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Author Roser, J.; Muñoz, E.; Barrientos, L.; Barrio, J.; Bernabeu, J.; Borja-Lloret, M.; Etxebeste, A.; Llosa, G.; Ros, A.; Viegas, R.; Oliver, J.F. doi  openurl
  Title Image reconstruction for a multi-layer Compton telescope: an analytical model for three interaction events Type Journal Article
  Year 2020 Publication Physics in Medicine and Biology Abbreviated Journal Phys. Med. Biol.  
  Volume 65 Issue 14 Pages 145005 - 17pp  
  Keywords (up) Compton camera; Compton imaging; hadron therapy; image reconstruction; lm-mlem; monte carlo simulations; multi-layer Compton telescope  
  Abstract Compton Cameras are electronically collimated photon imagers suitable for sub-MeV to few MeV gamma-ray detection. Such features are desirable to enablein vivorange verification in hadron therapy, through the detection of secondary Prompt Gammas. A major concern with this technique is the poor image quality obtained when the incoming gamma-ray energy is unknown. Compton Cameras with more than two detector planes (multi-layer Compton Cameras) have been proposed as a solution, given that these devices incorporate more signal sequences of interactions to the conventional two interaction events. In particular, three interaction events convey more spectral information as they allow inferring directly the incident gamma-ray energy. A three-layer Compton Telescope based on continuous Lanthanum (III) Bromide crystals coupled to Silicon Photomultipliers is being developed at the IRIS group of IFIC-Valencia. In a previous work we proposed a spectral reconstruction algorithm for two interaction events based on an analytical model for the formation of the signal. To fully exploit the capabilities of our prototype, we present here an extension of the model for three interaction events. Analytical expressions of the sensitivity and the System Matrix are derived and validated against Monte Carlo simulations. Implemented in a List Mode Maximum Likelihood Expectation Maximization algorithm, the proposed model allows us to obtain four-dimensional (energy and position) images by using exclusively three interaction events. We are able to recover the correct spectrum and spatial distribution of gamma-ray sources when ideal data are employed. However, the uncertainties associated to experimental measurements result in a degradation when real data from complex structures are employed. Incorrect estimation of the incident gamma-ray interaction positions, and missing deposited energy associated with escaping secondaries, have been identified as the causes of such degradation by means of a detailed Monte Carlo study. As expected, our current experimental resolution and efficiency to three interaction events prevents us from correctly recovering complex structures of radioactive sources. However, given the better spectral information conveyed by three interaction events, we expect an improvement of the image quality of conventional Compton imaging when including such events. In this regard, future development includes the incorporation of the model assessed in this work to the two interaction events model in order to allow using simultaneously two and three interaction events in the image reconstruction.  
  Address [Roser, J.; Munoz, E.; Barrientos, L.; Barrio, J.; Bernabeu, J.; Borja-Lloret, M.; Etxebeste, A.; Llosa, G.; Ros, A.; Viegas, R.; Oliver, J. F.] Inst Fis Corpuscular IFIC CSIC UVEG, Valencia, Spain, Email: Jorge.Roser@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:000552701600001 Approved no  
  Is ISI yes International Collaboration no  
  Call Number IFIC @ pastor @ Serial 4481  
Permanent link to this record
 

