Benlloch Baviera, Jose María
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- Publication2D feasibility study of joint reconstruction of attenuation and activity in limited angle TOF-PET(Institute of Electrical and Electronics Engineers, 2021-09) Vergara, Marina; Rezaei, Ahmadreza; Schramm, Georg; Rodríguez Álvarez, María José; Benlloch Baviera, Jose María; Nuyts, Johan; Departamento de Matemática Aplicada; Escuela Técnica Superior de Ingeniería Informática; Instituto de Instrumentación para Imagen Molecular; European Commission; Research Foundation Flanders; National Institutes of Health, EEUU; Ministerio de Economía y Competitividad; Agencia Estatal de Investigación[EN] Several research groups are studying organ-dedicated limited angle positron emission tomography (PET) systems to optimize performance-cost ratio, sensitivity, access to the patient, and/or flexibility. Often open systems are considered, typically consisting of two detector panels of various sizes. Such systems provide incomplete sampling due to limited angular coverage and/or truncation, which leads to artifacts in the reconstructed activity images. In addition, these organ-dedicated PET systems are usually stand-alone systems, and as a result, no attenuation information can be obtained from anatomical images acquired in the same imaging session. It has been shown that the use of time-of-flight (TOF) information reduces incomplete data artifacts and enables the joint estimation of the activity and the attenuation factors. In this work, we explore with simple 2-D simulations the performance and stability of a joint reconstruction algorithm, for imaging with a limited angle PET system. The reconstruction is based on the so-called maximum-likelihood attenuation correction factors (MLACF) algorithm and uses linear attenuation coefficients in a known-tissue-class region to obtain absolute quantification. Different panel sizes and different TOF resolutions are considered. The noise propagation is compared to that of MLEM reconstruction with exact attenuation correction (AC) for the same PET system. The results show that with good TOF resolution, images of good visual quality can be obtained. If also a good scatter correction can be implemented, quantitative PET imaging will be possible. Further research, in particular on scatter correction, is required.
- PublicationElectromagnetic pulse generation in laser-proton acceleration from conductive and dielectric targets(IOP Publishing, 2020-11) Seimetz, Michael; Bellido, P.; Mur, P.; Lera, R.; Ruiz-de la Cruz, A.; Sánchez, I.; Zaffino, R.; Benlliure, J.; Ruiz, C.; Roso, L.; Benlloch Baviera, Jose María; Instituto de Instrumentación para Imagen Molecular; Ministerio de Economía y Competitividad; Agencia Estatal de Investigación[EN] Laser-plasma interactions at high intensities are often accompanied by emission of a strong electromagnetic pulse (EMP) interfering with particle detectors or other electronic equipment. We present experimental evidence for significant differences in noise amplitudes in laser-proton acceleration from aluminium as compared to mylar target foils. Such dissimilarities have been consistently observed throughout two series of measurements indicating that, under otherwise identical conditions, the target conductivity is the principal parameter related to EMP generation. In addition, the lateral size of the target foils correlates with the absolute noise levels. A frequency analysis combined with numerical simulations allows for an identification of several sources of radiofrequency emission in the MHz-GHz regime. Further, the temporal evolution of single frequencies on the nanosecond scale provides information on distinct excitation mechanisms.
