Characterization of scintillating materials in use for brachytherapy fiber based dosimeters

S. Cometti, A. Gierej, A. Giaz, S. Lomazzi, T. Baghdasaryan, J. Van Erps, F. Berghmans, R. Santoro, M. Caccia, S. O'Keeffe

Research output: Contribution to journalArticlepeer-review

Abstract

This paper reports the characterization of two scintillating materials in powder form, Gadox and YVO embedded in a light-activated resin, used in a probe developed for oncological brachytherapy in-vivo dosimetry. The materials were characterized in terms of internal absorption, scintillation decay time, and light yield. The measurement of the optical characteristics highlighted a significant internal absorption at the scintillation light wavelength, with values of 6.5 dB/mm for Gadox and 14.1 dB/mm for YVO. Measurements of the characteristics scintillation time and of the light yield were performed with a novel method based on single photon counting, profiting from the long decay time of the materials under study. Measurements have been complemented by a two-step simulation with Geant4 to study the energy deposition followed by a ZEMAX OpticStudio® ray tracing to estimate the light collection efficiency. The decay time for scintillating materials were measured to be τGadox = (458 ± 3 ± 3) μs and τYVO = (451 ± 8 ± 3) μs and the estimated values of the light yield are (7.1 ± 0.5) × 104 photon/MeV for Gadox and (4.8 ± 0.5) × 104 photon/MeV for YVO.

Keywords

  • Brachytherapy
  • Inorganic scintillators
  • Light yield
  • Single photoelectron
  • SiPM

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