González Martínez, Antonio Javier
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- 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.
- PublicaciónA proof-of-concept of cross-luminescent metascintillators: testing results on a BGO: BaF2metapixel(IOP Publishing, 2023-01-21) Konstantinou, G.; Latella, Riccardo; Moliner Martínez, Laura; Zhang, L.; Benlloch Baviera, Jose María; González Martínez, Antonio Javier; Lecoq, Paul; Instituto de Instrumentación para Imagen Molecular; European Commission[EN] Objective: Time-of-flight positron emission tomography (PET)is the next frontier in improving the effective sensitivity. To achieve superior timing for time-of-flight PET, combined with high detection efficiency and cost-effectiveness, we have studied the applicability of BaF2 in metascintillators driven by the timing of cross-luminescence photon production. Approach: Based on previous simulation studies of energy sharing and analytic multi-exponential scintillation pulse, as well as sensitivity characteristics, we have experimentally tested a pixel of 3 × 3 × 15 mm3 based on 300 ¿m BGO and 300 ¿m BaF2 layers. To harness the deep ultraviolet cross-luminescent light component, which carries improved timing, we use the FBK VUV SiPM. Metascintillator energy sharing is addressed through a double integration approach. Main results: We reach an energy resolution of 22%, comparable to an 18% resolution of simple BGO pixels using the same readout, through the optimized use of the integrals of the metascintillator pulse in energy sharing calculation. We measure the energy sharing extent of each pulse with a resolution of 25% and demonstrate that experimental and simulation results agree well. Based on the energy sharing, a timewalk correction is applied, exhibiting significant improvements for both the coincidence time resolution (CTR) and the shape of the timing histogram. We reach 242 ps CTR for the entire photopeak, while for a subset of 13% of the most shared events, the CTR value improves to 108 ps, comparable to the 3 × 3 × 5 mm3 LYSO:Ce:Ca reference crystal. Significance: While we are considering different ways to improve further these results, this proof-ofconcept demonstrates the applicability of cross-luminescence for metascintillator designs through the application of VUV compatible SiPM coupling, and easily implementable digital algorithms. This is the first test of BaF2-based metascintillators of sufficient stoppng power to be included in a PET scanner, demonstrating the industrial applicability of such cross-luminescent metascintillators.
- PublicaciónPETIROC2 based readout electronics optimization for Gamma Cameras and PET detectors(IOP Publishing, 2017) Monzó Ferrer, José María; Aguilar -Talens, Albert; González Montoro, Andrea; Lamprou,E.; González Martínez, Antonio Javier; Hernández Hernández, Liczandro; Mázur, Dmytro; Colom Palero, Ricardo José; Benlloch Baviera, Jose María; Departamento de Ingeniería Electrónica; Escuela Técnica Superior de Ingeniería de Telecomunicación; Instituto de Instrumentación para Imagen Molecular; Ministerio de Economía, Industria y Competitividad[EN] Developing front-end electronics to improve charge detection and time resolution in gamma-ray detectors is one of the main tasks to improve performance in new multimodal imaging systems that merge information of Magnetic Resonance Imaging and Gamma Camera or PET tomographs. The aim of this work is to study the behaviour and to optimize the performance of an ASIC for PET and Gamma Camera applications based on SiPMs detectors. PETIROC2 is a commercial ASIC developed by Weeroc to provide accurate charge and time coincidence resolutions. It has 32 analog input channels that are independently managed. Each channel is divided into two signals, one for time stamping using a TDC and another for charge measurement. In this work, PETIROC2 is evaluated in an experimental setup composed of two pixelated LYSO crystals based detectors, each coupled to a Hamamatsu 4 x 4 SiPM array. Both detectors are working in coincidence with a separation distance between them that can be modified. In the present work, an energy resolution of 13 : 6% FWHM and a time coincidence resolution of 815 ps FWHM have been obtained. These results will be useful to optimize and improve PETIROC2 based PET and Gamma Camera systems.
- PublicaciónIn-depth evaluation of TOF-PET detectors based on crystal arrays and the TOFPET2 ASIC(Elsevier, 2020-10-11) Lamprou, Efthymios; Sánchez Martínez, Filomeno; Benlloch Baviera, Jose María; González Martínez, Antonio Javier; Instituto de Instrumentación para Imagen Molecular; European Commission; Generalitat Valenciana; Ministerio de Economía y Competitividad[EN] In recent years high efforts have been devoted to enhance spatial and temporal resolutions of PET detectors. However, accurately combining these two main features is, in most of the cases, challenging. Typically, a compromise has to be made between the number of readout channels, scintillator type and size, and photosensors arrangement if aiming for a good system performance, while keeping a moderate cost. In this work, we have studied several detector configurations for PET based on a set of 8x8 Silicon Photomultiplier (SiPMs) of 3x3 mm(2) active area, and LYSO crystal arrays with different pixel sizes. An exhaustive evaluation in terms of spatial, energy and timing resolution was made for all detector configurations. In some cases, when using pixel sizes different than SiPM active area, a significant amount of scintillation light may spread among several SiPMs. Therefore, we made use of a calibration method considering the different SiPM timing contributions. Best Detector Time Resolution (DTR) of 156 ps FWHM was measured when using 3x3 mm(2) crystal pixels directly coupled to the 3x3 mm(2) SiPMs. However, when using 1.5 mm crystal pixels with the same photosensor array, although we could clearly resolve all crystal pixels, an average DTR of 250 ps FWHM was achieved. We also shed light in this work on the timing dependency of the crystal pixel and photosensor alignment.
