Bioacoustics Research Lab
University of Illinois at Urbana-Champaign | Department of Electrical and Computer Engineering | Department of Bioengineering
Department of Statistics | Coordinated Science Laboratory | Beckman Institute | Food Science and Human Nutrition | Division of Nutritional Sciences | College of Engineering
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William D. O'Brien, Jr. publications:

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BRL Abstracts Database

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Your search for ultrasound produced 3296 results.

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Title Biophysical mechanisms of ultrasound.
Author Nyborg WL.
Journal Essentials Med Ultrasound
Volume
Year 1982
Abstract No abstract available.


Title Biophysics of ultrasound.
Author Frizzell LA, Dunn F.
Journal Book Chapter
Volume
Year 1982
Abstract Introduction: Ultrasound is acoustic energy beyond the audible range (i.e., frequencies above 20 kHz). This form of energy is used extensively in medical diagnosis as well as in therapeutic applications. In this chapter, (a) the physical characteristics of ultrasonic fields are presented, including discussion of the acoustic variables; (b) information is provided on ultrasonic sources and measurement methods; and (c) ultrasonic propagation in and interaction with tissues are described. It was considered essential to include the mathematical expressions which relate the various acoustic field variables and quantities which characterize the state of a system for a quantitative understanding of ultrasonic methods. While these equations are discussed in sufficient detail to be used to compute quantities of interest, their derivation have not been included. Readers desiring a deeper knowledge of the origin of these expressions are urged to consult the references provided. For the purpose of this discussion, infinitesimal amplitude (linearized relations) acoustic disturbances are presented, excepting the section entitles ?Propagation in and Interaction with Tissues.?


Title Biparietal diameter in premature rupture of membranes: Errors in estimating gestational age.
Author Wolfson RN Zador IE Halvorsen P Andrews B Sokol RJ.
Journal J Clin Ultrasound
Volume
Year 1983
Abstract Experience on our clinical service suggested that the real-time ultrasonically measured fetal biparietal diameter (BPD) might not accurately estimate gestational age in the preterm pregnancy complicated by premature rupture of membranes (PROM). Of 2510 consecutive pregnancies for which the BPD could be obtained on ultrasound examination at or beyond 26 weeks gestation, 122 were complicated by PROM. For pregnancies with and without PROM, the relationship, if any, between BPD and gestational age at the time of examination was determined by regression analysis and the resulting equations compared by F test. The regression equations were found to be significantly different (F = 17.2, P less than 0.01); the BPD was found to underestimate the true gestational age in the presence of PROM. To model the situation in which the pregnancy is recognizably very premature, the BPD/gestational age relationship was evaluated at less than or equal to 30 weeks. In these pregnancies the correlation of gestational age with BPD was not statistically significant in the presence of PROM. These results indicate that in the presence of PROM, the BPD may not be a reliable estimator of the gestational age of the fetus. In the presence of PROM, gestational age dependent management decisions would be better based on clinical and ultrasound criteria rather than the ultrasonically determined BPD.


Title Birth control for men: The pill, ultrasound, vaccines.
Author Unknown.
Journal Sci Dig
Volume
Year 1974
Abstract No abstract available..


Title Bistatic passive mapping of the field distribution of single element transducer in agar phantom
Author Nguyen T, Oelze M, Do M
Journal IEEE Int Ultrasonics Symp Proc
Volume
Year 2014
Abstract High intensity focused ultrasound (HIFU) can provide a means of noninvasive ablation or hyperthermia of tissues such as tumors. Real-time monitoring of the progression of the field distribution of the HIFU transducer during treatment is important for localizing the intersection of the beam with the tissue. By continuously visualizing the HIFU field in a tissue, better positioning of the HIFU beam for therapy can be obtained during treatment. To visualize the HIFU field in a tissue, a passive listening technique was employed using beamforming approaches and a linear array system co-aligned with the HIFU source. The passive array made use of the weakly scattered signal from the medium to reconstruct the field pattern of the HIFU field in the medium. The focus of a 6-MHz single-element transducer (f/3) was aligned perpendicular to the field of view from a linear array (L14-5) operated by a SonixRP system equipped with a Sonix-DAQ. A homogeneous tissue-mimicking phantom made of agar containing glass beads was placed at the focus between the 6-MHz source and the linear array. The 6-MHz source was excited with a pulse and the field scattered from the phantom was received by each element of the linear array. Beam forming techniques were used to focus the received field of the linear array around the focal region of the 6-MHz source. The intensity field pattern of the 6-MHz source was reconstructed from the scattered field. Next, a wire target was placed in the field and the intensity field pattern was reconstructed by moving the wire throughout the focal region. The intensity pattern from the phantom was compared to the nominal field characteristics of the 6-MHz source and to the field characterized by a wire. The beam width at the focus of the reconstructed intensity field pattern was estimated to be 1.7 mm. The nominal estimate of the beam width was pproximately 1.4 mm (-6 dB) and the beam width as estimated from the wire target field mapping was 1.5 mm. Therefore, the novel passive reconstruction technique can visualize the field of a focused source in a weakly scattering medium.


