Axial super-resolution in ultrasound imaging with application to non-destructive evaluation

Shastri, SK and Rudresh, SVS and Anand, R and Nagesh, S and Seelamantula, CS and Thittai, AK (2020) Axial super-resolution in ultrasound imaging with application to non-destructive evaluation. In: Ultrasonics, 108 .

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Abstract

A fundamental challenge in non-destructive evaluation using ultrasound is to accurately estimate the thicknesses of different layers or cracks present in the object under examination, which implicitly corresponds to accurately localizing the point-sources of the reflections from the measured signal. Conventional signal processing techniques cannot overcome the axial-resolution limit of the ultrasound imaging system determined by the wavelength of the transmitted pulse. In this paper, starting from the solution to the 1-D wave equation, we show that the ultrasound reflections could be effectively modeled as finite-rate-of-innovation (FRI) signals. The FRI modeling approach is a new paradigm in signal processing. Apart from allowing for the signals to be sampled below the Nyquist rate, the FRI framework also transforms the reconstruction problem into one of parametric estimation. We employ high-resolution parametric estimation techniques to solve the problem. We demonstrate axial super-resolution capability (resolution below the theoretical limit) of the proposed technique both on simulated as well as experimental data. A comparison of the FRI technique with time-domain and Fourier-domain sparse recovery techniques shows that the FRI technique is more robust. We also assess the resolvability of the proposed technique under different noise conditions on data simulated using the Field-II software and show that the reconstruction technique is robust to noise. For experimental validation, we consider Teflon sheets and Agarose phantoms of varying thicknesses. The experimental results show that the FRI technique is capable of super-resolving by a factor of three below the theoretical limit.

Item Type:	Journal Article
Publication:	Ultrasonics
Publisher:	Elsevier B.V.
Additional Information:	The copyright of this article belongs to Elsevier B.V.
Keywords:	Image resolution; Nondestructive examination; Optical resolving power; Parameter estimation; Ultrasonic imaging, Experimental validations; Finite rate of innovations (FRI); Non destructive evaluation; Reconstruction problems; Reconstruction techniques; Signal processing technique; Ultrasound imaging systems; Ultrasound reflections, Time domain analysis
Department/Centre:	Division of Electrical Sciences > Electrical Engineering
Date Deposited:	20 Aug 2020 08:43
Last Modified:	20 Aug 2020 08:43
URI:	http://eprints.iisc.ac.in/id/eprint/66036

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