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BRL Abstracts Database |
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Your search for ultrasound produced 3296 results. Page 204 out of 330
| Title |
Production of reversible changes in the central nervous system by ultrasound. |
| Author |
Fry FJ, Ades HW, Fry WJ. |
| Journal |
Science |
| Volume |
|
| Year |
1958 |
| Abstract |
No abstract available. |
| Title |
Production of thymine base damage in ultrasound-exposed EMT6 mouse mammary sarcoma cells. |
| Author |
Dooley DA, Sacks PG, Miller MW. |
| Journal |
Radiat Res |
| Volume |
|
| Year |
1984 |
| Abstract |
Mouse mammary sarcoma cells, line EMT6/Ro, were exposed for 1 min to 1 MHz continuous wave ultrasound over a range of intensities from 0.5 to 30 W/cm2 (spatial peak). The presence of thymine base damage (TBD) products of the 5,6-dihydroxydihydrothymine type was determined by an alkali degradation assay. Production of damage was found to be greatest (approximately 2.7 X 10(-3%) t'/T) at an intensity of 10 W/cm2 and fell off rapidly above and below this intensity. The amount of base damage produced at 10 W/cm2 ultrasound was approximately.equivalent to the damage produced by a gamma-ray absorbed dose of 12 krad. Assay of cells immediately after sonication at 10 W/cm2 showed that approximately 14% of the cells had been lysed. Tests showed that it was the DNA of the intact cells, however, which sustained all of the TBD. Survival data demonstrated that of the remaining unlysed cell population approximately 5% were viable, whereas cells exposed to 12 krad showed no survival. Additionally, cells were exposed for up to 5 min at 5 W/cm2. An increase in TBD was demonstrated with increasing time.of exposure such that the rate of production at 5 min was approximately three times greater than that of a 1-min exposure. TBD was found to be completely suppressed when cells were sonicated at 10 W/cm2 for 2 min under 4 bar of hydrostatic pressure. Addition of the radical scavengers beta-MEA and cystamine eliminated TBD but had minimal effect on survival. The pressure and scavenger experiments demonstrate that TBD results from cavitation-induced free radicals. Based on the values for both the half-life and diffusion distance of such radicals, our results indicate that at least part of the bubble collapse occurs intracellularly. |
| Title |
Production of uniformly sized serum albumin and dextrose microbubbles |
| Author |
Borrelli MJ, O'Brien WD Jr, Bernock LJ, Williams HR, Hamilton E, Wu J, Oelze ML, Culp WC. |
| Journal |
Ultrason Sonochem |
| Volume |
|
| Year |
2012 |
| Abstract |
Ultrasound tomography based on inverse scattering has the capability to resolve structures which are smaller than the wavelength of the incident wave, as opposed
to conventional ultrasound imaging using echo method. Some material properties such as sound contrast are very useful to detect small objects. Born Iterative Method (BIM) based on first-order Born approximation has been introduced as an
efficient diffraction tomography approach. However, this method has a high complexity because it has to solve large iterative forward and inverse problems. In this paper, we propose to replace Tikhonov regularization by l1-regularized
least squares problem (LSP) in solving the inverse problem in BIM. As a result, the quality of reconstruction is improved and the complexity is reduced. |
| Title |
Progress and problems in the neurological applications of focused ultrasound. |
| Author |
Ballantine HT Jr., Bell E, Manlapaz J. |
| Journal |
J Neurosurg |
| Volume |
|
| Year |
1960 |
| Abstract |
No abstract available. |
| Title |
Progress in studies of the potential use of medical ultrasonics. |
| Author |
Oka M. |
| Journal |
Wakayama Med Rep |
| Volume |
|
| Year |
1977 |
| Abstract |
Researches on medical ultrasonics at Wakayama during past ten years are reviewed with their appraisal of the contribution to develop the clinical use of ultrasound in both neurosurgery and general surgery. The postoperative follow-up study with the aid of echodiagnosis of A-mode and of B-mode tomography afforded an accurate and simple method to enable the regression and growth of malignant processes of surgery and neurosurgery after treatment, and those results were supported by basic studies of ultrasonic absorption coefficient of human brains and live organs. Pulsatile echoencephalography was studied by the analysis of time factors with a lot of result, which revealed potentials of differentiating occluded locations of cerebral arterial occlusive diseases, as well as of determining the state of brain death. The author has also achieved basic studies and applications of ultrasonic destruction of malignant tumors by making a comparison with the radiation therapy. |
| Title |
Progress report for the period 15 June 75 - 14 June 76 submitted to the National Science Foundation on the project tissue characterization with ultrasound. |
