(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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