Linear Accelerator Photon Spectra Reconstruction Using a Mixed Experimental Monte Carlo Method
Восстановление спектров фотонов линейного ускорителя с использованием смешанного экспериментального и Монте-Карло метода
2009-12-01
SCID: 54.1/p74er33d
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Elekta Precise 6-MeV linear acceleratorMCNP5 Monte CarloSchiff bremsstrahlung modelphoton spectrum reconstructionscatter analysis
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Abstract (AI)
The work focuses on reconstructing, by means of a scatter analysis method, the primary beam photon spectrum of a linear accelerator. This technique is based on irradiating the isocenter of a rectangular block made of methacrylate placed at 100 cm from the source and measuring scattered particles around the plastic at several specific positions with different scatter angles. The MCNP5 Monte Carlo code has been used to simulate the particle transport of monoenergetic beams and register the scatter measurement after contact with the attenuator. Measured ionization values are input necessary for calculating the spectrum as the sum of monoenergetic individual energy bins using the Schiff bremsstrahlung model. The measurements have been made in an Elekta Precise linac using a 6-MeV photon beam. Relative depth and profile dose curves calculated in a water phantom using the reconstructed spectrum agree with the experimentally measured dose data to within 5%.
Key Findings
1
A scatter analysis method reconstructs linear accelerator primary photon spectra by irradiating a methacrylate block at 100 cm and measuring scattered particles at multiple angles.
2
MCNP5 Monte Carlo simulations of monoenergetic beams were used to model particle transport and register scatter measurements for spectrum reconstruction.
3
Measured ionization values combined with the Schiff bremsstrahlung model allow the spectrum to be calculated as a sum of monoenergetic energy bins.
4
Method was applied to an Elekta Precise linac 6-MeV photon beam and produced reconstructed spectra used for dose calculations.
5
Relative depth and profile dose curves computed in a water phantom using the reconstructed spectrum agree with experimental dose data within 5%.
Research Object
Primary photon beam spectrum of a linear accelerator (6-MeV Elekta Precise linac)
Research Subject
Reconstruction of the primary photon spectrum via scatter analysis combining experimental scatter measurements around a methacrylate attenuator with MCNP5 monoenergetic simulations and Schiff bremsstrahlung model summation
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2009-12-01
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