Research on ultrasonic imaging systems based on scattering field theory

In an ultrasonic array system, increasing the effective aperture generally improves lateral resolution. However, conventional 2-D arrays require a proportional increase in hardware channels, which limits scalability. This makes it essential to develop an analysis technique that can reconstruct the shape and physical properties of scatterers in a finite time based on measurement data obtained from numerous ultrasonic elements. Herein, we developed an ultrasound imaging technique using a two-dimensional ultrasonic array system comprising N2 transmitter/receiver pairs and a technique for controlling it with a 2N-channel transmitter/receiver circuit. In addition, we derived a partial differential equation that describes wave propagation in the scattering field where the transmitter and receiver arrays are orthogonally arranged, based on scattering field theory. By analytically solving this equation, we derived an imaging function that incorporates the measurement data as boundary conditions. Moreover, we visualized the spatial distribution of reflection intensity corresponding to the target shape by measuring reflected waves from the target using this measurement system and performing reconstruction calculations based on scattering field theory. We demonstrated the feasibility of ultrasonic imaging by combining ultrasonic measurements using a smaller number of channels than the number of ultrasonic elements and scattering field theory, using the measurement results as boundary conditions.