- PublicationCharacterization of Viscoelastic Media Combining Ultrasound and Magnetic-Force Induced Vibrations on an Embedded Soft Magnetic Sphere(Institute of Electrical and Electronics Engineers, 2021-12) Cebrecos Ruiz, Alejandro; Jiménez González, Noé; Tarazona Tárrega, Rafael; Company, Miguel; Benlloch Baviera, Jose María; Camarena Femenia, Francisco; Departamento de Física Aplicada; Escuela Técnica Superior de Ingeniería Industrial; Escuela Politécnica Superior de Gandia; Instituto de Instrumentación para Imagen Molecular; GENERALITAT VALENCIANA; AGENCIA ESTATAL DE INVESTIGACION; UNIVERSIDAD POLITECNICA DE VALENCIA; Agència Valenciana de la Innovació[EN] We report a method to locally assess the complex shear modulus of a viscoelastic medium. The proposed approach is based on the application of a magnetic force to a millimeter-sized steel sphere embedded in the medium and the subsequent monitoring of its dynamical response. A coil is used to create a magnetic field inducing the displacement of the sphere located inside a gelatin phantom. Then, a phased-array system using 3 MHz ultrasound probe operating in pulse-echo mode is used to track the displacement of the sphere. Experiments were conducted on several samples and repeated as a function of phantom temperature. The dynamic response of the sphere measured experimentally is in good agreement with Kelvin¿Voigt theory. Since the magnetic force is not affected by weak diamagnetic media, our proposal results in an accurate estimation of the force acting on the inclusion. Consequently, the estimated viscoelastic parameters show excellent robustness and the elastic modulus agrees with the measurements using a quasi-static indentation method, obtaining errors below 10% in the whole temperature range. The use of the macroscopic inclusion limits the direct application of this method in a biomedical context, but it provides a robust estimation of the elastic modulus that can be used for material characterization in industrial applications.
- PublicationAcoustic Holograms for Bilateral Blood-Brain Barrier Opening in a Mouse Model(Institute of Electrical and Electronics Engineers, 2022-04) Jiménez-Gambín, Sergio; Jiménez González, Noé; Pouliopoulos, Antonios N.; Benlloch Baviera, Jose María; Konofagou, Elisa E.; Camarena Femenia, Francisco; Departamento de Física Aplicada; Escuela Técnica Superior de Ingeniería Industrial; Escuela Politécnica Superior de Gandia; Instituto de Instrumentación para Imagen Molecular; GENERALITAT VALENCIANA; AGENCIA ESTATAL DE INVESTIGACION; AGENCIA VALENCIANA DE LA INNOVACION; National Institutes of Health, EEUU; Agència Valenciana de la Innovació[EN] Transcranial focused ultrasound (FUS) in conjunction with circulating microbubbles injection is the sole non-invasive technique that temporally and locally opens the blood-brain barrier (BBB), allowing targeted drug delivery into the central nervous system (CNS). However, single-element FUS technologies do not allow the simultaneous targeting of several brain structures with high-resolution, and multi-element devices are required to compensate the aberrations introduced by the skull. In this work, we present the first preclinical application of acoustic holograms to perform a bilateral BBB opening in two mirrored regions in mice. The system consisted of a single-element focused transducer working at 1.68 MHz, coupled to a 3D-printed acoustic hologram designed to produce two symmetric foci in anesthetized mice in vivo and, simultaneously, compensate the aberrations of the wavefront caused by the skull bones. T1-weighed MR images showed gadolinium extravasation at two symmetric quasi-spherical focal spots. By encoding time-reversed fields, holograms are capable of focusing acoustic energy with a resolution near the diffraction limit at multiple spots inside the skull of small preclinical animals. This work demonstrates the feasibility of hologram-assisted BBB opening for low-cost and highly-localized targeted drug delivery in the CNS in symmetric regions of separate hemispheres.
- PublicationSemi-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.
