A GEM-based dose imaging detector with optical readout for proton radiotherapy

Klyachko, A.; Moskvin, V.; Nichiporov, D.; Solberg, K.

doi:10.1016/j.nima.2012.08.049

Cited by 12 publications

(13 citation statements)

References 33 publications

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“…In particular, the GEM's spatial resolution in optical readout mode can be well under 1 mm. However, the LET response of the studied detectors was found to be non-water equivalent, resulting in the detector under-response in the Bragg peak region by about 5-10% compared with ionization chambers (Timmer et al 2002, Klyachko et al 2012.…”

Section: Introductionmentioning

confidence: 88%

Characterization of a GEM-based scintillation detector with He–CF₄gas mixture in clinical proton beams

Nichiporov¹,

Coutinho

Klyachko³

2016

Phys. Med. Biol.

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Accurate, high-spatial resolution dosimetry in proton therapy is a time consuming task, and may be challenging in the case of small fields, due to the lack of adequate instrumentation. The purpose of this work is to develop a novel dose imaging detector with high spatial resolution and tissue equivalent response to dose in the Bragg peak, suitable for beam commissioning and quality assurance measurements. A scintillation gas electron multiplier (GEM) detector based on a double GEM amplification structure with optical readout was filled with a He/CF4 gas mixture and evaluated in pristine and modulated proton beams of several penetration ranges. 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 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, and especially in small-field applications.

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Section: Introductionmentioning

confidence: 88%

Characterization of a GEM-based scintillation detector with He–CF₄gas mixture in clinical proton beams

Nichiporov¹,

Coutinho

Klyachko³

2016

Phys. Med. Biol.

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“…A comparison with GAFCHROMIC® films [13], the GEMPix detector [14] -a triple-GEM stack coupled to a pixelated charge readout -, and Monte Carlo simulations using FLUKA [15] showed that the main contribution to the spatial resolution is most likely the isotropic emission of the scintillation photons. It should be emphasized that even if, to date, there is no precise information in the literature regarding the directionality of light emission in GEM-based detectors, there is a consensus that photons are emitted isotropically [16,17,18]. Based on this assumption and on the obtained results, we concluded that the isotropic emission of the scintillation light introduces an additional blurring in the image, worsening the spatial resolution measured with the lead block from 5.20 ± 0.10 mm (GEMPix) to 9.70 ± 0.09 mm (LaGEMPix).…”

Section: Lagempix: Original Versionmentioning

confidence: 99%

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

Oliveira

Akkerman

Braccini

et al. 2022

J. Phys.: Conf. Ser.

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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.

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“…GEM-based detectors coupled to CCD/CMOS cameras were previously studied for particle therapy [11,18,19]. However, the degradation of the camera due to radiation requires placing it outside the beam, leading to a more complex system with, for example, mirrors or lenses.…”

Section: Detector Designmentioning

confidence: 99%

Characterization with X-rays of a Large-Area GEMPix Detector with Optical Readout for QA in Hadron Therapy

et al. 2021

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Quality Assurance (QA) in hadron therapy is crucial to ensure safe and accurate dose delivery to patients. This can be achieved with fast, reliable and high-resolution detectors. In this paper, we present a novel solution that combines a triple Gas Electron Multiplier (GEM) and a highly pixelated readout based on a matrix of organic photodiodes fabricated on top of an oxide-based thin-film transistor backplane. The first LaGEMPix prototype with an active area of 60 × 80 mm2 was developed and characterized using low energy X-rays. The detector comprises a drift gap of 3.5 mm, a triple-GEM stack for electron amplification, and a readout featuring 480 × 640 pixels at a 126 µm pitch. Here, we describe the measurements and results in terms of spatial resolution for various experimental configurations. A comparison with GAFCHROMIC® films and the GEMPix detector used in the charge readout mode was performed to better understand the contribution to the spatial resolution from both the electron diffusion and the isotropic emission of photons. The measurements were compared to Monte Carlo simulations, using the FLUKA code. The simulation predictions are in good agreement with the GEMPix results. Future plans with respect to applications in hadron therapy are discussed.

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A GEM-based dose imaging detector with optical readout for proton radiotherapy

Cited by 12 publications

References 33 publications

Characterization of a GEM-based scintillation detector with He–CF₄gas mixture in clinical proton beams

Characterization of a GEM-based scintillation detector with He–CF₄gas mixture in clinical proton beams

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

Characterization with X-rays of a Large-Area GEMPix Detector with Optical Readout for QA in Hadron Therapy

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A GEM-based dose imaging detector with optical readout for proton radiotherapy

Cited by 12 publications

References 33 publications

Characterization of a GEM-based scintillation detector with He–CF4gas mixture in clinical proton beams

Characterization of a GEM-based scintillation detector with He–CF4gas mixture in clinical proton beams

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

Characterization with X-rays of a Large-Area GEMPix Detector with Optical Readout for QA in Hadron Therapy

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Characterization of a GEM-based scintillation detector with He–CF₄gas mixture in clinical proton beams

Characterization of a GEM-based scintillation detector with He–CF₄gas mixture in clinical proton beams