IMRT Course 2016

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:

approx.

dose deposition in the patient

ESTRO IMRT course 2016

Dose Calculation in Static and Rotational IMRT

London April 7th, 2016

-39-

• 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