- PublicaciónDetector blockbased on arrays of 144 SiPMs and monolithic scintillators: A performane study(Elsevier, 2015-07-01) González Martínez, Antonio Javier; Conde Castellanos, Pablo Eloy; Iborra Carreres, Amadeo; Aguilar, A.; Bellido, P.; Garcia-Olcina, R.; Hernández Hernández, Liczandro; Moliner Martínez, Laura; Rigla, J. P.; Rodríguez Álvarez, María José; Sánchez, F; Seimetz, Michael; Soriano Asensi, Antonio; Torres, Jose; Vidal San Sebastián, Luis Fernando; Benlloch Baviera, Jose María; Departamento de Matemática Aplicada; Escuela Técnica Superior de Ingeniería Informática; Instituto de Instrumentación para Imagen Molecular; European Regional Development Fund; Consejo Superior de Investigaciones Científicas[EN] We have developed a detector block composed by a monolithic LYSO scintillator coupled to a custom made 12 12 SiPMs array. The design is mainly focused to applications such as Positron Emission Tomography. The readout electronics is based on 3 identical and scalable Application Specific Integrated Circuits (ASIC). We have determined the main performance of the detector block namely spatial, energy, and time resolution but also the system capability to determine the photon depth of interaction, for different crystal surface treatments. Intrinsic detector spatial resolution values as good as 1.7 mm FWHM and energies of 15% for black painted crystals were measured. & 2014 Elsevier B.V. All rights reserved.
- PublicaciónFeasibility Study of a Small Animal PET Insert Based on a Single LYSO Monolithic Tube(Frontiers Media, 2018-11-28) González Martínez, Antonio Javier; Berr, Stuart S.; Cañizares-Ledo, Gabriel; Gonzalez-Montoro, Andrea; Orero Palomares, Abel; Correcher Salvador, Carlos; Rezaei, Ahmadreza; Nuyts, Johan; Sánchez Martínez, Filomeno; Majewski, Stan; Benlloch Baviera, Jose María; Instituto de Instrumentación para Imagen Molecular; European Commission; Ministerio de Economía y Competitividad; Research Foundation Flanders; University of Virginia[EN] There are drawbacks with using a Positron Emission Tomography (PET) scanner design employing the traditional arrangement of multiple detectors in an array format. Typically PET systems are constructed with many regular gaps between the detector modules in a ring or box configuration, with additional axial gaps between the rings. Although this has been significantly reduced with the use of the compact high granularity SiPM photodetector technology, such a scanner design leads to a decrease in the number of annihilation photons that are detected causing lower scanner sensitivity. Moreover, the ability to precisely determine the line of response (LOR) along which the positron annihilated is diminished closer to the detector edges because the spatial resolution there is degraded due to edge effects. This happens for both monolithic based designs, caused by the truncation of the scintillation light distribution, but also for detector blocks that use crystal arrays with a number of elements that are larger than the number of photosensors and, therefore, make use of the light sharing principle. In this report we present a design for a small-animal PET scanner based on a single monolithic annulus-like scintillator that can be used as a PET insert in high-field Magnetic Resonance systems. We provide real data showing the performance improvement when edge-less modules are used. We also describe the specific proposed design for a rodent scanner that employs facetted outside faces in a single LYSO tube. In a further step, in order to support and prove the proposed edgeless geometry, simulations of that scanner have been performed and lately reconstructed showing the advantages of the design.
