A Large Area GEMPix detector for treatment plan verification in hadron therapy

Abstract

Quality Assurance in hadron therapy is crucial to ensure a safe and accurate dose delivery to the patients. This requires fast and reliable detectors with high spatial resolution. A first LaGEMPix prototype that combines a triple Gas Electron Multiplier and a highly pixelated readout based on a matrix of organic photodiodes coated on an oxide thin film transistor backplane has been built. The first version of the LaGEMPix has proven to have a limited spatial resolution, mainly attributed to the isotropic emission of the scintillation photons within the GEM holes. To improve the spatial resolution and confirm our predictions of the role of the photons, we built a new version of the detector with a reduced gap between the last GEM foil and the readout. Experimental results acquired using different methods and experimental set-ups show that the spatial resolution significantly improved with the new design.

A high-resolution large-area detector for quality assurance in radiotherapy

“…As a first attempt to improve the spatial resolution, the gap between the last GEM and the readout was reduced to minimize the impact of this effect. Even though the results with the reduced gap 16 demonstrated an important improvement, the desired sub-millimetre spatial resolution was not achievable for a compact system with optical readout, i.e., without the introduction of collimators or lenses in the set-up [17][18][19][20] .…”