Directivity-only ultrasound computed tomography based on multiaxial devices

Multiaxial transducer technology uses orthogonal electric fields in the same transducer to detect with high precision the angle of incidence of a front wave using only a single detector. In this communication, we present the foundation for methods for ultrasound computed tomography (UCT) based only on direction of arrival (DOA) information and bent-ray theory, and a numerical demonstration of UCT reconstruction using this approach. Experimental DOA was calculated with a numerical solution of the viscoelastic equation and a method for directivity estimation using the phase map of pressure fields. A full wavefront ray tracer was used as the forward model during the inversion procedure. Results indicated that reconstruction of two phantoms, using fundamental ultrasound frequencies of 300 kHz and 600 kHz, was feasible using only DOA information and provides advantages over conventional methods. To the best of our knowledge, this is the first numerical demonstration that UCT image reconstruction is entirely possible using exclusively directivity information.