Thesis (PhD) -- University of Canberra, 2006. / Thesis submitted in fulfilment of the requirements for the degree of Master of Information Science in the School of Information Sciences and Engineering under the Division of Business, Law and Sciences at the University of Canberra, May 2006. Bibliography: leaves 120-132.

published_or_final_version / Computer Science / Master / Master of Philosophy

Made available in DSpace on 2015-06-17T19:34:19Z (GMT). No. of bitstreams: 0 Previous issue date: 2014-07-31. Added 1 bitstream(s) on 2015-06-18T12:49:04Z : No. of bitstreams: 1 000831392.pdf: 1327749 bytes, checksum: c3b1aa57fef6b19f5e5e19cb0ffbcd09 (MD5) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / Este trabalho teve como objetivo a otimização de imagens de radiografia computadorizada (CR, do inglês, computed radiography) de crânio e tórax de pacientes pediátricos entre 1 e 5 anos de idade. Para atingir esse objetivo foram desenvolvidos fantomas homogêneos pediátricos, que simularam a faixa etária em estudo, a partir de exames retrospectivos de tomografia computadorizada (CT, do inglês, computed tomography). Nesse procedimento foi utilizado um algoritmo computacional para quantificar as espessuras médias de tecidos biológicos (tecido pulmonar, adiposo, mole e ósseo) presentes nas regiões anatômicas em estudo. Essas espessuras foram convertidas em materiais simuladores (lucite e alumínio) de modo a compor os fantomas homogêneos de crânio e tórax. As incertezas relativas no processo de quantificação dos exames de crânio foram de 3,5% para tecido mole e 9,5% para tecido ósseo. Na quantificação dos exames de tórax a incerteza relativa foi de 19,4% para o tecido pulmonar, 13,0% para o tecido mole e 20,0% para o tecido ósseo. O fantoma de tórax foi construído com 7,3 cm de lucite distribuídos em 4 placas de mesma espessura (15,0 x 15,0 x 1,82) cm³ arranjadas em dois pares, separadas por um espaçamento de ar de 2,86 cm. Duas placas de alumínio de (15,0 x 15,0 x 0,13) cm³ e (150,0 x 150,0 x 1,0) mm³ foram inseridas, respetivamente, entre os pares superior e inferior de lucite. O fantoma de crânio foi construído com 11,98 cm de lucite distribuídos em cinco placas de mesma espessura (15,0 x 15,0 x 2,33) cm³. Duas placas de alumínio (15,0 x 15,0 x 0,16) cm³ e (15,0 x 15,0 x 0,12) cm³ foram inseridas, respectivamente, entre os pares superior e inferior de lucite. Os fantomas homogêneos foram utilizados no processo de otimização de imagens em sistemas CR, para calibração do feixe de raios X. No processo de calibração foram determinadas técnicas-teste (combinação kVp e mAs), que produziram índices de ... / The aim of this work was to optimize computed radiography techniques of skull and chest for pediatric patients between 1 and 5 years old. To achieve this goal, pediatric homogenous phantoms were developed from retrospective computed tomography (CT) scans. In this procedure, a computational algorithm was used to quantify the average thickness of biological tissue (lung, fat, soft and bone tissue) present on the anatomic region under study. These thicknesses were converted into simulators materials (Lucite and aluminum) to build the homogeneous phantoms of skull and chest. The relative uncertainties in the quantification process of skull examinations were 3.5% for soft tissue and 9.5% for bone tissue. In the chest examination, the relative uncertainties were 19.4% for lung tissue, 13.0% for soft tissue and 20.0% for bone tissue. The chest phantom was constructed with 7.3 cm of lucite distributed in four plates of the same thickness (15.0 x 15.0 x 1.82) cm³ arranged in two pairs, separated by a spacing of 2.86 cm of air. Two aluminum plates (15.0 x 15.0 x 0.13) cm³ and (15.0 x 15.0 x 0.10) mm³ were inserted, respectively, between the upper and lower pairs of Lucite. The skull phantom was constructed with 11.98 cm of Lucite distributed in five plates of the same thickness (15.0 x 15.0 x 2.33) cm³. Two aluminum plates (15.0 x 15.0 x 0.16) cm³ and (15.0 x 15.0 x 0.12) cm³ were inserted between the upper and lower pairs of Lucite. These homogeneous phantoms were used in the optimization process for CR systems to determine test techniques (kVp and mAs combination), which produced levels of exposure around 1.96 lgM. The test images, obtained in this process, were used in the determination of physical parameters such as the effective detective quantum efficiency (eDQE) and contrast-detail. These parameters were associated with the optimal images of skull and chest for adult patients obtained in previous studies. Optimal images obtained in ...

