Bioacoustics Research Lab
University of Illinois at Urbana-Champaign | Department of Electrical and Computer Engineering | Department of Bioengineering
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William D. O'Brien, Jr. publications:

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Your search for ultrasound produced 3296 results.

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Title Treatment of superficial human neoplasms by local hyperthermia induced by ultrasound.
Author Marmor JB, Pounds D, Postic TB, Hahn GM.
Journal Cancer
Volume
Year 1979
Abstract This study was designed to test the safety and efficacy of local heating of superficial tumors by ultrasound. Twenty-five patients were treated who had recurrent or metastatic tumor in superficial locations refractory to conventional treatment modalities. Heating was done with high intensity ultrasound fields produced by a 2 cm or 4 cm piezoelectric transducer at frequencies of 1-3 MHz. Tumors were held at 43, 44 or 45 C center temperature for 30 minutes each treatment. Analysis of response was done after 6 treatments. Ultrasound and thermal fields were carefully mapped. Some nonuniformity of tumor heating was noted despite relatively uniform output of ultrasound energy by the transducer. Twenty-one of the 25 patients were evaluable after 26 courses of local hyperthermia. Fourteen of 26 courses of treatment resulted in objective tumor response (54%). However, most responses were partial and median follow-up time was short (5 weeks) because many patients had systemic disease and died or were put on chemotherapy after treatment. Eight of 12 lesions in patients with squamous cell carcinoma of the head and neck regressed. Response rate did not correlate with central tumor temperature. Treatment was, in general, well tolerated although 10/26 courses of treatment caused significant local pain. Pain always subsided after treatment. Five of 26 courses of treatment resulted in small (0.5 cm) cutaneous burns. Previous irradiation did not limit heating. We conclude that superficial tumors can be safely and effectively heated by ultrasound. Objective tumor responses were seen with hyperthermia alone, although we stress that, because of the short follow-up time and, because most responses were partial, it is likely that the effects noted were transitory.


Title Treatment planning for hyperthermia with ultrasound phased arrays.
Author McGough RJ, Kessler ML, Ebbini ES, Cain CA.
Journal IEEE Trans UFFC
Volume
Year 1996
Abstract Treatment planning for ultrasound phased arrays suggests a strategy for hyperthermia therapy which satisfies therapeutic conditions at the target and spares other sensitive anatomical structures. To predict both desirable and harmful interactions between ultrasound and important structures such as the tumor, bones, and air pockets, a hyperthermia treatment planning system has been developed for ultrasound phased arrays. This collection of treatment planning routines consists of geometric and thermal optimization procedures specific to ultrasound phased arrays, where geometric treatment planning, combined with thermal treatment planning and three-dimensional visualization, provides essential information for the optimization of individual patient treatments. A patient image data set for cancer of the prostate, a difficult target situated in the midst of multiple pelvic bone obstructions, illustrates the geometric treatment planning algorithm and other tools for treatment analysis. The results indicate that the analysis of complex three-dimensional relationships between the applicator, anatomical structures, and incident fields provides an important means of predicting treatment limiting conditions, thereby allowing the hyperthermia applicator to electronically adapt to individual patients and specific sites


Title Triple-beam lens transducers for three-dimnesional ultrasonic fluid flow estimation.
Author Hein IA.
Journal IEEE Trans UFFC
Volume
Year 1995
Abstract This paper reports on estimating the 3-D flow velocity vector of blood with ultrasound triple-beam lens transducers. The design, construction, and characterization of experimental lens transducers is.described along with the theory of 3-D flow velocity estimation. A triple beam lens transducer consists of three piezoelectric elements mounted on the top surface of a lens. The lens acts to direct and focus the ultrasound from the elements such that three parallel, closely spaced ultrasound beams are generated. Blood cell scatterers are tracked as they move along the beams and from beam to beam using RF correlation techniques. Lenses from fused quartz and aluminum have been designed and fabricated, and the characteristics of the lenses along with lens design considerations and tradeoffs are discussed. The three-dimensional flow velocity vector of fluid in a blood flow phantom has been experimentally measured with an aluminum lens, indicating that the accurate estimation of the 3-D blood flow velocity vector is possible.


