Time-resolved imaging of prompt-gamma rays for proton range verification using a knife-edge slit camera based on digital photon counters
Autor: | Frauke Roellinghoff, S. Henrotin, Patricia Cambraia Lopes, Katia Parodi, Frédéric Stichelbaut, J. Huizenga, Damien Prieels, Enrico Clementel, Dennis R. Schaart, Paulo Crespo, Guillaume Janssens, Julien Smeets |
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Rok vydání: | 2015 |
Předmět: |
Neutrons
Physics Photons Radiological and Ultrasound Technology Proton business.industry Detector Collimator Bragg peak Radiation Dosage Lyso Collimated light law.invention Pencil (optics) Optics Gamma Rays law Proton Therapy Gamma Cameras Radiology Nuclear Medicine and imaging Protons business Proton therapy |
Zdroj: | Physics in Medicine and Biology. 60:6063-6085 |
ISSN: | 1361-6560 0031-9155 |
Popis: | Proton range monitoring may facilitate online adaptive proton therapy and improve treatment outcomes. Imaging of proton-induced prompt gamma (PG) rays using a knife-edge slit collimator is currently under investigation as a potential tool for real-time proton range monitoring. A major challenge in collimated PG imaging is the suppression of neutron-induced background counts. In this work, we present an initial performance test of two knife-edge slit camera prototypes based on arrays of digital photon counters (DPCs). PG profiles emitted from a PMMA target upon irradiation with a 160 MeV proton pencil beams (about 6.5 × 10(9) protons delivered in total) were measured using detector modules equipped with four DPC arrays coupled to BGO or LYSO : Ce crystal matrices. The knife-edge slit collimator and detector module were placed at 15 cm and 30 cm from the beam axis, respectively, in all cases. The use of LYSO : Ce enabled time-of-flight (TOF) rejection of background events, by synchronizing the DPC readout electronics with the 106 MHz radiofrequency signal of the cyclotron. The signal-to-background (S/B) ratio of 1.6 obtained with a 1.5 ns TOF window and a 3 MeV-7 MeV energy window was about 3 times higher than that obtained with the same detector module without TOF discrimination and 2 times higher than the S/B ratio obtained with the BGO module. Even 1 mm shifts of the Bragg peak position translated into clear and consistent shifts of the PG profile if TOF discrimination was applied, for a total number of protons as low as about 6.5 × 10(8) and a detector surface of 6.6 cm × 6.6 cm. |
Databáze: | OpenAIRE |
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