Orientador: José Ricardo de Arruda Miranda / Coorientador: Diana rodrigues de Pina / Banca: Sérgio Barbosa Duarte / Banca: Rozemeire Garcia Marques / Resumo: Este trabalho teve como objetivo a otimização de imagens de radiografia computadorizada (CR, do inglês, computed radiography) de crânio e tórax de pacientes pediátricos entre 1 e 5 anos de idade. Para atingir esse objetivo foram desenvolvidos fantomas homogêneos pediátricos, que simularam a faixa etária em estudo, a partir de exames retrospectivos de tomografia computadorizada (CT, do inglês, computed tomography). Nesse procedimento foi utilizado um algoritmo computacional para quantificar as espessuras médias de tecidos biológicos (tecido pulmonar, adiposo, mole e ósseo) presentes nas regiões anatômicas em estudo. Essas espessuras foram convertidas em materiais simuladores (lucite e alumínio) de modo a compor os fantomas homogêneos de crânio e tórax. As incertezas relativas no processo de quantificação dos exames de crânio foram de 3,5% para tecido mole e 9,5% para tecido ósseo. Na quantificação dos exames de tórax a incerteza relativa foi de 19,4% para o tecido pulmonar, 13,0% para o tecido mole e 20,0% para o tecido ósseo. O fantoma de tórax foi construído com 7,3 cm de lucite distribuídos em 4 placas de mesma espessura (15,0 x 15,0 x 1,82) cm³ arranjadas em dois pares, separadas por um espaçamento de ar de 2,86 cm. Duas placas de alumínio de (15,0 x 15,0 x 0,13) cm³ e (150,0 x 150,0 x 1,0) mm³ foram inseridas, respetivamente, entre os pares superior e inferior de lucite. O fantoma de crânio foi construído com 11,98 cm de lucite distribuídos em cinco placas de mesma espessura (15,0 x 15,0 x 2,33) cm³. Duas placas de alumínio (15,0 x 15,0 x 0,16) cm³ e (15,0 x 15,0 x 0,12) cm³ foram inseridas, respectivamente, entre os pares superior e inferior de lucite. Os fantomas homogêneos foram utilizados no processo de otimização de imagens em sistemas CR, para calibração do feixe de raios X. No processo de calibração foram determinadas técnicas-teste (combinação kVp e mAs), que produziram índices de ... / Abstract: The aim of this work was to optimize computed radiography techniques of skull and chest for pediatric patients between 1 and 5 years old. To achieve this goal, pediatric homogenous phantoms were developed from retrospective computed tomography (CT) scans. In this procedure, a computational algorithm was used to quantify the average thickness of biological tissue (lung, fat, soft and bone tissue) present on the anatomic region under study. These thicknesses were converted into simulators materials (Lucite and aluminum) to build the homogeneous phantoms of skull and chest. The relative uncertainties in the quantification process of skull examinations were 3.5% for soft tissue and 9.5% for bone tissue. In the chest examination, the relative uncertainties were 19.4% for lung tissue, 13.0% for soft tissue and 20.0% for bone tissue. The chest phantom was constructed with 7.3 cm of lucite distributed in four plates of the same thickness (15.0 x 15.0 x 1.82) cm³ arranged in two pairs, separated by a spacing of 2.86 cm of air. Two aluminum plates (15.0 x 15.0 x 0.13) cm³ and (15.0 x 15.0 x 0.10) mm³ were inserted, respectively, between the upper and lower pairs of Lucite. The skull phantom was constructed with 11.98 cm of Lucite distributed in five plates of the same thickness (15.0 x 15.0 x 2.33) cm³. Two aluminum plates (15.0 x 15.0 x 0.16) cm³ and (15.0 x 15.0 x 0.12) cm³ were inserted between the upper and lower pairs of Lucite. These homogeneous phantoms were used in the optimization process for CR systems to determine test techniques (kVp and mAs combination), which produced levels of exposure around 1.96 lgM. The test images, obtained in this process, were used in the determination of physical parameters such as the effective detective quantum efficiency (eDQE) and contrast-detail. These parameters were associated with the optimal images of skull and chest for adult patients obtained in previous studies. Optimal images obtained in ... / Mestre

