Gamma-ray sources imaging and test-beam results with MACACO III Compton camera

• Published in: Physica medica Vol. 117; p. 103199
• Main Authors: Barrientos, L., Borja-Lloret, M., Casaña, J.V., Dendooven, P., García López, J., Hueso-González, F., Jiménez-Ramos, M.C., Pérez-Curbelo, J., Ros, A., Roser, J., Senra, C., Viegas, R., Llosá, G.
• Format: Journal Article
• Language: English
• Published: Italy Elsevier Ltd 01-01-2024
• Subjects: Compton camera; Diagnostic Imaging; Gamma Rays; Hadron therapy; Monte Carlo Method; Proton Therapy; Scintillator crystals; Silicon photomultipliers; Spain; Spain; Scintillator crystals; Hadron therapy; Compton camera; Silicon photomultipliers
• ISSN: 1120-1797; 1724-191X
• DOI: 10.1016/j.ejmp.2023.103199

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.
•Compton camera consisting of three detector planes of LaBr3 scintillator crystals and silicon photomultipliers.•Images generated from different low and high-energy sources using all the system detection channels jointly.•Imaging capability tests with gamma-ray sources considerably larger than the size of the detectors.•Use of spectral image reconstruction code for identification of high-energy photons.•Differentiation of 1 mm range shifts with high-energy photons at different beam intensities.