Characterization of a beam-tagging hodoscope for hadrontherapy monitoring

Allegrini, O.; Cachemiche, J. -P.; Caplan, C. P. C.; Carlus, B.; Chen, X.; Curtoni, S.; Dauvergne, D.; Della Negra, R.; Gallin-Martel, M. -L.; Hérault, J.; Létang, J. M.; Morel, C.; Testa, É.; Zoccarato, Y.

doi:10.48550/arxiv.2101.02079

Cited by 1 publication

(1 citation statement)

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“…The scatterer is comprised of seven plane silicon detectors and the absorber is comprised of an array of Bi 12 GeO 20 scintillating crystals (Fontana et al, 2020;Krimmer et al, 2015). This camera is intended to be coupled to a beam hodoscope for beam-position and TOF measurement (Allegrini et al, 2021). The precision of the camera for the calculation of the Bragg peak fall-off position was compared using two different reconstruction methods: an iterative maximum likelihood expectation maximisation (MLEM) reconstruction (Maxim et al, 2015) and the analytic line-cone reconstruction (Roellinghoff et al, 2011).…”

Section: Introductionmentioning

confidence: 99%

Influence of sub-nanosecond time of flight resolution for online range verification in proton therapy using the line-cone reconstruction in Compton imaging

Livingstone¹,

Dauvergne²,

Etxebeste³

et al. 2021

Phys. Med. Biol.

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Online ion range monitoring in hadron therapy can be performed via detection of secondary radiation, such as prompt γ-rays, emitted during treatment. The prompt γ emission profile is correlated with the ion depth-dose profile and can be reconstructed via Compton imaging. The line-cone reconstruction, using the intersection between the primary beam trajectory and the cone reconstructed via a Compton camera, requires negligible computation time compared to iterative algorithms.A recent report hypothesised that time of flight (TOF) based discrimination could improve the precision of the γ fall-off position measured via linecone reconstruction, where TOF comprises both the proton transit time from the phantom entrance until γ emission, and the flight time of the γ-ray to the detector. The aim of this study was to implement such a method and investigate the influence of temporal resolution on the precision of the fall-off position. Monte Carlo simulations of a 160 MeV proton beam incident on a homogeneous PMMA phantom were performed using GATE. The Compton camera consisted of a silicon-based scatterer and CeBr 3 scintillator absorber. The temporal resolution of the detection system (absorber + beam trigger) was varied between 0.1 and 1.3 ns RMS and a TOF-based discrimination method applied to eliminate unlikely solution(s) from the line-cone reconstruction. The fall-off position was obtained for varying temporal resolutions and its precision obtained from its shift across 100 independent γ emission profiles compared to a high statistics reference profile. The optimal temporal resolution for the given camera geometry and 10 8 primary protons was 0.2 ns where a precision of 2.30 ± 0.15 mm (1σ) on the fall-off position was found. This precision is comparable to current stateof-the-art Compton imaging using iterative reconstruction methods or 1D imaging with mechanically collimated devices, and satisfies the requirement of being smaller than the clinical safety margins.

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