Introdução: A TB pulmonar com baciloscopia negativa (TPBN) representa 30-60% de todos os casos de TB. A mortalidade destes pacientes pode atingir 25% em populações com alta prevalência de infecção por HIV, e 10-20% da transmissão da TB, em níveis populacionais são atribuídos a casos de TPBN. Métodos: Um estudo retrospectivo foi desenvolvido para avaliar as características epidemiológicas, clínicas e radiológicas de pacientes com TPBN e comparar com pacientes diagnosticados como tendo TB pulmonar com baciloscopia positiva (TPBP). Todos os pacientes adultos (≥ 18 anos) com cultura positiva para Mycobacterium tuberculosis, e diagnóstico de TB pulmonar foram incluídos no estudo. Resultados: 198 pacientes preencheram os critérios do estudo (cultura positiva para Mycobacterium tuberculosis) e foram incluídos na análise. Destes, 69 (34,8%) tiveram cultura positiva (TPBP) e 129 (65,2%) cultura negativa (TPBN). Numa análise univariada, tosse, dispneia e hemoptise foram menos frequentes nos pacientes com baciloscopia negativa, em comparação com os com TPBP. Num modelo multivariável, não ter tosse e não ter padrão radiológico típico de TB foram características independentemente associadas com o diagnóstico de TPBN. Conclusões: Encontramos uma prevalência muito alta de TPBN entre pacientes com TB, num local com alta prevalência de TB e HIV. A ausência de tosse na presença de outros sintomas sugestivos de TB, e não ter padrão radiológico típico de TB foram preditores independentes para TPBN. / Introduction: Smear-negative pulmonary TB (SNPT) represents 30-60% of all pulmonary TB cases. The mortality of these patients can reach 25% in populations with high prevalence of HIV infection, and 10-20% of TB transmission at the population level are attributable to SNPT cases. Methods: We conducted a retrospective study to evaluate epidemiological, clinical, and radiological characteristics of patients with SNPT and to compare these with patients who were diagnosed as having smear-positive pulmonary TB (SPPT). All adult patients (≥ 18 years old) with a positive culture for Mycobacterium tuberculosis, and a diagnosis of pulmonary TB were included in the study. Results: 198 patients met the inclusion criteria (positive culture for Mycobacterium tuberculosis) and were included in the analysis. Of these patients, 69 (34,8%) were smear positive (SPPT) and 129 (65,2%) were smear negative (SNPT). In univariate analysis, cough, dyspnea, and hemoptysis were less frequent in SNPT patients in comparison with SPPT patients. In a multivariate model, having no cough and no radiographic pattern typical of TB were the characteristics independently associated with a diagnosis of SNPT. Conclusions: We found a very high prevalence of SNPT among patients with TB in a setting with high TB and HIV prevalence. The absence of cough in the presence of other symptoms suggestive of TB, and having no radiographic pattern typical of TB where independent predictors of SNPT.