 
Author Roser, J.; Barrientos, L.; Bernabeu, J.; Borja-Lloret, M.; Muñoz, E.; Ros, A.; Viegas, R.; Llosa, G. doi  openurl
  Title Joint image reconstruction algorithm in Compton cameras Type Journal Article
  Year 2022 Publication Physics in Medicine and Biology Abbreviated Journal Phys. Med. Biol.  
  Volume 67 Issue 15 Pages 155009 - 15pp  
  Keywords (up) Compton camera; compton imaging; hadron therapy; image reconstruction; LM-MLEM; Monte Carlo simulations; multi-layer compton telescope  
  Abstract Objective. To demonstrate the benefits of using an joint image reconstruction algorithm based on the List Mode Maximum Likelihood Expectation Maximization that combines events measured in different channels of information of a Compton camera. Approach. Both simulations and experimental data are employed to show the algorithm performance. Main results. The obtained joint images present improved image quality and yield better estimates of displacements of high-energy gamma-ray emitting sources. The algorithm also provides images that are more stable than any individual channel against the noisy convergence that characterizes Maximum Likelihood based algorithms. Significance. The joint reconstruction algorithm can improve the quality and robustness of Compton camera images. It also has high versatility, as it can be easily adapted to any Compton camera geometry. It is thus expected to represent an important step in the optimization of Compton camera imaging.  
  Address [Roser, J.; Barrientos, L.; Bernabeu, J.; Borja-Lloret, M.; Munoz, E.; Ros, A.; Viegas, R.; Llosa, G.] CSIC UV, Inst Fis Corpuscular IFIC, Valencia, Spain, Email: Jorge.Roser@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:000827830200001 Approved no  
  Is ISI yes International Collaboration no  
  Call Number IFIC @ pastor @ Serial 5298  
Permanent link to this record
 

 
Author Llosa, G.; Trovato, M.; Barrio, J.; Etxebeste, A.; Muñoz, E.; Lacasta, C.; Oliver, J.F.; Rafecas, M.; Solaz, C.; Solevi, P. doi  openurl
  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 (up) 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  
Permanent link to this record
 

 
Author Viegas, R.; Roser, J.; Barrientos, L.; Borja-Lloret, M.; Casaña, J.V.; Lopez, J.G.; Jimenez-Ramos, M.C.; Hueso-Gonzalez, F.; Ros, A.; Llosa, G. doi  openurl
  Title Characterization of a Compton camera based on the TOFPET2 ASIC Type Journal Article
  Year 2023 Publication Radiation Physics and Chemistry Abbreviated Journal Radiat. Phys. Chem.  
  Volume 202 Issue Pages 110507 - 11pp  
  Keywords (up) Compton camera; Hadron therapy; LaBr3; PETsys TOFPET2; Silicon photomultipliers  
  Abstract The use of Compton cameras for medical imaging and its interest as a hadron therapy treatment monitoring has increased in the last decade with the development of silicon photomultipliers. MACACOp is a Compton camera prototype designed and assembled at the IRIS group of IFIC-Valencia. This Compton camera is based on monolithic Lanthanum (III) Bromide crystals and silicon photomultipliers, and employs the novel TOFPET2 ASIC as readout electronics. This system emerged as an alternative to MACACO II prototype, with the aim of improving its limited time resolution. To test the performance of the ASIC in a Compton camera setup, the prototype was characterized, both in laboratory and in-beam. A time resolution of 1.5 ns was obtained after time corrections, which improves greatly the performance of the MACACO II. Moreover, the results obtained at high photon energies demonstrate the ability of the system to obtain 1 mm displacements of the reconstructed spots. The results reinforce the potential of the system as a monitoring device for hadron therapy.  
  Address [Viegas, R.; Roser, J.; Barrientos, L.; Borja-Lloret, M.; Casana, J., V; Hueso-Gonzalez, F.; Ros, A.; Llosa, G.] CSIC UV, Inst Fis Corpuscular IFIC, Valencia, Spain, Email: Rita.Viegas@ific.uv.es  
  Corporate Author Thesis  
  Publisher Pergamon-Elsevier Science Ltd Place of Publication Editor  
  Language English Summary Language Original Title  
  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN 0969-806x ISBN Medium  
  Area Expedition Conference  
  Notes WOS:000870840600006 Approved no  
  Is ISI yes International Collaboration no  
  Call Number IFIC @ pastor @ Serial 5392  
Permanent link to this record
 

