González Martínez, Antonio Javier
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- 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.
- 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.
- 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.
- PublicaciónEffect of noise in CT image reconstruction using QR- Decomposition algorithm(IEEE, 2013-11-02) Iborra, A.; Rodríguez Álvarez, María José; Soriano, A.; Sánchez Martínez, Filomeno; Bellido, P.; Conde, P.; Crespo, E.; González Martínez, Antonio Javier; Martos, F.; Moliner Martínez, Laura; Rigla, J. P.; Seimetz, Michael; 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; Generalitat Valenciana; Ministerio de Ciencia e Innovación[EN] The QR-Decomposition algorithm for CT 3D image reconstruction uses a linear system of equations to model the CT system response. Linear systems have a condition number that can be used to estimate the image noise. In this work the number of projections and the number of pixels in the detector have been studied to characterize the CT and the linear system of equations. The condition number of the system is estimated for the previous parameters used to generate the CT model with the aim of characterizing how these parameters affect the condition number and therefore bound the image noise level. It is shown that the condition number mainly depends on the size of pixels of the detector rather than the number of projections and this algorithm can be applied to low dose CT 3D image reconstruction without compromising image quality
- PublicaciónPerformance Evaluation of the Dual Ring MAMMI breast PET(IEEE, 2013-11-02) Soriano, A.; Sánchez Martínez, Filomeno; Carrilero, V.; Pardo, A.; Vidal San Sebastián, Luis Fernando; Vazquez, C.; Barbera, J.; Seimetz, Michael; Rodríguez Álvarez, María José; Rigla, J. P.; Moliner Martínez, Laura; Iborra, A.; Hernández, L.; González Martínez, Antonio Javier; Crespo, E.; Conde, P.; Bellido, P.; Caballero, L.; Benlloch Baviera, Jose María; Departamento de Matemática Aplicada; Escuela Técnica Superior de Ingeniería Informática; Instituto de Instrumentación para Imagen Molecular; Generalitat Valenciana; Ministerio de Ciencia e Innovación[EN] MAMMI is a dedicated breast positron emission tomograph (PET) based on monolythic LYSO crystals, with a transaxial field of view (FOV) of 170 mm. It has been upgraded by adding a second ring of detectors that extends the axial FOV from 40 mm to 94.4 mm, in order to improve its sensitivity and reduce the acquisition time. In this work we present the performance evaluation of the dual ring MAMMI breast PET and a discussion about the contribution of the addition of a second ring of detectors, the compensation of the detector blur and the increase of the scintillator thickness. Experimental measurements suggested on NEMA NU 4-2008 and NEMA NU 2-2007 have been conveniently adapted to the dimensions of the MAMMI. The addition of the second ring of detectors leads to a rise of the sensitivity from 1.8% to 3.6%. The spatial resolution at one-fourth of the axial FOV (1.5 mm axial, 1.6 mm tangential, 1.7 mm radial) is slightly better than that measured at the axial center (1.9 mm axial, 1.8 mm tangential and radial), because of the 14 mm gap in between detection rings. The results obtained after the evaluation reflect a substantial performance improvement, specially in the absolute sensitivity, because of the changes introduced in the MAMMI PET.
- PublicaciónTime reconstruction study using tubes of response backprojectors in List Mode algorithms, applied to amonolithic crystals based breast PET(IEEE, 2013-11-02) Moliner Martínez, Laura; Correcher, C.; González Martínez, Antonio Javier; Conde, P.; Crespo, E.; Hernandez, L.; Rigla, J. P.; Rodríguez Álvarez, María José; Sánchez Martínez, Filomeno; Soriano, A.; Iborra, A.; Bellido, P.; Seimetz, Michael; 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; Generalitat Valenciana; Ministerio de Ciencia e Innovación[EN] The LM-EM algorithm has the advantage to calculate the emission probabilities needed for the reconstruction process on the fly, without the need of a pre-calculated system matrix. The reconstruction time for this algorithm strongly depends on the used backprojector and the available statistics. This algorithm when implemented in systems using monolithic crystals to detect gamma radiation allows one to extensively exploit the virtual pixilation feature, not available for systems based on pixilated crystals. In this work we present a backprojector for LM-EM, the TOR method, which achieves a tradeoff between computational efficiency and image quality. Its temporal subset algorithm optimization (LM-OS) has also been implemented in order to achieve real-time reconstructions. To evaluate the performances of LM-OS algorithm with the TOR method backprojector and only with one iteration on the datasets, studies based on the system spatial resolution, uniformity, and contrast coefficients were carried out and they were compared with those obtained with LM-EM and MLEM algorithms using twelve iteration. Finally, a study on reconstruction time using LM-OS has been performed with breast patients data
- PublicaciónEM tomographic image reconstruction using polarvoxels(Institute of Physics: Hybrid Open Access, 2013-01) Soriano Asensi, Antonio; Rodríguez Álvarez, María José; Iborra Carreres, Amadeo; Sánchez Martínez, Filomeno; Carles Fariña, Montserrat; Conde Castellanos, Pablo Eloy; González Martínez, Antonio Javier; Hernández Hernández, Liczandro; Moliner Martínez, Laura; Orero Palomares, Abel; 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; Comisión Interministerial de Ciencia y Tecnología; Generalitat Valenciana; Ministerio de Ciencia e Innovación[EN] The splitting of the field of view (FOV) in polar voxels is proposed in this work in order to obtain an efficient description of a cone-beam computed tomography (CT) scanner. The proposed symmetric-polar pixelation makes it possible to deal with the 3D iterative reconstruction considering a number of projections and voxel sizes typical in CT preclinical imaging. The performance comparison, between the filtered backprojection (FBP) and 3D maximum likelihood expectation maximization (MLEM) reconstruction algorithm for CT, is presented. It is feasible to achieve the hardware spatial resolution limit with the considered pixelation. The image quality achieved with MLEM and FBP have been analyzed. The results obtained with both algorithms in clinical images have been compared too. Although the polar-symmetric pixelation is presented in the context of CT imaging, it can be applied to any other tomographic technique as long as the scan comprises the measurement of an object under several projection angles.
