Optimizing Beam Angles and Aperture Shapes Simultaneously for Station Parameter Optimized Radiation Therapy (SPORT)

activity. In the experimental arms (EA) of both trials (C-ART-2 and DDE-2) patients receive a 3-phase adaptive treatment of 30 fractions in total. Biological image-guided dose painting by numbers is applied during the first two phases of C-ART-2. Re-imaging is performed twice during treatment and once after treatment. Deformable image coregistration is used for automatic region-of-interest propagation and dose summation of the three treatment plans. Patients in the control arm (CA) of C-ART-2 receive standard IMRT of 32 fractions, while patients in the CA of DDE-2 receive a 2-phase non-adaptive IMRT treatment of 30 fractions in total. Results: The Table shows the total cost (in , 2012) per patient and per activity for both trials. The cost of ART is 2,100 (DDE-2) to 2,963 (CART-2) higher than the cost of IMRT, based on the higher costs for treatment preparation. The small differences in the cost of ART between both trials are explained by the biological image-guided dose painting applied for C-ART-2. The CA of DDE-2 involves two phases, making treatment planning more expensive compared to the CA of C-ART-2. Conclusions: Even within an experienced center and with automated tools for image fusion and contour propagation, ART is 30-45% more expensive than non-adaptive IMRT for HNC. The cost in other centers adopting ART will be critically dependent of the departmental activity, available tools and experience. This extra cost will have to be weighed against the expected improvement in clinical outcome. Author Disclosure: B. Vanderstraeten: None. D. Berwouts: None. B. Goddeeris: None. F. Duprez: None. W. De Neve: None. Y. Lievens: None.