Ray-based transmission ultrasound tomography for quantitative sound speed imaging: First in-vitro and in-vivo validations

This study presents the first experimental validation of ray-based image reconstruction techniques for high-resolution, quantitative sound speed imaging using transmission ultrasound. These methods model singly-scattered waves and reconstruct images by sequentially minimizing an objective function across increasing frequency bands, balancing computational efficiency with resolution. The methods were applied to in-vitro and in-vivo datasets from the University of Rochester Medical Center using an open-source MATLAB package. In-vitro accuracy was assessed by comparing reconstructed images with phantom data, demonstrating strong agreement. In-vivo results were evaluated against those from a full-field frequency-domain Helmholtz solver. The study highlights the computational efficiency and scalability of these techniques, demonstrating their potential for clinical ultrasound imaging. The open-source nature of these methods fosters future advancements in quantitative imaging.