Transversal dose profile reconstruction for clinical proton beams: A detectors inter-comparison.

The main purpose of this work is the inter-comparison between different devices devoted to the transversal dose profile recostruction for daily QA tests in proton therapy. The results obtained with the EBT3 radiochromic films, used as a reference, and other common quality control devices, have been compared with those obtained with a beam profiling system developed at the "Laboratori Nazionali del Sud" of Italian Institute for Nuclear Physics (INFN-LNS, Catania, Italy). It consists of a plastic scintillator screen (thickness 1 mm), mounted perpendicularly to the beam axis and coupled with a highly sensitive CCD detector in a light-tight box. The tests, carried out both at the INFN-LNS and Trento Proton Therapy Center facilities, show, in general, a good agreement between the different detectors. The beam profiling system, in particular, appears to be a promising quality control device for 2-D relative dosimetry, because of its linear response in a dose rate range useful for proton therapy treatments, its high spatial resolution and its short acquisition and processing time.

Catalano R ，Petringa G ，Cuttone G ，Bonanno VP ，Chiappara D ，Musumeci MS ，Puglia SMR ，Stella G ，Scifoni E ，Tommasino F ，Cirrone GAP ... -  《-》

Characterization of a commercial scintillation detector for 2-D dosimetry in scanned proton and carbon ion beams.

Pencil beam scanning technique used at CNAO requires beam characteristics to be carefully assessed and periodically checked to guarantee patient safety. This study aimed at characterizing the Lynx® detector (IBA Dosimetry) for commissioning and periodic quality assurance (QA) for proton and carbon ion beams, as compared to EBT3 films, currently used for QA checks. The Lynx® is a 2-D high-resolution dosimetry system consisting of a scintillating screen coupled with a CCD camera, in a compact light-tight box. The scintillator was preliminarily characterized in terms of short-term stability, linearity with number of particles, image quality and response dependence on iris setting and beam current; Lynx® was then systematically tested against EBT3 films. The detector response dependence on radiation LET was also assessed. Preliminary results have shown that Lynx is suitable to be used for commissioning and QA checks for proton and carbon ion scanning beams; the cross-check with EBT3 films showed a good agreement between the two detectors, for both single spot and scanned field measurements. The strong LET dependence of the scintillator due to quenching effect makes Lynx® suitable only for relative 2-D dosimetry measurements. Lynx® appears as a promising tool for commissioning and periodic QA checks for both protons and carbon ion beams. This detector can be used as an alternative of EBT3 films, allowing real-time measurements and analysis, with a significant time sparing.

Russo S ，Mirandola A ，Molinelli S ，Mastella E ，Vai A ，Magro G ，Mairani A ，Boi D ，Donetti M ，Ciocca M ... -  《-》

Feasibility study of a plastic scintillating plate-based treatment beam fluence monitoring system for use in pencil beam scanning proton therapy.

The purpose of this study was to describe a plastic scintillating plate-based gantry-attachable dosimetry system for pencil beam scanning proton therapy to monitor entrance proton beam fluence, and to evaluate the dosimetric characteristics of this system and its feasibility for clinical use. The dosimetry system, consisting of a plastic scintillating plate and a CMOS camera, was attached to a dedicated scanning nozzle and scintillation during proton beam irradiation was recorded. Dose distribution was calculated from the accumulated recorded frames. The dosimetric characteristics (energy dependency, dose linearity, dose rate dependency, and reproducibility) of the gantry-attachable dosimetry system for use with therapeutic proton beams were measured, and the feasibility of this system during clinical use was evaluated by determining selected quality assurance items at our institution. The scintillating plate shortened the range of the proton beam by the water-equivalent thickness of the plate and broadened the spatial profile of the single proton spot by 11% at 70 MeV. The developed system functioned independently of the beam energy (<1.3%) and showed dose linearity, and also functioned independently of the dose rate. The feasibility of the system for clinical use was evaluated by comparing the measured quality assurance dose distribution to that of the treatment planning system. The gamma passing rate with a criterion of 3%/3 mm was 97.58%. This study evaluated the dosimetric characteristics of a plastic scintillating plate-based dosimetry system for use with scanning proton beams. The ability to account for the interference of the dosimetry system on the therapeutic beam enabled offline monitoring of the entrance beam fluence of the pencil beam scanning proton therapy independent of the treatment system with high resolution and in a cost-effective manner.

Jeong S ，Chung K ，Ahn SH ，Lee B ，Seo J ，Yoon M ... -  《-》

Preliminary investigations on the determination of three-dimensional dose distributions using scintillator blocks and optical tomography.

Kroll F ，Pawelke J ，Karsch L 《-》

Characterizing the response of miniature scintillation detectors when irradiated with proton beams.

Archambault L ，Polf JC ，Beaulieu L ，Beddar S ... -  《-》