Advanced Physics for Brachytherapy 2018

Inverse Optimisation and Planning

Objectives and Objective Functions:

The selected and defined Dose-Volume parameters, usually D V optimisation process determine the Objectives of the optimisation.

, for the inverse

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 =  = N   i

p

  

(

)

p

*

−

L

i d d

p

i

For p = 2, i.e. L 2

we have the Euclidean distance.