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Characterization of a plastic dosimeter based on organic semiconductorphotodiodes and scintillator

Posar, Jessie A., Davis, Jeremy, Brace, Owen, Sellin, Paul, Griffith, Matthew J., Dhez, Olivier, Wilkinson, Dean, Lerch, Michael L.F, Rosenfield, Anatoly and Petasecca, Marco (2020) Characterization of a plastic dosimeter based on organic semiconductorphotodiodes and scintillator Physics & Imaging in Radiation Oncology, 14. pp. 48-52.

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Background and purpose: Measurement of dose delivery is essential to guarantee the safety of patients under-going medical radiation imaging or treatment procedures. This study aimed to evaluate the ability of organic semi conductors, coupled with a plastic scintillator, to measure photon dose in clinically relevant conditions, and establish its radiation hardness. Thereby, proving organic devices are capable of being a water-equivalent, mechanically flexible, real-time dosimeter. Materials and methods: The shelf-life of an organic photodiode was analyzed to 40 kGy by comparison of the charge-collection-efficiency of a 520 nm light emitting diode. A non-irradiated and pre-irradiated photodiode was coupled to a plastic scintillator and their response to 6 MV photons was investigated. The dose linearity,dose-per-pulse dependence and energy dependence was characterized. Finally, the percentage depth dose (PDD)between 0.5 and 20 cm was compared with ionization chamber measurements.Results:Sensitivity to 6 MV photons was (190 ± 0.28) pC/cGy and (170 ± 0.11) pC/cGy for the non-irra-diated and pre-irradiated photodiode biased at −2 V. The response was independent of the dose-per-pulsebetween 0.031 and 0.34 mGy/pulse. An energy dependence was found for low keV energies, explained by theenergy dependence of the scintillator which plateaued between 70 keV and 1.2 MeV. The PDD was within ± 3%of the ionization chamber. Conclusion: Coupling an organic photodiode with a plastic scintillator provided reliable measurement of a rangeof photon energies. Dose-per-pulse and energy independence advocate their use as a dosimeter, specifically image-guided treatment without beam-quality correction factors. Degradation effects of organic semi conducting materials deteriorate sensor response but can be stabilized.

Item Type: Article
Divisions : Faculty of Engineering and Physical Sciences > Physics
Authors :
Posar, Jessie A.
Davis, Jeremy
Brace, Owen
Griffith, Matthew J.
Dhez, Olivier
Wilkinson, Dean
Lerch, Michael L.F
Rosenfield, Anatoly
Petasecca, Marco
Date : 27 May 2020
Funders : Australian Government Research Training Program
DOI : 10.1016/j.phro.2020.05.007
Copyright Disclaimer : © 2020 The Authors. Published by Elsevier B.V. on behalf of European Society of Radiotherapy & Oncology. This is an open access article under the CC BY-NC-ND license (
Additional Information : Embaro OK Metadata Pending
Depositing User : James Marshall
Date Deposited : 19 Jun 2020 08:55
Last Modified : 19 Jun 2020 08:55

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