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Summary of Point Kernel model properties
• Heterogeneities are considered through scaling of the rectilinear
transport along all lines, hence it models:
– loss of CPE for small fields and in lung
– penumbra broadening in lung
– rebuildup after low density media
• Major limitations:
– rectilinear scaling coarse approximation for multiple scattering
– angular discretization effects
• Use of media specific
en
in primary raytrace yield dose to medium in
medium (not water in medium) but is implementation dependent!
• The dose calculation time for
N
3
voxels is with the Collapsed Cone
approach reduced from being proportional to N
7
operations to to
M
.
N
3
where
M
is the number of transport directions
• Core calculation loops only a few hundred lines of code, much less
complex than a multisource beam modelling code