Quantifying Accuracy of Optical Imaging Surface Dosimetry
Presentations
PO-GePV-T-205 (Sunday, 7/10/2022) [Eastern Time (GMT-4)]
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Purpose: Optical methods camera systems originally developed for imaging Cherenkov radiation from tissue, can also be used to measure the light emission from scintillating reflective dots. These can be used as a linear reporter of the dose at the patient’s skin. This research seeks to improve the accuracy of Cherenkov and scintillation measurement relative to the delivered dose, by independent confirmation with TLDs measuring co-located values and using those values to provide dose calibration for Cherenkov imaging systems.
Methods: An anthropomorphic skin-tissue phantom was irradiated using a Varian TrueBeam linear accelerator. Field size, beam energy, and monitor units (MU) delivered were all iteratively adjusted to provide a comprehensive set of treatment conditions. Dose was measured with TLDs placed on the phantom surface. Scintillator dots were also placed on the phantom surface and were monitored by a Cherenkov imaging camera.
Results: The dose and scintillation data were collected and used to create calibration curves for the Cherenkov imaging system. Calibration curves were made based on field size, beam energy, and MU delivered. Curves were also produced based on fitting the scintillation response to a gaussian, and as a linear dose response.
Conclusion: The calibration curves produced by this work act as a proof of concept. The data was acquired using a planar, homogenous, phantom and thus does not account for many contours and topographical features present on real patients. Future work will shape and manipulate the phantom such that it can better replicate inhomogeneities and obliquities present in current treatments such as cranial, abdominal and breast treatments.
Funding Support, Disclosures, and Conflict of Interest: Cherenkov imaging cameras and software provided by C-Dose, co-founded by Dr. Brian Pogue.
Keywords
Optical Dosimetry, Quantitative Imaging, Quality Assurance
Taxonomy
Not Applicable / None Entered.
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