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Ultrasound Computer Tomography (USCT) is a novel and a promising low-cost technology for breast cancer imaging. USCT can provide speed-of-sound, attenuation and reflectivity information about the analyzed area. Among USCT methods, the ray-based approach (transmission tomography) is faster and it can offer a-priori information as initialization for more complex USCT methods. To contribute to the generation of such initializations, this work presents, on simulated media, how the use of a spatial filter jointly with refraction can improve the image reconstructed by transmission USCT. The following were used: k-wave toolbox for data generation on a heterogeneous medium; a numerical phantom with objects whose speed of sound are between [1460−1570]m/s; all objects have equal density and attenuation; a Refraction Tomography as transmission reconstruction algorithm (with and without regularization), where the forward problem was solved by Dijkstra’s shortest-path algorithm and the inverse problem with Simultaneous Iterative Reconstruction Technique; an alternative of the Modified Median Filter (m-MMF) as a spatial filter. Two sets of data were generated using 100 and 192 transducers (400kHz) respectively. All transducers were uniformly distributed around the medium. Evaluations were based on Relative-Residual-Error (RRE), normalized-root-mean-square-error (NRMSE) and structural similarity (Q). Comparing the reconstructions, better performance (NRMSE < 0.01) was found when the filter was applied with the Refraction Tomography, regardless of the use or not of the regularization. As expected, the reconstructions improved their performance as the number of transducers was increased. The results suggest that it is possible to improve and obtain satisfactory reconstructions via Transmission reconstruction algorithm in conjunction with a spatial filter.
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