Title Blood cell banding in ultrasonic standing wave fields: a physical analysis.
Author ter Haar G, Wyard SJ.
Journal Ultrasound Med Biol
Volume
Year 1978
Abstract Blood cell flow can be arrested in living tissue by exposing the blood vessels to ultrasound in a stationary wave field. The cells form into bands at half wavelength intervals in the blood vessels. This phenomenon is described, and the forces that may be involved are discussed. The forces considered include standing wave radiation pressure, inter-cellular forces, and Oseen forces. A computer model is described and the computed trajectories of cells under the action of these forces are shown.


Title Blood chemical and hematological effects of ultrasonic irradiation of mice.
Author Glick D, Nolen HW 3d, Edmonds PD.
Journal Ultrasound Med Biol
Volume
Year 1981
Abstract Batteries of 23 chemical and 7 hematological blood constituents and factors were determined to indicate possible damage to female albino Swiss-Webster mice of ultrasonic irradiation in vivo (2 MHz continuous wave, 1 W/cm2, 34 C). Untreated, sham-treated, and treated mice were used. Effects observed 2 and 24 hr after ultrasonic exposure for 200 sec, and those seen 24 hr after 50 and 200 sec exposure, were compared. These comparisons showed: (1) Sham treatment alone induced significant changes in levels of certain of the blood constituents. (2) Some significant differences between the treatment and the sham-treatment groups were separately apparent 2 and 24 hr after irradiation, indicating recovery at 24 hr from certain of the 2 hr effects. Other changes, probably more significant, were still present 24 hr after treatment. (3) Changes found with 200, but not 50, sec of irradiation indicate that there is a threshold between these times for the appearance of the changes evoked under the conditions used.


Title Blood flow cooling and ultrasonic lesion formation.
Author Kolios MC, Sherar MD, Hunt JW.
Journal Med Phys
Volume
Year 1996
Abstract This article examines lesion formation using focused ultrasound and demonstrates how blood flow may affect lesion dimensions using a theoretical model. The effects of blood flow on temperature distributions during ultrasonic lesioning are examined for both regional cooling by the microvasculature and localized cooling due to thermally significant vessels. Regional cooling was critically assessed using two models: the Pennes bioheat transfer equation and the scalar effective thermal conductivity equation. Localized cooling was modeled by adding an advective term in the heat diffusion equation in regions enclosed by thermally significant vessels. A finite difference approach was used to solve the basic equations of heat transfer in perfused tissues in cylindrical coordinates. The extent of the lesioned tissue was determined by the accumulated thermal dose at each location. The size of the lesion was then calculated from the boundaries of the thermal isodose curves generated by the simulations. The results were compared to published in vivo lesion data in rat liver. It was shown that even for short ultrasound exposure times (approximately 8 s), blood flow may play an important role in the thermal dose distribution.


Title Blood flow measured by doppler frequency shift of back-scattered ultrasound.
Author Franklin DL, Schlegel W, Rushmer RF.
Journal Science
Volume
Year 1962
Abstract The doppler shift of ultrasound, scattered from moving elements within a stream of blood, is related to the velocity of blood flow. A flowmeter based on this principle has been constructed and was used to record blood flow through intact vessel in dogs.


Title Blood flow measurements by ultrasound correlation techniques.
Author Dotti D, Gatti E, Svelto V, Ugge A, Vidali P.
Journal Energia Nucl
Volume
Year 1976
Abstract In this article a device is described for blood flow velocity measurements through a non-intrusive technique. This is based on the use of short ultrasonic pulses forwarded from the outside into the blood vessel, and on the correlation analysis of the range-gated echo signals. The preliminary results of the measurements performed up to now are also presented, and in particular the velocity profile of blood in a plexiglas tube.


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