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Accurate, high-spatial resolution dosimetry in proton therapy is a time consuming task and may be challenging, due to the lack of adequate instrumentation. The paper describes the development of a novel dose imaging detectors based on gas electron multiplierz (GEM). Multiple needs are addressed in a single package by applying new detector technology to improve the speed, accuracy and cost-effectiveness of the quality assurance procedures.
A scintillation detector based on a double GEM amplification structure with optical readout was evaluated in pristine and modulated proton beams. The detector's performance was characterized in terms of linearity in dose rate, spatial resolution, short- and long-term stability and tissue-equivalence of response at different energies. Depth-dose profiles measured with the GEM detector in the 115 – 205 MeV energy range were compared with the profiles measured under similar conditions using the PinPoint 3D small-volume ion chamber. The GEM detector filled with a He-based gas mixture has a nearly tissue equivalent response in the proton beam and may become an attractive and efficient tool for high-resolution 2D and 3D dose imaging in proton dosimetry, in particular in small-field applications.
Scintillation GEM detector is also well suited for proton radiography applications, particularly in proposed efficient method for proton radiography-based QA of patient-specific devices based on the developed detector with the goal of improving accuracy, completeness and cost-effectiveness of the QA process in comparison with available alternatives.
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