Thesis (M. Sc.)--Carleton University, 2001. / Includes bibliographical references (p. 86-96). Also available in electronic format on the Internet.

This thesis examines the way in which purpose and identity are realised in the written case reports of radiography students in comparison with those of professional writers. Students entering a new discourse community have to take on a new social identity and this identity is expressed by means of familiarity with the appropriate discourse conventions, including genre as the most overt expression of rhetorical purpose. Also important are the pragmatic choices used by writers to guide readers’ understanding of text and to construct interaction between them, i.e. metadiscourse, which here provides an additional and complementary way of viewing purpose and identity. The study aims, at a more theoretical level, to make a contribution to writing research by integrating genre analysis and metadiscourse analysis within a single framework to provide new insight into the resources available to writers to construe identity in text. At a descriptive level, it provides analyses of a hitherto neglected genre of medical writing. Because the study compares the writing of novices and professionals, the description of this genre makes findings available for pedagogical application. Radiographers and radiologists work as members of the same professional teams and both publish case reports, often in the same journals. Data for the study is provided by two corpora of reports, one produced by radiography students and the other published in national journals by professionals. The genre analysis establishes the move structure of the radiological case study for both corpora and a cross-corpus analysis of metadiscourse demonstrates how identity is realised in the text as the moves unfold. Both quantitative and qualitative approaches are adopted with regard to the data. The student reports appear to be examples of a sub-genre of case reports with the move structure and metadiscoursal strategies differing in several significant ways, reflecting the different purposes and identities of the writers. Student writers are found not to be concerned with the more persuasive rhetorical functions of the genre and tend to align themselves with the viewpoint of the patient rather than the medical profession, drawing on school essay discourse and making use of metadiscoursal strategies associated with textbooks. / Linguistics and Modern Languages / D.Litt. et Phil. (Linguistics)

M.Tech. (Radiography) / The Radiology Information System and the Picture Archiving and Communication System have contributed to improved patient care by eradicating delays in the clinical management of patients. This is achieved by permitting access to instantaneous radiology interpretations and secondary consultations; creating a basis for teleradiology and reducing storage costs by replacing conventional archives with cheaper digital storage. However, the former has attributed to the recent rise in confidentiality breaches involving medical data in the United States of America. Yet, reports of this nature remain unknown in the South African context. Breaches by authorised users remain an under investigated issue and continue to threaten the confidentiality of data. This assumption was employed as the conceptual basis for this study while, the Theory of Planned Behaviour was utilised to generate probable causes of deviant behaviour. A sample of health professionals (n=115) and information technologists (n=2) was drawn to collect data. The extent of compliance was expressed as a percentage error of the discrepancy between the observed behaviour and the regulations stipulated by the Health Insurance Portability and Accountability Act. The independent variable (work practices) were categorised into access restriction, intrinsic security measures and the actual breach incidences. The non-parametric Chi-Square test was used to calculate statistical significance the correlational extent of which was determined using the phi coefficient. Both Research Settings indicated poor compliance (percentage errors of 67.3 and 70.37) with the mandated regulations. The study provides insight about the confidentiality status within the South African context. This is the kind of information sought by regulators to aid keep pace with the rapid advances in Information Technology.

This research was conducted to obtain information regarding the feasibility of using non-medical personnel to obtain measurements of radiologic total lung capacity (TLC). Operators from each of four groups (general undergraduates, nursing students, medical students, radiologists) differing in the amount of medical training and/or experience reading x-rays, performed each of two tasks. The first task was the measurement of radiologic TLC for a set of twenty x-rays. The second task consisted of tracing the outline of the anatomical structures that must be identified in the execution of the radiologic TLC measurement task. Data from the radiologic TLC measurement task were used to identify possible group differences in the reliability and validity of the measures. The reliability analyses were performed within the framework of Generalizability Theory. While the results are not conclusive, due to small sample sizes, the analyses suggest that group differences in reliability of the measures, if they exist, are small. The concurrent validity of the measures was assessed by obtaining, for each experience level, the correlation between the group mean radiologic TLC for a film set and the TLC for that patient, obtained from a body plethysmograph. Only small differences in the group correlation coefficients were observed. A liberal test of these differences indicated they were not statistically significant. Additionally, two experience level by film sets ANOVAs were performed to determine possible group differences in how well the actual magnitudes of the radiologic TLC measures approximated those obtained with the body plethysmograph. These analyses indicated that the magnitude of the differences between radiologic and plethysmographic TLC measures were smaller for the undergraduates than for the nursing students and radiologists. Lastly, a number of analyses of the anatomical structure tracings were performed. Few interpretable group differences were found.

