validated with results obtained from the experimental analysis conducted in this same study. Inter-scatterer distance was also evaluated to explore randomness in scatterer position during ultrasound scattering in computation level. The level of significance of each parameter toward the diversification of peak density was evaluated during the study.