ResumoO desempenho de monitores tem grande importância na qualidade da imagem de sistemas radiográficos digitais. Em ambientes sem filmes, tornou-se necessário implementar testes de aceitação e controle de qualidade em monitores usados para interpretação de imagens médicas. Os monitores dedicados ao radiodiagnóstico devem fornecer informações que representam pequenas diferenças em atenuação de raios X ou pequenas diferenças de alguma região anatômica de interesse. Isso deve resultar também em pequenas diferenças em luminância de uma imagem representada. Os fatores que afetam a qualidade das imagens médicas são contraste, ruído, resolução, artefatos e distorções. Por isso, um monitor deve possuir características específicas, para que tornem possível ao médico radiologista realizar uma avaliação que leve ao melhor diagnóstico. Com base na necessidade de avaliar monitores para diagnóstico nas mais diversas aplicações radiológicas, esse trabalho visa apresentar um resumo para a execução e padronização dos testes que são recomendados pela publicação AAPM Report 03. Palavras-chave: radiologia diagnóstica, controle de qualidade, monitores de intrepretação. Abstract The performance monitors has great importance in image quality of digital radiographic systems. In environments without films, it became necessary to implement acceptance testing and quality control monitors used for interpretation of medical images. The monitors dedicated to radiodiagnostic should provide information that represent slight differences in x-ray attenuation or minor differences in some anatomical region of interest. This should also result in small differences
Abstract-The aim of this study is to compare cold lesions detectability in myocardial perfusion SPECT images acquired by two cameras: a conventional SPECT with scintillation detector (Philips Cardio MD) and a cadmium-zinc-telluride (CZT) semiconductor detector system(GE Discovery NM 530C). The test object was an anthropomorphic torso phantom with cardiac insert, filled with 99m Tc, simulating a SPECT myocardial perfusion acquisition. Images were reconstructed using the standard clinical department protocol, and analyzed by axial and lateral count profiles, and polar distributions. The lateral profile showed that the contrast between the lesion region and background in the Cardio MD camera is higher (62.2%) than in the CZT camera (42.5%). The axial profile showed a higher contrast (37.0%) in the CZT camera compared to the Cardio MD (31.9%). CZT showed a higher contrast between background and the maximum activity point along the line (68.2%) than in the Cardio MD (57.5%). Performing the maximum relative count region and the lesion area analysis, it was verified that the contrast between these regions are 31.2% and 25.5% to CZT and Cardio MD, respectively. The polar map in the CZT camera displays a better uniformity between the segments' counting, which means the lesion identification is clearer than in the Cardio MD camera, where the distribution is diffuse and the lesion is unclear. The results showed that the cold myocardium lesion detectability is enhanced in the CZT camera. In conclusion, the physical performance of CZT camera is higher than conventional camera, but further studies are required to evaluate other parameters such as the influence of positioning and attenuation.
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