Quality assurance of carbon ion and proton beams: A feasibility study for using the 2D MatriXX detector.

The quality assurance (QA) procedures in particle therapy centers with active beam scanning make extensive use of films, which do not provide immediate results. The purpose of this work is to verify whether the 2D MatriXX detector by IBA Dosimetry has enough sensitivity to replace films in some of the measurements. MatriXX is a commercial detector composed of 32×32 parallel plate ionization chambers designed for pre-treatment dose verification in conventional radiation therapy. The detector and GAFCHROMIC® films were exposed simultaneously to a 131.44MeV proton and a 221.45MeV/u carbon-ion therapeutic beam at the CNAO therapy center of Pavia - Italy, and the results were analyzed and compared. The sensitivity MatriXX on the beam position, beam width and field flatness was investigated. For the first two quantities, a method for correcting systematic uncertainties, dependent on the beam size, was developed allowing to achieve a position resolution equal to 230μm for carbon ions and less than 100μm for protons. The beam size and the field flatness measured using MatriXX were compared with the same quantities measured with the irradiated film, showing a good agreement. The results indicate that a 2D detector such as MatriXX can be used to measure several parameters of a scanned ion beam quickly and precisely and suggest that the QA would benefit from a new protocol where the MatriXX detector is added to the existing systems.

Varasteh Anvar M ，Attili A ，Ciocca M ，Donetti M ，Fanola Guarachi LK ，Fausti F ，Giordanengo S ，Marchetto F ，Molinelli S ，Monaco V ，Sacchi R ，Vignati A ，Cirio R ... -  《-》

Design of a QA method to characterize submillimeter-sized PBS beam properties using a 2D ionization chamber array.

Lin Y ，Bentefour H ，Flanz J ，Kooy H ，Clasie B ... -  《-》

Dosimetric commissioning and quality assurance of scanned ion beams at the Italian National Center for Oncological Hadrontherapy.

Mirandola A ，Molinelli S ，Vilches Freixas G ，Mairani A ，Gallio E ，Panizza D ，Russo S ，Ciocca M ，Donetti M ，Magro G ，Giordanengo S ，Orecchia R ... -  《-》

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 ... -  《-》

Use of a novel two-dimensional ionization chamber array for pencil beam scanning proton therapy beam quality assurance.

Lin L ，Kang M ，Solberg TD ，Mertens T ，Baeumer C ，Ainsley CG ，McDonough JE ... -  《-》