Benlloch Baviera, Jose María

Organizational Units

Organizational Unit

Instituto de Instrumentación para Imagen Molecular

ORCID

0000-0001-6073-1436

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https://www.upv.es/ficha-personal/jobenba

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Now showing 1 - 10 of 98

Scanner calibration of a small animal PET camera based on continuous LSO crystals and flat panel PSPMTs
(Elsevier, 2007-02-01) Benlloch Baviera, Jose María; Carrilero, V.; González Martínez, Antonio Javier; Catret, J.; Lerche, Christoph Werner; Abellan, D.; García de Quiros, F.; Gimenez, M.; Modia, J.; Sánchez, Filomeno; Ros García, Ana; Martínez, J.; Sebastia Cortes, Angel; Instituto de Instrumentación para Imagen Molecular
[EN] We have constructed a small animal PET with four identical detector modules, each consisting of a continuous LYSO crystal attached to a Position Sensitive Photomultiplier Tube (PSPMT). The dimensions of the continuous crystal are 50 x 50 mm 2 and 10 mm thickness. The modules are separated 11 cm between each other in the scanner. In this paper we discuss the method used for the calibration of the camera for this special system with continuous detectors. We also present the preliminary values for the main performance parameters such as spatial and energy resolution, and sensitivity of the system. (c) 2006 Elsevier B.V. All rights reserved.
ALBIRA: A small animal PET/SPECT/CT imaging system
(American Association of Physicists in Medicine: Medical Physics, 2013-05) Sánchez Martínez, Filomeno; Orero Palomares, Abel; Soriano Asensi, Antonio; Correcher Salvador, Carlos; Conde Castellanos, Pablo Eloy; González Martínez, Antonio Javier; Hernández Hernández, Liczandro; Moliner Martínez, Laura; Rodríguez Álvarez, María José; Vidal San Sebastián, Luis Fernando; Benlloch Baviera, Jose María; Chapman, S.E.; Leevy, W.M.; Departamento de Matemática Aplicada; Escuela Técnica Superior de Ingeniería Informática; Instituto de Instrumentación para Imagen Molecular; Ministerio de Ciencia e Innovación; Generalitat Valenciana
Purpose: The authors have developed a trimodal PET/SPECT/CT scanner for small animal imaging. The gamma ray subsystems are based on monolithic crystals coupled to multianode photomultiplier tubes (MA-PMTs), while computed tomography (CT) comprises a commercially available microfocus x-ray tube and a CsI scintillator 2D pixelated flat panel x-ray detector. In this study the authors will report on the design and performance evaluation of the multimodal system. Methods: X-ray transmission measurements are performed based on cone-beam geometry. Individual projections were acquired by rotating the x-ray tube and the 2D flat panel detector, thus making possible a transaxial field of view (FOV) of roughly 80 mm in diameter and an axial FOV of 65 mm for the CT system. The single photon emission computed tomography (SPECT) component has a dual head detector geometry mounted on a rotating gantry. The distance between the SPECT module detectors can be varied in order to optimize specific user requirements, including variable FOV. The positron emission tomography (PET) system is made up of eight compact modules forming an octagon with an axial FOV of 40 mm and a transaxial FOV of 80 mm in diameter. The main CT image quality parameters (spatial resolution and uniformity) have been determined. In the case of the SPECT, the tomographic spatial resolution and system sensitivity have been evaluated with a99mTc solution using single-pinhole and multi-pinhole collimators. PET and SPECT images were reconstructed using three-dimensional (3D) maximum likelihood and ordered subset expectation maximization (MLEM and OSEM) algorithms developed by the authors, whereas the CT images were obtained using a 3D based FBP algorithm. Results: CT spatial resolution was 85μm while a uniformity of 2.7% was obtained for a water filled phantom at 45 kV. The SPECT spatial resolution was better than 0.8 mm measured with a Derenzo-like phantom for a FOV of 20 mm using a 1-mm pinhole aperture collimator. The full width at half-maximum PET radial spatial resolution at the center of the field of view was 1.55 mm. The SPECT system sensitivity for a FOV of 20 mm and 15% energy window was 700 cps/MBq (7.8 × 10−2%) using a multi-pinhole equipped with five apertures 1 mm in diameter, whereas the PET absolute sensitivity was 2% for a 350–650 keV energy window and a 5 ns timing window. Several animal images are also presented. Conclusions: The new small animal PET/SPECT/CT proposed here exhibits high performance, producing high-quality images suitable for studies with small animals. Monolithic design for PET and SPECT scintillator crystals reduces cost and complexity without significant performance degradation.
Performance of a DOI-encoding small animal PET system with monolithic scintillators
(Elsevier, 2012-12-11) Carles Fariña, Montserrat; Lerche, Christoph Werner; Sánchez Martínez, Filomeno; Orero Palomares, Abel; Moliner Martínez, Laura; Soriano Asensi, Antonio; Benlloch Baviera, Jose María; Instituto de Instrumentación para Imagen Molecular
