Print Email Facebook Twitter A contrast source method for nonlinear acoustic wave fields in media with spatially inhomogeneous attenuation Title A contrast source method for nonlinear acoustic wave fields in media with spatially inhomogeneous attenuation Author Demi, L. Van Dongen, K.W.A. Verweij, M.D. Faculty Applied Sciences Department IST/Imaging Science and Technology Date 2011-03-09 Abstract Experimental data reveals that attenuation is an important phenomenon in medical ultrasound. Attenuation is particularly important for medical applications based on nonlinear acoustics, since higher harmonics experience higher attenuation than the fundamental. Here, a method is presented to accurately solve the wave equation for nonlinear acoustic media with spatially inhomogeneous attenuation. Losses are modeled by a spatially dependent compliance relaxation function, which is included in the Westervelt equation. Introduction of absorption in the form of a causal relaxation function automatically results in the appearance of dispersion. The appearance of inhomogeneities implies the presence of a spatially inhomogeneous contrast source in the presented full-wave method leading to inclusion of forward and backward scattering. The contrast source problem is solved iteratively using a Neumann scheme, similar to the iterative nonlinear contrast source (INCS) method. The presented method is directionally independent and capable of dealing with weakly to moderately nonlinear, large scale, three-dimensional wave fields occurring in diagnostic ultrasound. Convergence of the method has been investigated and results for homogeneous, lossy, linear media show full agreement with the exact results. Moreover, the performance of the method is demonstrated through simulations involving steered and unsteered beams in nonlinear media with spatially homogeneous and inhomogeneous attenuation. Subject bioacousticsbiomedical ultrasonicsiterative methodsnonlinear acousticspatient diagnosisultrasonic absorptionultrasonic measurementultrasonic scattering To reference this document use: http://resolver.tudelft.nl/uuid:167aa63d-c9d3-4acb-a94c-8f5139f0de34 DOI https://doi.org/10.1121/1.3543986 Publisher Acoustical Society of America Embargo date 2011-09-09 ISSN 0001-4966 Source Journal of the Acoustical Society of America , 129 (3), 2011 Part of collection Institutional Repository Document type journal article Rights (c) 2011 The Author(s)Acoustical Society of America Files PDF Demi_2011.pdf 1.33 MB Close viewer /islandora/object/uuid:167aa63d-c9d3-4acb-a94c-8f5139f0de34/datastream/OBJ/view