ESTRO 2023 - Abstract Book

S726

Monday 15 May 2023

ESTRO 2023

Target coverage is better for the reoptimized treatments, with DIR performing best (Fig. 1). PSNN on average yields good results but fails for one patient with NSCLC showing its limited robustness.

Conclusion Our results suggest that it is possible to perform online ART without the need to manually adjust most of the OARs for NSCLC and HNC patients because the geometric contour differences have only a minor effect on the daily fraction dose. Contrarily, manual adjustment of the target is recommended to ensure target coverage and OAR sparing (results not shown). MO-0879 real-time absorbed 4D-dose calculation for carbon ion therapy C. Galeone 1,2,3 , T. Steinsberger 1 , M. Donetti 4 , F.M. Milian 2,5,6 , A. Paz 1 , A. Vignati 2,5 , L. Volz 1 , M. Durante 1,7 , S. Giordanengo 2,5 , C. Graeff 1,3 1 GSI, Biophysics, Darmstadt, Germany; 2 University of Torino, Physics, Torino, Italy; 3 Technical University of Darmstadt, Electrical Engineering and Information Technology, Darmstadt, Germany; 4 Fondazione CNAO, Medical physics, Pavia, Italy; 5 National Institute of Nuclear Physics, Division of Torino, Torino, Italy; 6 Universidade Estadual de Santa Cruz, Department of Exact and Technological Sciences , Ilheus, Brazil; 7 Technical University of Darmstadt, Condensed Matter Physics, Darmstadt, Germany Purpose or Objective The estimation of dose errors is a key part of online adaptive particle therapy. Interplay distorts dose distributions leading to non-ideal tumor coverage and higher dose to healthy tissues. Fast forward dose calculation (FDC) is mandatory to verify the efficacy of motion mitigation strategies during treatment. We propose and validate in silico a system to reconstruct the planned and delivered absorbed 4D dose in real-time, i.e. within the spill pauses (<5 s) present during the carbon ion therapy delivery. Materials and Methods The algorithm used for the FDC, was based on the existing RIDOS dose calculation tool, implemented on Graphic Processing Units (GPUs). For real-time delivered dose calculation, the fast FDC was interfaced with the research version of the CNAO Dose Delivery System (DDS) at GSI through a TCP/IP connection, providing measured and planned spot properties (MU, beam position, and motion phase) during the delivery. The algorithm evaluates the cumulative delivered and prescribed dose distributions within the inter-spill pause and performs a gamma-index comparison. The results are updated on a graphical user interface (Fig. 1).