Thesis (Ph.D.)--Brown University, 2005. / Vita. Thesis advisor: Constantine Gatsonis. Includes bibliographical references (leaves 106-111). Also available online.

Thesis--Danmarks Tandlægehøjskole. / "Resumé" : p. [81]-83. "Case records" : p. [85]-188. Bibliography: p. [84].

Thesis (M. Med. Sc.)--University of Queensland, 2001. / Includes bibliographical references.

Magnetic Induction Tomography (MIT) is a non-invasive technique that utilises the passive electrical properties of a material to produce cross-sectional images. In MIT system, the signals detected by the sensors must be measured using a phase sensitive technique. A sub-millidegree phase stability is typically required for biological tissues, where the objects to be imaged have relatively low conductivity (< 2S/m). The phase noise and thermal related phase drift in the receiver's signal chain of currently available MIT systems are the major limiting factors of MIT performance for practical measurements. This thesis describes the development of a high precision DSP based signal measurement platform. It utilises multi-channel high speed digitisers to sample two or more signals simultaneously and phase differences between the signals are calculated by using FFT based algorithms. The algorithms are optimised for higher speed performance using parallel processing on both multi-core PC and graphic card processors. A faster approach based on a dedicated DSP processor for each MIT channel is later suggested to reduce data transfer speed limitations between the digitiser and the signal processing hardware. By formulating a phase noise estimation model to optimise the digitiser's setting, it is shown that better phase measurement precision and dynamic range can be achieved. To improve the phase drift for practical MIT measurements, a novel instrumentation amplifier was designed and it was incorporated into a new 5-channel annular array MIT prototype. The prototype was fully developed into a 14-channel Cardiff MIT-MKIIa system and both systems demonstrated sub-millidegree phase noise performance with a highly stable phase drift characteristic. To further investigate the MIT system for practical applications, phantom measurements were carried out to investigate the MIT system precision for detecting cerebral stroke and a single channel multi-frequency MIT system was built to perform spectroscopy measurements on biological samples.

Dissertation submitted in partial compliance with the requirements for the Master’s Degree in Technology: Chiropractic, Durban University of Technology, 2011. / Background: Low back pain is a common condition and affects most people at least once in their lives. The causes of low back pain (LBP) are numerous and may include non-specific mechanical causes, or specific causes which may be of a more serious nature. Researchers have tried to link specific history and physical examination findings with certain disorders, but as of yet, have been unsuccessful. Research has shown that x-rays may be over utilized and the guidelines for referral are not always adhered to. Furthermore, there is a paucity of literature on the role of x-rays in influencing the management of patients with low back pain. Objectives: The objectives of this retrospective study were: 1) to determine the relationship between the clinical and the radiographic diagnoses of patients with LBP, 2) to record the consultation at which a lumbar spine x-ray was requested by the student or clinician and the reasons thereof, 3) to record the suspected clinical diagnoses and management of the selected patients prior to referral for lumbar spine x-rays, 4) to determine the number of incidental radiographic findings in the selected patients’ x-rays, and 5) to determine any change in the clinical diagnoses and management following radiographic reporting of the selected patients’ x-rays. Method: The Chiropractic Day Clinic (CDC) at the Durban University of Technology (DUT) archives were searched for lumbar spine radiographs and the corresponding patient files of patients who presented with LBP from 1 January 1997 to 31 July 2010. Data collection was in a stepwise process with the anteroposterior and lateral lumbar spine x-rays being read first, without any knowledge of the patient’s main complaint and then the corresponding patient files were evaluated and selected clinical variables were recorded. Statistical analysis included the use of frequency counts, percentages, mean, standard deviation and range for the descriptive objectives. Diagnoses were categorized into specific groups and indicator variables were used to construct two-by-two tables of absence or presence of radiographic vs. clinical diagnosis for each specific diagnosis to determine any possible associations. Results: The mean age of the patients was 43.9 (± 16.9) years and the number of male and female patients were 40 and 34 respectively. It was not possible to correlate the clinical and radiographic diagnoses because the categories were too different for any statistical test to be performed. Spondylosis was the most common radiographic finding. The majority of the lumbar spine x-rays were requested at the first consultation. No suitable reason for obtaining the x-ray was provided in 14.6% of the x-rays requested and 20.7% were requested to examine for an unspecified pathology. Of the 74 patients in this study, 44 patients did not have a change in diagnosis, which means that 59.5% of the diagnoses stayed the same after x-ray examination. However, in 30 (40.5%) of cases the clinical diagnosis was changed following x-ray examination. This may indicate an overuse of x-rays at the CDC. Most patients were diagnosed with the non specific mechanical causes of low back pain. A wide range of treatment modalities were utilized both before and after x-rays were taken, including soft tissue therapies, electrotherapies and spinal manipulation. Following x-ray imaging there was a greater use of spinal manipulation ie. 62% versus only 39% of cases prior to imaging. Conclusion: Lumbar spine x-rays may be over utilised at the CDC but their findings were influential in the diagnosis and management in 30 (40.5%) of the patients. The majority of the clinical diagnoses were of the mechanical or non-specific causes of low back pain. / Durban University of Technology.

