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<p>To properly display digital X-ray images for visual diagnosis, a proper display range needs to be identified. This can be difficult when the image contains collimators or large background areas which can dominate the histograms. Also, when there are both underexposed and overexposed areas in the image it is difficult to display these properly at the same time. The purpose of this thesis is to find a way to solve these problems. A few different approaches are evaluated to find their strengths and weaknesses. Based on Local Histogram Equalization, a new method is developed to put various constraints on the mapping. These include alternative ways to perform the histogram calculations and how to define the local histograms. The new method also includes collimator detection and background suppression to keep irrelevant parts of the image out of the calculations. Results show that the new method enables proper display of both underexposed and overexposed areas in the image simultaneously while maintaining the natural look of the image. More testing is required to find appropriate parameters for various image types.</p>

To properly display digital X-ray images for visual diagnosis, a proper display range needs to be identified. This can be difficult when the image contains collimators or large background areas which can dominate the histograms. Also, when there are both underexposed and overexposed areas in the image it is difficult to display these properly at the same time. The purpose of this thesis is to find a way to solve these problems. A few different approaches are evaluated to find their strengths and weaknesses. Based on Local Histogram Equalization, a new method is developed to put various constraints on the mapping. These include alternative ways to perform the histogram calculations and how to define the local histograms. The new method also includes collimator detection and background suppression to keep irrelevant parts of the image out of the calculations. Results show that the new method enables proper display of both underexposed and overexposed areas in the image simultaneously while maintaining the natural look of the image. More testing is required to find appropriate parameters for various image types.

<p>The Swedish field of digital X-ray imaging has since several years relied heavily on distributed information systems and digital storage containers. </p><p>To ensure accurate and safe radiological reporting, Swedish software-firm eCare AB delivers a system called Feedback—the first and only quality assurance IT support product of its kind. This thesis covers several aspects of the design and implementation of future versions of this software platform. </p><p>The focus lies on distributed directory services and models for secure and robust data propagation in TCP/IP networks. For data propagation, a new application, InfoBroker, has been designed and implemented to facilitate integration between Feedback and other medical IT support systems. The directory services, introduced in this thesis as the Feedback Directory Services, have been designed on the architectural level. A combination of CORBA and Java Enterprise Edition is suggested as the implementation platform.</p>

Low-energy trauma and fragility fractures represent a major public health problem. The societal cost of the fragility fractures that occurred in Sweden 2010 has been estimated at €4 billion. In rheumatoid arthritis (RA), patient outcomes have improved greatly in recent years. However, the therapeutic decision making is still hampered by a lack of effective validated biomarkers. The cost of RA in Sweden 2010 has been estimated at €600 million, of which biologic drugs was €180 million. Digital X-ray radiogrammetry (DXR) is a method to measure bone mineral density (BMD) in the metacarpals of the hand. It can be applied opportunistically in several workflows where a person is already at an X-ray machine, including fracture repositioning follow up, mammography screening and hand imaging in RA. This thesis explored DXR-BMD as a marker to identify individuals who would benefit from anti-osteoporotic treatment, change rate of DXR-BMD as a biomarker in RA and under what conditions historical X-ray images can be used to estimate DXR-BMD. An automated method for measurement of joint space width in metacarpophalangeal and interphalangeal joints was also developed and evaluated as a biomarker in RA. Low DXR-BMD was predictive for hip fractures and predicted fragility fractures to a comparable degree as other BMD measurement sites. Rapid decrease of DXR-BMD was a strong and independent predictor for progression of radiographic damage in RA when manual radiographic progression scores were not available. Change of metacarpal joint space width was a statistically significant but weak predictor of joint space narrowing score progression. Guidelines and considerations for use of historical X-ray radiographs for DXR-BMD measurements in clinical trials have been developed and published.

