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An evaluation of transvaginal ultrasound in the assessment of endometrial thickness in black South African patients presenting with postmenopausal uterine bleedingMoodley, Premla January 2004 (has links)
Dissertation submitted in full compliance with the requirements for the Master's degree in Technology: Radiography, Durban Institute of Technology, Durban, 2004. / The object of this study was to use Transvaginal ultrasound to evaluate the thickness of the endometrium to exclude endometrial abnormality in Black South African women with postmenopausal uterine bleeding. Transvaginal ultrasound is an excellent diagnostic method for assessing endometrial pathology. The study was carried out at the Gynaecological Ultrasound Department, King Edward VIII Hospital. The study included 76 Black women with postmenopausal uterine bleeding. The thickness of the endometrium was measured by Transvaginal ultrasound. The measurement included both endometrial layers (double-layer technique). The Transvaginal ultrasound measurement was compared with the histopathological diagnosis of the biopsy specimens. At the end of the investigation, findings obtained were 3.9% non-representative, 44.8% endometrial adenocarcinomas, 14.5% benign polyp, 3.9% chronic Endometritis, 17.1% benign endometrium, 5.3% endometrial hyperplasia, 9.2% atrophic endometrium, 3.9% myometrial invasion and 1.3% Malignant Mixed Mullerian Tumour. In this study, the thickness of the endometrial echo varied from 5mm to 35mm, with a mean of 18,2mm. When the thickness of the endometrial echo was compared with the histopathological results, the mean value for non-representative was 7.83mm, much lower than the thickness of an active endometrium (13.25mm). In cases with atrophic endometrium, the thickness ranged from 6mm to 30mm with a mean of 15.86mm. The mean value obtained for cases with endometrial adenocarcinoma was 20.32mm (range 11 to 35mm). The sensitivity, specificity and accuracy of Transvaginal ultrasound for detecting endometrial malignancy were 100% if the cutoff limit of 4mm was used
In conclusion, this study using Transvaginal ultrasound demonstrated that a thickness limit greater than 8mm was considered in detecting malignancy. No malignant endometrium was thinner than 5mm. Therefore in women with postmenopausal uterine bleeding and an endometrium less than 4mm, it may be justified not to perform further investigations. Transvaginal ultrasound is a simple,
well-tolerated safe and reliable method for identifying endometrial thickness in postmenopausal Black South African women. / M
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A random signal ultrasonic test system for highly attenuating mediaWhite, John D. H. January 1992 (has links)
No description available.
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Ultrasonic absorption by metal chelatesBartner, Jeffrey January 2011 (has links)
Digitized by Kansas Correctional Industries
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Effects of ultrasonic vibrations on heat transfer to liquids by natural convection and by boiling.Wong, Sau Wai. January 1966 (has links)
No description available.
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Control of travelling-wave ultrasonic motorsChung, Sheung-wai. January 2006 (has links)
Thesis (Ph. D.)--University of Hong Kong, 2006. / Title proper from title frame. Also available in printed format.
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Fundamental aspects of ultrasound contrast agent dynamic behaviors and inertial cavitation quantification /Tu, Juan. January 2006 (has links)
Thesis (Ph. D.)--University of Washington, 2006. / Vita. Includes bibliographical references (leaves 172-185).
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Attenuation models for material characterizationMaess, Johannes Thomas 18 November 2004 (has links)
Ultrasonic attenuation is a useful tool in characterizing the
damage state of different materials. The attenuation coefficients
for the incident longitudinal and transverse waves are both
derived from the scattering cross section of the material.
Scattering cross section is defined as the ratio of the scattered
energy to the incident energy. The incident wave field can be
scattered at inclusions, voids and material defects; there is also
grain boundary scattering in polycrystalline materials. For
accurate material characterization, it is important to distinguish
between the different types of scattering and to relate the
attenuation to its appropriate source. This study first solves the
single scatterer problem using either the Born approximation (for
difficult scatterer shapes and for anisotropic scatterers), or the
exact solution (in cases where it is necessary to provide an
accurate description of the viscoelastic behavior of the
surrounding effective medium). Multiple scattering effects are
investigated by a differential self-consistent scheme and a
self-consistent scheme. Both multiple scattering approaches are
applicable for each single scatterer solution. The differential
self-consistent scheme describes the scattering cross section
dependent on the volume fraction of the scatterers, and is
restricted to low volume fractions and materials, where the
surrounding material is clearly distinguished from the inclusions.
The self-consistent scheme is applicable to high volume fractions
of inclusions as well as to polycrystalline materials, where the
distinction between surrounding material and inclusions is not
possible.
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Ultrasonic characterization of layered composite systemsForbes, Michael F. 01 January 1986 (has links)
No description available.
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The Evaluation of the Material Deterioration of the Boiler Tubes.Wang, Ping-Chih 09 August 2005 (has links)
This research aims to develop a method to evaluate the deterioration of the tube material within a boiler, in order to reduce the failure of it. In this thesis, natural frequency measurement method and ultrasonic attenuation method are mainly applied, and it has reached to a conclusion that the ultrasonic attenuation method is more reliable.
Traditionally, the inspectors used the ultrasonic thickness measurement machine to evaluate the thickness and track the condition of a boiler. However, besides the thickness, the inspectors could not have clear understanding of the material and situation within a boiler. To improve the inspection effectiveness, the researcher measures the natural frequencies of the tube material in the new and old boilers by using natural frequency measurement. They found that the used tube material has been altered due to the difference between the natural frequencies.
The ultrasonic attenuation conditions of the tubes are also evaluated in this thesis. The echoes of the ultrasound propagating through the thickness of the tube can be analyzed by relative comparison and absolute comparison, respectively. The relative comparison compares the echoes of the multiple back reflections of the ultrasound between the tubes of old and new boilers. In addition, the absolute comparison analyzes the amplitude of the echoes of the ultrasonic multiple back reflection to calculate the ultrasonic attenuation of the tube. Besides the two major techniques, the material analysis, metallurgical analysis, internally scale analysis and mechanical property evaluation are also applied in this thesis to help developing a method to evaluate the deterioration of the tube material within a boiler.
This research demonstrates that the ultrasonic attenuation measuring methods can offer reliable results to evaluate the quality of the boiler.
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Acoustical methods to evaluate pore fluid saturant through casingGarcía Osuna, Fernando, January 2001 (has links)
Thesis (Ph. D.)--University of Texas at Austin, 2001. / Vita. Includes bibliographical references. Available also from UMI Company.
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