- PublicaciónPilot performance of a dedicated prostate PET suitable for diagnosis and biopsy guidance(SpringerOpen (part of Springer Nature), 2020-06-05) Cañizares-Ledo, Gabriel; Gonzalez-Montoro, Andrea; Freire, Marta; Lamprou, Efthymios; Barrio, John; Sánchez Martínez, Filomeno; Benlloch Baviera, Jose María; Hernandez, Liczandro; Moliner Martínez, Laura; Vidal San Sebastián, Luis Fernando; Torres, Irene; Sopena, Pablo; Vera-Donoso, Cesar D.; Bello, Pilar; Barbera, Julio; González Martínez, Antonio Javier; Instituto de Instrumentación para Imagen Molecular; European Commission; Generalitat Valenciana; European Regional Development Fund; Ministerio de Economía y Competitividad[EN] Background: Prostate cancer (PCa) represents one of the most common types of cancers facing the male population. Nowadays, to confirm PCa, systematic or multiparametric MRI-targeted transrectal or transperineal biopsies of the prostate are required. However, due to the lack of an accurate imaging technique capable to precisely locate cancerous cells in the prostate, ultrasound biopsies sample random parts of the prostate and, therefore, it is possible to miss regions where those cancerous cells are present. In spite of the improvement with multiparametric MRI, the low reproducibility of its reading undermines the specificity of the method. Recent development of prostatespecific radiotracers has grown the interest on using positron emission tomography (PET) scanners for this purpose, but technological improvements are still required (current scanners have resolutions in the range of 4¿5 mm). Results: The main goal of this work is to improve state-of-the-art PCa imaging and diagnosis. We have focused our efforts on the design of a novel prostate-dedicated PET scanner, named ProsPET. This system has small scanner dimensions defined by a ring of just 41 cm inner diameter. In this work, we report the design, implementation, and evaluation (both through simulations and real data) of the ProsPET scanner. We have been able to achieve < 2 mm resolution in reconstructed images and high sensitivity. In addition, we have included a comparison with the Philips Gemini-TF scanner, which is used for routine imaging of PCa patients. The ProsPET exhibits better contrast, especially for rod sizes as small as 4.5 mm in diameter. Finally, we also show the first reconstructed image of a PCa patient acquired with the ProsPET. Conclusions: We have designed and built a prostate specific PET system, with a small footprint and improved spatial resolution when compared to conventional whole-body PET scanners. The gamma ray impact within each detector block includes accurate DOI determination, correcting for the parallax error. The potential role of combined organdedicated prostate-specific membrane antigen (PSMA) PET and ultrasound devices, as a prebiopsy diagnostic tool, could be used to guide sampling of the most aggressive sites in the prostate.
- PublicaciónCharacterization of protons accelerated from a 3 TW table-top laser system(IOP Publishing, 2017-05) Bellido-Millán, Pablo Jesús; Lera, Roberto; Seimetz, Michael; Ruiz-de la Cruz, Alexandro; Torres Peiró, Salvador; Galán, M.; Mur, P.; Sánchez, I.; Zaffino, R.; Vidal San Sebastián, Luis Fernando; Soriano Asensi, Antonio; Sánchez-Góez, Sebastián; Sánchez Martínez, Filomeno; Rodríguez Álvarez, María José; Rigla, J.P.; Moliner Martínez, Laura; Iborra Carreres, Amadeo; Hernández Hernández, Liczandro; Grau-Ruiz, Daniel; González Martínez, Antonio Javier; García Garrigós, Juan José; Díaz Caballero, Elena; Conde-Castellanos, Pablo Eloy; Aguilar-Talens, Albert; Roso, Luis; Benlloch Baviera, Jose María; Departamento de Matemática Aplicada; Escuela Técnica Superior de Ingeniería Informática; Instituto de Instrumentación para Imagen Molecular; Ministerio de Economía y Competitividad; Ministerio de Ciencia e Innovación[EN] We report on benchmark tests of a 3 TW/50 fs, table-top laser system specifically developed for proton acceleration with an intrinsic pump rate up to 100 Hz. In two series of single-shot measurements differing in pulse energy and contrast the successful operation of the diode pumped laser is demonstrated. Protons have been accelerated up to 1.6 MeV in interactions of laser pulses focused on aluminium and mylar foils between 0.8 and 25 mu m thickness. Their spectral distributions and maximum energies are consistent with former experiments under similar conditions. These results show the suitability of our system and provide a reference for studies of laser targets at high repetition rate and possible applications.
- 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).
- PublicaciónCalibration and Performance Tests of Detectors for Laser-Accelerated Protons(Institute of Electrical and Electronics Engineers (IEEE), 2015) Seimetz, Michael; Bellido, P.; Soriano Asensi, Antonio; García López, J.; Jiménez-Ramos, M.C.; Fernández, B.; Conde Castellanos, Pablo Eloy; Crespo Navarro, Efren; González Martínez, Antonio Javier; Hernández Hernández, Liczandro; Iborra Carreres, Amadeo; Moliner Martínez, Laura; Rigla Pérez, Juan Pablo; Rodríguez Álvarez, María José; Sanchez, F.; Sanchez, S.; Vidal San Sebastián, Luis Fernando; Benlloch Baviera, Jose María; Departamento de Matemática Aplicada; Escuela Técnica Superior de Ingeniería Informática; Instituto de Instrumentación para Imagen Molecular; Ministerio de Ciencia e Innovación; Generalitat Valenciana; Ministerio de Economía y Competitividad; Consejo Superior de Investigaciones Científicas; European Social FundWe present the calibration and performance tests carried out with two detectors for intense proton pulses accelerated by lasers. Most of the procedures were realized with proton beams of 0.46-5.60 MeV from a tandem accelerator. One approach made use of radiochromic films, for which we calibrated the relation between optical density and energy deposition over more than three orders of magnitude. The validity of these results and of our analysis algorithms has been confirmed by controlled irradiation of film stacks and reconstruction of the total beam charge for strongly non-uniform beam profiles. For the spectral analysis of protons from repeated laser shots, we have designed an online monitor based on a plastic scintillator. The resulting signal from a photomultiplier directly measured on a fast oscilloscope is especially useful for time-of-flight applications. Variable optical filters allow for suppression of saturation and an extension of the dynamic range. With pulsed proton beams we have tested the detector response to a wide range of beam intensities from single particles 3 x 10(5) to protons per 100 ns time interval.