ESTRO 2023 - Abstract Book

S1587

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ESTRO 2023

Results Compared to scenario A (current clinical situation), scenario B (range verification with current PGI system to trigger OAPT) reduces the current range uncertainty margins, which are already considerably smaller than commonly used margins based on single-energy CTs, by 57% to 3mm while maintaining setup uncertainty margins. In scenario C (OAPT workflow with volumetric imaging and adaptation before irradiation), also the setup uncertainty margins are reduced by 66% to 1mm (Tab. 1). In the exemplary patient case, reduced range uncertainty and reduced setup uncertainty margins resulted in locally reduced dose to surrounding tissue of 10% and 3%, respectively (Fig. 1b).