Title Tumor irradiation with intense ultrasound.
Author Fry FJ, Johnson LK.
Journal Ultrasound Med Biol
Volume
Year 1978
Abstract Tumors implanted in the hamster flank have been irradiated in vivo with intense focused ultrasound at a spatial peak intensity of 907 W/cm2. A matrix of points was irradiated under c.w. conditions through the central plane of the tumor and perpendicular to the longitudinal axis of the sound field. A center spacing of 4 mm between matrix points and a time-on period of 2.5 sec at each point produced no cures. A spacing distance of 2 mm with 7 sec time-on period at each point increased mean survival time in non-cured animals and produced a cure rate of 29.4%. Combining the second regime of ultrasound treatment with administration of a chemotherapeutic agent (BCNU) 24 hr after irradiation did not increase mean survival time in the non-cured animals compared to the BCNU non-irradiated shams; however, the cure rate increased to 40%. Secondary tumors which were not seen in any ultrasound shams or controls were observed in all other regimes including BCNU non-irradiated shams. The incidence of secondary tumors was inversely related to the cure rate.


Title Two approaches for tomographic density imaging using inverse scattering.
Author Lavarello RJ, Oelze ML.
Journal IEEE Int Ultrasonics Symp Proc
Volume
Year 2008
Abstract Most acoustic tomography methods neglect density variations in order to obtain speed of sound and attenuation profiles. However, density may provide additional sources of image contrast. In this work, two approaches for density imaging using inverse scattering were explored through simulations in order to evaluate the feasibility of density imaging. The first method consisted of inverting the wave equation by solving for a single functional that depended on both speed of sound and density variations. Density profiles were separated by combining reconstructions at two frequencies (DF-DBIM approach). The second method consisted of solving for two functionals simultaneously: one that depended only on compressibility and one that depended only on density variations. A T-matrix approach was used to relate these functionals to the scattered data. The DF-DBIM approach allowed separation of density and speed of sound profiles at low termination tolerance values and less than an order of magnitude between the largest and smallest frequencies used. However, the convergence of DF-DBIM was compromised even when moderate (around 2%) termination tolerances were used. The T-matrix approach converged when multiple frequency data was used, but required a ka product smaller than one at the lowest frequency. The DF-DBIM requires a very high SNR to obtain reliable quantitative density reconstructions, while the T-matrix approach requires excessively large bandwidths when imaging large targets. These limitations will serve as reference points for further algorithmic improvements required for practical implemenatation of density imaging on ultrasound tomographic systems.


Title Two dimensional ultrasonography in obstetrics.
Author Kossoff G, Robinson DE, Garrett WJ.
Journal Diagn Ultrasound
Volume
Year 1966
Abstract No abstract available.


Title Two forms of repair in the DNA of human lymphocytes damaged by ultrasound exposure in vitro.
Author Pinamonti S, Pavone E, Mazzeo V, Grandi G, Rossi A.
Journal Mediterr J Radiol Imaging
Volume
Year 1990
Abstract Human lymphocytes sonicated in vitro with pulsed ultrasound of the same frequency and intensity as those used for diagnostic purposes appear to cause two different types of damage to DNA molecules. One can be repaired within a short time (60 minutes) and involves single strand breaking. The other one requires a longer time for repair (20 to 24 hours) and appears to be due to the formation of large excision repairs leading to Sister Chromatid Exchange (SCE). A spectrofluorimetric method evidencing these two types of damage is described. Electrophoretic anomalies of damaged molecules are shown, along with morphological ones, by transmission electron microscopy (TE).


