Bent ray ultrasound tomography reconstruction using virtual receivers for reducing time cost

Bent ray ultrasound sound speed tomography reconstruction can improve image quality comparing to straight ray. However, it suffers from time consuming ray linking, which finds bent ray to link a pair of given emitter and receiver. Currently, multi ray tracing always be required for single ray linking, but all of traced rays will be discarded excepting one which links the given emitter and receiver. It is important for reducing time cost to avoid the discarding and decrease ray tracing number. For this purpose, a novel bent ray reconstruction method (BRRM) using virtual receiver was proposed in this study. Single reconstruction iteration of proposed method includes five steps. Firstly, travel time difference map (TTDM) is picked by first peak method. Secondly, launch angles for straight rays are obtained. Thirdly, ray tracing for each obtained launch angle is implemented and their arrival positions in transducer ring are recorded. Fourthly, TTDM for virtual receivers, which are placed in each bent ray arrival position, is estimated by interpolation of picked TTDM. Fifthly, simultaneous algebraic reconstruction technique (SART) is employed for reconstruction. To evaluated proposed method, ultrasound tomography RF data of simple and complex sound speed models are simulated by PZFlex. Reconstruction results show that proposed method can reduce ray tracing number to be about 20% and time cost to be one third of previous BRRM with similar image quality. In this study, a novel BRRM using virtual receiver is proposed to reduce ray tracing number and time cost of BRRM without image quality decreasing.