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Author (up) Gillam, J.E.; Solevi, P.; Oliver, J.F.; Rafecas, M.
Title Simulated one-pass list-mode: an approach to on-the-fly system matrix calculation Type Journal Article
Year 2013 Publication Physics in Medicine and Biology Abbreviated Journal Phys. Med. Biol.
Volume 58 Issue 7 Pages 2377-2394
Keywords
Abstract In the development of prototype systems for positron emission tomography a valid and robust image reconstruction algorithm is required. However, prototypes often employ novel detector and system geometries which may change rapidly under optimization. In addition, developing systems generally produce highly granular, or possibly continuous detection domains which require some level of on-the-fly calculation for retention of measurement precision. In this investigation a new method of on-the-fly system matrix calculation is proposed that provides advantages in application to such list-mode systems in terms of flexibility in system modeling. The new method is easily adaptable to complicated system geometries and available computational resources. Detection uncertainty models are used as random number generators to produce ensembles of possible photon trajectories at image reconstruction time for each datum in the measurement list. However, the result of this approach is that the system matrix elements change at each iteration in a non-repetitive manner. The resulting algorithm is considered the simulation of a one-pass list (SOPL) which is generated and the list traversed during image reconstruction. SOPL alters the system matrix in use at each iteration and so behavior within the maximum likelihood-expectation maximization algorithm was investigated. A two-pixel system and a small two dimensional imaging model are used to illustrate the process and quantify aspects of the algorithm. The two-dimensional imaging system showed that, while incurring a penalty in image resolution, in comparison to a non-random equal-computation counterpart, SOPL provides much enhanced noise properties. In addition, enhancement in system matrix quality is straightforward (by increasing the number of samples in the ensemble) so that the resolution penalty can be recovered when desired while retaining improvement in noise properties. Finally the approach is tested and validated against a standard (highly accurate) system matrix using experimental data from a prototype system-the AX-PET.
Address [Gillam, J. E.; Solevi, P.; Oliver, J. F.; Rafecas, M.] Univ Valencia, CSIC, IFIC, Inst Fis Corpuscular, Valencia, Spain, Email: john.gillam@ific.uv.es
Corporate Author Thesis
Publisher Iop Publishing Ltd Place of Publication Editor
Language English Summary Language Original Title
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0031-9155 ISBN Medium
Area Expedition Conference
Notes WOS:000316181300024 Approved no
Is ISI yes International Collaboration no
Call Number IFIC @ pastor @ Serial 1370
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Author (up) Llosa, G.; Barrillon, P.; Barrio, J.; Bisogni, M.G.; Cabello, J.; Del Guerra, A.; Etxebeste, A.; Gillam, J.E.; Lacasta, C.; Oliver, J.F.; Rafecas, M.; Solaz, C.; Stankova, V.; de La Taille, C.
Title High performance detector head for PET and PET/MR with continuous crystals and SiPMs Type Journal Article
Year 2013 Publication Nuclear Instruments & Methods in Physics Research A Abbreviated Journal Nucl. Instrum. Methods Phys. Res. A
Volume 702 Issue Pages 3-5
Keywords Monolithic crystals; SiPM; MG-APD; PET; High resolution; Position determination
Abstract A high resolution PET detector head for small animal PET applications has been developed. The detector is composed of a 12 mm x 12 mm continuous LYSO crystal coupled to a 64-channel monolithic SiPM matrix from FBK-irst. Crystal thicknesses of 5 mm and 10 mm have been tested, both yielding an intrinsic spatial resolution around 0.7 mm FWHM with a position determination algorithm that can also provide depth-of-interaction information. The detectors have been tested in a rotating system that makes it possible to acquire tomographic data and reconstruct images of Na-22 sources. An image reconstruction method specifically adapted for continuous crystals has been employed. The Full Width at Half Maximum measured from a point source reconstructed with ML-EM was 0.7 mm with the 5 mm crystal and 0.8 mm with the 10 mm crystal.
Address [Llosa, G.; Barrio, J.; Cabello, J.; Etxebeste, A.; Gillam, J. E.; Lacasta, C.; Oliver, J. F.; Rafecas, M.; Solaz, C.; Stankova, V.] Univ Valencia, CSIC, Inst Fis Corpuscular, Valencia, Spain, Email: gabriela.llosa@ific.uv.es
Corporate Author Thesis
Publisher Elsevier Science Bv Place of Publication Editor
Language English Summary Language Original Title
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0168-9002 ISBN Medium
Area Expedition Conference
Notes WOS:000314682300002 Approved no
Is ISI yes International Collaboration yes
Call Number IFIC @ pastor @ Serial 1330
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Author (up) Llosa, G.; Barrio, J.; Cabello, J.; Crespo, A.; Lacasta, C.; Rafecas, M.; Callier, S.; de la Taille, C.; Raux, L.
