ESTRO 2023 - Abstract Book

S793

Monday 15 May 2023

ESTRO 2023

structures such as left ventricle (LV) and left anterior descending artery (LAD) for this case showed small difference (0.3 0.4Gy) in mean dose. The opposite is seen for left sided tumours as shown in Fig 2B’s example.

Conclusion Doses vary considerably as a structure moves in and out of a high dose region, due to contour uncertainties and motion. In the clinical setting, an OAR’s vulnerability to such dose uncertainties can differ significantly between cases, as tumour and OAR positions relative to high dose gradient regions vary. Automatic segmentation tools can be helpful to provide time efficient and consistent contours, but being able to predict “uncertainty regions” adds significant further value. This work demonstrates the feasibility of predicting a “dose region” where the true dose most likely falls, rather than seeing DVHs as single curves per structure. This can flag vulnerable OARs – with a potential role in cardiotoxicity research on dose variations and outcomes, and to aid personalised plan optimisation in the future. While our automated tool is designed for cardiac structures, the methods described can also potentially be applied to other OARs. MO-0945 Radical carbon-ion rt for unresectable thoracoabdominal soft tissue sarcomas: efficacy and safety S.P. Bianchi 1 , V. Vitolo 2 , A. Barcellini 2 , M.R. Fiore 2 , A. Chalaszczyk 2 , A. Ghirelli 2 , S. Russo 2 , G. Fontana 2 , C. Sangalli 3 , M. Ciocca 2 , E. Orlandi 2 1 University of Milan Bicocca - Department of Radiation Oncology, Monza, National Center of Oncological Hadrontherapy, (CNAO), Clinical Departement, Pavia, Italy; 2 National Center of Oncological Hadrontherapy, (CNAO), Clinical Departement, Pavia, Italy; 3 Fondazione IRCCS Istituto Nazionale dei Tumori, Department of Radiotherapy, Milan, Italy Purpose or Objective Poor outcomes have been reported with conventional photon-based radiotherapy (RT) for soft tissue sarcomas (STS) deemed unfit for surgery. This retrospective study aimed to evaluate the preliminary results of carbon ion radiotherapy (CIRT) in patients with STS treated with radical intent. Mini-Oral: Sarcoma - Haematology

Materials and Methods