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Browsing by Author "Almeida, P."

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  • Adipose tissue in attenuation and scattering correction in myocardial perfusion SPECT/CT: a phantom study
    Publication . Guerreiro, B.; Pereira, P.; Rosa, R.; Valente, S.; Sousa, Eva; Almeida, P.; Branco, F.; Freixo, T.; Jonge, F. D.; Ferreira, T. C.; Vieira, Lina
    Assess the influence of thoracic AT on cardiac SPECT/CT counts, after attenuation correction and scatter correction.
    2017-10Conference object Open access Show more
  • Demand response model for hardware implementation
    Publication . Capitão, B.; Lagarto, João; Pereira, Rita; Almeida, P.; Fonte, Pedro M
    Demand response actions allow to support an adequate domestic load management, considering consumer preferences. In order to develop a hardware tool based on Arduino used to support consumers load management and decisions, an optimization mathematical model is developed and detailed in this paper. In the developed mathematical model, household appliances and electric vehicle are considered as controllable loads. The existence of a storage system based on batteries is considered as well as energy provided by the power grid and solar panel self-generation. The model is implemented using optimization software GAMS (General Algebraic Modeling System) as a Mixed Integer Programming (MIP) problem, where its outputs are used as inputs applied to the hardware used as interface between the optimization mathematical model and controllable loads.
    2020-08-20Conference object Open access Show more
  • Monte Carlo simulation of the basic features of the GE Millennium MG single photon emission computed tomography gamma camera
    Publication . Vieira, Lina; Vaz, Tânia; Costa, Durval C.; Almeida, P.
    Objective - To describe and validate the simulation of the basic features of GE Millennium MG gamma camera using the GATE Monte Carlo platform. Material and methods - Crystal size and thickness, parallel-hole collimation and a realistic energy acquisition window were simulated in the GATE platform. GATE results were compared to experimental data in the following imaging conditions: a point source of 99mTc at different positions during static imaging and tomographic acquisitions using two different energy windows. The accuracy between the events expected and detected by simulation was obtained with the Mann–Whitney–Wilcoxon test. Comparisons were made regarding the measurement of sensitivity and spatial resolution, static and tomographic. Simulated and experimental spatial resolutions for tomographic data were compared with the Kruskal–Wallis test to assess simulation accuracy for this parameter. Results - There was good agreement between simulated and experimental data. The number of decays expected when compared with the number of decays registered, showed small deviation (≤0.007%). The sensitivity comparisons between static acquisitions for different distances from source to collimator (1, 5, 10, 20, 30cm) with energy windows of 126–154 keV and 130–158 keV showed differences of 4.4%, 5.5%, 4.2%, 5.5%, 4.5% and 5.4%, 6.3%, 6.3%, 5.8%, 5.3%, respectively. For the tomographic acquisitions, the mean differences were 7.5% and 9.8% for the energy window 126–154 keV and 130–158 keV. Comparison of simulated and experimental spatial resolutions for tomographic data showed no statistically significant differences with 95% confidence interval. Conclusions - Adequate simulation of the system basic features using GATE Monte Carlo simulation platform was achieved and validated.
    2014Journal article Restricted access Show more