Medical ultrasound imager based on time delay spectrometry

Heyser, Richard C.; Hestenes, J. D.; Rooney, James A.; Gammell, Paul M.; Croissette, D. H. Le

doi:10.1016/0041-624x(89)90006-1

Cited by 16 publications

(3 citation statements)

References 17 publications

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“…Dashed lines show direct phase measurements after adding linear functions to correct for hydrophone depth discrepancy (see previous section). The direct (after linear adjustment) and indirect measurements show consistent agreement over the usable frequency band(5)(6)(7)(8)(9)(10)(11)(12)(13)(14)(15)(16)(17)(18) to within a few degrees, with root-mean-square differences of 1.76 degrees (PVDF spot-poled bilaminar membrane hydrophone), 3.10 degrees (PVDF capsule hydrophone), 3.43 degrees (PVDF needle hydrophone) and 3.36 degrees (ceramic needle hydrophone).…”

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confidence: 66%

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Time-delay spectrometry measurement of magnitude and phase of hydrophone response

Wear

Gammell

Maruvada

et al. 2011

IEEE Trans. Ultrason., Ferroelect., Freq. Contr.

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A method based on time-delay spectrometry (TDS) was developed for measuring both magnitude and phase response of a hydrophone. The method was tested on several types of hydrophones used in medical ultrasound exposimetry over the range from 5 to 18 MHz. These included polyvinylidene fluoride (PVDF) spot-poled membrane, needle, and capsule designs. One needle hydrophone was designed for high-intensity focused ultrasound (HIFU) applications. The average reproducibility (after repositioning the hydrophone) of the phase measurement was 2.4°. The minimum-phase model, which implies that the phase response is equal to the inverse Hilbert transform of the natural logarithm of the magnitude response, was tested with TDS hydrophone data. Direct TDS-based measurements of hydrophone phase responses agreed well with calculations based on the minimum-phase model, with rms differences of 1.76° (PVDF spot-poled membrane hydrophone), 3.10° (PVDF capsule hydrophone), 3.43° (PVDF needle hydrophone), and 3.36° (ceramic needle hydrophone) over the range from 5 to 18 MHz. Therefore, phase responses for several types of hydrophones may be inferred from measurements of their magnitude responses. Calculation of phase response based on magnitude response using the minimumphase model is a relatively simple and practical alternative to direct measurement of phase.

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confidence: 66%

“…Another approach employs time delay spectrometry (TDS), a swept-frequency technique originally proposed for audio applications [9,10] and later extended to biomedical applications [11,12]. In hydrophone characterization TDS has been used primarily for measurement of magnitude of hydrophone transfer function [13][14][15][16][17].…”

Section: Introductionmentioning

confidence: 99%

Time-delay spectrometry measurement of magnitude and phase of hydrophone response

Wear

Gammell

Maruvada

et al. 2011

IEEE Trans. Ultrason., Ferroelect., Freq. Contr.

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show abstract

“…The tracking filter both discriminates against signals other than those with the desired time-of-flight and also provides the signal-to-noise enhancement of a narrow-band receiver. By using moderately slow sweep rates, a signalto-noise improvement equivalent to averaging over 100,000 pulsed signals can typically be provided in around 50 msl (7] Since this TDS system used hetrodyne techniques, a fixed intermediate-frequency (i-f) filter determines the effective response of the tracking filter. The early arrival half of the response of this tracking filter is shown in Figure 1.…”

Section: Technique and Resultsmentioning

confidence: 99%