An ultrasonic time-delay spectrometry system employing digital processing

Gammell, Paul M.; Maruvada, Subha; Harris, Gerald R.

doi:10.1109/tuffc.2007.349

Cited by 18 publications

(13 citation statements)

References 17 publications

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“…TDS has been used by several authors to measure the magnitude of hydrophone response [19][20][21][22][23]. In the present study, TDS was used to measure both magnitude and phase.…”

Section: A Tds-based Measurement Of Magnitude and Phase Responsementioning

confidence: 97%

Improved measurement of acoustic output using complex deconvolution of hydrophone sensitivity

Wear

Gammell

Maruvada

et al. 2014

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

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The traditional method for calculating acoustic pressure amplitude is to divide a hydrophone output voltage measurement by the hydrophone sensitivity at the acoustic working frequency, but this approach neglects frequency dependence of hydrophone sensitivity. Another method is to perform a complex deconvolution between the hydrophone output waveform and the hydrophone impulse response (the inverse Fourier transform of the sensitivity). In this paper, the effects of deconvolution on measurements of peak compressional pressure (p+), peak rarefactional pressure (p_), and pulse intensity integral (PII) are studied. Time-delay spectrometry (TDS) was used to measure complex sensitivities from 1 to 40 MHz for 8 hydrophones used in medical ultrasound exposimetry. These included polyvinylidene fluoride (PVDF) spot-poled membrane, needle, capsule, and fiber-optic designs. Subsequently, the 8 hydrophones were used to measure a 4-cycle, 3 MHz pressure waveform mimicking a pulsed Doppler waveform. Acoustic parameters were measured for the 8 hydrophones using the traditional approach and deconvolution. Average measurements (across all 8 hydrophones) of acoustic parameters from deconvolved waveforms were 4.8 MPa (p+), 2.4 MPa (p_), and 0.21 mJ/cm(2) (PII). Compared with the traditional method, deconvolution reduced the coefficient of variation (ratio of standard deviation to mean across all 8 hydrophones) from 29% to 8% (p+), 39% to 13% (p_), and 58% to 10% (PII).

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“…TDS has been used by several authors to measure the magnitude of hydrophone response [19][20][21][22][23]. In the present study, TDS was used to measure both magnitude and phase.…”

Section: A Tds-based Measurement Of Magnitude and Phase Responsementioning

confidence: 97%

Improved measurement of acoustic output using complex deconvolution of hydrophone sensitivity

Wear

Gammell

Maruvada

et al. 2014

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

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“…Also, analyzing higher frequencies in the 5-12 MHz range resulted in greater attenuation loss and thus further enhanced the SNR. The temperature dependent sound speed was measured using time delay spectrometry [4], where the egg white was placed in a 2 cm-thick sample holder with Mylar membrane windows and then heated to the desired temperature. The thermal properties of targeted tissues, e.g.…”

Section: Methodsmentioning

confidence: 99%

Temperature-dependent physical properties of egg white for HIFU applications

Liu¹,

Maruvada²,

Herman³

et al. 2012

AIP Conference Proceedings

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Because egg white denatures at elevated temperature due to its protein content, it has the potential for use as a blood coagulation surrogate in pre-clinical evaluations of thermal therapy procedures such as high intensity focused ultrasound (HIFU) surgery. We therefore have measured the relevant physical properties of egg white, including coagulation temperature, frequency-dependent attenuation, sound speed, viscosity, and thermal properties, as a function of temperature (20 -95 ºC). Thermal coagulation and attenuation (5-12 MHz) of cow blood, pig blood, and human blood also were assessed and compared with egg white. For a 30 s thermal exposure, both egg white and blood samples started to denature at 65 ºC and coagulate into an elastic gel at 85 ºC. The temperature-dependent parameters were found to be similar to that of the blood samples. For example, the attenuation of egg white ranged from 0.23f 1.09 to 2.7f 0.5 dB/cm over the 20 ºC -95 ºC range. These results suggest that egg white would make a useful blood mimic for bench testing of therapeutic ultrasound devices.

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“…Regarding sensitivity phase calibration, the literature reports some approaches claiming the merit of being able to disclose the sensitivity phase as well, although the reported methods are mainly of comparison, instead of absolute, i.e., there is a need of a calibrated device to depict the hydrophone phase sensitivity. These approaches rely on time delay spectrometry [10][11][12][13][14][15][16] or optical reference hydrophone [17][18][19][20].…”

Section: Introductionmentioning

confidence: 99%