Thesis (MScEng (Mathematical Sciences. Applied Mathematics))--Stellenbosch University, 2008. / The medical radiation treatment facility at iThemba Labs requires a precise and robust patient positioning system. The current system makes use of an accurately calibrated multi-camera stereophotogrammetry (SPG) setup that is vulnerable to physical disruptions that invalidate system calibration. The task in this thesis is to design a vision system that can be used to verify the correct operation of the SPG system. We propose an unscented Kalman filter (UKF) based structure from motion (SFM) system for this purpose. Our SFM system does not rely on calibration information used by the SPG system and provides accurate reconstruction for verification purposes. The system is critically evaluated against a set of synthetic and real motion sequences.

Ao longo da evolução dos equipamentos e exames radiológicos, a exposição dos pacientes e trabalhadores envolvidos tem aumentado em grande proporção. Esta exposição não deve ser subestimada, uma vez que acumulada ao longo dos anos pode trazer riscos para a saúde do indivíduo exposto. O objetivo deste trabalho foi verificar a taxa de exposição de trabalhadores à radiação ionizante. Foram realizadas simulações do exame de uretrocistografia utilizando-se de uma câmara de ionização, para verificar a taxa de exposição, colocando-se dosímetros termoluminescentes de em cada espalhador verificando a dose efetiva em locais específicos do corpo do indivíduo ocupacionalmente exposto durante o procedimento. A posição da mesa de exames foi variada durante a exposição para avaliar se esta tem influencia na dose recebida pelos trabalhadores. Os resultados revelaram uma grande diminuição da dose quando a posição da mesa está na horizontal. O aumento da distância dos espalhadores ao paciente teve uma diminuição significativa da taxa de exposição. A maioria dos resultados se apresentou abaixo dos limites preconizados, porém o dosímetro colocado na altura do tórax do espalhador posicionado mais próximo ao paciente excedeu este limite. Portanto, os procedimentos de trabalho devem ser sempre observados com o intuito de manter os limites dentro de um nível de segurança. / Throughout the evolution of radiological equipment and tests, the exposure of patients and workers involved has increased to a great extent. This exhibition should not be underestimated, since accumulated over the years can bring risks to the health of the exposed individual. The objective of this study was to determine the rate of exposure of workers in an X-ray room. Examining urethrocystography simulations were performed using an ionization chamber, to verify the exposure rate, and thermoluminescent dosimeters in each cap to check the effective dose in specific locations of the individual's body occupationally exposed in the examen. The position of the examination table was varied during exposure to assess whether this has influence on the dose received by the workers. The results showed a large decrease in dose when the table position is horizontally. Increased distance spreaders of the patient had a significant decrease in exposure rate. The majority of results presented below recommended limits, but the dosimeter positioned at the height of the thorax on the spreader lens closest to the patient exceeded this limit. Therefore, work procedures should always be observed in order to keep within the limits of a security level.

Ao longo da evolução dos equipamentos e exames radiológicos, a exposição dos pacientes e trabalhadores envolvidos tem aumentado em grande proporção. Esta exposição não deve ser subestimada, uma vez que acumulada ao longo dos anos pode trazer riscos para a saúde do indivíduo exposto. O objetivo deste trabalho foi verificar a taxa de exposição de trabalhadores à radiação ionizante. Foram realizadas simulações do exame de uretrocistografia utilizando-se de uma câmara de ionização, para verificar a taxa de exposição, colocando-se dosímetros termoluminescentes de em cada espalhador verificando a dose efetiva em locais específicos do corpo do indivíduo ocupacionalmente exposto durante o procedimento. A posição da mesa de exames foi variada durante a exposição para avaliar se esta tem influencia na dose recebida pelos trabalhadores. Os resultados revelaram uma grande diminuição da dose quando a posição da mesa está na horizontal. O aumento da distância dos espalhadores ao paciente teve uma diminuição significativa da taxa de exposição. A maioria dos resultados se apresentou abaixo dos limites preconizados, porém o dosímetro colocado na altura do tórax do espalhador posicionado mais próximo ao paciente excedeu este limite. Portanto, os procedimentos de trabalho devem ser sempre observados com o intuito de manter os limites dentro de um nível de segurança. / Throughout the evolution of radiological equipment and tests, the exposure of patients and workers involved has increased to a great extent. This exhibition should not be underestimated, since accumulated over the years can bring risks to the health of the exposed individual. The objective of this study was to determine the rate of exposure of workers in an X-ray room. Examining urethrocystography simulations were performed using an ionization chamber, to verify the exposure rate, and thermoluminescent dosimeters in each cap to check the effective dose in specific locations of the individual's body occupationally exposed in the examen. The position of the examination table was varied during exposure to assess whether this has influence on the dose received by the workers. The results showed a large decrease in dose when the table position is horizontally. Increased distance spreaders of the patient had a significant decrease in exposure rate. The majority of results presented below recommended limits, but the dosimeter positioned at the height of the thorax on the spreader lens closest to the patient exceeded this limit. Therefore, work procedures should always be observed in order to keep within the limits of a security level.

