Thesis (Ph.D.) -- University of Texas at Arlington, 2007.

Thesis (Ph. D.)--Rutgers University, 2009. / "Graduate Program in Electrical and Computer Engineering." Includes bibliographical references (p. 96-106).

Thesis (M. Phil.)--Hong Kong University of Science and Technology, 2003. / Includes bibliographical references (leaves 60-62). Also available in electronic version. Access restricted to campus users.

Thesis (M. S.)--Electrical and Computer Engineering, Georgia Institute of Technology, 2010. / Committee Chair: Jayant, Nikil; Committee Member: Anderson, David; Committee Member: Lee, Chin-Hui. Part of the SMARTech Electronic Thesis and Dissertation Collection.

By integrating three complementary imaging techniques - ultrasound, elasticity and photoacoustic imaging, a hybrid imaging system utilizing an array transducer is proposed for various biomedical imaging applications including cancer detection, diagnosis and therapy monitoring. Simultaneous imaging of the anatomy (ultrasound imaging), changes in biomechanical properties (elasticity imaging) and cancer-induced angiogenesis (photoacoustic imaging) of tissue is based on many synergistic features of these modalities and may result in a unique and important imaging tool. In this study, numerical analysis and experimental studies are presented to demonstrate the feasibility, to evaluate the performance, and also to improve the quality of the combined array-based ultrasound, elasticity and photoacoustic imaging system. To estimate spatial resolution, a point source was imaged using ultrasound and photoacoustic imaging modes. Then, several tissue mimicking phantoms were examined using ultrasound, photoacoustic and elasticity imaging. In elasticity imaging, ultrasound frames were acquired during deformation of the tissue. To reduce the data acquisition time of the system, high frame rate imaging was used. High frame rate imaging is possible by transmitting a broader and less focused ultrasound beam but the image quality is sacrificed. Thus, we compared the quality of the high frame rate and conventional ultrasound images. In photoacoustic imaging, acoustic transients are generated simultaneously in the entire volume of the laser irradiated tissue. Hence, image formation (beamforming) algorithms were developed based on the characteristics of the photoacoustic signals. Then, adaptive beamforming method is suggested to improve the image quality of the photoacoustic imaging. The results of the numerical analyses and experimental studies clearly indicate that ultrasound, elasticity and photoacoustic imaging techniques complement each other and together provide critical information needed for the reliable detection and diagnosis of diseases. / text

Not available / text

This thesis traces the developments of imaging technologies used for medical diagnosis. Giddens' sociological theory of modernity serves as a basis for the consideration of the bureaucratisation of medicine and the use of the patient file as source of information about health. The importance of 'inscriptions', in relation to scientific knowledge and power, is analysed through Bruno Latour's theory. Donna Haraway's call to rethink objectivity, not as a quality of universal knowledge, but as a given point of view, also influence the approach of this discussion of diagnostic practices. / The author demonstrates the need for abstract concepts of patient and disease to achieve modern medicine. The links between theoretical notions (anatomical pathology, in particular) and diagnostic practices, as well as the concept of objectivity underlying the use of technology to gather information about health are examined. The effects of the biostatistical method used to evaluate health are also discussed. Finally, the importance of context in the experience of illness is noted.

In this study, fluorescein angiograms of the ocular fundus have been digitised to enable them to be processed and analysed by computer. A fully automated technique for counting microaneurysms (MA) in these images was developed with a view to producing an objective, accurate and highly repeatable way of quantifying these lesions. Prior to any other image processing, a number of pre-processing stages were applied in order to compensate for non-uniformaties and to remove the background fluorescence component present in all the images. Matched filters modelled on two-dimensional Gaussian distributions were employed to detect MA in the 'shade-corrected' images. A binary image representation of the vascular network was constructed. This 'vessel mask', used in conjunction with the original match-filtered images, enabled MA to be detected by grey-level thresholding the filtered images. The resulting binary objects could then be counted by the computer as MA. The automated technique was assessed by comparing the computer's results for six fluorescein angiograms with MA counts obtained by ophthalmologists analysing both analogue and digital images. The performance of both man and machine were judged with respect to 'gold standards' compiled from prints of the original negatives. The best results were obtained by the clinicians analysing the analogue prints, although they differed greatly in their ability to detect microaneurysms. The computer performed better than the clinicians when they were counting MA in the digital images and produced highly repeatable results. To improve the performance of the automated technique, images were captured at approximately four times the previous spatial resolution and a smaller area of each image was analysed. Additionally, more complex image-processing techniques were employed to increase the accuracy of the computer analysis. Although the performance of the automated technique was improved, the computer results only matched those of the clinicians' analogue analyses for two of the images.

Early detection is one of the most important factors in the survival of patients diagnosed with breast cancer. For this reason the development of improved screening mammography methods is one of primary importance. One problem that is present in standard planar mammography, which is not solved with the introduction of digital mammography, is the possible masking of lesions by normal breast tissue because of the inherent collapse of three-dimensional anatomy into a two-dimensional image. Digital tomosynthesis imaging has the potential to avoid this effect by incorporating into the acquired image information on the vertical position of the features present in the breast. Previous studies have shown that at an approximately equivalent dose, the contrast-detail trends of several tomosynthesis methods are better than those of planar mammography. By optimizing the image acquisition parameters and the tomosynthesis reconstruction algorithm, it is believed that a tomosynthesis imaging system can be developed that provides more information on the presence of lesions while maintaining or reducing the dose to the patient. Before this imaging methodology can be translated to routine clinical use, a series of issues and concerns related to tomosynthesis imaging must be addressed. This work investigates the relevant physical processes to improve our understanding and enable the introduction of this tomographic imaging method to the realm of clinical breast imaging. The processes investigated in this work included the dosimetry involved in tomosynthesis imaging, x-ray scatter in the projection images, imaging system performance, and acquisition geometry. A comprehensive understanding of the glandular dose to the breast during tomosynthesis imaging, as well as the dose distribution to most of the radiosensitive tissues in the body from planar mammography, tomosynthesis and dedicated breast computed tomography was gained. The analysis of the behavior of x-ray scatter in tomosynthesis yielded an in-depth characterization of the variation of this effect in the projection images. Finally, the theoretical modeling of a tomosynthesis imaging system, combined with the other results of this work was used to find the geometrical parameters that maximize the quality of the tomosynthesis reconstruction.

Thesis (M.S.)--Ohio University, August, 2007. / Title from PDF t.p. Includes bibliographical references.