Cosima Ruzzo

Semester Work
Supervisors: Dr. Richard Rau

Image-based wavefront correction for ultrasound reconstruction

As a widely applicable, non-invasive and non-ionizing imaging method, ultrasound imaging is a method with great potential which has still not been explored to its full extent. Imaging the underlying distribution of the speed of sound (SoS) is an ultrasound imaging modality which has recently received increasing interest, due to its potential of detecting and differentiating malignant and benign lesions. State-of-the-art implementations of SoS imaging assume that the acoustic wave signal travels on straight paths through the tissue and thus neglect diffraction, refraction or other general wave phenomena. Making this assumption, possibly severe degrades of the performance have to be accepted. Thus this work introduces an algorithm which simulates the wave propagation through tissue with a given distribution of the SoS under consideration of refraction. The results indicate that the algorithm is able to provide reasonable estimates for the wave propagation paths and the resulting reconstructions are comparable with results generated by the existing approach, despite the rather different nature of the paths. As an additional result, a measurement method is presented which can be used to monitor cases where refraction effects play a major role during wave propagation.