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(Reference retrieved automatically from Web of Science through information on FAPESP grant and its corresponding number as mentioned in the publication by the authors.)

Instantaneous Phase Threshold for Reflector Detection in Ultrasonic Images

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Prado, Vander Teixeira [1] ; Higuti, Ricardo Tokio [1] ; Kitano, Claudio [1] ; Martinez-Graullera, Oscar [2]
Total Authors: 4
[1] Univ Estadual Paulista UNESP, Fac Engn Ilha Solteira, Dept Elect Engn, Ilha Solteira, SP - Brazil
[2] CSIC, Inst Tecnol Fis & Informac Leonardo Torres Queved, Madrid - Spain
Total Affiliations: 2
Document type: Journal article
Web of Science Citations: 4

A method for reflector detection, based on the instantaneous phase of the aperture data for ultrasonic images, is proposed. The instantaneous phase (IP) image is obtained by replacing the amplitude information by the instantaneous phase in the delay-and-sum (DAS) beamforming. From the analysis of the IP image, a threshold level is defined in terms of the number of signals used for imaging. This threshold is applied to the IP image, resulting in a two-level image which gives a statistical indication of whether the pixels of a region in the image are related to a reflector or noise/artifacts. Because the proposed method uses only the instantaneous phase of the signals, it is less sensitive to attenuation than conventional DAS amplitude images. The point spread function of a 32-element array with half-wavelength pitch at 5 MHz in water is simulated and the reflector is detected for signal-to-noise ratio values larger than -29.6 dB. A phantom and an aluminum plate with artificial defects are tested with the proposed technique, using linear arrays of 64 and 16 elements, respectively. When compared with DAS amplitude images and with two-level images obtained by thresholding the amplitude images using empirical threshold values, the proposed technique reduced artifacts and dead zone, and detected all reflectors, increasing reflectors' detectability and decreasing the occurrence of false indication of reflectors. The proposed technique can be used as additional information for amplitude image analysis, with the advantages that it does not need time-gain compensation and that it considers an objective threshold value. (AU)

FAPESP's process: 10/16400-0 - Ultrasonic non-destructive testing of plate-like structures using piezoelectric arrays transducers
Grantee:Vander Teixeira Prado
Support type: Scholarships in Brazil - Doctorate (Direct)
FAPESP's process: 10/02240-0 - Non-destructive testing of structures using guided acoustic waves
Grantee:Ricardo Tokio Higuti
Support type: Regular Research Grants
FAPESP's process: 13/00330-0 - Beamforming for ultrasonic array imaging of plate structures using lamb waves
Grantee:Vander Teixeira Prado
Support type: Scholarships abroad - Research Internship - Doctorate (Direct)