Tuberculosis is a major concern in low- and middle-income countries, but may be diagnosed using standard chest x-rays. Conventional film-screen x-ray detectors require more maintenance than digital x-ray detectors and need a good supply chain of developer chemicals and film, which make them difficult to maintain in low-infrastructure areas of the world. Current digital x-ray technology is prohibitively expensive for this market, although it brings the possibility of tele-radiology and tele-medicine, quicker diagnosis time, and virtually no cost per test compared to other diagnostics for tuberculosis. This thesis examines the requirements on a small-sized, low-cost digital x-ray detector for this application. Two small x-ray detectors were integrated into x-ray systems, then characterized for detector performance using metrics known as modulation transfer function, noise power spectrum, and detective quantum efficiency. The system designs and the results of the experiments are shown. Details are also shown about the setup of the x-ray lab, including the door interlock system for a lead-lined x-ray cabinet. To determine whether a smaller x-ray detector is diagnostically accurate enough for tuberculosis diagnosis compared to full-size chest radiography equipment, a medical study was designed and run using a web-based survey of radiologists in Pakistan, where tuberculosis is a recognized disease. In an attempt to compare x-ray detector performance, MATLAB code was written to measure the modulation transfer function, noise power spectrum, and detective quantum efficiency of x-ray systems. The details about this code, and challenges in simulating the performance of physically different detectors are explained in the thesis.

The Swedish field of digital X-ray imaging has since several years relied heavily on distributed information systems and digital storage containers. To ensure accurate and safe radiological reporting, Swedish software-firm eCare AB delivers a system called Feedback—the first and only quality assurance IT support product of its kind. This thesis covers several aspects of the design and implementation of future versions of this software platform. The focus lies on distributed directory services and models for secure and robust data propagation in TCP/IP networks. For data propagation, a new application, InfoBroker, has been designed and implemented to facilitate integration between Feedback and other medical IT support systems. The directory services, introduced in this thesis as the Feedback Directory Services, have been designed on the architectural level. A combination of CORBA and Java Enterprise Edition is suggested as the implementation platform.

