Percorrer por autor "Oliveira, M."
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- 10 kVp rule - An anthropomorphic pelvis phantom imaging study using a CR system: impact on image quality and effective dose using AEC and manual modePublication . Lança, Luís; Franco, L.; Ahmed, A.; Harderwijk, M.; Nasir, S.; Ndlovu, J.; Oliveira, M.; Santiago, A.; Hogg, PeterPurpose: This study aims to investigate the influence of tube potential (kVp) variation in relation to perceptual image quality and effective dose for pelvis using automatic exposure control (AEC) and non-AEC in a computed radiography (CR) system. Methods and Materials: To determine the effects of using AEC and non-AEC by applying the 10 kVp rule in two experiments using an anthropomorphic pelvis phantom. Images were acquired using 10 kVp increments (60-120 kVp) for both experiments. The first experiment, based on seven AEC combinations, produced 49 images. The mean mAs from each kVp increment were used as a baseline for the second experiment producing 35 images. A total of 84 images were produced and a panel of 5 experienced observers participated for the image scoring using the 2 AFC visual grading software. PCXMC software was used to estimate the effective dose. Results: A decrease in perceptual image quality as the kVp increases was observed both in non-AEC and AEC experiments, however no significant statistical differences (p> 0.05) were found. Image quality scores from all observers at 10 kVp increments for all mAs values using non-AEC mode demonstrates a better score up to 90 kVp. Effective dose results show a statistical significant decrease (p=0.000) on the 75th quartile from 0.3 mSv at 60 kVp to 0.1 mSv at 120 kVp when applying the 10 kVp rule in non-AEC mode. Conclusion: No significant reduction in perceptual image quality is observed when increasing kVp whilst a marked and significant effective dose reduction is observed.
- 10 kVp rule – An anthropomorphic pelvis phantom imaging study using a CR system: impact on image quality and effective dose using AEC and manual modePublication . Lança, Luís; Franco, L.; Ahmed, A.; Harderwijk, M.; Marti, C.; Nasir, S.; Ndlovu, J.; Oliveira, M.; Santiago, A.; Hogg, PeterBackground - Pelvis and hip radiography are consistently found to be amongst the highest contributors to the collective effective dose (E) in all ten DOSE DATAMED countries in Europe, representing 2.8 to 9.4% of total collective dose (S) in the TOP 20 exams list. The level of image quality should provide all the diagnostic information in order not to jeopardise the diagnosis, but being able to provide the needed clinical information with the minimum dose. A recent study suggests further research to determine whether the “10 kVp rule” would have value for a range of examinations using Computed Radiography (CR) systems. As a “rule of thumb” increasing the kVp by 10 whilst halving the mAs is suggested to give a similar perceptual image quality when compared to the original exposure factors. Aims - In light of the 10kVp rule, this study aims to investigate the influence of tube potential (kVp) variation in relation to perceptual image quality and E for pelvis imaging using automatic exposure control (AEC) and non-AEC in a Computed Radiography (CR) system. Research questions - Does the 10kVp rule works for the pelvis in relation to image quality in a CR system? Does the image quality differs when the AEC is used instead of manual mode using the 10kVp rule and how this impacts on E?
- Carcinoma medular da tiroide com neoplasia papilar síncrona: metástase ganglionar inaugural diagnosticada por citologia aspirativaPublication . Araújo, A.; Pires, Carolina; Oliveira, M.; Roque, RubenA citologia aspirativa por agulha fina (CAAF) é um método essencial na caracterização das adenopatias cervicais, permitindo a distinção entre lesões benignas e malignas. O carcinoma medular da tiroide, uma neoplasia neuroendócrina rara, derivada das células C da tiroide, pode apresentar-se inicialmente como metástase ganglionar. Este artigo descreve o caso clínico de uma mulher de 62 anos com adenomegalia supraclavicular, cuja primeira CAAF foi sugestiva de neoplasia epitelial sem origem definida. Posteriormente, realizou nova CAAF, o que suscitou a hipótese de metástase de carcinoma medular da tiroide. A confirmação diagnóstica foi obtida por técnicas de imunocitoquímica (avaliação dos biomarcadores TTF1 e calcitonina). A tiroidectomia total com esvaziamento cervical revelou um carcinoma medular no lobo direito, com invasão vascular, e um microcarcinoma papilar folicular no lobo esquerdo. Este caso consubstancia o papel da citologia na abordagem inicial das adenopatias, evidenciando a importância da CAAF na obtenção de amostras representativas e com preservação morfológica adequada, mesmo sendo um método minimamente invasivo. Aliada a um processamento eficaz e acompanhada por técnicas complementares, revela-se fundamental para um diagnóstico citopatológico exato e para a correta orientação clínica.