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ESTRO IMRT course 2015
Dose Calculation in Static and Rotational IMRT
Brussels October 8th, 2015
-37-
Kernel-based methods:
2D-superposition methods: Pencil Kernel algorithms
As for 3D point kernel methods, the superposition integral is a convolution
integral, if the pencil kernel in spatially invariant (
homogeneous media
)
→
very fast dose calculation
using Fast Fourier Transformation
Approximate methods
to handle
inhomogeneous media:
• density corrections: mainly effective pathlength rescaling along beam direction
• simplified modelling of phantom scatter: local
lateral scatter
effects not
modelled correctly
• neglect energy spectrum changes
• simplified modelling of head scatter: requires
correction factors
for the output-factor
…and approximations to the
head model
approx.
dose deposition in the patient