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Verfasst von:Nwankwo, Obioma [VerfasserIn]   i
 Glatting, Gerhard [VerfasserIn]   i
 Wenz, Frederik [VerfasserIn]   i
 Fleckenstein, Jens [VerfasserIn]   i
Titel:A single-source photon source model of a linear accelerator for Monte Carlo dose calculation
Verf.angabe:Obioma Nwankwo, Gerhard Glatting, Frederik Wenz, Jens Fleckenstein
E-Jahr:2017
Jahr:September 8, 2017
Umfang:17 S.
Fussnoten:Gesehen am 15.02.2018
Titel Quelle:Enthalten in: PLOS ONE
Ort Quelle:San Francisco, California, US : PLOS, 2006
Jahr Quelle:2017
Band/Heft Quelle:12(2017,9) Artikel-Nummer e0183486, 17 Seiten
ISSN Quelle:1932-6203
Abstract:Purpose: To introduce a new method of deriving a virtual source model (VSM) of a linear accelerator photon beam from a phase space file (PSF) for Monte Carlo (MC) dose calculation. Materials and methods: A PSF of a 6 MV photon beam was generated by simulating the interactions of primary electrons with the relevant geometries of a Synergy linear accelerator (Elekta AB, Stockholm, Sweden) and recording the particles that reach a plane 16 cm downstream the electron source. Probability distribution functions (PDFs) for particle positions and energies were derived from the analysis of the PSF. These PDFs were implemented in the VSM using inverse transform sampling. To model particle directions, the phase space plane was divided into a regular square grid. Each element of the grid corresponds to an area of 1 mm2 in the phase space plane. The average direction cosines, Pearson correlation coefficient (PCC) between photon energies and their direction cosines, as well as the PCC between the direction cosines were calculated for each grid element. Weighted polynomial surfaces were then fitted to these 2D data. The weights are used to correct for heteroscedasticity across the phase space bins. The directions of the particles created by the VSM were calculated from these fitted functions. The VSM was validated against the PSF by comparing the doses calculated by the two methods for different square field sizes. The comparisons were performed with profile and gamma analyses. Results: The doses calculated with the PSF and VSM agree to within 3% /1 mm (>95% pixel pass rate) for the evaluated fields. Conclusion: A new method of deriving a virtual photon source model of a linear accelerator from a PSF file for MC dose calculation was developed. Validation results show that the doses calculated with the VSM and the PSF agree to within 3% /1 mm.
DOI:doi:10.1371/journal.pone.0183486
URL:kostenfrei: Volltext: http://dx.doi.org/10.1371/journal.pone.0183486
 kostenfrei: Volltext: http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0183486
 DOI: https://doi.org/10.1371/journal.pone.0183486
Datenträger:Online-Ressource
Sprache:eng
Sach-SW:Approximation methods
 Electrons
 Monte Carlo method
 Particle accelerators
 Photons
 Polynomials
 Power distribution
 Simulation and modeling
K10plus-PPN:1569875987
Verknüpfungen:→ Zeitschrift
 
 
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