Global ETD Search
Search theses and dissertations gathered from participating repositories worldwide. Every result links back to the library that holds it. No account is needed.
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Showing 1 to 20 of 42 for “"Ultrasonic imaging"”.
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Improving ultrasonic imaging using novel coded excitation techniques
In ultrasound imaging, the axial resolution depends on the source bandwidth. Recently, a novel coded excitation and pulse compression technique, known as Resolution Enhancement Compression (REC), was developed. REC enhances the -6 dB bandwidth of an ultrasonic imaging system. In this dissertation, …
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Virtual source aperture ultrasonic imaging for non destructive testing
Ultrasonic testing is of huge importance when it comes to assessing the integrity of a huge variety of structures and components. Virtual Source Aperture (VSA) is an new advanced method of testing and is considered to be a hybrid between traditional phased array (PA) techniques and full matrix …
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Multiplexer Design for a Multi-Array Ultrasonic Imaging System
… of a novel conformable multi-array ultrasound imaging system. Synthetic array ultrasound data is acquired and processed using delay-and-sum beamforming to form individual array images, then the images are combined to provide an expanded field of view compared to a single-array system.
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All-optical photoacoustic and laser-ultrasonic imaging in heterogeneous tissue
… probe and image tissues up to centimeters deep. Ultrasonic (US) imaging is the most well-known modality used to image acoustic density and velocity contrasts. US is useful for imaging overall structure in tissue, however, acoustic contrasts are relatively low in biological tissue. In contrast, …
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Ultrasonic imaging methods for quantitative musculoskeletal tissue assessment and improved prosthetic interface design
… are limited since it relies on expensive imaging technologies and robotic indentation devices. Medical ultrasound imaging, a cost-effective modality that can be used at the bedside, is a promising and clinically-viable solution. In order for ultrasound to become a viable scanning method …
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A Column-Row-Parallel ASIC architecture for 3D wearable / portable medical ultrasonic imaging
… bonded to a 16x16 capacitive micromachined ultrasonic transducer (CMUT) to demonstrate the compact, low-power front-end assembly. A 3D plane-wave coherent compounding algorithm is designed for fast volume rate (62.5 volume/s), high quality 3D ultrasonic imaging. An interleaved checker board …
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Surface detection and object recognition in a real-time three-dimensional ultrasonic imaging system
Thesis (M.Eng.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 1999.
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Improved Techniques for Statistical Analysis of the Envelope of Backscattered Ultrasound Using the Homodyned K Distribution
Biomedical ultrasound is a prominent imaging modality for diagnostics. Conventional ultrasonic imaging is qualitative in nature with spatial resolution up to hundreds of micrometers. Quantitative ultrasound techniques based on ultrasonic backscatter can provide estimates describing tissue …
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Spatiotemporal excitation sequence manipulation and processing for Doppler ultrasound and pulse-echo sound speed imaging applications
Over the past several decades, plane wave based ultrasonic imaging applications have dominated the research landscape in biomedical ultrasonography. This is predominantly due to the inherent advantages of coherent plane wave compounding, in which steered plane waves are coherently summed to …
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New Developments on Quantitative Imaging Using Ultrasonic Waves
Although ultrasound imaging is widely used for medical applications, conventional sonographic B-mode images are qualitative. As a consequence, medical diagnosis using sonograms is commonly subjective and depends on the expertise of the operator. The need to obtain quantitative information from …
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Machining induced defects in Relaxor ferroelectric PMN-PT crystals
… sonar detectors as well as broad band medical ultrasonic imaging devices. Production of phased array probes utilizing these types of high performance ceramics requires dicing these crystals to arrays with pitches of less than the desired wavelength, ranging from tens to hundreds of micrometers. …
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Information theoretic design of breast sonography
… approaches to the design of medical ultrasonic imaging systems for specific visual tasks are being explored. Our study focuses on breast cancer diagnosis and is based on the ideal observer concept for visual discrimination tasks, whereby tasks based on five clinical features are …
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Minimally invasive capacitive micromachined ultrasonic transducers array For biomedical applications
… to medical diagnosis and treatment. The ultrasonic transducer plays an important role in determining the resolution, sensitivity, as well as other critical diagnostic capabilities of an ultrasonic detection or imaging system. Currently piezoelectric ultrasonic transducers dominate the …
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Quantification of Ultrasound Contrast Agents Using High-Frequency Ultrasound
… UCAs enhance the diagnostic capabilities of ultrasonic imaging. UCAs are associated with therapeutic or enhancing therapeutic applications of ultrasound and with possible adverse bioeffects. Quantification of the in vivo concentration of microbubbles is therefore essential to establishing a …
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Experiments and simulations on a metamaterial based ultrasonic scanner
… form of biometrics used to identify individuals. Ultrasonic fingerprint scanners use acoustic waves to obtain the fingerprint image and their performance is invariant to the surface conditions typically found on the finger surface due the ability of ultrasound to penetrate into sub-surfaces. This …
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Echogenic Biomaterials for Medical Ultrasound Tracking
… only capable of being tracked through x-ray imaging, will routinely experience complications due to thrombosis or accidental dislodgement from poor at-home care. Routinely, elderly patients will be forced to revisit the hospital to have the catheter replaced using x-ray imaging, exposing them …
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Acoustic Radiation Force on a Fluid to Fluid Boundary by Phase Plate Focused Ultrasound
… this study, the physics and applications of the ultrasonic radiation force at the interface between two immiscible fluids were investigated. These studies were performed using low-profile discrete-stepped lenses to the modify the phase of the incident radiation generating multiple field …
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High-resolution ultrasonic non-destructive testing
The use of ultra-short pulse wideband ultrasonic transducers in Non-Destructive-Testing (NDT) has been investigated both theoretically and experimentally. It is demonstrated that the resolution of pulse-echo NDT is affected by diffraction effects which also complicate the interpretation of echo …
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Null subtraction imaging technique for biomedical ultrasound imaging
In ultrasonic imaging, reduction of lateral sidelobes results in an improved image with less distortion and fewer artifacts. In general, apodization is used to lower sidelobes in exchange for increasing the width of the mainlobe and thus decreasing lateral resolution. Null subtraction imaging (NSI) …
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