González Martínez, Antonio Javier
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- 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.
- PublicaciónDetector block performance based on a monolithic LYSO crystal using a novel signal multiplexing method(Elsevier, 2018-12-21) González, A.; Sánchez Martínez, Filomeno; Martí, Rosana; Hernández Hernández, Liczandro; Aguilar-Talens, Albert; BARBERA BALLESTER, JULIO; CATRET MASCARELL, JUAN VICENTE; Cañizares-Ledo, Gabriel; Conde-Castellanos, Pablo Eloy; Lamprou, Efthymios; Martos Pedrosa, Francisco; Sánchez-Góez, Sebastián; Vidal San Sebastián, Luis Fernando; Benlloch Baviera, Jose María; González Martínez, Antonio Javier; Instituto de Instrumentación para Imagen Molecular; Ministerio de Economía y Competitividad[EN] Organ dedicated PET devices provide improved imaging performance when compared to whole body systems. The present study summarizes the test carried out to study a new detector block designed for an organ dedicated PET system. This block includes three novel components namely the scintillator geometry and a retroreflector layer coupled to the entrance face, the photosensor and the readout electronics. We used arrays of 12 x 12 SiPM photosensors with 3 x 3 mm(2) active area each and a pitch of 4.2 mm. We are proposing a new readout electronics that permits to reduce the 12 row and columns signals to only 8 without significant detector performance degradation. This approach also allows for resolving radioactive sources in the whole volume of the proposed crystal, significantly reducing the edge effect that typically rejects these events. An overall spatial resolution of about 1.8 mm FWHM is obtained for the whole scintillation volume, with an average energy resolution of 13% FWHM and a photon depth of interaction resolution (FWHM) of 3.7 mm. (C) 2018 Elsevier B.V. All rights reserved.
- PublicaciónDesign and evaluation of the MAMMI dedicated breast PET(American Association of Physicists in Medicine, 2012-09) Moliner Martínez, Laura; González Martínez, Antonio Javier; Soriano Asensi, Antonio; Sánchez Martínez, Filomeno; Correcher Salvador, Carlos; Orero Palomares, Abel; Carles Fariña, Montserrat; Vidal San Sebastián, Luis Fernando; Barberá Ballester, Julio; Caballero Ontanaya, Luis; Seimetz, Michael; Vazquez Barreiros, Carlos; Benlloch Baviera, Jose María; Instituto de Instrumentación para Imagen Molecular; Ministerio de Ciencia e Innovación; Generalitat ValencianaPurpose: A breast dedicated positron emission tomography (PET) scanner has been developed based on monolithic LYSO crystals coupled to position sensitive photomultiplier tubes (PSPMTs). In this study, we describe the design of the PET system and report on its performance evaluation. Methods: MAMMI is a breast PET scanner based on monolithic LYSO crystals. It consists of 12 compact modules with a transaxial field of view (FOV) of 170 mm in diameter and 40 mm axial FOV that translates to cover up to 170 mm. The patient lies down in a prone position that facilitates maximum breast elongation. Quantitative performance analysis of the calculated method for the attenuation correction specifically developed for MAMMI, and based on PET image segmentation, has also been conducted in this evaluation. In order to fully determine the MAMMI prototype’s performance, we have adapted the measurements suggested for National Electrical Manufacturers Association (NEMA) NU 2-2007 and NU 4-2008 protocol tests, as they are defined for whole-body and small animal PET scanners, respectively. Results: Spatial resolutions of 1.6, 1.8, and 1.9 mm were measured in the axial, radial, and tangential directions, respectively. A scatter fraction of 20.8% was obtained and the maximum NEC was determined to be 25 kcps at 44 MBq. The average sensitivity of the system was observed to be 1% for an energy window of (250 keV–750 keV) and a maximum absolute sensitivity of 1.8% was measured at the FOV center. Conclusions: The overall performance of the MAMMI reported on this evaluation quantifies its ability to produce high quality PET images. Spatial resolution values below 3 mm were measured in most of the FOV. Only the radial component of spatial resolution exceeds the 3 mm at radial positions larger than 60 mm. This study emphasizes the need for standardized testing methodologies for dedicated breast PET systems similar to NEMA standards for whole-body and small animal PET scanners