| Author |
Waag RC. |
| Journal |
Rep Univ Rochester Dept Elect Eng |
| Volume |
|
| Year |
1975-1976 |
| Abstract |
The purpose of this research is to establish noninvasive tissue characterization with ultrasound by adapting the concepts used in x-ray diffraction and atmospheric probing with radar. The initial period of the research included (a) hardware acquisition and assembly for the collection of ultrasound scattering and optical image data, (b) software development for data acquisition, processing, and display, (c) mathematical analysis of factors influencing measurement of ultrasound scattering by tissue, and (d) correlation studies of ultrasound and optical data. Presentations describing the concepts, methods, and preliminary data have been made at scientific meetings to disseminate information to other investigators and potential users. |
| Title |
Projection ultrasound and ultrasound CT using a PE-CMOS sensor: a preliminary study. |
| Author |
Liu CC, Lo SCB, Freedman MT, Rich D, Kula J, lasser B, Lasser ME, Zeng JC, Ro D. |
| Journal |
Ultrason Imaging |
| Volume |
|
| Year |
2004 |
| Abstract |
The purpose of this study is to investigate the feasibility of generating 3D projection ultrasound computed tomography images using a transmission ultrasound system via a piezoelectric material coated CMOS ultrasound sensing array. There are four main components in the laboratory setup: (1) a transducer operated at 5MHz frequency generating unfocused ultrasound plane waves, (2) an acoustic compound lens that collects the energy and focuses ultrasound signals onto the detector array, and (3) a CMOS ultrasound sensing array (Model I100, Imperium Inc. Silver Spring, MD) that receives the ultrasound and converts the energy to analog voltage followed by a digital conversion, and (4) a stepping motor that controls the rotation of the target for each projection view. The CMOS array consists of 128×128 pixel elements with 85μm per pixel. The system can generate an ultrasound attenuation image similar to a digital image obtained from an x-ray projection system. A computed tomography (CT) study using the ultrasound projection was performed. The CMOS array acquired ultrasound attenuation images of the target. A total of 400 projections of the target image were generated to cover 180o rotation of the CT scan, each with 0.45° increment. Based on these 400 projection views, we rearranged each line profile in the corresponding projection views to form a sinogram. For each sinogram, we computed the cross section image of the target at the corresponding slice. Specifically, the projection ultrasound computed tomography (PUCT) images were reconstructed by applying the filtered back-projection method with scattering compensation technique. Based on the sequential 2D PUCT images of the target, we generated the 3D PUCT image. |
| Title |
Propagation of broadband ultrasound in attenuating media. |
| Author |
Simonds RM. |
| Journal |
Ultrason Imaging |
| Volume |
|
| Year |
1983 |
| Abstract |
An expression describing the time dependent evolution of broadband ultrasound wave forms is derived for signals propagating in a homogeneous tissue equivalent medium with an attenuation coefficient which is linearly proportional to frequency and for a class of pulse modulations which are analytic in the complex frequency plane. Results of the analysis are compared with those obtained by using a simple Gaussian modulation. It is shown that the frequency down shift produced by the medium causes predictable modifications in ultrasound beam widths and theoretical estimates are compared with published experimental data. |
| Title |
Propagation of finite-amplitude ultrasound in a relaxing liquid. |
| Author |
Ryan RP, Attanasio CR, Beyer RT. |
| Journal |
J Acoust Soc Am |
| Volume |
|
| Year |
1965 |
| Abstract |
Perturbation analysis is used to obtain expressions for the harmonic content of finite-amplitude waves propagated in a relaxing liquid. Comparison is made with similar expressions for the nonrelaxing case. Experimental measurements were made with 2.57 MHz fr pulses in a 0.2 M aqueous solution of MnSO4 to test the theoretical results. Agreement is excellent for the fundamental frequency. The second-harmonic curves have the correct shape but are 10-15% smaller in absolute magnitude. |
| Title |
Propagation of ultrasonic waves in suspensions and emulsions. 2. Relation between ultrasonic properties and certain characteristics of the medium. |
| Author |
Piotrowska A. |
| Journal |
Ultrasonics |
| Volume |
|
| Year |
1971 |
| Abstract |
The results obtained in the measurement of ultrasound velocity and absorption coefficient in pigment suspensions merit an attempt to interpret the functional dependence of these ultrasonic properties on suspension concentration and dispersion degree. |
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