title: Computational models of distributed aberration in ultrasound breast imaging.
abstract: Two methods for simulation of ultrasound wavefront distortion are introduced and compared with aberration produced in simulations using digitized breast tissue specimens and a conventional multiple time-shift screen model. In the first method, aberrators are generated using a computational model of breast anatomy. In the second method, 10 to 12 irregularly shaped, strongly scattering inclusions are superimposed on the multiple-screen model to create a screen-inclusion model. Linear 2-D propagation of a 7.5-MHz planar, pulsed wavefront through each aberrator is computed using a first-order k-space method. The anatomical and screen-inclusion models reproduce two characteristics of arrival-time fluctuations observed in simulations using the digitized specimens that are not represented in simulations using the multiple-screen model: non-Gaussian first-order statistics and sharp changes in the rms arrival-time fluctuation as a function of propagation distance. The anatomical and screen-inclusion models both produce energy- level fluctuations similar to the digitized specimens, but the anatomical model more closely matches the pulse-shape distortion produced by the specimens. Both aberration models can readily be extended to 3-D, and the screen-inclusion model has the advantage of simplicity of implementation. Both models should enable more rigorous evaluation of adaptive focusing algorithms than is possible using conventional time-shift screen models.
authors.affiliation: Department of Electrical and Computer Engineering, University of Western Ontario, London, Ontario, Canada.
authors.forename: Yi-Ting
authors.initials: YT
authors.lastname: Shen
authors.forename: Mohammad I
authors.initials: MI
authors.lastname: Daoud
authors.forename: James C
authors.initials: JC
authors.lastname: Lacefield
mesh_terms: D000465:Algorithms; D000704:Analysis of Variance; D001940:Breast / Q000033:anatomy & histology*; D003198:Computer Simulation; D005260:Female; D006801:Humans; D007091:Image Processing, Computer-Assisted / Q000379:methods*; D008953:Models, Anatomic; D008954:Models, Biological; D018709:Statistics, Nonparametric; D016217:Ultrasonography, Mammary / Q000379:methods*