 
Author Barrientos, L.; Borja-Lloret, M.; Etxebeste, A.; Muñoz, E.; Oliver, J.F.; Ros, A.; Roser, J.; Senra, C.; Viegas, R.; Llosa, G. doi  openurl
  Title Performance evaluation of MACACO II Compton camera Type Journal Article
  Year 2021 Publication Nuclear Instruments & Methods in Physics Research A Abbreviated Journal Nucl. Instrum. Methods Phys. Res. A  
  Volume 1014 Issue Pages 165702 - 7pp  
  Keywords (up) Compton camera; Hadron therapy; LaBr3; Silicon photomultipliers  
  Abstract The IRIS group at IFIC-Valencia has developed a second version of a Compton camera prototype for hadron therapy treatment monitoring, with the aim of improving the performance with respect to its predecessor. The system is composed of three Lanthanum (III) bromide (LaBr3) crystals coupled to silicon photomultipliers (SiPMs). The detector energy resolution has been improved to 5.6% FWHM at 511 keV and an angular resolution of 8.0 degrees has been obtained. Images of a Na-22 point-like source have been reconstructed selecting two and three interaction events. Moreover, the experimental data have been reproduced with Monte Carlo simulations using a Compton camera module (CCMod) in GATE v8.2 obtaining a good correlation.  
  Address [Barrientos, L.; Borja-Lloret, M.; Munoz, E.; Oliver, J. F.; Ros, A.; Roser, J.; Senra, C.; Viegas, R.; Llosa, G.] Univ Valencia, Inst Fis Corpuscular, CSIC, Valencia, Spain, Email: lbarrien@ific.uv.es  
  Corporate Author Thesis  
  Publisher Elsevier 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:000701263400010 Approved no  
  Is ISI yes International Collaboration yes  
  Call Number IFIC @ pastor @ Serial 4976  
Permanent link to this record
 

 
Author Muñoz, E.; Barrio, J.; Etxebeste, A.; Ortega, P.G.; Lacasta, C.; Oliver, J.F.; Solaz, C.; Llosa, G. doi  openurl
  Title Performance evaluation of MACACO: a multilayer Compton camera Type Journal Article
  Year 2017 Publication Physics in Medicine and Biology Abbreviated Journal Phys. Med. Biol.  
  Volume 62 Issue 18 Pages 7321-7341  
  Keywords (up) Compton imaging; Compton camera; continuous LaBr3 crystal; silicon photomultiplier; hadron therapy  
  Abstract Compton imaging devices have been proposed and studied for a wide range of applications. We have developed a Compton camera prototype which can be operated with two or three detector layers based on monolithic lanthanum bromide (LaBr3) crystals coupled to silicon photomultipliers (SiPMs), to be used for proton range verification in hadron therapy. In this work, we present the results obtained with our prototype in laboratory tests with radioactive sources and in simulation studies. Images of a Na-22 and an Y-88 radioactive sources have been successfully reconstructed. The full width half maximum of the reconstructed images is below 4 mm for a Na-22 source at a distance of 5 cm.  
  Address [Munoz, Enrique; Barrio, John; Etxebeste, Ane; Ortega, Pablo G.; Lacasta, Carlos; Oliver, Josep F.; Solaz, Carles; Llosa, Gabriela] Univ Valencia, CSIC, Inst Fis Corpuscular, Valencia, Spain, Email: Enrique.Munoz@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:000408229900003 Approved no  
  Is ISI yes International Collaboration yes  
  Call Number IFIC @ pastor @ Serial 3253  
Permanent link to this record
 

