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Yes / Digital image processing used in modern cardiac interventional x-ray systems may have the potential to enhance image quality such that it allows for lower radiation doses. The aim of this research was to quantify the reduction in radiation dose facilitated by image processing alone for percutaneous coronary intervention (PCI) patient angiograms, without reducing the perceived image quality required to confidently make a diagnosis. Incremental amounts of image noise were added to five PCI patient angiograms, simulating the angiogram having been acquired at corresponding lower dose levels (by 10-89% dose reduction). Sixteen observers with relevant background and experience scored the image quality of these angiograms in three states - with no image processing and with two different modern image processing algorithms applied; these algorithms are used on state-of-the-art and previous generation cardiac interventional x-ray systems. Ordinal regression allowing for random effects and the delta method were used to quantify the dose reduction allowed for by the processing algorithms, for equivalent image quality scores. The dose reductions [with 95% confidence interval] from the state-of-the-art and previous generation image processing relative to no processing were 24.9% [18.8- 31.0%] and 15.6% [9.4-21.9%] respectively. The dose reduction enabled by the state-of-the-art image processing relative to previous generation processing was 10.3% [4.4-16.2%]. This demonstrates that statistically significant dose reduction can be facilitated with no loss in perceived image quality using modern image enhancement; the most recent processing algorithm was more effective in preserving image quality at lower doses. / The study was funded by Philips Healthcare (the Netherlands).

Submitted by Kamila Costa (kamilavasconceloscosta@gmail.com) on 2015-06-11T20:01:02Z No. of bitstreams: 1 Dissertação-Daily D de O Rodrigues.pdf: 2391223 bytes, checksum: 06b57d0d17da9e4844b2d8482ac25cb0 (MD5) / Approved for entry into archive by Divisão de Documentação/BC Biblioteca Central (ddbc@ufam.edu.br) on 2015-06-15T18:06:50Z (GMT) No. of bitstreams: 1 Dissertação-Daily D de O Rodrigues.pdf: 2391223 bytes, checksum: 06b57d0d17da9e4844b2d8482ac25cb0 (MD5) / Approved for entry into archive by Divisão de Documentação/BC Biblioteca Central (ddbc@ufam.edu.br) on 2015-06-15T18:08:28Z (GMT) No. of bitstreams: 1 Dissertação-Daily D de O Rodrigues.pdf: 2391223 bytes, checksum: 06b57d0d17da9e4844b2d8482ac25cb0 (MD5) / Made available in DSpace on 2015-06-15T18:08:28Z (GMT). No. of bitstreams: 1 Dissertação-Daily D de O Rodrigues.pdf: 2391223 bytes, checksum: 06b57d0d17da9e4844b2d8482ac25cb0 (MD5) Previous issue date: 2015-02-27 / FAPEAM - Fundação de Amparo à Pesquisa do Estado do Amazonas / The enhancement of underwater images in applications in the area of Amazonian rivers has been increasingly required and needs further study especially where the rivers have high turbidity and low light. There is increasingly demand for automatic enhancement methods to carry out monitoring of fauna and flora intensive rivers, as well as for the maintenance of pipelines and underwater cables. The enhancement methods specified, developed and validated for using in the rivers of the Amazonia are faced with the problem of imaging quality. The research related to underwater am environments of the Amazon has to dead with high turbidity of the water, caused mainly due to particles in suspension and interaction of light with the environment. The underwater images extraction with satisfiable visibility of the environments of Amazonian rivers has become extremely indispensable and relevant, given that there are natural treasures still unexplored into the depths of these rivers, as well as there is need to maintain the underwater part of the transportation system gas LPG (Liquefied Petroleum Gas) Coari-Manaus. Given this promising scenario, this study aims to improve these images by applying techniques of enhancement using nonlinear filters, which promote the minimization of the light interaction characteristics with the environment, loss of contrast and color in images extracted from turbid underwater environments. The method was experimentally validated with images acquired from simulations of underwater scenes and images acquired in outdoor underwater environments. The proposed method is compared to two other techniques of highlighting or enhancement of images. As in this study, these techniques also require a single image as input. The results return images with enhanced visual quality, considering a large set of experiments with simulation data and real outdoors scenes. / O realce de imagens subaquáticas em aplicações na região dos rios amazônicos é cada vez mais requisitado e carece de um estudo mais aprofundado especialmente nos casos em que os rios apresentam alto índice de turbidez e baixa luminosidade. Estes rios têm demandado cada vez mais métodos de realce automáticos que realizem o monitoramento de sua fauna e flora, bem como manutenção de dutos e cabos subaquáticos. Os métodos de realce especificados, desenvolvidos e validados para uso nos rios da região, se deparam com o problema da qualidade de captação de imagens. As pesquisas relacionadas aos ambientes subaquáticos da Amazônia são prejudicadas pelo alto nível de turbidez de suas águas, causadas principalmente devido às partículas em suspensão e à interação da luz com o meio. A extração de imagens subaquáticas de visibilidade adequada aos ambientes dos rios amazônicos em geral, tem se demonstrado imprescindível e relevante, haja vista que, existem tesouros naturais ainda inexplorados nas profundezas desses rios. Por outro lado, verifica-se a necessidade de manutenção da parte subaquática do sistema de transporte de gás GLP (Gás Liquefeito de Petróleo) Coari-Manaus. Diante deste cenário promissor, este trabalho objetiva a melhoria dessas imagens através da aplicação de técnicas de realce com uso de filtros não lineares, que promovam a minimização das características da interação da luz com o meio, perda de contraste e cores em imagens extraídas de ambientes subaquáticos turvos. O método proposto é comparado a duas outras técnicas de realce ou melhoria de imagens que, como neste trabalho, também requerem uma única imagem como entrada. Os resultados obtidos retornam imagens com melhor qualidade visual, considerando-se um grande conjunto de experimentos realizados com dados de simulação e cenas reais obtidas em ambientes externos.