Simulation of proton range monitoring in an anthropomorphic phantom using multi-slat collimators and time-of-flight detection of prompt-gamma quanta

• Verfasst von: Lopes, Patricia Cambraia [VerfasserIn]
• Verfasst von: Crespo, Paulo [VerfasserIn]
• Verfasst von: Simões, Hugo [VerfasserIn]
• Verfasst von: Ferreira Marques, Rui [VerfasserIn]
• Verfasst von: Parodi, Katia [VerfasserIn]
• Verfasst von: Schaart, Dennis R [VerfasserIn]
• Titel: Simulation of proton range monitoring in an anthropomorphic phantom using multi-slat collimators and time-of-flight detection of prompt-gamma quanta
• Verf.angabe: Patricia Cambraia Lopes, Paulo Crespo, Hugo Simões, Rui Ferreira Marques, Katia Parodi, Dennis R Schaart
• E-Jahr: 2018
• Jahr: [October 2018]
• Umfang: 14 S.
• Illustrationen: Illustrationen
• Fussnoten: Available online 17 September 2018 ; Gesehen am 09.07.2019
• Titel Quelle: Enthalten in: Physica medica
• Ort Quelle: Amsterdam : Elsevier, 1996
• Jahr Quelle: 2018
• Band/Heft Quelle: 54(2018), Seite 1-14
• ISSN Quelle: 1724-191X
• DOI: doi:10.1016/j.ejmp.2018.09.001
• Datenträger: Online-Ressource
• Sprache: eng
• Sach-SW: Anthropomorphic phantom
• Sach-SW: Multi-slat collimator
• Sach-SW: Prompt gamma imaging
• Sach-SW: Shifting time-of-flight
• K10plus-PPN: 166879666X

Abstract

Prompt-gamma (PG) imaging has the potential for monitoring proton therapy in real time. Different approaches are investigated. We focus on developing multi-slat collimators to image PG quanta, aiming at optimizing collimator performance to detect deviations in treatment delivery. We investigated six different multi-slat configurations, which have either optimal (analytical) intrinsic spatial resolution at fixed efficiency, or otherwise; at different distances from the proton pencil-beam axis (15cm-35cm). We used Geant4 to simulate irradiations of the head (energy: 130MeV) and pelvis (200MeV) of an anthropomorphic phantom, with and without physiologic/morphologic or setup changes of clinical dosimetric relevance. The particles escaping the phantom were transported through each of these multi-slat configurations and the gamma counts profiles were recorded at the collimator exit. Median filtering was applied to the registered PG-profiles to mitigate the effects of septa shadowing and statistical fluctuations. Time-of-flight discrimination was used to enhance the signal-to-background ratio, which appeared crucial for 200MeV irradiations. Visual detection of the artificially introduced changes was possible by comparing the PG to the depth-dose profiles. Moreover, 2mm range shifts could be detected in the head irradiation case using a simple linear regression fit to the falloff of the PG-profile. The influence of changes in complex, patient-like dose distributions on the PG-profiles obtained with multi-slat collimation is first studied in this work, which further gives insight on collimator design optimization and highlights its potential and simplicity for detecting proton treatment deviations over a wide range of Bragg peak positions.