IMRT 2018
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 is spatially invariant ( homogeneous media )
→ very fast dose calculation using Fast Fourier Transformation
approx. dose deposition in the patient
Approximate methods to handle inhomogeneous media:
• density corrections: mainly effective path length 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
ESTRO IMRT course 2017 Dose Calculation in Static and Rotational IMRT Madrid April 13th, 2017
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