O presente trabalho tem como objetivo principal à otimização do processo de leitura de idade óssea. Os diversos métodos existentes consistem na análise da maturidade esquelética, baseada nos detalhes dos ossos da mão e do punho. O método mais eficaz é o proposto por Tanner&Whitehouse TW, o qual, gera resultados cerca de cinco vezes mais precisos que o método utilizado freqüentemente, devido à simplicidade dos processos de leitura, proposto por Grelish&Pyle GP. Entretanto, o método TW não é utilizado atualmente no Hospital das Clinicas da Faculdade de Medicina de Ribeirão Preto HCFMRP, pois apresenta alto grau de complexidade. Assim, um programa computacional foi desenvolvido para auxiliar nos processos exigidos, com o intuito de viabilizar a implementação do referido método para promover as leituras de idade óssea do HCFMRP. Com esse objetivo, foi desenvolvido um sistema óptico-digitalizador de imagens radiográficas. Assim sendo, utilizando o sistema as imagens são capturadas pelo computador diretamente do negatoscópio, o qual permite realizar ajustes nas imagens adquiridas. A qualidade das imagens radiográficas de extremidades é de fundamental importância. Associada à redução da dose de radiação exposta, principalmente, por se tratar de pacientes jovens, os quais, são mais vulneráveis aos efeitos nocivos causados pela radiação ionizante. Entretanto, há necessidade de se garantir a qualidade na produção de imagens em equipamentos de raios-X, assim como, otimizar a técnica radiográfica visando evitar erros nos diagnósticos devido à formação de imagens de má qualidade. Contudo, a determinação da idade óssea de um paciente é de grande importância para alguns diagnósticos, principalmente em pediatria. As imagens produzidas têm mostrado uma melhoria sensível em sua qualidade, permitindo a visibilização de maiores detalhes, incorporadas a uma diminuição significativa na dose de exposição, ao redor de 20%. O custo sistema de digitalização de imagens utilizado neste trabalho é aproximadamente cinco vezes menor que existente no HCFMRP, mantendo a qualidade das imagens. A automatização dos processos, pelo programa computacional, dinamiza o método TW, bem como, não interfere no valor da idade óssea lida. Conseqüentemente, produz maior rapidez e segurança em diagnósticos com base na leitura de idade óssea, pois 19% das leituras comparadas apresentam erros que comprometem este tipo de informação para o diagnóstico. / The present work has as main objective to the otimization of the process of reading of bony age. The several existent methods consist of the analysis of the skeletal maturity, based on the details of the bones of the hand and of the fist. The most effective method is it proposed by Tanner&Whitehouse TW, which, it generates results about more precise five times than the method frequently used, due to the simplicity of the reading processes, proposed by Grelish&Pyle GP. However, the method TW is not used now in the Hospital of the Clinics of Ribeirão Preto HCRP, because it presents high complexity degree. Thus, a software was developed to aid in the demanded processes, seeking to implement of the referred method to promote the readings of bony age of HCRP. With that I objectify, a system was developed optical-digitizer of X-ray film images. Like this being, using the system the images is captured directly by the computer of the negatoscopy, which allows accomplishing fittings in the acquired images. The quality of the X-ray film images of extremities is of fundamental importance. Associated to the reduction of the exposed dose radiation, mainly, for being of young patients, the ones that, they are more vulnerable to the sick caused by the radiation. However, there is need to guarantee the quality in the production of images in equipments of ray-X, following the approaches demanded by the competent organs, as well as, to standardize the image technical seeking to avoid possible mistakes in the diagnoses due to images of bad quality. Thus, the determination of the bony age of a patient one is of great importance for some diagnoses, mainly in pediatrics. The produced images have been showing a sensitive improvement in its quality, allowing see more details, incorporated to a significant decrease in the exhibition dose, around 20%. The cost of digitizer equipment is five times cheaper than the utilized in HCRP, keeping the same quality of images. The automation of the processes, of way software, becomes the method TW most dynamic, interfere less in the results of reading of bone age. Consequently, it produces larger fast and safety in diagnoses with base in the reading of bony age, because 19% of the reads shows errors.

The term“Digital X-ray Imaging" refers to a variety of technologies that electronically capture x-ray images. Once captured the images may be electronically processed, stored, displayed and communicated. Digital imaging has the potential to overcome weaknesses inherent in traditional screen-film imaging, with high detection efficiency, high dynamic range and the capability for contrast enhancement. Image processing also makes possible innovative techniques such as computer-aided diagnosis, tomosynthesis, dual-energy imaging, and digital subtraction imaging. Several different approaches to digital imaging are being studied, and in some cases, have been developed and are being marketed. Common to all these approaches are a number of technological and medical issues to be resolved. One of the technological issues is the optimal pixel size for any particular image sensor technology. In general, the spatial resolution of the digital image is limited by the pixel size. Unfortunately while reducing pixel size improves spatial resolution this comes at the expense of signal to noise ratio (SNR). In a scintillator-charge-coupled device (CCD) system, the signal can be increased by improving the efficiency of the scintillator or by reducing noise. This study used a very low noise CCD to determine if image quality, as indicated by the modulation transfer function (MTF), the noise power spectrum (NPS) and the detective quantum efficiency (DQE), could be maintained while reducing pixel size. Two scintillators, one a commonly used radiographic screen the other a thallium doped cesium iodide scintillator, were used and the results compared. The results of this study show that image quality can be maintained as pixel size is reduced and that high DQE can be attained and maintained over a wide range of spatial frequencies with a well designed scintillator.