 
Author Muñoz, E.; Barrientos, L.; Bernabeu, J.; Borja-Lloret, M.; Llosa, G.; Ros, A.; Roser, J.; Oliver, J.F. doi  openurl
  Title A spectral reconstruction algorithm for two-plane Compton cameras Type Journal Article
  Year 2020 Publication Physics in Medicine and Biology Abbreviated Journal Phys. Med. Biol.  
  Volume 65 Issue 2 Pages 025011 - 17pp  
  Keywords (up) Compton imaging; Compton camera; hadron therapy; image reconstruction  
  Abstract One factor limiting the current applicability extent of hadron therapy is the lack of a reliable method for real time treatment monitoring. The use of Compton imaging systems as monitors requires the correct reconstruction of the distribution of prompt gamma productions during patient irradiation. In order to extract the maximum information from all the measurable events, we implemented a spectral reconstruction method that assigns to all events a probability of being either partial or total energy depositions. The method, implemented in a list-mode maximum likelihood expectation maximization algorithm, generates a four dimensional image in the joint spatial-spectral domain, in which the voxels containing the emission positions and energies are obtained. The analytical model used for the system response function is also employed to derive an analytical expression for the sensitivity, which is calculated via Monte Carlo integration. The performance of the method is evaluated through reconstruction of various experimental and simulated sources with different spatial and energy distributions. The results show that the proposed method can recover the spectral and spatial information simultaneously, but only under the assumption of ideal measurements. The analysis of the Monte Carlo simulations has led to the identification of two important degradation sources: the mispositioning of the gamma interaction point and the missing energy recorded in the interaction. Both factors are related to the high energy transferred to the recoil electrons, which can travel far from the interaction point and even escape the detector. These effects prevent the direct application of the current method in more realistic scenarios. Nevertheless, experimental point-like sources have been accurately reconstructed and the spatial distributions and spectral emission of complex simulated phantoms can be identified.  
  Address [Munoz, Enrique; Barrientos, Luis; Bernabeu, Jose; Borja-Lloret, Marina; Llosa, Gabriela; Ros, Ana; Roser, Jorge; Oliver, Josep F.] Univ Valencia, CSIC, Inst Fis Corpuscular, Valencia, Spain, Email: Enrique.Munoz@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:000520111400001 Approved no  
  Is ISI yes International Collaboration no  
  Call Number IFIC @ pastor @ Serial 4332  
Permanent link to this record
 

 
Author Muñoz, E.; Barrio, J.; Bemmerer, D.; Etxebeste, A.; Fiedler, F.; Hueso-Gonzalez, F.; Lacasta, C.; Oliver, J.F.; Romer, K.; Solaz, C.; Wagner, L.; Llosa, G. doi  openurl
  Title Tests of MACACO Compton telescope with 4.44 MeV gamma rays Type Journal Article
  Year 2018 Publication Journal of Instrumentation Abbreviated Journal J. Instrum.  
  Volume 13 Issue Pages P05007 - 13pp  
  Keywords (up) Compton imaging; Instrumentation for hadron therapy; Gamma detectors (scintillators, CZT, HPG, HgI etc); Photon detectors for UV, visible and IR photons (solid state) (PIN diodes, APDs, Si PMTs, G APDs, CCDs, EBCCDs, EMCCDs etc)  
  Abstract Hadron therapy offers the possibility of delivering a large amount of radiation dose to tumors with minimal absorption by the surrounding healthy tissue. In order to fully exploit the advantages of this technique, the use of real-time beam monitoring devices becomes mandatory. Compton imaging devices can be employed to map the distribution of prompt gamma emission during the treatment and thus assess its correct delivery. The Compton telescope prototype developed at IFIC-Valencia for this purpose is made of three layers of LaBr3 crystals coupled to silicon photomultipliers. The system has been tested in a 4.44 MeV gamma field at the 3 MV Tandetron accelerator at HZDR, Dresden. Images of the target with the system in three different positions separated by 10 mm were successfully reconstructed. This indicates the ability of MACACO for imaging the prompt gamma rays emitted at such energies.  
  Address [Munoz, E.; Barrio, J.; Etxebeste, A.; Lacasta, C.; Oliver, J. F.; Solaz, C.; Llosa, G.] Univ Valencia, CSIC, Inst Fis Corpuscular, Parque Cient,C Catedrat Jose Beltran 2, E-46980 Paterna, Valencia, Spain, Email: Enrique.Munoz@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 1748-0221 ISBN Medium  
  Area Expedition Conference  
  Notes WOS:000431716900001 Approved no  
  Is ISI yes International Collaboration yes  
  Call Number IFIC @ pastor @ Serial 3575  
Permanent link to this record
 