PET systems designed for specific applications require high resolution and sensitivity instrumentation. In dedicated system design smaller ring diameters and deeper crystals are widely used in order to increase the system sensitivity. However, this design increases the parallax error, which degrades the spatial image resolution gradually from the center to the edge of the field-of-view (FOV). Our group has designed a depth of interaction(DOI)-encoding small animal PET system based on monolithic crystals. In this work we investigate the restoration of radial resolution for transaxially off-center sources using the DOI information provided by our system. For this purpose we have designed a support for point like sources adapted to our system geometry that allows a spatial compression and resolution response study. For different point source radial positions along vertical and horizontal axes of a FOV transaxial plane we compare the results obtained by three methods: without DOI information, with the DOI provided by our system and with the assumption that all the ¿-rays interact at half depth of the crystal thickness. Results show an improvement of the mean resolution of 10% with the half thickness assumption and a 16% achieved using the DOI provided by the system. Furthermore, a 10% restoration of the resolution uniformity is obtained using the half depth assumption and an 18% restoration using measured DOI. © 2011 Elsevier B.V.
Dosimetric Calibration of Radiochromic Film For Laser-accelerated Proton Beams
(IEEE, 2013-11-02) Bellido, P.; Seimetz, Michael; Soriano, A.; Huertas, C.; García Lopez, J.; Jimenez-Ramos, M. C:; Fernandez, B.; Conde, P.; Crespo, E.; González Martínez, Antonio Javier; Hernández, L.; Iborra, A.; Martos, F.; Moliner Martínez, Laura; Rigla, J. P.; Rodríguez Álvarez, María José; Sánchez Martínez, Filomeno; 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
[Otros] When an ultra-intense and ultra-short laser pulse interacts with solid matter a fraction of the laser pulse can be converted into kinetic energy of a beam of charged particles. Radiochromic film (RCF), widely used as radiation detector in the field of conventional radiotherapy, can be used as detector for laser-accelerated protons. If used in stack configuration it is a useful and versatile tool to obtain 2D spatial distribution and energetic information of proton beams. In order to obtain dosimetric information from RCF it must be properly calibrated. Irradiating film pieces under well known conditions allows us to establish a relation between the optical density (OD) of the radiochromic film, which is measured through a flat bed scanner operating in transmission mode, and the deposited energy in the active layer. A calibration curve over a large dynamic range (3 orders of magnitude) has been obtained for few MeV protons. Our calibration process has been performed at the Spanish National Accelerator Center at Sevilla. We have irradiated several areas of a single RCF with a constant 50 pA beam current and fixed 4 MeV energy from a 3 MV tandem accelerator. We have calculated the deposited energy in the films under the same conditions. We demonstrate that this technique can be used to measure the spectrum and total energy of a laser-accelerated mixed-energy proton beam. This detector has been calibrated for a near future application at the Center of Pulsed, Ultra-short, Ultra-intense Lasers (CLPU) at Salamanca (Spain). We present the calibration procedure and results, the design optimization, and a comparison with similar experiments.
The MINDVIEW project: First results
(Elsevier, 2018-04) Benlloch Baviera, Jose María; González Martínez, Antonio Javier; Pani, R.; Preziosi, Enrico; Jackson, C.; Murphy, J.; Barbera Ballester, Julio; Correcher Salvador, Carlos; Aussenhofer, Sebastian; Gareis, D.; Visvikis, Dimitris; Bert, J.; Langstrom, B.; Farde, Lars; Toth, M.; Haggkvist, J.; Caixeta, F.; Kullander, K.; Somlai-Schweiger, I.; Schwaiger, Markus; Instituto de Instrumentación para Imagen Molecular; European Commission
[EN] We present the first results of the MINDVIEW project. An innovative imaging system for the human brain examination, allowing simultaneous acquisition of PET/MRI images, has been designed and constructed. It consists of a high sensitivity and high resolution PET scanner integrated in a novel, head-dedicated, radio frequency coil for a 3T MRI scanner. Preliminary measurements from the PET scanner show sensitivity 3 times higher than state-of-the-art PET systems that will allow safe repeated studies on the same patient. The achieved spatial resolution, close to 1 mm, will enable differentiation of relevant brain structures for schizophrenia. A cost-effective and simple method of radiopharmaceutical production from C-11-carbon monoxide and a mini-clean room has been demonstrated. It has been shown that C-11-raclopride has higher binding potential in a new VAAT null mutant mouse model of schizophrenia compared to wild type control animals. A significant reduction in TSPO binding has been found in gray matter in a small sample of drug-naive, first episode psychosis patients, suggesting a reduced number or an altered function of immune cells in brain at early stage schizophrenia. (c) 2018 Elsevier Masson SAS. All rights reserved.
2D 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.
Attenuation correction without transmission scan for the MAMMI breast PET
(Elsevier, 2011-08-21) Soriano Asensi, Antonio; González Martínez, Antonio Javier; Orero Palomares, Abel; Moliner Martínez, Laura; Carles Fariña, Montserrat; Sánchez Martínez, Filomeno; Benlloch Baviera, Jose María; Correcher Salvador, Carlos; Carrilero Lopez, Vicente; Seimetz, Michael; Instituto de Instrumentación para Imagen Molecular; European Commission
