title: PET-based dose delivery verification in proton therapy: a GATE based simulation study of five PET system designs in clinical conditions.
abstract: PET is a promising technique for in vivo treatment verification in hadrontherapy. Three main PET geometries dedicated to in-beam treatment monitoring have been proposed in the literature: the dual-head PET geometry, the OpenPET geometry and the slanted-closed ring geometry. The aim of this work is to characterize the performance of two of these dedicated PET detectors in realistic clinical conditions. Several configurations of the dual-head PET and OpenPET systems were simulated using GATE v6.2. For the dual-head configuration, two aperture angles (15° and 45°) were studied. For the OpenPET system, two gaps between rings were investigated (110 and 160 mm). A full-ring PET system was also simulated as a reference. After preliminary evaluation of the sensitivity and spatial resolution using a Derenzo phantom, a real small-field head and neck treatment plan was simulated, with and without introducing patient displacements. No wash-out was taken into account. 3D maps of the annihilation photon locations were deduced from the PET data acquired right after the treatment session (5 min acquisition) using a dedicated OS-EM reconstruction algorithm. Detection sensitivity at the center of the field-of-view (FOV) varied from 5.2% (45° dual-head system) to 7.0% (full-ring PET). The dual-head systems had a more uniform efficiency within the FOV than the OpenPET systems. The spatial resolution strongly depended on the location within the FOV for the ϕ = 45° dual-head system and for the two OpenPET systems. All investigated architectures identified the magnitude of mispositioning introduced in the simulations within a 1.5 mm accuracy. The variability on the estimated mispositionings was less than 2 mm for all PET systems.
authors.affiliation: IMNC-UMR 8165 CNRS, Universités Paris 7 et Paris 11, Bât 440, F-91406 Orsay, France.
authors.forename: Charlotte
authors.initials: C
authors.lastname: Robert
authors.forename: Nicolas
authors.initials: N
authors.lastname: Fourrier
authors.forename: David
authors.initials: D
authors.lastname: Sarrut
authors.forename: Simon
authors.initials: S
authors.lastname: Stute
authors.forename: Pierre
authors.initials: P
authors.lastname: Gueth
authors.forename: Loïc
authors.initials: L
authors.lastname: Grevillot
authors.forename: Irène
authors.initials: I
authors.lastname: Buvat
mesh_terms: D006258:Head and Neck Neoplasms / Q000000981:diagnostic imaging / Q000532:radiotherapy; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008297:Male; D009010:Monte Carlo Method; D049268:Positron-Emission Tomography; D011471:Prostatic Neoplasms / Q000000981:diagnostic imaging / Q000532:radiotherapy; D061766:Proton Therapy / Q000379:methods*; D011829:Radiation Dosage; D011879:Radiotherapy Dosage; D011880:Radiotherapy Planning, Computer-Assisted; D061089:Radiotherapy, Image-Guided / Q000379:methods*