Speaker
Description
Medical ultrasound images are frequently reconstructed using simplifying assumptions regarding acoustic wave propagation. A prevalent assumption is that sound speed is uniform across the imaging medium. However, different tissue types posess varying sound speeds, which leads to image distortions and defocusing. This talk introduces a precise and computationally efficient method for ultrasonic ray tracing in layered media. We present a geometrical acoustics based algorithm that corrects aberrations in layered media using a modified time-of-flight (ToF) calculation additionally considering sound speed variations and the resulting refraction effects. The focusing delays, required for the calculation of the ultimate image, are corrected using accurate ToF results obtained from a nonlinear system of the equations, which was derived using geometrical acoustics. Our interpolation method extends traditional bilinear interpolation by using annular sector area ratios to establish generalized barycentric coordinates, facilitating effective interpolation over smoothly curved geometries. When compared to ground truth time-of-flight values, our method consistently achieves errors small enough to be negligible when applied in image reconstruction. This result demonstrates that our method makes a step towards improved real-time aberration correction in ultrasound imaging.
