CARLOS HENRIQUE DE MESQUITA

CARLOS HENRIQUE DE MESQUITA

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Image quality analysis of an industrial instant non-scanning tomography system with different collimators
2019 - VELO, A.F.; ALVAREZ, A.G.; HAMADA, M.M.; MESQUITA, C.H.
An instant non-scanning tomography system is being developed at the IPEN. This type of tomography system, due to its configurations, provides a low spatial resolution; however, it presents a high temporal resolution as an advantage. In this sense, it has high applicability in industrial processes involving dynamic multiphase processes, like distillation columns. Thereby, to obtain the best conditions of image acquisition, this tomography system comprising different collimators was simulated with Monte Carlo using the MCNP4C.The image quality was evaluated with Matlab® 2013b analyzing the contrast to noise ratio (CNR), root mean square ratio (RMSE), signal to noise ratio (SNR) and the spatial resolution by the Modulation Transfer Function (MTF(f)), to identify which collimator fits better to the tomography in development. It was simulated three situations; (i) with no collimator; (ii) ø 25x 50 mm2 cylindrical collimator with a septum of ø5.0 x 50 mm2; (iii) ø25 x 50 mm2 cylindrical collimator with a slit septum of 24 x 5.0 x 50 mm3. RMSE values for no collimator presented better results. CNR showed that no collimator and slit collimator reaches the same CNR values, but no collimator decreases more than the slit collimator as the number of iteration rises. The hole collimator reaches a higher CNR value, however decreases more than the others. The spatial resolution with no collimator and slit collimator were around 31.9 mm, and for the hole collimator was around 20 mm.
Gallium-67 citrate used as a tracer of acetone production routes
2019 - MESQUITA, C.H. de; CALVO, W.A.P.; AOKI, P.E.; SILVA, V.C. da; HARAGUCHI, M.I.; VELO, A.F.; ALVAREZ, A.G.; HAMADA, M.M.
In this work the pathway of the chemical product and the kinetics parameters were evaluated in a laboratory plant settled, using 0.4 GBq (10 mL) of 67Ga citrate as radiotracer and 18 NaI(Tl) radiation detectors. The AnaComp program was used to estimate the kinetic para ameters of the acetone production. The yield of the acetone production was estimated by the percentage ratio between the areas under the curve (AUC) of the curve profiles of the final product compartment divided by the concentration found inside the chemical reactor whose result was 87% yield during the first 30 minutes of reaction.
Evaluation of iterative algorithms for tomography image reconstruction
2019 - VELO, A.F.; ALVAREZ, A.G.; HAMADA, M.M.; MESQUITA, C.H.
The greatest impact of the tomography technology currently occurs in medicine. The success is due to the fact that human body presents standardized dimensions with well-established composition. These conditions are not found in industrial objects. In industry, there is a great deal of interest in using the tomography in order to know the inner part of (i) manufactured industrial objects or (ii) the machines and their means of production. In these cases, the purpose of the tomography is: (a) to control the quality of the final product and (b) to optimize the production, contributing to the pilot phase of the projects and analyzing the quality of the means of production. This scan system is a non-destructive, efficient and fast method for providing sec-tional images of industrial objects and it is able to show the dynamic processes and the dispersion of the ma-terials structures within these objects. In this context, it is important that the reconstructed image may present a great spatial resolution with a satisfactory temporal resolution. Thus, the algorithm to reconstruct the imag-es has to meet these requirements. This work consists in the analysis of three different iterative algorithm methods, namely the Maximum Likelihood Estimation Method (MLEM), the Maximum Likelihood Trans-mitted Method (MLTR) and the Simultaneous Iterative Reconstruction Method (SIRT. The analyses in-volved the measurement of the contrast to noise ratio (CNR), the root mean square error (RMSE) and the Modulation Transfer Function (MTF),in order to know which algorithm fits the conditions to optimize the system better. The algorithms and the image quality analyses were performed by Matlab® 2013b.
A third generation tomography system with fifteen detectors simulated by Monte Carlo method
2019 - VELO, A.F.; ALVAREZ, A.G.; CARVALHO, D.V..S.; FERNANDEZ, V.; SOMESSARI, S.; SPRENGER, F.F.; HAMADA, M.M.; MESQUITA, C.H.
This paper describes the Monte Carlo simulation, using MCNP4C, of a multichannel third generation tomography system containing a two radioactive sources 192I (316.5 – 468 KeV) and 137Cs (662 KeV), and a set of fifteen NaI(Tl) detectors, with dimensions of 1 inch diameter and 2 inches thick, in fan beam geometry, positioned diametrically opposite. Each detector moves 10 steps of 0,24o, totalizing 150 virtual detectors per projection, and then the system rotate 2 degrees. The Monte Carlo simulation was performed to evaluate the viability of this configuration. For this, a multiphase phantom containing polymethyl methacralate (PMMA ((  1.19 g/cm3)), iron (  7.874 g/cm3), aluminum (  2.6989 g/cm3) and air (  1.20479E-03 g/cm3) was simulated. The simulated number of histories was 1.1E+09 per projection and the tally used were the F8, which gives the pulse height of each detector. The data obtained by the simulation was used to reconstruct the simulated phantom using the statistical iterative Maximum Likelihood Estimation Method Technique (ML-EM) algorithm. Each detector provides a gamma spectrum of the sources, and a pulse height analyzer (PHA) of 10% on the 316.5 KeV and 662 KeV photopeaks was performed. This technique provides two reconstructed images of the simulated phantom. The reconstructed images provided high spatial resolution, and it is supposed that the temporal resolution (spending time for one complete revolution) is about 2.5 hours.