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  5. Preliminary Characterization of a Stemless Plastic Scintillation Detector

Preliminary Characterization of a Stemless Plastic Scintillation Detector

M Hupman1*, T Monajemi1,2,3 , I Hill1 , A Syme1,2,3 , (1) Department of Physics & Atmospheric Science, Dalhousie University, Halifax, NS, B3H 4R2, Canada (2) Department of Radiation Oncology, Dalhousie University, Halifax, NS, B3H 4R2, Canada (3) Department of Medical Physics, Nova Scotia Health Authority, QEII Health Science Centre, Halifax, NS, B3H 1V7, Canada

Presentations

(Sunday, 7/14/2019) 1:00 PM - 2:00 PM

Room: Stars at Night Ballroom 1

Purpose: To characterize a stemless plastic scintillation detector (SPSD) with respect to linearity and reproducibility and assess its dependence on energy, dose per pulse and direction.

Methods: An organic bulk heterojunction photodiode was fabricated on an ITO-coated glass substrate by spin coating a blend of P3HT and PCBM, and depositing aluminum top contacts. Eljen scintillators (EJ-204 or EJ-260) were placed on the opposite side of the glass. To measure linearity, the SPSD was irradiated with doses ranging from 20-1000 cGy with 6 MV photons, 10x10 cm² field size, at a depth of 5 cm in solid water, and an SSD of 95 cm. Dose per pulse dependence was measured with the same setup except the SSD was varied from 75-125 cm. Energy dependence was measured by using 100, 180, and 300 kVp photon beams from an orthovoltage treatment unit (Xstrahl 300) and 6 and 18 MV photons from a Varian iX accelerator. Directional dependence was observed for a 16 MeV electron beam and compared to a diamond detector. Surface measurements were taken at an SSD of 107 cm and 3 cm of solid water was placed on top for depth measurements.

Results: The device showed excellent linearity with r² of 1 over the dose range. The coefficient of variability over 10 identical measurements was 0.4%. Variation with dose per pulse was within 2.5% of the value measured at 95cm SSD. The largest change in response with energy was 3.2 times from 100 kV to 6 MV for EJ-260. The SPSD exhibited a directional dependence of less than 4% when compared to a diamond detector, however, correction for Cerenkov generated in the scintillator has not yet been evaluated.

Conclusion: A SPSD demonstrated excellent linearity, increase response with energy, and a small directional dependence without a Cerenkov correction.

Funding Support, Disclosures, and Conflict of Interest: NSERC Discovery Grant (Award # RGPIN/06113 - 2014) and NSERC PGS-D

Keywords

Scintillators, Diodes, Tissue Equivalency

Taxonomy

TH- Radiation dose measurement devices: scintillators

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