 
Author Llosa, G. doi  openurl
  Title Recent developments in photodetection for medical applications Type Journal Article
  Year 2015 Publication Nuclear Instruments & Methods in Physics Research A Abbreviated Journal Nucl. Instrum. Methods Phys. Res. A  
  Volume 787 Issue Pages 353-357  
  Keywords (up) Detectors; Photodetectors; Medical applications; PET; SPECT; Hadron Therapy  
  Abstract The use of the most advanced technology in medical imaging results in the development of high performance detectors that can significantly improve the performance of the medical devices employed in hospitals. Scintillator crystals coupled to photodetectors remain to be essential detectors in terms of performance and cost for medical imaging applications in different imaging modalities. Recent advances in photodetectors result in an increase of the performance of the medical scanners. Solid state detectors can provide substantial performance improvement, but are more complex to integrate into clinical detectors due mainly to their higher cost. Solid state photodetectors (APDs, SiPMs) have made new detector concepts possible and have led to improvements in different imaging modalities. Recent advances in detectors for medical imaging are revised.  
  Address UVEG, 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:000354869900079 Approved no  
  Is ISI yes International Collaboration no  
  Call Number IFIC @ pastor @ Serial 2233  
Permanent link to this record
 

 
Author Barrientos, L.; Borja-Lloret, M.; Casaña, J.V.; Dendooven, P.; Garcia Lopez, J.G.; Hueso-Gonzalez, F.; Jiméeez-Ramos, M.C.; Perez-Curbelo, J.; Ros, A.; Roser, J.; Senra, C.; Viegas, R.; Llosa, G. doi  openurl
  Title Gamma-ray sources imaging and test-beam results with MACACO III Compton camera Type Journal Article
  Year 2024 Publication Physica Medica Abbreviated Journal Phys. Medica  
  Volume 117 Issue Pages 103199 - 10pp  
  Keywords (up) Hadron therapy; Compton camera; Scintillator crystals; Silicon photomultipliers  
  Abstract Hadron therapy is a radiotherapy modality which offers a precise energy deposition to the tumors and a dose reduction to healthy tissue as compared to conventional methods. However, methods for real-time monitoring are required to ensure that the radiation dose is deposited on the target. The IRIS group of IFIC-Valencia developed a Compton camera prototype for this purpose, intending to image the Prompt Gammas emitted by the tissue during irradiation. The system detectors are composed of Lanthanum (III) bromide scintillator crystals coupled to silicon photomultipliers. After an initial characterization in the laboratory, in order to assess the system capabilities for future experiments in proton therapy centers, different tests were carried out in two facilities: PARTREC (Groningen, The Netherlands) and the CNA cyclotron (Sevilla, Spain). Characterization studies performed at PARTREC indicated that the detectors linearity was improved with respect to the previous version and an energy resolution of 5.2 % FWHM at 511 keV was achieved. Moreover, the imaging capabilities of the system were evaluated with a line source of 68Ge and a point-like source of 241Am-9Be. Images at 4.439 MeV were obtained from irradiation of a graphite target with an 18 MeV proton beam at CNA, to perform a study of the system potential to detect shifts at different intensities. In this sense, the system was able to distinguish 1 mm variations in the target position at different beam current intensities for measurement times of 1800 and 600 s.  
  Address [Barrientos, L.; Borja-Lloret, M.; Casana, J. V.; Hueso-Gonzalez, F.; Perez-Curbelo, J.; Ros, A.; Roser, J.; Senra, C.; Viegas, R.; Llosa, G.] CSIC UV, Inst Fis Corpuscular IFIC, Valencia, Spain, Email: Luis.Barrientos@ific.uv.es  
  Corporate Author Thesis  
  Publisher Elsevier Sci Ltd Place of Publication Editor  
  Language English Summary Language Original Title  
  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN 1120-1797 ISBN Medium  
  Area Expedition Conference  
  Notes WOS:001145147400001 Approved no  
  Is ISI yes International Collaboration yes  
  Call Number IFIC @ pastor @ Serial 5892  
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