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Objectives and Objective Functions:
The selected and defined Dose-Volume parameters, usually
D
V
, for the inverse
optimisation process determine the
Objectives
of the optimisation.
The measure of how well these values are achieved defines the “
Metrics
” – the
Objective Functions
of the optimisation methodology (algorithm).
A natural measure quantifying the similarity of a dose distribution at N
sampling points with dose values
d
i
to the corresponding desired dose values
d
i
*
is a distance measure. A common measure is the
L
p
norm:
(
)
1
1
*
i
p
p
N
i
p
i
d d
L
−
=
=
For
p
= 2, i.e. L
2
we have the Euclidean distance.
Inverse Optimisation and Planning