- PublicationSimulation Study of Clinical PET Scanners With Different Geometries, Including TOF and DOI Capabilities.(Institute of Electrical and Electronics Engineers, 2024-07) Cañizares-Ledo, Gabriel; Jiménez Serrano, Santiago; Lucero-Ruiz, Alejandro; Morera-Ballester, Constantino; Muñoz, Enrique; Benlloch Baviera, Jose María; González Martínez, Antonio Javier; Departamento de Sistemas Informáticos y Computación; Escuela Técnica Superior de Ingeniería Informática; Instituto de Instrumentación para Imagen Molecular; European Research Council; European Regional Development Fund; Universitat Politècnica de València; Conselleria de Sanitat Universal i Salut Pública de la Generalitat Valenciana[EN] Total Body Positron Emission Tomography (TB-PET) scanners provide high-quality images due to the large sensitivity. Our motivation is to design a TB-PET system with up to 70 cm axial coverage that mitigates the parallax error degradation by using a detector concept based on semi-monolithic LYSO crystals. Furthermore, this detector approach allows to simultaneously reach an accurate Coincidence Time Resolution (CTR) to enhance the image quality by means of Time of Flight (TOF) reconstruction algorithms. We have simulated and compared two Positron Emission Tomography (PET) prototypes with about 70 cm but a different number of detector rings (7 vs. 5). The NEMA NU 2 2018 protocol has been implemented. By correcting the parallax error with the Depth of Interaction (DOI) information, the spatial resolution remains homogeneous and below 3 mm in the entire Field of View (FOV), differently from designs based on pixelated crystals. The sensitivity reaches values of 58 and 115 cps/kBq, for the 5 and 7 rings configurations, respectively. The Noise Equivalent Count Rate (NECR) was found at 563 kcps/mL. This value is lower than other systems, most likely due to the requirement to process a larger number of channels to characterize the DOI. Percent contrasts obtained for two different phantoms are in general beyond 80% for the largest spheres, nearly 100% for the 7 rings configuration once TOF is applied during the reconstruction process. In conclusion, although the sensitivity and NECR results for the 5-rings configuration are lower compared to the 7-rings approach, its overall performance is enhanced by the addition of TOF and parallax error correction, improving that of conventional Whole Body PET scanners (axial length: 20 ¿ 30 cm) in terms of image quality.
- PublicationSimulation Study for Designing a Dedicated Cardiac TOF-PET System(MDPI AG, 2020-03) Oliver Gil, Sandra; Moliner Martínez, Laura; Ilisie, V.; Benlloch Baviera, Jose María; Rodríguez Álvarez, María José; Departamento de Física Aplicada; Departamento de Matemática Aplicada; Escuela Técnica Superior de Ingeniería Industrial; Instituto Universitario de Seguridad Industrial, Radiofísica y Medioambiental; Escuela Técnica Superior de Ingeniería Informática; Instituto de Instrumentación para Imagen Molecular; European Commission; Generalitat Valenciana; European Regional Development Fund; Ministerio de Economía y Competitividad[EN] The development of dedicated positron emission tomography scanners is an active area of research, especially aiming at the improvement of lesion detection and in support of cancer treatment and management. Recently, dedicated Positron Emission Tomography (PET) systems with different configurations for specific organs have been developed for improving detection effectiveness. Open geometries are always subject to distortion and artifacts in the reconstructed images. Therefore, the aim of this work is to determine the optimal geometry for a novel cardiac PET system that will be developed by our team, and determine the time resolution needed to achieve reasonable image quality for the chosen geometry. The proposed geometries consist of 36 modules. These modules are arranged in two sets of two plates, each one with different configurations. We performed Monte Carlo simulations with different TOF resolutions, in order to test the image quality improvement in each case. Our results show, as expected, that increasing TOF resolution reduces distortion and artifact effects. We can conclude that a TOF resolution of the order of 200 ps is needed to reduce the artifacts, to acceptable levels, generated in the simulated cardiac-PET open geometries.
- PublicationSimultaneous imaging of hard and soft biological tissues in a low-field dental MRI scanner(Nature Publishing Group, 2020-12-08) Algarín Guisado, José Miguel; Díaz-Caballero, Elena; Borreguero Morata, José; Galve, Fernando; Grau-Ruiz, Daniel; Rigla, Juan P.; Bosch Esteve, Ruben; González-Hernández, José Manuel; Pallás Lodeiro, Eduardo; Corberán, Miguel; Gramage, Carlos; Aja-Fernández, Santiago; Ríos, Alfonso; Benlloch Baviera, Jose María; Alonso, Joseba; Instituto de Instrumentación para Imagen Molecular; European Commission; Generalitat Valenciana; Agencia Estatal de Investigación; European Regional Development Fund[EN] Magnetic Resonance Imaging (MRI) of hard biological tissues is challenging due to the fleeting lifetime and low strength of their response to resonant stimuli, especially at low magnetic fields. Consequently, the impact of MRI on some medical applications, such as dentistry, continues to be limited. Here, we present three-dimensional reconstructions of ex-vivo human teeth, as well as a rabbit head and part of a cow femur, all obtained at a field strength of 260 mT. These images are the first featuring soft and hard tissues simultaneously at sub-Tesla fields, and they have been acquired in a home-made, special-purpose, pre-medical MRI scanner designed with the goal of demonstrating dental imaging at low field settings. We encode spatial information with two pulse sequences: Pointwise-Encoding Time reduction with Radial Acquisition and a new sequence we have called Double Radial Non-Stop Spin Echo, which we find to perform better than the former. For image reconstruction we employ Algebraic Reconstruction Techniques (ART) as well as standard Fourier methods. An analysis of the resulting images shows that ART reconstructions exhibit a higher signal-to-noise ratio with a more homogeneous noise distribution.