[EN] Whole-body Positron Emission Tomography (PET) scanners are required in order to span large Fields of View (FOV). Therefore, reaching the sensitivity and spatial resolution required for early stage breast tumor detection is not straightforward. MAMMI is a dedicated breast PET scanner with a ring geometry designed to provide PET images with a spatial resolution as high as 1.5 mm, being able to detect small breast tumors ðo1 cmÞ. The patient lays down in prone position during the scan, thus making possible to image the whole breast, up to regions close to the base of the pectoral without the requirement of breast compression. Attenuation correction (AC) for PET data improves the image quality and the quantitative accuracy of radioactivity distribution determination. In dedicated, high resolution breast cancer scanners, this correction would enhance the proper diagnosis in early disease stages. In whole-body PET scanners, AC is usually taken into account with the use of transmission scans, either by external radioactive rod sources or by Computed Tomography (CT). This considerably increases the radiation dose administered to the patient and time needed for the exploration. In this work we propose a method for breast shape identification by means of PET image segmentation. The breast shape identification will be used for the determination of the AC. For the case of a specific breast PET scanner the procedure we propose should provide AC similar to that obtained by transmission scans as we take advantage of the breast anatomical simplicity. Experimental validation of the proposed approach with a dedicated breast PET prototype is also presented. The main advantage of this method is an important dose reduction since the transmission scan is not required.
Expectation maximization (EM) algorithms using polar symmetriesfor computed tomography(CT) image reconstruction
(Elsevier, 2013-09-01) Rodríguez Álvarez, María José; Soriano Asensi, Antonio; Iborra Carreres, Amadeo; Sánchez Martínez, Filomeno; González Martínez, Antonio Javier; Conde, P.; 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; Ministerio de Ciencia e Innovación; Generalitat Valenciana
We suggest a symmetric-polar pixellation scheme which makes possible a reduction of the computational cost for expectation maximization (EM) iterative algorithms. The proposed symmetric-polar pixellation allows us to deal with 3D images as a whole problem without dividing the 3D problem into 2D slices approach. Performance evaluation of each approach in terms of stability and image quality is presented. Exhaustive comparisons between all approaches were conducted in a 2D based image reconstruction model. From these 2D approaches, that showing the best performances were finally implemented and evaluated in a 3D based image reconstruction model. Comparison to 3D images reconstructed with FBP is also presented. Although the algorithm is presented in the context of computed tomography (CT) image reconstruction, it can be applied to any other tomographic technique as well, due to the fact that the only requirement is a scanning geometry involving measurements of an object under different projection angles. Real data have been acquired with a small animal (CT) scanner to verify the proposed mathematical description of the CT system.
Retroreflector arrays for better light collection efficiency of γ-ray imaging detectors with continuous scintillation crystals without DOI misestimation
(IOP Publishing, 2014-04) Ros, A.; Lerche, Christoph Werner; Sebastia Cortes, Angel; Sanchez, F.; Benlloch Baviera, Jose María; Instituto de Instrumentación para Imagen Molecular
A method to improve light collection efficiency of γ-ray imaging detectors by using retroreflector arrays has been tested, simulations of the behaviour of the scintillation light illuminating the retroreflector surface have been made. Measurements including retroreflector arrays in the setup have also been taken. For the measurements, positron emission tomography (PET) detectors with continuous scintillation crystals have been used. Each detector module consists of a continuous LSO-scintillator of dimensions 49x49x10 mm3 and a H8500 position-sensitive photomultiplier (PSPMT) from Hamamatsu. By using a continuous scintillation crystal, the scintillation light distribution has not been destroyed and the energy, the centroids along the x- and y-direction and the depth of interaction (DOI) can be estimated. Simulations have also been run taking into account the use of continuous scintillation crystals. Due to the geometry of the continuous scintillation crystals in comparison with pixelated crystals, a good light collection efficiency is necessary to correctly reconstruct the impact point of the γ-ray. The aim of this study is to investigate whether micro-machine retro-reflectors improve light yield without misestimation of the impact point. The results shows an improvement on the energy and centroid resolutions without worsening the depth of interaction resolution. Therefore it can be concluded that using retroreflector arrays at the entrance side of the scintillation crystal improves light collection efficiency without worsening the impact point estimation.
Time 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