- PublicaciónStatistical moments of scintillation light distribution analysis with dSiPMs and monolithic crystals(IEEE, 2013-11-02) Conde, P.; González Martínez, Antonio Javier; Hernández, L.; Bellido, P.; Crespo, E.; Iborra, A.; Moliner Martínez, Laura; Rigla, J. P.; Rodríguez Álvarez, María José; Sánchez Martínez, Filomeno; Seimetz, Michael; Soriano, A.; 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; Generalitat Valenciana; Ministerio de Ciencia e Innovación[EN] Monolithic scintillation crystals offer the possibility to preserve the scintillation light distribution, specially when black painted. Furthermore, the statistical moments of that distribution can provide accurate information about the three spatial components. Nevertheless, for monolithic crystal the moments estimation has an associated error due to the symmetry truncation of the light distribution towards the crystal borders. For the 2-D impact coordinates determination, this error is called compression as it is accentuated near the edges. The computation of all centered moments is, therefore, affected by this error. Digital SiPMs (dSiPMs) can offer complete information about the light distribution, since all cells are purely digital detectors, so that other ways to obtain ¿-impact coordinates can be performed. In this work, a comparison between the statistical moments analysis and an alternative fitting the light distribution for each event to a theoretical distribution has been made. With the fitted approach, compression is avoided and an approximately constant spatial resolution is obtained for the entire photodetection area. Moreover, DOI information is improved and preserved all over the crystal.
- PublicaciónNoise Analysis in Computed Tomography (CT) Image Reconstruction using QR-Decomposition Algorithm(Institute of Electrical and Electronics Engineers (IEEE), 2015-06) Iborra Carreres, Amadeo; Rodríguez Álvarez, María José; Soriano Asensi, Antonio; Sanchez, F.; Bellido, P.; Conde Castellanos, Pablo Eloy; Crespo Navarro, Efren; González Martínez, Antonio Javier; Moliner Martínez, Laura; Rigla Pérez, Juan Pablo; Seimetz, Michael; 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; Generalitat Valenciana; Ministerio de Economía y CompetitividadIn this paper, the noise of 3D computed tomography (CT) image reconstruction using QR-Decomposition is analyzed. There are several types of image noise that can interfere with the interpretation of an image. Here, the noise introduced by the reconstruction process is studied. In this analysis, condition numbers are calculated with different CT model parameters, three dimensional (3D) CT image reconstruction with simulated and real data are performed, image noise analysis is performed through various image quality parameters and the condition number of the linear system is related with the image quality parameters. Results show the condition number’s dependence on the CT model. Image reconstructions with simulated data show errors significantly below the condition number theoretical bound and image reconstructions with real data show that quality improvements depend strongly on the condition number. This allows a reduction on the number of projections without compromising image quality and places this reconstruction method as a strong candidate for low-dose 3D CT imaging reconstruction.
- PublicaciónAnalysis of the Statistical Moments of the Scintillation Light Distribution With dSiPMs(Institute of Electrical and Electronics Engineers (IEEE), 2015-10) Conde Castellanos, Pablo Eloy; González Martínez, Antonio Javier; Gonzalez, A.; Hernández Hernández, Liczandro; Bellido, P.; Crespo Navarro, Efren; Iborra Carreres, Amadeo; Moliner Martínez, Laura; Rigla Pérez, Juan Pablo; Rodríguez Álvarez, María José; Sanchez, F.; Seimetz, Michael; Soriano Asensi, Antonio; 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 ValencianaIn gamma-ray detectors, monolithic scintillation crystals offer the possibility of preserving the scintillation light distribution especially when painted black. The statistical moments of this distribution provide accurate information on the three photon impact coordinates, including their depth of interaction (DOI). Digital SiPMs (dSiPMs) return digital information based on pixels about the collected light distribution, since the signal is a digital sum of the trigger bins. In this work we present, for the first time, an accurate analysis of the statistical moments of the light distribution using monolithic painted black crystals and state-of-the-art dSiPMs. Two 32.6 x 32.6 mm(2) monolithic LYSO crystals covering the entire photodetectors area have been used in coincidence with 10 mm in thickness. The photosensor tiles were kept at a stable temperature of T = 20 degrees C. Energy resolution of about 18% was reached in relation to the zeroth moment. The first moment, related to the impact position, determined a spatial resolution of about 3 mm near the crystal center, but quadratically degrading towards the crystal borders. The DOI resolution, measured by means of the second moment, was found to be nearing 4 mm in the crystal center region. The third order moment, the so-called skewness, is related to the degree of truncation and once calibrated minimizes the compression effects. A corrected spatial resolution of about 3 mm was then measured for the entire crystal surface. DOI resolution improved at the crystal's center, reaching 3.5 mm, but a degradation towards the borders remained due to truncation of the scintillation light distribution.