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BRL Abstracts Database |
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Your search for ultrasound produced 3296 results. Page 154 out of 330
| Title |
Information exchange and problem assessment in ultrasound. |
| Author |
Report if Task Group 2. |
| Journal |
Rep Natl Sci Foundation APRTD |
| Volume |
|
| Year |
1976 |
| Abstract |
No abstract available. |
| Title |
Initial investigation of computed tomography for breast imaging with focused ultrasound beams. |
| Author |
Carson PL, Dick DE, Thieme GA, Dick ML, Bayly EJ, Oughton TV, Dubuque GL, Bay HP. |
| Journal |
Proc Twenty-second Annu Meet AIUM |
| Volume |
|
| Year |
1977 |
| Abstract |
No abstract available. |
| Title |
Initial testing of a clinical ultrasound mammography. |
| Author |
Devaney AJ. |
| Journal |
Acoust Imaging |
| Volume |
|
| Year |
1991 |
| Abstract |
No Abstract Available. |
| Title |
Initiation of polymerization with ultrasound in methyl methacrylate. |
| Author |
Kruus P, Patraboy TJ. |
| Journal |
J Phys Chem |
| Volume |
|
| Year |
1985 |
| Abstract |
Experiments with methyl methacrylate prove that polymerization can be initiated in a pure vinyl monomer with intense ultrasound. Variation of the polymerization rate with time, volume, and intensity are explained by a simple reaction mechanism. The number average molecular weight of the polymer produced is about 400 000 g mol(-1); rate constants for the polymerization mechanism obtained from the molecular weight data agree well with literature values. Presence of the radical scavenger DPPH inhibits the polymerization. The temperature dependence of the DPPH reaction is explained well over a wide (-17 to 40?C) temperature range by relations based on reversible or irreversible adiabatic collapse of the cavitation bubble. Furthermore it is in agreement with sonochemical experiments where composition rather than temperature was changed to vary the vapor pressure. Initiation rates calculated from polymerization rates and DPPH consumption rates are of the same order of magnitude but show an unexplainable difference in temperature dependence. A colored compound appears if the cavitation is carried out at lower temperatures. |
| Title |
Injury and recovery of spirogyra exposed to ultraound. |
| Author |
Goldman DE, Lepeschkin WW. |
| Journal |
Rep Nav Med Res Inst |
| Volume |
|
| Year |
1956 |
| Abstract |
The time sequence of morphological changes in Spirogyra filaments during exposure to ultrasound at 400 and 700 kc. shows a definite pattern. Injury to the cells increases to a maximum at 5 to 15 minutes, and is followed by a partial recovery which is maintained for an hour, provided that the ultrasound is of moderate intensity. Intense ultrasound produces a rapid progressive injury and death of cells with no maximum in the injury-time curve. Temperature changes and small concentrations of ethyl ether affect the injury-recovery processes. The behavior of the system is fairly well described by a rather simple, non-linear differential equation. |
| Title |
Injury induced in isolated muscle fiber by locally applied ultrasound. |
| Author |
Wilson WL,Wiercinski FJ,Schnitzler RM. |
| Journal |
J Acoust Soc Am |
| Volume |
|
| Year |
1965 |
| Abstract |
A muscle fiber was sonated by means of a needle machined into the tip of a steel acoustic horn. During sonation of a fiber in Ringer solution, there is a breakdown of cross striations in the region close to the needle tip and a movement of sarcoplasm toward this injured region. At cessation of sonation, the movement of sarcoplasm towards the injured region ceases and reverses direction: striation breakdown proceeds along the length of the fiber. Sonation does not evoke injury or sarcoplasmic movement when a fiber is immersed in paraffin oil, calcium-free Ringer, or in isotonic solutions of KCl, NaCl, or Na oxalate. If any one of these solutions is replaced by unbuffered Ringer, or if calcium ion is added to any one of these solutions, movement and injury can be evoked. Sarcoplasmic movement and injury occur in CaCl2 solutions as dilute as 0.001 M. This response to ultrasound appears to be calcium-ion-dependent. Apparently sonation increases membrane permeability to calcium ion. |