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No description available.

The shoulder is a complex anatomical structure and imaging plays an important role in the diagnosis and management of shoulder conditions. The complexity of the shoulder’s anatomy has led to the development of multiple radiographic projections and techniques within plain film imaging with each projection intended to demonstrate specific aspects of the anatomy of the shoulder. However, reproducing the required projections can be difficult especially if radiographers are not familiar with the projections and their evaluation criteria. Literature has revealed the importance of a comprehensive knowledge and understanding of anatomy, patient positioning, beam direction and centring point, and evaluation criteria to ensure a quality projection for accurate diagnoses. The aim of the study was to determine the knowledge and understanding of radiographers with regard to the supraspinatus outlet projection (SOP) for shoulder impingement syndrome (SIS) and its evaluation criteria. The inferences derived from the research findings were used to develop guidelines for a structured in-service training programme for practising radiographers to optimise their knowledge and understanding of the supraspinatus outlet projection in shoulder impingement syndrome. The proposed study followed a quantitative approach. Furthermore, a descriptive, exploratory, contextual design was employed. The research population consisted of practising radiographers working in the public and private hospitals of the Nelson Mandela Bay Municipality. The data were collected by means of a structured self-administered questionnaire. The questionnaire comprised of three sections. The first section requested demographic information from the participants. The second section assessed their knowledge and understanding regarding the scapular ‘Y’ and the supraspinatus outlet projections and shoulder impingement syndrome. The third section assessed their knowledge and understanding of anatomy and image evaluation/critiquing. The reliability and validity of the data collection instrument was ensured by conducting a pilot study and comparing the results with those of the main study. In addition, the expertise and guidance of a radiographer experienced in the clinical training of radiographers, the supervisor (who has twenty years’ experience in the teaching of radiographers) and a statistician was obtained. Descriptive and inferential statistical analyses were performed by means of a statistical programme and with the guidance of a statistician. The researcher ensured that the study was conducted in an ethical manner by adhering to the ethical principles of beneficence, justice and respect for persons.

No description available.

This dissertation presents the characterization and evaluation of a new radiological imaging modality, Toshiba Computed Radiography (TCR) 201. The characteristics of the TCR storage phosphor imaging plates such as energy-dependent x-ray quantum efficiency, stored signal decay, low exposure rate signal build-up, and spontaneous and stimulated gain measures are presented. The TCR 201 system is characterized by the signal transfer curve, the total root-mean-squared (rms) output noise, the signal-to-noise ratio, the modulation transfer function (MTF), its noise power spectrum (NPS), and the detective quantum efficiency (DQE). The system rms noise is photon-limited for exposures less than 1.0 mR, but has contributions from phosphor structure and quantization noise for exposures higher than 1.0 mR. The phosphor's information factor is shown to explain deviations from ideal photon-limited noise for exposures of less than 1.0 mR. The MTF of the system is measured for standard imaging plates, 10% at 2.8 lp/mm, and for high resolution imaging plates, 10% at 4.4 lp/mm. An expression for the NPS is statistically derived, and experimental measurements confirm the expression and show an increase in uncorrelated noise power above 1.0 mR which is consistent with rms measurements. Expressions for the DQE are presented. A psychophysical study is performed to directly compare the TCR to film/screen combinations in imaging low-contrast objects. The results of this study show the TCR provides better images for detectability as a function of exposure. Also, the use of the TCR 201 as a two dimensional dosimeter and in single-shot dual energy subtraction is presented.