Title Two-dimensional array transducers using thick film connection technology.
Author Smith SW, Light ED.
Journal IEEE Trans UFFC
Volume
Year 1993
Abstract Two-dimensional array ultrasound transducers have been previously developed in our laboratory by hand wiring 16 x 16 arrays of PZT-5H elements operating at 2.5 MHz with element spacing of 0.5 mm x 0.5 mm. There are severe difficulties in electrical connection to such elements which are less than one ultrasound wavelength on a side. To solve this problem, a new connection technique has been developed by combining a conductive lamba/4 mismatching layer with a multi-layer ceramic (MLC) connector (thick-film microelectronic technology). The connector consists of 20 thick films of alumina and screen printed metallization with customized interconnections between the layers called vias. Ten ground layers are interleaved between ten signal layers to reduce electrical cross talk. A lamba/4 mismatching layer of conductive epoxy is bonded between each PZT element and the silver metal pad of the MLC connector to provide an effective low impedance backing. In the current configuration, a 16 x 16 transducer array, 0.6 mm element spacing, is expanded to a 16 x 16 grid of connector pins at a standard spacing of 2.5 mm. Vector impedance, sensitivity, bandwidth, interelement uniformity, and cross talk are all in good agreement with arrays of conventional fabrication. However, an array with MLC connector can be fabricated more quickly independent of the number of elements. Thick-film microelectronic circuit technology shows promise for solving the fabrication problems of 2-D array transducers of over a thousand elements at frequencies approaching 10 MHz.


Title Two-dimensional arrays for medical ultrasound.
Author Smith SW, Trahey GE, von Ramm OT.
Journal Ultrason Imaging
Volume
Year 1992
Abstract The design, fabrication and evaluation of two-dimensional transducer arrays are described for medical ultrasound imaging. A 4 x 32, 2.8 MHz array was developed to use new signal processing techniques for improved B-scan imaging including elevation focusing, phase correction and synthetic aperture imaging. Laboratory measurements from typical array elements showed 50 omega insertion loss of -56 dB, -6 dB fractional bandwidth of 43%, interelement crosstalk of -19 dB, and -6 dB pulse-echo angular response of 62 degrees. Simulations of pulse-echo beam plots have shown grating lobes 20 dB below the main lobe at +/- 7 degrees in the elevation direction. The complete 2-D array has been used for measurements of phase aberrations in breast, and the individual 32 element linear arrays have been used to obtain conventional B-scans. Several 16 x 16 arrays have also been developed for high speed volumetric imaging. These include 96 transmit elements and 32 receive channels. With a lambda/4 matching layer, laboratory measurements show 50 omega insertion loss of -72 dB, -6 dB fractional bandwidth of 63%, interelement crosstalk of -29 dB and -6 dB angular response of 25 degrees. Pulse-echo sensitivity was improved by 21 dB through the use of integrated circuit preamplifiers of high impedance mounted in the transducer handle. In vivo cardiac, abdominal, and obstetric B-scans with elevation focusing, as well as high speed C-scans, have been obtained with these 2-D arrays.


Title Two-dimensional echocardiographic image texture analysis: Reduction of regional variability using polar coordinates.
Author Aylward PE, Knosp BN, McPherson DD, Eltoft DA, Yurkonis CE, Bean JA, Skorton DJ, Collins SM.
Journal Ultrason Imaging
Volume
Year 1985
Abstract Factors inherent to the ultrasound imaging system can influence quantitative ultrasound image texture and may produce changes that mask or mimic those due to alterations in tissue structure. In this study, we assessed the effect of the method of image data acquisition and analysis on the variations in quantitative texture measures that occurred solely due to the position of a region of interest (ROI) within the field of view. When ROI's, which varied in range and azimuth within the image of a tissue equivalent phantom (of uniform composition), were assessed by conventional analysis of scan-converted (rectangular coordinate) data, over 50 percent of all texture measures showed significant differences. Pseudo polar analysis reduced the number of texture measures showing regional variation by 80 percent (p less than 0.01) and true polar coordinate data analysis reduced the number by 74 percent (p less than 0.01). True polar analysis completely abolished differences in texture measures between ROI's separated in azimuth. Acquisition and analysis of tissue texture data using polar coordinates should allow a more definitive identification of abnormal tissue.


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