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Characterization of a Novel Scintillator Imaging-Based Surface Dosimeter

I Tendler1*, P Bruza1 , M Jermyn2 , X Cao1 , B Williams3,4 , L Jarvis3,4 , B Pogue1,2,3 , D Gladstone1,3,4 , (1) Thayer School of Engineering, Dartmouth College, Hanover, NH, (2) DoseOptics LLC, Lebanon, NH, (3) Dept. of Medicine, Geisel School of Medicine, Dartmouth College, Hanover, NH (4) Norris Cotton Cancer Center, Dartmouth-Hitchcock Med. Ctr., Lebanon, NH, (5)

Presentations

(Sunday, 7/14/2019) 5:00 PM - 6:00 PM

Room: Stars at Night Ballroom 1

Purpose: The system described in this study is comprised of a time-gated intensified camera and plastic scintillating targets that are directly attached to the patient skin surface. Light emission from these scintillators is converted to dose via a custom fitting algorithm. This study assesses the clinical performance and physical characteristics of this new scintillator imaging-based surface dosimetry system.

Methods: To test the effects of dose rate (100 – 1000 MU/min), incident energy (6 – 18 MeV and MV), temperature (15 – 40 °C), and radiation damage (<15,000 Gy) on dosimeter performance, scintillators (15 mm ⌀ x 1 mm thick) were attached a flat-faced phantom and irradiated with photon and electron beams. Scintillator-to-scintillator variation (n = 30 dosimeters), as well as the effects of varying dosimeter diameter (5 – 30 mm) and thickness (0.65 – 3.13 mm) on scintillator light output, were also evaluated using this same setup. The emission spectra and impact of dosimeter thickness on surface dose were determined.

Results: Scintillators were found to have a 422 nm wavelength of maximum emission and increased underlying surface dose by 3.9% (comparable to standard optically stimulated luminescence detectors, OSLD). Scintillator light output increased linearly with thickness (~1.9×/mm) and all dosimeter diameters were able to accurately measure surface dose. The thinnest and thickest dosimeters increased surface dose by 2.6% and 6.6%, respectively – these values are comparable to commercially available technologies like OSLDs. Within the batch of scintillators, there existed a variation of 0.3 ± 0.2% in light output. Scintillators were found to function independent of temperature, energy, radiation damage and dose rate.

Conclusion: Scintillators utilized in this study can provide accurate surface dose information remotely and rapidly without any post-exposure processing. These dosimeters are a viable alternative to existing surface dosimetry technologies and have the potential to improve associated clinical workflow.

Funding Support, Disclosures, and Conflict of Interest: M. Jermyn is an employee and B. Pogue is a president of DoseOptics LLC. P Bruza is principal investigator in SBIR subaward B02463 (prime award NCI R44CA199681, DoseOptics LLC).

Keywords

Scintillators, In Vivo Dosimetry, Electron Therapy

Taxonomy

TH- External beam- electrons: Development (new technology and techniques)

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