Percorrer por autor "Dinis, Maria de Lurdes"
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- Radiation dose reduction in CT exams with iterative and deep learning reconstruction: A systematic reviewPublication . Coelho, Sandra; Dinis, Maria de Lurdes; Freitas, Marco; Baptista, João SantosThis systematic review evaluated the effectiveness of iterative reconstruction (IR) and deep learning reconstruction (DLR) in reducing radiation dose in computed tomography (CT) while preserving diagnostic image quality. We systematically searched PubMed, Scopus, and Web of Science (last search 22 March 2025); the protocol was registered in the OSF (DOI: 10.17605/OSF.IO/TUQDS). Eligible studies were English-language adult (≥18 years) investigations published between 2020 and 2025 that used IR or DLR and reported radiation-dose outcomes; studies on paediatric, phantom, cadaver, cone-beam, and spectral CT were excluded. In accordance with PRISMA 2020 guidelines, 4371 records were identified, and 30 met the inclusion criteria. Risk of bias was assessed using the NIH Quality Assessment Tool; most studies were deemed to be at low risk. Data were narratively synthesised and structured by a reconstruction approach and anatomical region. Across the 30 studies, IR achieved a dose reduction of 24–50% (mean ≈ 45%) and a DLR reduction of 34–89% (mean ≈ 58%); several DLR protocols enabled reductions of ≥75% without impairing diagnostic quality. Thirty studies in total were included (total N = 2581; range 24–289). It was determined that both approaches substantially reduce radiation exposure while maintaining diagnostic image quality; DLR generally demonstrates greater noise suppression and dose efficiency, especially in ultra-low-dose applications. However, heterogeneity in methods, designs, and scanner technologies limits the ability to draw uniform conclusions. Standardised protocols, multi-vendor prospective studies, and longterm evaluations are needed.
- The influence of coal-fired power plants operations on environmental radioactivity and assessment of the associated radiation hazardPublication . Dinis, Maria de Lurdes; Fiúza, António; Góis, Joaquim; Carvalho, José S. de; Meira Castro, Ana C.The natural radioactivity of coal and by-products from coal-fired power plants has been reported in many countries. Most of these studies focus on the radioactivity levels of airborne discharges with enhanced concentration in fly ashes. However, the distribution of natural radionuclides in the environment is crucial to estimate the radiological impact and the resulting risk to the potential exposed nearby population. The activity released into the atmosphere from of a coal-fired power plants depends on many factors: the radionuclides concentration in coal, the ash content and inert matter of the coal, the combustion’s temperature, the portioning between bottom and fly ash and the efficiency of the filtering system. Therefore, marked differences should be expected between the by-products produced and the amount of activity discharged, per unit of energy produced, from different coal-fired power plants (Dinis et al., 2014). At national level, data from coal-fired power plants is not available as radionuclides measurements are not compulsory; regulations are only restricted to airborne discharges of SO2, NOx and suspended particles. The consequent radiological impact is rather difficult to estimate as there is no data concerning the radiological elements released. This study aims to evaluate the influence of a coal-fired power plant operation on the environmental radioactivity and the assessment of the resulting radiation hazard through the radium equivalent index (Raeq). The spatial distribution of the radionuclides found in the surroundings of a coal plant, and the hazard index, were investigated by statistic and geostatistics tools. The current study was applied to a coal plant located in the southwest coastline of Portugal. This power plant started working in 1985 with two operational stacks, both with 225 m height, and fuelled by bituminous coal. The main concern from this coal power plant results mainly from past atmospheric emissions. In fact, the amount of particulate matter released from this coal-fired power plant into the atmosphere decreased substantially in the last ten years: 1 740 tons (2001); 812 tons (2004); 587 tons (2007); 394 (2009); 130 tons (2010); 99.7 tons (2010); 286 (2011); 178 ton (2012) (E-PRTR, 2014).