Specifying carbon ion doses for radiotherapy: the heidelberg approach.

There are currently no guidelines for prescribing and reporting radiation therapy (RT) with ion beams. In this paper an overview over some technical aspects and their implication on ion RT are reported. This includes a discussion of the difference in the treatment planning systems currently used for active and passive beam shaping systems, aspects of patient positioning and target definition and dose prescription. Special emphasis is put on the questions arising from the use of the beam scanning methods in combination with biological treatment plan optimization, which is used in the German heavy ion therapy facility at GSI and will also be introduced at the hospital based facility in Heidelberg. Furthermore, the Heidelberg approach for the clinical dose prescription is compared with the methods developed at HIMAC in Chiba, Japan.