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BRL Abstracts Database |
Your search for ultrasound produced 3296 results. Page 222 out of 330
Title |
Safety levels for exposure of cornea and lens to very high-frequency ultrasound. |
Author |
Silverman RH Lizzi FL Ursea BG Cozzarelli L Ketterling JA Deng CX Folberg R Coleman DJ. |
Journal |
J Ultrasound Med |
Volume |
|
Year |
2001 |
Abstract |
OBJECTIVE: Very high-frequency (50-MHz) ultrasound is widely used for imaging the anterior segment of the eye. Our aim was to determine whether exposures to ultrasound at and above those used in diagnostic imaging systems might cause bioeffects in ocular tissues. METHODS: We characterized the output parameters of a polyvinylidene difluoride transducer using a needle hydrophone. We exposed sites on the cornea or lens of rabbits for up to 30 minutes at a 10-kHz pulse repetition frequency. Tissue obtained immediately or 24 hours after exposure was examined by light microscopy. A numeric model was implemented to calculate expected temperature elevations in the cornea and lens under experimental conditions. RESULTS: No tissue changes were observed directly or by slit lamp. Light microscopy showed no abnormalities attributable to ultrasound exposure. Simulations showed that even long-term exposures should produce temperature elevations of less than 1 degree C in both the cornea and lens. CONCLUSION: With the use of exposure parameters 4 to 5 orders of magnitude greater than encountered in a clinical situation, no tissue changes were observed. This is consistent with the small (0.2 degrees C) temperature rises computed in simulations. The lack of biological effects is attributable to the small dimensions of the focal zone, allowing rapid dissipation of heat, and the low total acoustic power produced by the transducer. |
Title |
Safety of coronary ultrasound angioplasty: effects of sonication on intact canine coronary arteries. |
Author |
Rosenschein U, Rozenszajn LA, Bernheim J, Keren G, Alter A, Frimerman A, Laniado S, Roth A, Miller HI. |
Journal |
Cathet Cardiovasc Diagn |
Volume |
|
Year |
1995 |
Abstract |
The purpose of this work was to examine in vivo the safety of sonication in the coronary arteries in a live animal model. In intact dogs (n = 8), balloon dilatation was performed on the proximal left anterior descending artery (LAD) followed by sonication to the left circumflex artery (LCX) in power levels found to be optimal for thrombus ablation. Post-dilatation and post-ultrasound coronary angiography, echocardiography, histopathology, CK-MB, indices of hemolysis, and coagulation were compared. Sonication did not induce changes in the ECG or blood pressure. Coronary angiography.revealed no adverse side effects or change in arterial diameter (2.3 +/-.0.7 vs. 2.4 +/- 0.3 mm). Echocardiography showed transient.opacification of the myocardium. Histopathology revealed a.comparable minimal degree of endothelial denudation. After sonication there were no changes in the level of CK-MB (312 +/- 168.vs. 283 +/- 207 IU), hemoglobin (11.3 +/- 0.9 vs. 12.7 +/- 1.1.gr%), haptoglobin (479 +/- 136 vs. 451 +/- 121 mg/dL), fibrinogen (142 +/- 18 vs. 165 +/- 28 mg%), partial thromboplastin time (17.3.+/- 3.2 vs. 17.6 +/- 3.4 sec), prothrombin time (13.3 +/- 7.8 vs. 11.5 +/- 2.9 sec), and degree of platelet aggregation (55 +/- 17 vs..62 +/- 8%). Thus, the data suggest that transluminal coronary sonication exerts no overt adverse effects in vivo. |
Title |
Safety of diagnostic ultrasound - Evidence from therapy studies. |
Author |
ter Haar G. |
Journal |
Proc Int Symp Recent Adv Ultrasound Diagn - Dubrovnik |
Volume |
|
Year |
1979 |
Abstract |
No abstract available. |
Title |
Safety of diagnostic ultrasound in obstetrics. |
Author |
Hellman LM, Duffus GM, Donald I, Sunden B. |
Journal |
Lancet |
Volume |
|
Year |
1970 |
Abstract |
Ultrasound examinations were carried out on 1114 apparently normal pregnant women cared for in three different centres, at various stages of pregnancy and with differing ultrasonic frequencies throughout. The incidence of fetal abnormality in the group was 2-7%. Neither the time in gestation of the first examination nor the number of examinations seemed to increase the risk of fetal abnormality. |
Title |
Safety of medical ultrasound. |
Author |
ter Haar G. |
Journal |
Prog Med Ultrasound |
Volume |
|
Year |
1981 |
Abstract |
As the number of reports of biological changes induced by diagnostic ultrasound beams increases, it becomes more important that the intensity levels used in diagnostic examinations are kept to the minimum required to acquire the information needed. It should be remembered, however, that a biological change does not necessarily constitute a hazard to the patient. In this paper recent reports (published between September 1979 and September 1980) of ultrasonically induced changes in cells, in plants and in mammalian tissues are discussed in the context of earlier published observations. |
Title |
Safety of medical ultrasound. |
Author |
ter Haar G. |
Journal |
Prog Med Ultrasound |
Volume |
|
Year |
1980 |
Abstract |
A review is given and it is concluded that there are, at present, no substantiated reports that the risks of diagnostic ultrasound outweigh the benefits to be gained from its use. |
Title |
Safety of ultrasound with selective emphasis for obstetrics. |
Author |
O'Brien WD Jr. |
Journal |
Semin Ultrasound CT MR |
Volume |
|
Year |
1984 |
Abstract |
The need to understand the physical concepts which quantify the output of ultrasound equipment is fundamental. Manufacturers of equipment are beginning to provide these types of data. As clinical ultrasound equipment and its usage increase in sophistication, and the output power levels increase as the frequencies increase in response to the demands for improved resolution, quantitative output data may become essential information to the physician in the diagnostic decision. This section discusses the output exposure quantities of power and intensity in terms of what they mean and what their typical values are for current clinical equipment. During these discussions, the terms ?radiation? and ?irradiation? are employed. These are physical concepts that describe the nature and process of energy being transmitted as a wave. They do not necessarily mean that energy is ionizing. Throughout this article, the term radiation, when used by itself, means ultrasound radiation, and the term irradiation describes the wave process of ultrasonic energy. |
Title |
Safety of ultrasound. |
Author |
Nyborg WL. |
Journal |
Proc Third Eur Congr Ultrason Med - Bologna |
Volume |
|
Year |
1978 |
Abstract |
No abstract available. |
Title |
Safety of ultrasound. |
Author |
O'Brien WD Jr. |
Journal |
Book Chapter |
Volume |
|
Year |
1978 |
Abstract |
No abstract available. |
Title |
Safety standard for diagnostic ultrasound equipment. |
Author |
Unknown. |
Journal |
Rep NEMA |
Volume |
|
Year |
1981 |
Abstract |
No abstract available. |
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