(Sunday, 7/12/2020) [Eastern Time (GMT-4)]
Room: AAPM ePoster Library
Purpose: Multipoint detectors are very interesting toward developing new phantoms and making measurements in constrained space. This study aims at assessing the performance of the HYPERSCINT dosimetry research platform (Medscint inc., Québec, Canada) with a high spatial resolution 3-point plastic scintillation detector for application to high energy photon beam dosimetry.
Methods: A 3-point mPSD composed respectively of BCF10, BCF12 and BCF60 scintillating fiber (Saint-Gobain Crystals, Hiram, USA) separated by clear optical fiber was built. Both scintillation and Cerenkov signals were collected through a single 1-mm diameter transport fiber of 17-m long which was coupled to the HYPERSCINT, first commercially available scintillation dosimetry platform capable of multi-point dosimetry. Scintillation spectra in absence of Cerenkov light were acquired with an orthovolage unit to perform a deconvolution of the total signal using a hyperspectral approach. Dose calibration of each scintillator signal was accomplished with repeated irradiations of 100 cGy (6 MV). Using a solid-water phantom, measurements covering a wide range of doses and dose rates along with beam profile, percent depth dose and small field output factors were realized.
Results: Signal characterization of all scintillators displays a linear dose-light relationship for the whole range of doses and dose rates tested. The scintillation signal shows a discrepancy with the predicted dose that reaches 2.1% at 1 cGy but falls within ±0.7% above 10 cGy. Percent depth dose and FWHM region of the profile were accurately measured with a maximum deviation of 1.1% and 2.3% of the predicted dose, respectively. Output factor measurements exhibit an average difference of 1.0% for field size as small as 2x2 cm².
Conclusion: The ability to measure dosimetric characteristics of a clinical photon beam using a 3-point mPSD coupled to the HYPERSCINT was shown. The present study opens up new perspectives for further multipoint applications, especially for small field dosimetry.
Funding Support, Disclosures, and Conflict of Interest: Francois Therriault-Proulx is Co-founder and CEO at Medscint inc., a company developing scintillation dosimetry systems. This work was not financially supported by Medscint.
Keywords
Scintillators, Dosimetry, Small Fields
Taxonomy
TH- External Beam- Photons: Quality Assurance - Linear accelerator
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