| Title |
Insonation of fixed porcine kidney by a prototype sector-vortex-phased array applicator. |
| Author |
Umemura SI, Holmes KR, Frizzell LA, Cain CA. |
| Journal |
Int J Hyperthermia |
| Volume |
|
| Year |
1992 |
| Abstract |
The sector-vortex applicator, an ultrasound phased array with a geometric focus having multiple sectors and tracks, can directly synthesize, without scanning, diffuse focal patterns useful for hyperthermia. A perfused tissue phantom, consisting of an alcohol-fixed porcine kidney with thermocouples placed in the cortex, is insonated by a prototype sector-vortex applicator with 16 sectors and two tracks at an ultrasound frequency of 750 kHz. Steady-state temperature distributions are measured for a wide range of perfusion rates. Results demonstrate that the radius of the heated region can be controlled effectively by choosing the focal mode of the applicator as it is predicted by theoretical analysis. |
| Title |
Instantaneous frequency-based ultrasonic temperature estimation during focused ultrasound thermal therapy. |
| Author |
Liu HL, Li ML, Shih TC, Huang SM, Lu IY, Lin DY, Lin SM, Ju KC. |
| Journal |
Ultrasound Med Biol |
| Volume |
|
| Year |
2009 |
| Abstract |
Focused ultrasound thermal therapy relies on temperature monitoring for treatment guidance and assurance of targeting and dose control. One potential approach is to monitor temperature change through ultrasonic-backscattered signal processing. The current approach involves the detection of echo time-shifts based on cross-correlation processing from segmented radiofrequency (RF) data. In this study, we propose a novel ultrasonic temperature-measurement approach that detects changes in instantaneous frequency along the imaging beam direction. Focused ultrasound was used as the heating source, and the 1-D beamformed RF signals provided from an ultrasound imager were used to verify the proposed algorithm for temperature change estimation. For comparison, a conventional cross-correlation technique was also evaluated. Heating experiments testing tissue-mimicking phantoms and ex vivo porcine muscles were conducted. The results showed that temperature can be well estimated by the proposed algorithm in the temperature range, where the relationship of sound speed versus temperature is linear. Compared with the cross-correlation-based algorithm, the proposed new algorithm yields a six-fold increase in computational efficiency, along with comparable contrast-detection ability and precision. This new algorithm may serve as an alternative method for implementing temperature estimation into a clinical ultrasound imager for thermal therapy guidance. (E-mail: kcju@isu.edu.tw). |
| Title |
Instrument for microscopical observation of the biophysical effects of ultrasound. |
| Author |
Miller DL. |
| Journal |
J Acoust Soc Am |
| Volume |
|
| Year |
1976 |
| Abstract |
In this instrument, a quartz driver, thickness resonant at 1 MHz, and a thin cover were concentrically mounted on the stage of a microscope. Electroding was omitted over a central area to allow transmitted-light observation of the test space between them. We approximate the acoustic field generated in the cylindrical test volume by a standing-wave solution to the linearized wave equation. The boundary values were (i) zero pressure and the radial boundary and (ii) interferometrically determined values of the acoustic displacement at the driver and cover. The truncated-series solution was successfully used to explain the radiation-force-induced migration of small polystyrene spheres suspended in the water-filled test space. In addition, the determined pressure distribution substantially agreed with independent measurements obtained by interferometrically detecting (via the acousto-optical interaction) the pressure oscillations, averaged over height. |
| Title |
Intense focused ultrasound in medicine. Some practical guiding physical principles from sound source to focal site in tissue. |
| Author |
Fry FJ. |
| Journal |
Eur Uro |
| Volume |
|
| Year |
1993 |
| Abstract |
No Abstract available. |
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