Title Detector characterization and first coincidence tests of a Compton telescope based on LaBr3 crystals and SiPMs Type Journal Article
Year 2012 Publication Nuclear Instruments & Methods in Physics Research A Abbreviated Journal Nucl. Instrum. Methods Phys. Res. A
Volume 695 Issue Pages 105-108
Keywords Hadron therapy; Compton imaging; LaBr3; Continuous crystal; SiPM; MPPC; G-APD
Abstract A Compton telescope for dose monitoring in hadron therapy consisting of several layers of continuous LaBr3 crystals coupled to silicon photomultiplier (SiPM) arrays is under development within the ENVISION project. In order to test the possibility of employing such detectors for the telescope, a detector head consisting of a continuous 16 mm x 18 mm x 5 mm LaBr3 crystal coupled to a SiPM array has been assembled and characterized, employing the SPIROC1 ASIC as readout electronics. The best energy resolution obtained at 511 key is 6.5% FWHM and the timing resolution is 3.1 ns FWHM. A position determination method for continuous crystals is being tested, with promising results. In addition, the detector has been operated in time coincidence with a second detector layer, to determine the coincidence capabilities of the system. The first tests are satisfactory, and encourage the development of larger detectors that will compose the telescope prototype.
Address [Llosa, G.; Barrio, J.; Cabello, J.; Crespo, A.; Lacasta, C.; Rafecas, M.] UVEG, CSIC, IFIC, Inst Fis Corpuscular, Valencia, Spain, Email: gabriela.llosa@ific.uv.es
Corporate Author Thesis
Publisher Elsevier Science Bv Place of Publication Editor
Language English Summary Language Original Title
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0168-9002 ISBN Medium
Area Expedition Conference
Notes WOS:000311469900020 Approved no
Is ISI yes International Collaboration yes
Call Number IFIC @ pastor @ Serial 1235
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Author (up) Llosa, G.; Rafecas, M.
Title Hybrid PET/Compton-camera imaging: an imager for the next generation Type Journal Article
Year 2023 Publication European Physical Journal Plus Abbreviated Journal Eur. Phys. J. Plus
Volume 138 Issue 3 Pages 214 - 19pp
Keywords
Abstract Compton cameras can offer advantages over gamma cameras for some applications, since they are well suited for multitracer imaging and for imaging high-energy radiotracers, such as those employed in radionuclide therapy. While in conventional clinical settings state-of-the-art Compton cameras cannot compete with well-established methods such as PET and SPECT, there are specific scenarios in which they can constitute an advantageous alternative. The combination of PET and Compton imaging can benefit from the improved resolution and sensitivity of current PET technology and, at the same time, overcome PET limitations in the use of multiple radiotracers. Such a system can provide simultaneous assessment of different radiotracers under identical conditions and reduce errors associated with physical factors that can change between acquisitions. Advances are being made both in instrumentation developments combining PET and Compton cameras for multimodal or three-gamma imaging systems, and in image reconstruction, addressing the challenges imposed by the combination of the two modalities or the new techniques. This review article summarizes the advances made in Compton cameras for medical imaging and their combination with PET.
Address [Llosa, Gabriela] CSIC UV, Inst Fis Corpuscular IFIC, Catedrat Beltran 2, Paterna 46980, Spain, Email: gabriela.llosa@ific.uv.es;
Corporate Author Thesis
Publisher Springer Heidelberg Place of Publication Editor
Language English Summary Language Original Title
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 2190-5444 ISBN Medium
Area Expedition Conference
Notes WOS:000945407400001 Approved no
Is ISI yes International Collaboration yes
Call Number IFIC @ pastor @ Serial 5488
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Author (up) Llosa, G.; Trovato, M.; Barrio, J.; Etxebeste, A.; Muñoz, E.; Lacasta, C.; Oliver, J.F.; Rafecas, M.; Solaz, C.; Solevi, P.
Title First Images of a Three-layer compton Telescope prototype for Treatment Monitoring in hadron Therapy Type Journal Article
Year 2016 Publication Frontiers in Oncology Abbreviated Journal Front. Oncol.
Volume 6 Issue Pages 14 - 6pp
Keywords Compton camera; Compton telescope; hadron therapy; treatment monitoring; LaBr3
Abstract A Compton telescope for dose monitoring in hadron therapy is under development at IFIC. The system consists of three layers of LaBr3 crystals coupled to silicon photomulti-plier arrays. Na-22 sources have been successfully imaged reconstructing the data with an ML-EM code. Calibration and temperature stabilization are necessary for the prototype operation at low coincidence rates. A spatial resolution of 7.8 mm FWHM has been obtained in the first imaging tests.
Address [Llosa, Gabriela; Trovato, Marco; Barrio, John; Etxebeste, Ane; Munoz, Enrique; Lacasta, Carlos; Oliver, Josep F.; Rafecas, Magdalena; Solaz, Carles; Solevi, Paola] Inst Fis Corpuscular IFIC CSIC UVEG, Valencia, Spain, Email: gabriela.llosa@ific.uv.es
Corporate Author Thesis
Publisher Frontiers Media Sa Place of Publication Editor
Language English Summary Language Original Title
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 2234-943x ISBN Medium
Area Expedition Conference
Notes WOS:000369799800001 Approved no
Is ISI yes International Collaboration no
Call Number IFIC @ elepoucu @ Serial 2785
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