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Monte Carlo Investigation of the Perspective Direction Dependence of Cherenkov Emission

T Dou1*, E Larochelle2, T Zhu3, (1) Texas Center for Proton Therapy, Irving, TX, (2) Dartmouth College, Hanover, NH (3) University Pennsylvania, Philadelphia, PA

Presentations

(Sunday, 7/12/2020)   [Eastern Time (GMT-4)]

Room: AAPM ePoster Library

Purpose:
Cherenkov light emission can potentially provide real-time monitoring of the skin dose for external beam radiotherapy because of the linear relationship between Cherenkov signal and radiation dose. To investigate the factors that can cause the deviation from this linearity, comparison study is performed between measured and Monte Carlo-simulated Cherenkov radiation for Total Skin Electron Therapy (TSET).

Methods:
Cherenkov emission data are recorded using a time-gated camera-system that is synchronized with linac irradiation. For TSET treatment delivery setting, Monte Carlo (MC) modeling was used to simulate the generation of Cherenkov light for different gantry angles and its propagation in tissue with tissue optical properties (ma = 0.4 cm?¹ and ms’ = 11.7 cm?¹) measured for the PVC phantom. GAMOS MC toolkit with optics plug-in was used for electron beam simulation that incorporated Varian linac component parameters and phase space file. The factors of tissue optical property and perspective direction are investigated for their effects on altering the linearity between measured Cherenkov signal and dose.

Results:
The depth dose and profile are compared between the simulated and measured dose distribution. A similar comparison is made between the simulated and measured Cherenkov emission using a PVC phantom. From phantoms with known optical properties, the correction factors are found for the light-to-dose conversion factors. Camera perspective is accounted for at a set of incident gantry angles.

Conclusion:
The study demonstrates a dependence of the ratio of Cherenkov signal intensity to dose as a function of perspective directions. The result is compared with measured Cherenkov intensity as well as OSLD/diode measurements.

Download ePoster [PDF]

Funding Support, Disclosures, and Conflict of Interest: The authors would like to acknowledge funding support from NATIONAL CANCER INSTITUTE: 1R21CA239127-01A1.

Keywords

Electron Therapy, Total Skin Irradiation, Optical Imaging

Taxonomy

TH- External Beam- Electrons: Development (new technology and techniques)

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