Design and simulation of a 2-D array flexible ultrasound transducer system for tissue characterization – A pilot study

Abstract

Noninvasive diagnosis of bone density and mechanical properties using non-radiation imaging modality is an emerging area with promising in early prediction of osteopenia and treatment effectiveness in the clinic and functional disuse, i.e., long-term bedrest and space mission. Advances in quantitative ultrasound have shown advantages in measuring both bone density and mechanical strength, non-radiation, imaging capability, and easy to use. The challenge that remained is the poor penetration of ultrasound signals passing through trabecular and cortical bones and acoustic energy scattering. A new scanning confocal ultrasound technology is developed in this lab to detect the alteration of bone to provide diagnostic results in bone density and structure properties. A software-controlled flexible ultrasound system with 2-D dual array transducer is developed and proposed for the purpose of noninvasive bone density diagnosis and assessment of bone loss. Transmitting (Tx) transducer elements are divided into sub-blocks to excite the ultrasound signals in sequence to decrease the system complexity while maintaining beam pattern properties by the signal processing procedure at receiving (Rx) side. Apodization is also applied to reduce acoustic side lobes and to make the resolution in the ultrasound field of view (FOV) more uniform. This study may provide basic understanding of modulated confocal ultrasound beam forming for tissue characterization, such as trabecular bone structual and strength properties.