González Martínez, Antonio Javier
Cargando...
Unidades organizativas
Unidad organizativa
Puesto de trabajo
ORCID
Página personal
Página personal Panorama
Nombre
Dirección de correo electrónico
5 resultados
Resultados de la búsqueda
Mostrando 1 - 5 de 5
- PublicaciónCalibration of Gamma Ray Impacts in Monolithic-Based Detectors Using Voronoi Diagrams(Institute of Electrical and Electronics Engineers, 2020-05) Freire, Marta; Gonzalez-Montoro, Andrea; Sánchez Martínez, Filomeno; Benlloch Baviera, Jose María; González Martínez, Antonio Javier; Instituto de Instrumentación para Imagen Molecular; European Commission; Ministerio de Economía y Competitividad[EN] Molecular imaging systems, such as positron emission tomography (PET), use detectors providing energy and a 3-D interaction position of a gamma ray within a scintillation block. Monolithic crystals are becoming an alternative to crystal arrays in PET. However, calibration processes are required to correct for nonuniformities, mainly produced by the truncation of the scintillation light distribution at the edges. We propose a calibration method based on the Voronoi diagrams. We have used $50 \times 50 \times 15$ mm(3) LYSO blocks coupled to a $12\times 12$ SiPMs array. We have first studied two different interpolation algorithms: 1) weighted average method (WAM) and 2) natural neighbor (NN). We have compared them with an existing calibration based on 1-D monomials. Here, the crystal was laterally black painted and a retroreflector (RR) layer added to the entrance face. The NN exhibited the best results in terms of XY impact position, depth of Interaction, and energy, allowing us to calibrate the whole scintillation volume. Later, the NN interpolation has been tested against different crystal surface treatments, allowing always to correct edge effects. Best energy resolutions were observed when using the reflective layers (12%-14%). However, better linearity was observed with the treatments using black paint. In particular, we obtained the best overall performance when lateral black paint is combined with the RR.
- PublicaciónTiming results using an FPGA-based TDC with large arrays of 144 SiPMs(Institute of Electrical and Electronics Engineers (IEEE), 2015-02) Aguilar, A.; González Martínez, Antonio Javier; Torres, J.; García Olcina, Raimundo; Martos, J.; Soret, J.; Conde Castellanos, Pablo Eloy; Hernández Hernández, Liczandro; Sanchez, F.; Benlloch Baviera, Jose María; Instituto de Instrumentación para Imagen Molecular; Universitat de ValènciaSilicon photomultipliers (SiPMs) have become an alternative to traditional tubes due to several features. However, their implementation to form large arrays is still a challenge especially due to their relatively high intrinsic noise, depending on the chosen readout. In this contribution, two modules composed of SiPMs with an area of roughly mm mm are used in coincidence. Coincidence resolving time (CRT) results with a field-programmable gate array, in combination with a time to digital converter, are shown as a function of both the sensor bias voltage and the digitizer threshold. The dependence of the CRT on the sensor matrix temperature, the amount of SiPM active area and the crystal type is also analyzed. Measurements carried out with a crystal array of 2 mm pixel size and 10 mm height have shown time resolutions for the entire 288 SiPM two-detector set-up as good as 800 ps full width at half maximum (FWHM).
- PublicaciónMetascintillators: New Results for TOF-PET Applications(Institute of Electrical and Electronics Engineers, 2022-05) Lecoq, Paul; Konstantinou, Georgios; Latella, Riccardo; Moliner Martínez, Laura; Nuyts, Johan; Zhang, Lei; Barrio Toala, John; Benlloch Baviera, Jose María; González Martínez, Antonio Javier; Departamento de Ingeniería Electrónica; Escuela Técnica Superior de Ingeniería de Telecomunicación; Instituto de Instrumentación para Imagen Molecular; European Commission; European Research Council[EN] We report on the progress on a first generation of realistic size metascintillators for time-of-flight PET. These heterostructures combine dense LYSO or BGO plates, interleaved with fast scintillator layers producing a bunch of prompt photons from the energy leakage of the recoil photoelectric electron. From a Geant4 simulation of the energy sharing distribution between the dense and the fast scintillator on 42 LYSO-based and 42 BGO-based configurations, a detailed study of the timing performance has been performed on a selection of the most promising 12 LYSO-based and 14 BGO-based metascintillators. A Monte Carlo simulation was first performed to extrapolate from direct measurements of the performance of the metascintillator components, the detector time resolution (DTR), and sensitivity on the basis of the simulated amount of energy leakage to the fast scintillator. An analytic algorithm was then applied to determine an equivalent coincidence time resolution (CTR) from the random association of the DTR distributions from two metapixels in coincidence. This equivalent CTR is calculated in order to obtain the same variance in the reconstructed image as the combination of the DTR distributions of 2 metapixels. Preliminary results confirm that with these simple and still nonoptimized configurations, an equivalent CTR of 150 ps for BGO-based and 140 ps for LYSO-based metapixels of realistic size can be obtained
- PublicaciónSemi-Monolithic Meta-Scintillator Simulation Proof-of-Concept, Combining Accurate DOI and TOF(Institute of Electrical and Electronics Engineers, 2024-05) Konstantinou, Georgios; Zhang, Lei; Bonifacio, Daniel; Latella, Riccardo; Benlloch Baviera, Jose María; González Martínez, Antonio Javier; Lecoq, Paul; Instituto de Instrumentación para Imagen Molecular; European Commission[EN] In this study, we propose and examine a unique semimonolithic metascintillator (SMMS) detector design, where slow scintillators (BGO or LYSO) are split into thin slabs and read by an array of SiPM, offering depth-of-interaction (DOI) information. These are alternated with thin segmented fast scintillators (plastic EJ232 or EJ232Q), also read by single SiPMs, which provides pixel-level coincidence time resolution (CTR). The structure combines layers of slow scintillators of size 0.3 x 25.5 x (15 or 24) mm(3) with fast scintillators of size 0.1 x 3.1 x (15 or 24) mm(3). We use a Monte Carlo Gate simulation to gauge this novel semimonolithic detector's performance. We found that the time resolution of SMMS is comparable to pixelated metascintillator designs with the same materials. For example, a 15-mm deep LYSO-based SMMS yielded a CTR of 121 ps before applying timewalk correction (after correction, 107-ps CTR). The equivalent BGO-based SMMS presented a CTR of 241 ps, which is a 15% divergence from metascintillator pixel experimental findings from previous works. We also applied neural networks to the photon distributions and timestamps recorded at the SiPM array, following guidelines on semimonolithic detectors. This led to determining the DOI with less than 3-mm precision and a confidence level of 0.85 in the best case, plus more than 2 standard deviations accuracy in reconstructing energy sharing and interaction energy. In summary, neural network prediction capabilities outperform standard energy calculation methods or any analytical approach on energy sharing, thanks to the improved understanding of photon distribution.
- PublicaciónCharacterization of a High-Aspect Ratio Detector With Lateral Sides Readout for Compton PET(Institute of Electrical and Electronics Engineers, 2020-09) Barrio, John; Cucarella, Neus; González Martínez, Antonio Javier; Freire, Marta; Ilisie, Victor; Benlloch Baviera, Jose María; Instituto de Instrumentación para Imagen Molecular; European Commission