Quenching-free fluorescence signal from plastic-fibres in proton dosimetry: understanding the influence of Čerenkov radiation

Jeppe Brage Christensen*, Erik Almhagen, Håkan Nyström, Claus E. Andersen

*Corresponding author for this work

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    Abstract

    The origin of photons emitted in optical fibres under proton irradiation has been attributed to either entirely Čerenkov radiation or light consisting of fluorescence with a substantial amount of Čerenkov radiation. The source of the light emission is assessed in order to understand why the signal from optical fibres irradiated with protons is reportedly quenching-free. The present study uses the directional emittance of Čerenkov photons in 12 MeV and 20 MeV electron beams to validate a Monte Carlo model for simulating the emittance and transmission of Čerenkov radiation in optical fibres. We show that fewer than 0.01 Čerenkov photons are emitted and guided per 225 MeV proton penetrating the optical fibre, and that the Čerenkov signal in the optical fibre is completely negligible at the Bragg peak. Furthermore, on taking the emittance and guidance of both fluorescence and Čerenkov photons into account, it becomes evident that the reported quenching-free signal in PMMA-based optical fibres during proton irradiation is due to fluorescence.
    Original languageEnglish
    Article number065001
    JournalPhysics in Medicine and Biology
    Volume63
    Issue number6
    Number of pages10
    ISSN0031-9155
    DOIs
    Publication statusPublished - 2018

    Keywords

    • Ionization quenching
    • Dosimetry
    • Fluorescence
    • Čerenkov radiation
    • Proton therapy
    • Quenching-free

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