Cerebral ischemia is a vascular disorder that is characterized by the reduction of blood supply to the brain, resulting in impaired metabolism and finally death of brain cells. Cerebral ischemia is a major clinical problem associated with global morbidity and mortality rates of about 30%. Clinical management of cerebral ischemia relies heavily on perfusion analysis using dynamic susceptibility contrast MRI (DSC-MRI). DSC-MRI analysis is performed using mathematical models that simulate the underlying vascular physiology of brain. Cerebral perfusion is calculated using perfusion imaging and is used as a marker of tissue health status; low perfusion being an indicator of impaired tissue metabolism. In addition to measurement of cerebral perfusion, it is possible to quantify the blood flow variation within the capillary network referred to as cerebral microvascular hemodynamics. It has been hypothesized that microvascular hemodynamics are closely associated with tissue oxygenation and that hemodynamics might undergo a considerable amount of variation to maintain normal tissue metabolism under conditions of ischemic stress. However with DSC-MRI perfusion imaging, quantification of cerebral hemodynamics still remains a big challenge. Singular Value Decomposition (SVD) is currently a standard methodology for estimation of cerebral perfusion with DSC-MRI in both research and clinical settings. It is a robust technique for quantification of cerebral perfusion, however, the quantification of hemodynamic information cannot be achieved with SVD methods because of the non-physiological behaviour of SVD in microvascular hemodynamic estimation. SVD is sensitive to the noise in the MR signal which appears in the calculated microvascular hemodynamics, thus making it difficult to interpret for pathophysiological significance. Other methods, including model-based approaches or methods based on likelihood estimation, stochastic modeling and Gaussian processes, have been proposed. However, none of these have become established as a means to study tissue hemodynamics in perfusion imaging. Possibly because of the associated constrains in these methodologies that limited their sensitivity to hemodynamic variation in vivo. The objective of the research presented in this thesis is to develop and to evaluate a method to perform a quantitative estimation of cerebral hemodynamics using DSC-MRI. A new Control Point Interpolation (CPI) method has been developed to perform a non-parametric analysis for DSC-MRI. The CPI method was found to be more accurate in estimation of cerebral perfusion than the alternative methods. Capillary hemodynamics were calculated by estimating the transit time distribution of the tissue capillary network using the CPI method. The variations in transit time distribution showed quantitative differences between normal tissue and tissue under ischemic stress. The method has been corrected for the effects of macrovascular bolus dispersion and tested over a larger clinical cohort of patients with atherosclerosis. CPI method is thus a promising method for quantifying cerebral hemodynamics using perfusion imaging. CPI method is an attempt to evaluate the use of quantitative hemodynamic information in diagnostic and prognostic monitoring of patients with ischemia and vascular diseases.

Thesis (D.Tech.: Radiography)-Dept. of Radiography, Durban Institute of Technology, 2006 xxiii, 166 leaves / The purpose of this study was to evaluate 99mTc- methoxyisobutylisonitrile (MIBI) imaging, in terms of sensitivity and specificity, for non invasively detecting extracutaneous involvement of Kaposi’s sarcoma (KS) and for differentiating pulmonary infection from malignancy in acquired immunodeficiency syndrome (AIDS) patients before and after treatment. Current investigations are invasive.

Thesis (D.Tech.: Radiography)-Dept. of Radiography, Durban Institute of Technology, 2006 xxiii, 166 leaves / The purpose of this study was to evaluate 99mTc- methoxyisobutylisonitrile (MIBI) imaging, in terms of sensitivity and specificity, for non invasively detecting extracutaneous involvement of Kaposi’s sarcoma (KS) and for differentiating pulmonary infection from malignancy in acquired immunodeficiency syndrome (AIDS) patients before and after treatment. Current investigations are invasive.