Sound Speed Image Reconstruction of Ultrasound Computed Tomography Based on GPU Acceleration

In recent years, more and more studies have shown that Ultrasound Computed Tomography(USCT) has a good application prospect in the early detection of breast cancer. The sound speed image of USCT reveals the sound speed distribution of the tissue. As the sound speeds of normal tissues and tumors have different distributions, the sound speed image can help identify tumors more accurately. The ray-based reconstruction method is commonly used for sound speed image reconstruction. The method mainly consists of two steps, the forward path matrix calculation, and the reverse parameter optimization. Due to the huge amount of data of USCT, it is time-consuming to reconstruct the sound speed image on the CPU. Considering that both the forward path matrix calculation and the reverse parameter optimization process can be divided into different independent calculation processes, this paper utilizes the parallel computing capabilities of GPU to reconstruct the sound speed image. Multi-thread parallel calculations are performed for the calculation of each emit-receive path, the calculation of the grid gradient, and the construction of the inverse of the Hessian matrix. The experimental data are captured by the USCT system developed by the Medical Ultrasound Laboratory of Huazhong University of Science and Technology for verification. The results show no substantial difference between the sound speed image reconstructed on GPU and CPU. When the number of emitting array elements are 256, 512, and 1024, the speedup ratio is 47.27, 69.93, and 111.56 respectively.