O presente trabalho tem como objetivo principal à otimização do processo de leitura de idade óssea. Os diversos métodos existentes consistem na análise da maturidade esquelética, baseada nos detalhes dos ossos da mão e do punho. O método mais eficaz é o proposto por Tanner&Whitehouse TW, o qual, gera resultados cerca de cinco vezes mais precisos que o método utilizado freqüentemente, devido à simplicidade dos processos de leitura, proposto por Grelish&Pyle GP. Entretanto, o método TW não é utilizado atualmente no Hospital das Clinicas da Faculdade de Medicina de Ribeirão Preto HCFMRP, pois apresenta alto grau de complexidade. Assim, um programa computacional foi desenvolvido para auxiliar nos processos exigidos, com o intuito de viabilizar a implementação do referido método para promover as leituras de idade óssea do HCFMRP. Com esse objetivo, foi desenvolvido um sistema óptico-digitalizador de imagens radiográficas. Assim sendo, utilizando o sistema as imagens são capturadas pelo computador diretamente do negatoscópio, o qual permite realizar ajustes nas imagens adquiridas. A qualidade das imagens radiográficas de extremidades é de fundamental importância. Associada à redução da dose de radiação exposta, principalmente, por se tratar de pacientes jovens, os quais, são mais vulneráveis aos efeitos nocivos causados pela radiação ionizante. Entretanto, há necessidade de se garantir a qualidade na produção de imagens em equipamentos de raios-X, assim como, otimizar a técnica radiográfica visando evitar erros nos diagnósticos devido à formação de imagens de má qualidade. Contudo, a determinação da idade óssea de um paciente é de grande importância para alguns diagnósticos, principalmente em pediatria. As imagens produzidas têm mostrado uma melhoria sensível em sua qualidade, permitindo a visibilização de maiores detalhes, incorporadas a uma diminuição significativa na dose de exposição, ao redor de 20%. O custo sistema de digitalização de imagens utilizado neste trabalho é aproximadamente cinco vezes menor que existente no HCFMRP, mantendo a qualidade das imagens. A automatização dos processos, pelo programa computacional, dinamiza o método TW, bem como, não interfere no valor da idade óssea lida. Conseqüentemente, produz maior rapidez e segurança em diagnósticos com base na leitura de idade óssea, pois 19% das leituras comparadas apresentam erros que comprometem este tipo de informação para o diagnóstico. / The present work has as main objective to the otimization of the process of reading of bony age. The several existent methods consist of the analysis of the skeletal maturity, based on the details of the bones of the hand and of the fist. The most effective method is it proposed by Tanner&Whitehouse TW, which, it generates results about more precise five times than the method frequently used, due to the simplicity of the reading processes, proposed by Grelish&Pyle GP. However, the method TW is not used now in the Hospital of the Clinics of Ribeirão Preto HCRP, because it presents high complexity degree. Thus, a software was developed to aid in the demanded processes, seeking to implement of the referred method to promote the readings of bony age of HCRP. With that I objectify, a system was developed optical-digitizer of X-ray film images. Like this being, using the system the images is captured directly by the computer of the negatoscopy, which allows accomplishing fittings in the acquired images. The quality of the X-ray film images of extremities is of fundamental importance. Associated to the reduction of the exposed dose radiation, mainly, for being of young patients, the ones that, they are more vulnerable to the sick caused by the radiation. However, there is need to guarantee the quality in the production of images in equipments of ray-X, following the approaches demanded by the competent organs, as well as, to standardize the image technical seeking to avoid possible mistakes in the diagnoses due to images of bad quality. Thus, the determination of the bony age of a patient one is of great importance for some diagnoses, mainly in pediatrics. The produced images have been showing a sensitive improvement in its quality, allowing see more details, incorporated to a significant decrease in the exhibition dose, around 20%. The cost of digitizer equipment is five times cheaper than the utilized in HCRP, keeping the same quality of images. The automation of the processes, of way software, becomes the method TW most dynamic, interfere less in the results of reading of bone age. Consequently, it produces larger fast and safety in diagnoses with base in the reading of bony age, because 19% of the reads shows errors.