High resolution imaging methods for circular-array based ultrasound computed tomography

A full waveform inversion method is presented for ultrasound computed tomography imaging based on the circular array. Different from conventional ultrasound computed tomography methods, such as delay-and-sum and time-of-flight tomography, this method fully considers the sound propagation effects including transmitting, reflecting, and scattering. The acoustic parametric image of the target is reconstructed by fitting the synthetic and observed data. Based on the circular-array acquisition system, numerical and experimental tests are designed to evaluate algorithms, including ray-based (i.e., delay-and-sum and time-of-flight tomography) and wave-equation based (i.e., full waveform inversion) methods. Imaging results are compared to analyze the theoretical and practical aspects. The results of simulation and physical experiments show that full waveform inversion, which fully considers multiple physical characteristics of the received data, can reconstruct the parametric image at high resolution. Full waveform inversion can be combined with traditional methods to design an effective ultrasonic computed tomography imaging system.