Computational cost reduction by avoiding ray-linking iteration in bent-ray method for sound speed image reconstruction in ultrasound computed tomography

Bent-ray reconstruction method can improve sound speed image quality, compared with straight-ray reconstruction. However, it suffers from time-consuming ray-linking iteration, because multiple rays with different launch angles have to be iteratively traced to find the ray linking the given emitter and receiver. In this study, a novel virtual receiver bent-ray method (VRBRM) was proposed to avoid the ray-linking iteration. In this method, the angle of the straight line connecting a given emitter and receiver is calculated as the launch angle, and only one ray with the calculated launch angle is traced and its arrival position at the ring transducer is recorded as the virtual receiver position. Then, the sound propagation time from the given emitter to the virtual receiver is interpolated. The results of simulation, phantom and ex vivo experiments demonstrate that the proposed method can reduce the reconstruction time to about 30% without reduction of the reconstruction quality.