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Barrientos L, Borja-Lloret M, Casaña JV, Dendooven P, García López J, Hueso-González F, Jiménez-Ramos MC, Pérez-Curbelo J, Ros A, Roser J, Senra C, Viegas R, Llosá G. Gamma-ray sources imaging and test-beam results with MACACO III Compton camera. Phys Med 2024; 117:103199. [PMID: 38142615 DOI: 10.1016/j.ejmp.2023.103199] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/28/2023] [Revised: 10/05/2023] [Accepted: 12/19/2023] [Indexed: 12/26/2023] Open
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.
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Affiliation(s)
- L Barrientos
- Instituto de Física Corpuscular (IFIC), CSIC-UV, Valencia, Spain.
| | - M Borja-Lloret
- Instituto de Física Corpuscular (IFIC), CSIC-UV, Valencia, Spain
| | - J V Casaña
- Instituto de Física Corpuscular (IFIC), CSIC-UV, Valencia, Spain
| | - P Dendooven
- Particle Therapy Research Center (PARTREC), Department of Radiation Oncology, University Medical Center Groningen, Groningen, The Netherlands
| | - J García López
- Centro Nacional de Aceleradores (Universidad de Sevilla, CSIC and Junta de Andalucía), E-41092 Sevilla, Spain; Departamento de Física Atómica, Molecular y Nuclear, Universidad de Sevilla, Sevilla, Spain
| | - F Hueso-González
- Instituto de Física Corpuscular (IFIC), CSIC-UV, Valencia, Spain
| | - M C Jiménez-Ramos
- Centro Nacional de Aceleradores (Universidad de Sevilla, CSIC and Junta de Andalucía), E-41092 Sevilla, Spain; Departamento de Física Aplicada II, Universidad de Sevilla, 41012 Sevilla, Spain
| | - J Pérez-Curbelo
- Instituto de Física Corpuscular (IFIC), CSIC-UV, Valencia, Spain
| | - A Ros
- Instituto de Física Corpuscular (IFIC), CSIC-UV, Valencia, Spain
| | - J Roser
- Instituto de Física Corpuscular (IFIC), CSIC-UV, Valencia, Spain
| | - C Senra
- Instituto de Física Corpuscular (IFIC), CSIC-UV, Valencia, Spain
| | - R Viegas
- Instituto de Física Corpuscular (IFIC), CSIC-UV, Valencia, Spain
| | - G Llosá
- Instituto de Física Corpuscular (IFIC), CSIC-UV, Valencia, Spain.
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Tomazinaki ME, Stiliaris E. A stochastic alternative technique for Compton Maximum Likelihood Expectation-Maximization (MLEM) reconstruction. Comput Biol Med 2023; 166:107502. [PMID: 37769463 DOI: 10.1016/j.compbiomed.2023.107502] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2023] [Revised: 08/18/2023] [Accepted: 09/15/2023] [Indexed: 09/30/2023]
Abstract
Even though iterative methods and particularly Maximum Likelihood Expectation-Maximization (MLEM) algorithms have been established in reconstruction with Compton data, their detailed design with respect to physical rules and processes dominate their plain implementation in the form of a system matrix. A new elementary but efficient alternative for the well-known system matrix with respect to Compton Camera image reconstruction is presented in this work. For each detected event there is a weighting factor inserted as an accumulated probability which carries all the necessary information. This probability which involves only the Compton scattering angle of the incident photon corresponds to a map that correlates all events within all possible source origins. Based on maximizing likelihood principles, the proposed model weights in a stochastic way the difference of the scatterer-to-source angle θ0, as it is determined by the deposited energy on the absorber, and any other potential scattering angle θJ, specified by the position coordinates on the reconstruction matrix. Obtained image spatial resolution, angular distortions and response to focal length determination are a few of the studied cases for the algorithms' evaluation via simulations in GEANT4/GATE with a set of radioactive sources and phantoms with in- and out-of-plane arrangement.
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Affiliation(s)
| | - Efstathios Stiliaris
- Department of Physics, National and Kapodistrian University of Athens, Greece; Institute of Accelerating Systems & Applications (IASA), Athens, Greece.