Introdução: A TB pulmonar com baciloscopia negativa (TPBN) representa 30-60% de todos os casos de TB. A mortalidade destes pacientes pode atingir 25% em populações com alta prevalência de infecção por HIV, e 10-20% da transmissão da TB, em níveis populacionais são atribuídos a casos de TPBN. Métodos: Um estudo retrospectivo foi desenvolvido para avaliar as características epidemiológicas, clínicas e radiológicas de pacientes com TPBN e comparar com pacientes diagnosticados como tendo TB pulmonar com baciloscopia positiva (TPBP). Todos os pacientes adultos (≥ 18 anos) com cultura positiva para Mycobacterium tuberculosis, e diagnóstico de TB pulmonar foram incluídos no estudo. Resultados: 198 pacientes preencheram os critérios do estudo (cultura positiva para Mycobacterium tuberculosis) e foram incluídos na análise. Destes, 69 (34,8%) tiveram cultura positiva (TPBP) e 129 (65,2%) cultura negativa (TPBN). Numa análise univariada, tosse, dispneia e hemoptise foram menos frequentes nos pacientes com baciloscopia negativa, em comparação com os com TPBP. Num modelo multivariável, não ter tosse e não ter padrão radiológico típico de TB foram características independentemente associadas com o diagnóstico de TPBN. Conclusões: Encontramos uma prevalência muito alta de TPBN entre pacientes com TB, num local com alta prevalência de TB e HIV. A ausência de tosse na presença de outros sintomas sugestivos de TB, e não ter padrão radiológico típico de TB foram preditores independentes para TPBN. / Introduction: Smear-negative pulmonary TB (SNPT) represents 30-60% of all pulmonary TB cases. The mortality of these patients can reach 25% in populations with high prevalence of HIV infection, and 10-20% of TB transmission at the population level are attributable to SNPT cases. Methods: We conducted a retrospective study to evaluate epidemiological, clinical, and radiological characteristics of patients with SNPT and to compare these with patients who were diagnosed as having smear-positive pulmonary TB (SPPT). All adult patients (≥ 18 years old) with a positive culture for Mycobacterium tuberculosis, and a diagnosis of pulmonary TB were included in the study. Results: 198 patients met the inclusion criteria (positive culture for Mycobacterium tuberculosis) and were included in the analysis. Of these patients, 69 (34,8%) were smear positive (SPPT) and 129 (65,2%) were smear negative (SNPT). In univariate analysis, cough, dyspnea, and hemoptysis were less frequent in SNPT patients in comparison with SPPT patients. In a multivariate model, having no cough and no radiographic pattern typical of TB were the characteristics independently associated with a diagnosis of SNPT. Conclusions: We found a very high prevalence of SNPT among patients with TB in a setting with high TB and HIV prevalence. The absence of cough in the presence of other symptoms suggestive of TB, and having no radiographic pattern typical of TB where independent predictors of SNPT.

Introdução: A TB pulmonar com baciloscopia negativa (TPBN) representa 30-60% de todos os casos de TB. A mortalidade destes pacientes pode atingir 25% em populações com alta prevalência de infecção por HIV, e 10-20% da transmissão da TB, em níveis populacionais são atribuídos a casos de TPBN. Métodos: Um estudo retrospectivo foi desenvolvido para avaliar as características epidemiológicas, clínicas e radiológicas de pacientes com TPBN e comparar com pacientes diagnosticados como tendo TB pulmonar com baciloscopia positiva (TPBP). Todos os pacientes adultos (≥ 18 anos) com cultura positiva para Mycobacterium tuberculosis, e diagnóstico de TB pulmonar foram incluídos no estudo. Resultados: 198 pacientes preencheram os critérios do estudo (cultura positiva para Mycobacterium tuberculosis) e foram incluídos na análise. Destes, 69 (34,8%) tiveram cultura positiva (TPBP) e 129 (65,2%) cultura negativa (TPBN). Numa análise univariada, tosse, dispneia e hemoptise foram menos frequentes nos pacientes com baciloscopia negativa, em comparação com os com TPBP. Num modelo multivariável, não ter tosse e não ter padrão radiológico típico de TB foram características independentemente associadas com o diagnóstico de TPBN. Conclusões: Encontramos uma prevalência muito alta de TPBN entre pacientes com TB, num local com alta prevalência de TB e HIV. A ausência de tosse na presença de outros sintomas sugestivos de TB, e não ter padrão radiológico típico de TB foram preditores independentes para TPBN. / Introduction: Smear-negative pulmonary TB (SNPT) represents 30-60% of all pulmonary TB cases. The mortality of these patients can reach 25% in populations with high prevalence of HIV infection, and 10-20% of TB transmission at the population level are attributable to SNPT cases. Methods: We conducted a retrospective study to evaluate epidemiological, clinical, and radiological characteristics of patients with SNPT and to compare these with patients who were diagnosed as having smear-positive pulmonary TB (SPPT). All adult patients (≥ 18 years old) with a positive culture for Mycobacterium tuberculosis, and a diagnosis of pulmonary TB were included in the study. Results: 198 patients met the inclusion criteria (positive culture for Mycobacterium tuberculosis) and were included in the analysis. Of these patients, 69 (34,8%) were smear positive (SPPT) and 129 (65,2%) were smear negative (SNPT). In univariate analysis, cough, dyspnea, and hemoptysis were less frequent in SNPT patients in comparison with SPPT patients. In a multivariate model, having no cough and no radiographic pattern typical of TB were the characteristics independently associated with a diagnosis of SNPT. Conclusions: We found a very high prevalence of SNPT among patients with TB in a setting with high TB and HIV prevalence. The absence of cough in the presence of other symptoms suggestive of TB, and having no radiographic pattern typical of TB where independent predictors of SNPT.

