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Source size modelling by TPSs - 1
Elekta Oncentra
,
Physics and Algorithms v4.3
Source modelling is part of the calculation of direct photon energy fluence (the energy fluence of non-
scattered photons reaching the patient which calculated on a 1mm matrix resolution).
• Beam source model: Elliptical, 2D Gaussian distribution
• Source size:
Determined individually for each machine and beam energy
using measured data (fitting measured profiles and small field output
factors)
• Source is discretised on a 2D grid; amplitudes on each position
renormalized to sum up to unity
• The resolution of the source grid depends on its size, the resolution of the
energy fluence matrix and the distance to the collimators; derived at
runtime (10×10
40×40)
•Source of finite size (not point)
•Explicit source model
•Parameters of model determined from measured data