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Barrientos L, Borja-Lloret M, Casaña J, Hueso-González F, Ros A, Roser J, Senra C, Solaz C, Viegas R, Llosá G. System characterization and performance studies with MACACO III Compton camera. Radiat Phys Chem Oxf Engl 1993 2023. [DOI: 10.1016/j.radphyschem.2023.110922] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/03/2023]
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Llosá G, Rafecas M. Hybrid PET/Compton-camera imaging: an imager for the next generation. EUROPEAN PHYSICAL JOURNAL PLUS 2023; 138:214. [PMID: 36911362 PMCID: PMC9990967 DOI: 10.1140/epjp/s13360-023-03805-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 03/30/2022] [Accepted: 02/11/2023] [Indexed: 06/18/2023]
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.
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Affiliation(s)
- Gabriela Llosá
- Instituto de Física Corpuscular (IFIC), CSIC-UV, Catedrático Beltrán, 2., 46980 Paterna, Valencia, Spain
| | - Magdalena Rafecas
- Institute of Medical Engineering (IMT), Universität zu Lübeck, Ratzeburger Allee 160, 23562 Lübeck, Germany
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Roser J, Barrientos L, Bernabéu J, Borja-Lloret M, Muñoz E, Ros A, Viegas R, Llosá G. Joint image reconstruction algorithm in Compton cameras. Phys Med Biol 2022; 67. [DOI: 10.1088/1361-6560/ac7b08] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2022] [Accepted: 06/21/2022] [Indexed: 11/11/2022]
Abstract
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.
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Compton imaging for medical applications. Radiol Phys Technol 2022; 15:187-205. [PMID: 35867197 DOI: 10.1007/s12194-022-00666-2] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2022] [Revised: 07/04/2022] [Accepted: 07/04/2022] [Indexed: 12/18/2022]
Abstract
Compton imaging exploits inelastic scattering, known as Compton scattering, using a Compton camera consisting of a scatterer detector in the front layer and an absorber detector in the back layer. This method was developed for astronomy, and in recent years, research and development for environmental and medical applications has been actively conducted. Compton imaging can discriminate gamma rays over a wide energy range from several hundred keV to several MeV. Therefore, it is expected to be applied to the simultaneous imaging of multiple nuclides in nuclear medicine and prompt gamma ray imaging for range verification in particle therapy. In addition, multiple gamma coincidence imaging is expected to be realized, which allows the source position to be determined from a single coincidence event using nuclides that emit multiple gamma rays simultaneously, such as nuclides that emit a single gamma ray simultaneously with positron decay. This review introduces various efforts toward the practical application of Compton imaging in the medical field, including in vivo studies, and discusses its prospects.
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Proton range verification with MACACO II Compton camera enhanced by a neural network for event selection. Sci Rep 2021; 11:9325. [PMID: 33927324 PMCID: PMC8085220 DOI: 10.1038/s41598-021-88812-5] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2020] [Accepted: 04/13/2021] [Indexed: 11/09/2022] Open
Abstract
The applicability extent of hadron therapy for tumor treatment is currently limited by the lack of reliable online monitoring techniques. An active topic of investigation is the research of monitoring systems based on the detection of secondary radiation produced during treatment. MACACO, a multi-layer Compton camera based on LaBr3 scintillator crystals and SiPMs, is being developed at IFIC-Valencia for this purpose. This work reports the results obtained from measurements of a 150 MeV proton beam impinging on a PMMA target. A neural network trained on Monte Carlo simulations is used for event selection, increasing the signal to background ratio before image reconstruction. Images of the measured prompt gamma distributions are reconstructed by means of a spectral reconstruction code, through which the 4.439 MeV spectral line is resolved. Images of the emission distribution at this energy are reconstructed, allowing calculation of the distal fall-off and identification of target displacements of 3 mm.
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The SiFi-CC project – Feasibility study of a scintillation-fiber-based Compton camera for proton therapy monitoring. Phys Med 2020; 76:317-325. [DOI: 10.1016/j.ejmp.2020.07.013] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/31/2020] [Revised: 06/19/2020] [Accepted: 07/09/2020] [Indexed: 11/15/2022] Open
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