Mobile chest radiography remains the most appropriate test for critical care patients with cardiorespiratory changes and with patients who have chest tubes and lines as a monitoring tool, and to detect complications related to their use. However, one of the most frequent issues recognized radiographically with patients in critical care is chest tubes and lines malposition. This can be related to technical quality reasons which can affect their appearance in the chest radiography. This research considers how the technical quality of the ICU/CCU chest radiography can impact upon the appearance of chest tubes/lines and how that appearance can impact on the decision making. Results show that the methods used in the chest phantom experiment to estimate the degree of angulation have a large effect upon the appearance of anatomical structures, but it does not have a particularly large effect upon the apparent changes of tube/line position central venous catheter and endotracheal tube (CVC, ETT). The study also shows that there was a little difference between the two image processing algorithms, apart from the visualisation of sharp reproduction of the trachea and proximal bronchi, which was significantly better using the standard algorithm compared to the inverted algorithm. The two methods used to estimate the degree of angulation and the apparent position of the CVC/ETT on 17 mobile chest radiographs provide limited useful information to the image interpreter in estimating the degree of angulation and degree of malpositioning of the tube and line.

no / Background Neonatal chest radiography is a frequently performed diagnostic examination, particularly in preterm infants where anatomical and/or biochemical immaturity impacts on respiratory function. However, the quality of neonatal radiographic images has been criticized internationally and a prevailing concern has been that radiographers (radiologic technologists) fail to appreciate the unique nature of neonatal and infant anatomical proportions. The aim of this study was to undertake a retrospective evaluation of neonatal chest radiography image acquisition techniques against key technical criteria. Methods Hundred neonatal chest radiographs, randomly selected from all those acquired in 2014, were retrospectively evaluated. Inclusion criteria for radiographs acquisition were as follows: anterior-posterior supine; within 30 days of birth; and with all preprocessed collimation boundaries visible. Image evaluation was systematically undertaken using an image assessment tool. To test for statistical significance, Student's t-test, χ2 test, and logistic regression were undertaken. Results Only 47% of the radiographs were considered straight in both upper and lower thoraces. The cranial collimation border extended beyond the upper border of the third cervical vertebra in 30% of cases, and the caudal border extended below the lower border of the first lumbar vertebra in 20% of cases, suggesting high possibility of neonatal overirradiation. Upper thorax rotation was significantly associated with head position (χ2 = 10.907; P < .001) as has been stated in many published textbooks internationally, but arm position had no apparent influence on rotation of the upper thorax (χ2 = 5.1260; P = .275). Birth weight was associated with accurate midline centering of central ray (logistic regression; OR = 1.0005; P = .009; CI, 1.00139–1.000957) with greater accuracy observed in images of neonates with higher birth weight. Conclusion This study has highlighted areas for neonatal chest radiography improvement. Importantly, the findings bring into question commonly advocated radiographic techniques relating to arm positioning and assessment of rotation while confirming the importance of other technical factors. These findings begin the work toward developing the evidence base to underpin neonatal chest radiograph acquisition, but further prospective work and multicenter/multinational data comparison are required to confirm the findings.

No description available.