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BRL Abstracts Database |
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Your search for ultrasound produced 3296 results. Page 36 out of 330
| Title |
An extremely simple and rapid method for registration of ultrasonic field patterns. |
| Author |
Sarvazyan AP, Pashovkin TN, Shilnikov GV. |
| Journal |
Proc Ultrason Symp IEEE |
| Volume |
|
| Year |
1985 |
| Abstract |
Conventional methods of visualization of ultrasonic field patterns for characterization of transducers and checking the output of ultrasonic therapy generators, for many applications of ultrasound in nondestructing evaluation in industry, medicine and biology require complicated specialized equipment. A very simple and rapid method of visualization of ultrasonic fields which requires only a piece of white paper, a water tank and a few drops of a dye is described. |
| Title |
An histological study of the effect of ultrasound on growth of Vicia faba roots. |
| Author |
Miller MW, Vorhees SM, Carstensen EL, Eames FA. |
| Journal |
Radiat Bot |
| Volume |
|
| Year |
1974 |
| Abstract |
Ultrasound (2 MHz) at intensities of 8, 12, and 20 W/cm2 induced immediately rupture of the cortical cell walls in the elongation zone of the primary root. At the low intensity individual or small clusters of necrotic nuclei in collapsing cells were observed at 12 hr post-sonication; root integrity appeared to be maintained. At the high intensity, cell rupture, loss of turgor, and loss of internal organization were observed. It is postulated that the effects of ultrasound are mediated by mechanical factors. |
| Title |
An ideal observer approach to mechanical limits in B-Mode ultrasound imaging |
| Author |
Abbey CK, Nguyen NQ, O'Brien WD Jr, Insana MF. |
| Journal |
34th Annual International Conference of the IEEE EMBS |
| Volume |
|
| Year |
2012 |
| Abstract |
In medical applications, the amplitude of
ultrasonic pulses is often constrained by mechanical
considerations summarized by a mechanical index. We
apply the ideal observer approach in a simulation
environment to evaluating the role of mechanical index
limits on task performance in b-mode ultrasonic imaging.
We simulate a linear array operating at 15MHz and 60%
fractional bandwidth, and consider three tasks related to
breast sonography at a depth of 4cm. The ideal observer
suggests that there are gains in performance – and hence
the quantity of diagnostic information – as the limit on
mechanical index is raised. However these gains are
almost completely erased after computation of a
standard b-mode envelope. |
| Title |
An image‐guided ultrasound phased array system for noninvasive surgery. |
| Author |
Ebbini ES, Vanbaren PD, Simon C. |
| Journal |
J Acoust Soc Am |
| Volume |
|
| Year |
1998 |
| Abstract |
An integrated image‐guided therapeutic phased array system for noninvasive surgical applications is being developed. The therapeutic array utilizes piezocomposite transducer technology and operates (therapeutically) at 1 and 2 MHz. It has 64 elements on a spherical shell with a geometric center at 100 mm from its apex. The array was shown to be capable of producing well‐defined thermal lesions in tissue media at depths from 40 to 60 mm and to scan therapeutic foci up to ±15 mm from its geometric center. Image guidance is provided by a modified diagnostic ultrasound scanner which, in addition to providing standard B‐scan images of the target region, provides real‐time images of the temperature rise due to the therapeutic beam. The temperature information is obtained using a correlation based algorithm for echo displacement estimation, which can be directly related to local variation in tissue temperature due to the therapeutic beam. A complete description of the system will be given along with illustrative examples of image‐guided tissue ablation and temperature estimation and control. In addition, experimental data demonstrating the use of the therapeutic array in an imaging mode will be presented. |
| Title |
An in vitro study of the effect of ultrasound on the cell membrane permeability of ascites tumor cells to adenine-8-C-14. |
| Author |
Cannon MP. |
| Journal |
Thesis(MS): Catholic Univ of America |
| Volume |
|
| Year |
1962 |
| Abstract |
No abstract available. |
| Title |
An in vivo rat model simulating imaging of human kidney by diagnostic ultrasound with gas-body contrast agent. |
| Author |
Miller DL, Dou C, Wiggins RC, Wharram BL, Goyal M, Williams AR. |
| Journal |
Ultrasound Med Biol |
