Scatterer number density estimation using frequency modulated pulse

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Title: Scatterer number density estimation using frequency modulated pulse
Author: Rao, Navalgund; Zhu, Hui
Abstract: Ultrasound echoes, backscattered from an inhomogeneous medium, have the character of a random signal, which is mainly responsible for the speckle pattern observed in the images. These random signals, nevertheless. bear information related to the random scattering structure of the medium. If the medium is represented as a uniform matrix material with scattering bodies distributed randomly, then the scatterer number density can be estimated from the second and higher statistical moments of the signal. However, the estimate is biased because the statistical nature of the signal also depends on the resolution cell volume of the imaging system, which in turn depends on the center frequency lo, and the bandwidth Af of the interrogating short pulse and the beam profile of the transducer. If a frequency modulated pulse is used for imaging, an additional cross correlation step is needed to compress the pulse, but f, and AI can be varied independently. Using such a pulse, we have performed A-line simulation of the backscattered signal from a specially designed mathematical phantom. Such a phantom allows us to study the signal variations as a function of changing resolution cell volume. The model predicts that Kurtosis, calculated from 2nd and 4th moments, should change linearly with another parameter Fs, that depends on the resolution cell volume. The slope depends on the scatterer number density, and serves as an unbiased estimator (Refer to PDF file for exact formulas).
Description: "Scatterer number density estimation using frequency modulated pulse," Proceedings of the IEEE Ultrasonics Symposium. Institute of Electrical and Electronics Engineers. Held in Montreal, Quebec, Canada: 3-6 October 1989. ©1989 Institute of Electrical and Electronics Engineers (IEEE). Personal use of this material is permitted. However, permission to reprint/republish this material for advertising or promotional purposes or for creating new collective works for resale or redistribution to servers or lists, or to reuse any copyrighted component of this work in other works must be obtained from the IEEE. This material is presented to ensure timely dissemination of scholarly and technical work. Copyright and all rights therein are retained by authors or by other copyright holders. All persons copying this information are expected to adhere to the terms and constraints invoked by each author's copyright. In most cases, these works may not be reposted without the explicit permission of the copyright holder.
Record URI: http://hdl.handle.net/1850/3225
Date: 1989-10-03

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