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Geant4 Monte Carlo Characterization of Novel Electronic Brachytherapy System

Geant4 Monte Carlo Characterization of Novel Electronic Brachytherapy System. Derek Liu E. Poon, M. Bazalova, B. Reniers, M. Evans J. Seuntjens, T. Rusch*, F. Verhaegen McGill University * Xoft, Inc. Axxent Miniature X-ray Tube. Project Objectives. Characterize x-ray tube

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Geant4 Monte Carlo Characterization of Novel Electronic Brachytherapy System

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  1. Geant4 Monte Carlo Characterization of Novel Electronic Brachytherapy System Derek Liu E. Poon, M. Bazalova, B. Reniers, M. Evans J. Seuntjens, T. Rusch*, F. Verhaegen McGill University * Xoft, Inc.

  2. Axxent Miniature X-ray Tube

  3. Project Objectives • Characterize x-ray tube • Monte Carlo with experimental verification • Beam quality • HVL • Attenuation curve • Photon Spectrum • Spectrum • 2-D Dose distribution • Gafchromic film in Lucite Phantom

  4. NE 2571 farmer 2 mm Pb collimator 0.5 cm aperture Src-collimator: 1” Src-Al foil: 2” Src-detector: 10” Attenuation Curve • Output fluctuation Output monitor • Beam hardening Chamber response • Scatter Subtract scatter

  5. Amp-Tek CdTe 1 mm Crystal 4 mil Be Window 2 mm W collimator 2 mm aperture Src-CdTe: 1.5 m Spectrum • Air attenuation Attenuation correction • Detector response Stripping procedure • Energy Calibration 31.0 keV Ba-133 decay 14.9 keV Yttrium K-alpha

  6. Why use Geant? Complex geometry Low energy physics C++ Coding flexibility Geometry Tip thickness 0.2 mm Transmission Tungsten target thickness 0.7 um 2 mm water Geant 4.8.1

  7. Geant 4 Bremsstrahlung Production Bremsstrahlung mean free path Bremsstrahlung angular distribution

  8. Geant 4 Bremsstrahlung Production

  9. Source to Source Variation

  10. Comparison between Measured Spectra and Geant

  11. Source to Source Variation

  12. Aging Effects

  13. Gafchromic EBT films Lucite Phantom 2-D Dose Distribution • Src parallel to film • Src-film: 1.5 cm • Exposure time: 5 min • Max dose: 5 Gy • Calibration Ir-192 calibrated in water • Film scanning Document scanner • Image registration Matlab correlation routine

  14. Gaf EBT in Lucite: Relative Dose distribution at 1.5cm

  15. Conclusion • Geant4 Bremsstrahlung production comparable with EGS • Angular distribution • Bremsstrahlung mean free path • Bremsstrahlung spectrum • Spectral measurements • Spectra in agreement with Geant4 • Attenuation curve measurements • HVL in agreement with spectral HVL and Geant4 • Observed factors affecting beam quality • Source variation • Aging effect • Dose distribution measurements • General agreement with Geant4 • Deviation in forward and aft directions

  16. Acknowledgement • This project is partially funded by Xoft, Inc. • CdTe spectrometer funded by Research Institute of MUHC

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