| Volume |
|
| Year |
2007 |
| Abstract |
One kidney of anesthetized rats was imaged by diagnostic ultrasound with contrast agent under conditions simulating both the geometry and the attenuation encountered during human perfusion imaging. Contrary to earlier predictions, glomerular capillary rupture with blood loss into Bowman’s space and proximal tubules occurred in our clinically relevant model system. Quantitative analysis of histologic sections showed that 37 ± 5% of the glomeruli at the center of the scan plane had blood cells in Bowman’s space after imaging for 1 min with 1.8 MPa (mechanical index equivalent, MIe = 1.5) with a 1 s image trigger interval during IV injection of 10 μl/kg/min of Definity® contrast agent (as recommended by the manufacturer). This percentage decreased rapidly with decreasing peak rarefactional pressure amplitude to an apparent threshold of 0.73 MPa (MIe = 0.6). The percentage of glomeruli with hemorrhage decreased in proportion to dose when reduced below the recommended value, but leveled-off at doses above it. The percentage of glomerular hemorrhage increased with increasing numbers of image exposures, with an initial rate of 1.1% per image. The glomerular hemorrhage also depended on the frame trigger interval with no hemorrhage evident for continuous imaging but a maximal effect for trigger intervals greater than about 1 s. These results indicated that there is a potential for clinical diagnostic ultrasound with contrast agent to induce glomerular hemorrhage. |
| Title |
An investigation into possible chromosome damaging effects of.ultrasound on human blood cells. |
| Author |
Buckton KE, Baker NV. |
| Journal |
Br J Radiol |
| Volume |
|
| Year |
1972 |
| Abstract |
No abstract available. |
| Title |
An investigation into the effect of pulsed ultrasound on the brain. |
| Author |
Garg AG, Taylor AR. |
| Journal |
Ultrasonics |
| Volume |
|
| Year |
1967 |
| Abstract |
The effect of pulsed ultrasound on the human brain, for longer times that that administered in diagnostic work, in five adult patients and one child was studied by clinical evaluation, electro-encephalography, biochemical and histopathological studies. Exposure for one hour to pulsed ultrasound, through scalp and bone, with a 2MHz frequency crystal, emitting 430 pulses/sec, with each pulse lasting for 1ms, was found harmless. The pulse strength of the apparatus used in one microsecond is about 10 watts, resulting in a mean strength of about 5 milliwatts and an ultrasonic dose of 1 milliwatt per centimeter square. |
| Title |
An investigation into the possible genetic hazards of ultrasound. |
| Author |
Lyon MF, Simpson GM. |
| Journal |
Br J Radiol |
| Volume |
|
| Year |
1974 |
| Abstract |
Tests for genetic damage were made on mice whose gonads had been exposed to ultrasound of frequency 1.5 MHz for 15 minutes, while they were anaesthetized and suspended in water. The ultrasonic exposure as either continuous wave (intensity 1.6 W/cm2) or pulsed in milliseconds (1 msec pulse; mark: space ratio 1:3; average intensity 1.6 W/cm2) or microseconds (30 microsecond pulse; mark: space ratio 1:49; average intensity 0.9 W/cm2) and results were compared with those from similarly anaesthetized and submersed controls and from mice exposed to 100 rad X rays in air. There was no evidence of induction by ultrasound of dominant lethal mutations or sterility in males, no drop in testes weight or sperm count, and no induction of translocations or chromosome fragments in spermatocytes, for up to eight weeks after treatment..Similarly, in females no dominant lethal induction was detected in he period from several days before mating to the day of mating. By contrast, clear genetic damage was observed in the X-ray treated animals. There was a significant increase in sterile matings among females treated with 30 microsecond pulsed ultrasound one to several days prior to mating, or with continuous wave ultrasund n the da of mating. Thus, the doses used were near to the maximum that could be given without sterilizing the animals. From these results it is considered unlikely that the use of ultrasound in antenatal diagnosis presents any genetic hazards to mother or fetus. |
| Title |
An investigation into ultrasonic methods of imaging the tissue ablation induced during focused ultrasound surgery. |
| Author |
Malcolm AL. |
| Journal |
Thesis(PhD): Univ of London |
| Volume |
|
| Year |
Unknown |
| Abstract |
No abstract available. |
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