Dresden 2011 – scientific programme
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ST: Fachverband Strahlen- und Medizinphysik
ST 1: Radiation Therapy I Fast Ions: Production, Physical Dosimetry, Biological Effets, Medical Effects
ST 1.9: Talk
Monday, March 14, 2011, 16:30–16:45, POT 112
Fractionated treatment of moving tumors with scanned heavy ion beams — •Jens Wölfelschneider1, 2, Michael Scholz1, Marco Durante1, 3, and Christoph Bert1 — 1GSI, Darmstadt — 2Fachhochschule Giessen-Friedberg — 3Technische Universität Darmstadt
Scanned beam irradiation of moving targets typically results in inhomogeneous dose distributions if only margins are used. To overcome this so called interplay effect, currently technically elaborative methods, such as beam tracking, gating or rescanning, are proposed.
With respect to absorbed dose, the dose homogenization that can be achieved with volumetric rescanning is comparable to a conventional fractionated treatment. In the scope of this work we investigated if fractionated dose delivery also results in homogeneous target coverage if the biological effect is incorporated.
By using the treatment planning system TRiP 4D together with α and β values of the Linear-Quadratic-Model, we calculated the equivalent uniform dose (EUD) for tumor and organs at risk in a fractionated treatment of lung tumors. The motion parameters were changed in each fraction, resulting in different interplay patterns. The summed dose distributions after varying the number of fractions were determined.
Homogenization of the resulting dose distribution with increasing number of fractions was observed for the absorbed dose. The degree of homogenization for the biologically effective dose is currently analyzed. Results and the comparison to other treatment methods will be presented.