Details

Autor(en) / Beteiligte

• Cambraia Lopes, Patricia
• Clementel, Enrico
• Crespo, Paulo
• Henrotin, Sebastien
• Huizenga, Jan
• Janssens, Guillaume
• Parodi, Katia
• Prieels, Damien
• Roellinghoff, Frauke
• Smeets, Julien
• Stichelbaut, Frederic
• Schaart, Dennis R

Titel

Time-resolved imaging of prompt-gamma rays for proton range verification using a knife-edge slit camera based on digital photon counters

Ist Teil von

• Physics in medicine & biology, 2015-08, Vol.60 (15), p.6063-6085

Ort / Verlag

England: IOP Publishing

Erscheinungsjahr

2015

Quelle

MEDLINE

Beschreibungen/Notizen

• 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   ×   109 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   ×   108 and a detector surface of 6.6 cm  ×  6.6 cm.