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Ultrasonic imaging using a computed point spread function
Published in
2008
PMID: 18334351
Volume: 55
   
Issue: 2
Pages: 451 - 464
Abstract
An explicit point spread function (PSF) evaluator in the frequency domain is described for an ultrasonic transducer operating in the pulse-echo mode. The PSF evaluator employs the patch element model for transducer field determination and scattered field assessment from a small but finite "point" reflector. The PSF for a planar transducer in a medium has been evaluated in the near and the far field. The computed PSFs were used to deconvolve and restore surface images, obtained experimentally, of a single hole and a five-hole cluster in an Al calibration block. A calibration plot is arrived at for estimating, without the need for deconvolution, the actual diameters of circular reflectors from apparent diameters obtained experimentally for a single-medium imaging configuration. The PSF, when the transducer and the point reflector are in two media separated by a planar interface, was evaluated in the near and far field. The computed PSFs were used to deconvolve and restore subsurface images, obtained experimentally, of flat bottom holes (FBHs) in an Al calibration block. We show that the PSF, in the presence of a planar interface, can be obtained from a single-medium PSF model using an effective single-medium path length concept. The PSFs and modulation transfer functions (MTFs) are evaluated for spherical focused and annular transducers and compared with those for the planar transducer. We identify imaging distances to get better-resolved images when using planar, spherical focused, and annular transducers. © 2008 IEEE.
About the journal
JournalIEEE Transactions on Ultrasonics, Ferroelectrics, and Frequency Control
ISSN08853010
Open AccessNo
Concepts (26)
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    FLAT BOTTOM HOLES (FBH)
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    PATCH ELEMENT MODEL
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    PLANAR INTERFACE
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    PULSE-ECHO MODE
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    Deconvolution
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    Frequency domain analysis
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    Optical transfer function
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    Transducers
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    Ultrasonic imaging
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    Algorithm
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    Article
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    Computer assisted diagnosis
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    Echography
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    Evaluation
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    Image enhancement
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    Methodology
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    Radiation scattering
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    Reproducibility
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    Sensitivity and specificity
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    Three dimensional imaging
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    Algorithms
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    Image interpretation, computer-assisted
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    Imaging, three-dimensional
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    Reproducibility of results
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    Scattering, radiation
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    Ultrasonography