Advanced Physics for Brachytherapy 2018

Inverse Optimisation and Planning

General Concept: The Inverse Problem

➔ {Ψ} : D = Ψ . A

{D}

Ψ is for a single stepping source delivery system (afterloader) the Source Propagation Function A is the energy absorption per unit mass (dose) and unit energy fluence or the Dose Kernel

ሶ

= ෍ =

. .

−

,

=

or

+∞

= ,

= ෍ =

. .

−

,

= න

´

− ´

−∞

With N ASDPs the total number of source dwell positions (steps) at which positions r i

and with what dwell times t i ?