Description

Ultrasound speckle carries information about the interrogated scattering microstructure. The complex signal is represented as a superposition of signals due to all scatterers within a resolution cell volume, VE. A crossbeam geometry with separate transmit and receive transducers is well suited for such studies. The crossbeam volume, VE is defined in terms of the overlapping diffraction beam patterns. Given the focused piston transducer's radius and focal distance, a Lommel diffraction formulation suitable for monochromatic excitation is used to calculate VE as a function of frequency and angle. This formulation amounts to a Fresnel approximation to the diffraction problem and is not limited to the focal zone or the far field. Such diffraction corrections as VE are needed to remove the system effects when trying to characterize material using moment analysis. Theoretically, VE is numerically integrated within the overlapping region of the product of the transmit-receive transfer functions. Experimentally, VE was calculated from the field pattern of a medium-focused transducer excited by a monochromatic signal detected by a 0.5mm diameter PVDF membrane hydrophone. We present theoretical and experimental evaluations of VE for the crossbeam geometry at frequencies within the transducers' bandwidth, and its application to tissue microstructure characterization (Refer to PDF file for exact formulas).

Date of creation, presentation, or exhibit

2002

Comments

Medical Imaging 2002: Ultrasonic Imaging and Signal Processing 4687 (2002) 334-344 Copyright 2002 Society of Photo-Optical Instrumentation Engineers. This paper was published in Proceedings of SPIE -- Volume 4687 Medical Imaging 2002: Ultrasonic Imaging and Signal Processing, Michael F. Insana, William F. Walker, Editors, April 2002 and is made available as an electronic reprint with permission of SPIE. One print or electronic copy may be made for personal use only. Systematic or multiple reproduction, distribution to multiple locations via electronic or other means, duplication of any material in this paper for a fee or for commercial purposes, or modification of the content of the paper are prohibited. The authors would like to thank Dr. D. Dalecki at the University of Rochester department of Biomedical Engineering for the use of the Imotec Messtechnik PVDF Needlehydrophone. ISBN: 081-94-4438-3Note: imported from RIT’s Digital Media Library running on DSpace to RIT Scholar Works in February 2014.

Document Type

Conference Proceeding

Department, Program, or Center

Chester F. Carlson Center for Imaging Science (COS)

Campus

RIT – Main Campus

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