- PublicationEffect of the early use of antivirals on the COVID-19 pandemic. A computational network modeling approach(Elsevier, 2020-11) Benlloch Baviera, Jose María; Cortés López, Juan Carlos; Martínez-Rodríguez, David; San Julián Garcés, Raúl; Villanueva Micó, Rafael Jacinto; Facultad de Administración y Dirección de Empresas; Departamento de Matemática Aplicada; Departamento de Comunicaciones; Instituto Universitario de Matemática Multidisciplinar; Instituto de Instrumentación para Imagen Molecular; Generalitat Valenciana; European Research Council; Agencia Estatal de Investigación[EN] It seems that we are far from controlling COVID-19 pandemics, and, consequently, returning to a fully normal life. Until an effective vaccine is found, safety measures as the use of face masks, social distancing, washing hands regularly, etc., have to be taken. Also, the use of appropriate antivirals in order to alleviate the symptoms, to control the severity of the illness and to prevent the transmission, could be a good option that we study in this work. In this paper, we propose a computational random network model to study the transmission dynamics of COVID-19 in Spain. Once the model has been calibrated and validated, we use it to simulate several scenarios where effective antivirals are available. The results show how the early use of antivirals may significantly reduce the incidence of COVID-19 and may avoid a new collapse of the health system. (c) 2020 Elsevier Ltd. All rights reserved.
- PublicationBeamforming for large-area scan and improved SNR in array-based photoacoustic microscopy(Elsevier, 2021) Cebrecos Ruiz, Alejandro; García Garrigós, Juan José; Descals, A.; Jiménez González, Noé; Benlloch Baviera, Jose María; Camarena Femenia, Francisco; Departamento de Física Aplicada; Escuela Técnica Superior de Ingeniería Industrial; Escuela Politécnica Superior de Gandia; Instituto de Instrumentación para Imagen Molecular; European Social Fund; Generalitat Valenciana; Agencia Estatal de Investigación; European Regional Development Fund; Universitat Politècnica de València; Agència Valenciana de la Innovació[EN] Beamforming enhances the performance of array-based photoacoustic microscopy (PAM) systems for large-area scan. In this study, we quantify the imaging performance of a large field-of-view optical-resolution photoacoustic-microscopy system using an phased-array detector. The system combines a low-cost pulsed-laser diode with a 128-element linear ultrasound probe. Signal-to-noise ratio (SNR) and generalized contrast-to-noise ratio (gCNR) are quantified using the phased-array detector and applying three beamforming strategies: a no-beamforming method equivalent to a single-element flat transducer, a fixed focus beamforming method that mimics a single-element focused transducer, and a dynamic focus beamforming using a delay-and-sum (DAS) algorithm. The imaging capabilities of the system are demonstrated generating high-resolution images of tissue-mimicking phantoms containing sub-millimetre ink tubes and an ex vivo rabbit¿s ear. The results show that dynamic focus DAS beamforming increases and homogenizes SNR along 1-cm2 images, reaching values up to 15 dB compared to an unfocused detector and up to 30 dB compared to out-of-focus regions of the fixed focus configuration. Moreover, the obtained values of gCNR using the DAS beamformer indicate an excellent target visibility, both on phantoms and ex vivo. This strategy makes it possible to scan larger surfaces compared to standard configurations using single-element detectors, paving the way for advanced array-based PAM systems.