ESTRO 2021 Abstract Book

S1176

ESTRO 2021

literature or measures irrelevant to monitoring the long-term effects of radiotherapy. In one patient case, artefacts on the CT image prevented reliable measurements: intra-observer variation for this CT image showed an overall SD of 5.5 mm versus <=2.6 mm on all other images. A total of 558 measures were completed correctly by the 7 observers and could be used for inter-observer analysis. Inter-observer variation showed an overall SD of <=2.8mm for all images. 1 measure was excluded due to poor observer agreement, leaving 20 potentially reproducible measures to be described in the atlas (see table).

Conclusion An atlas of 20 craniofacial measures was developed to standardise the assessment craniofacial growth in CCS. Further work will include validation in a larger dataset, including a larger range of ages. The next step will be developing methods to measure asymmetry automatically on routine follow-up images of paediatric cancer patients, using this atlas as a benchmark. PO-1432 Proton-therapy in pediatric patients with central nervous system tumors: a systematic review. B. Rombi 1 , M. Roggio 2 , L. Ronchi 3 , F. Bertini 3,4 , L. Cavallini 3,5 , E. Deraco 3,6 , F. Medici 3,6 , M. Amichetti 1 , A.G. Morganti 3,6 , S. Cammelli 3,6 1 Proton Therapy Center, Santa Chiara Hospital, Trento, Italy; 2 Anaesthesiology and Intensive Care Unit, Central Hospital, Bolzano, Italy; 3 Radiation Oncology, IRCCS Azienda Ospedaliero-Universitaria di Bologna, Bologna, Italy; 4 Department of Experimental, Diagnostic, and Specialty Medicine (DIMES), Alma Mater Studiorum University of Bologna, Bologna, Italy; 5 Department of Experimental, Diagnostic, and Specialty Medicine (DIMES), Alma Mater Studiorum University of Bologna, Bologna, Italy; 6 Department of Experimental, Diagnostic, and Specialty Medicine (DIMES), Alma Mater Studiorum University of Bologna, Bologna, Italy Purpose or Objective Pediatric patients with central nervous system tumors may develop severe long-term complications after radiotherapy. Proton-therapy (PT) has theoretical advantages over conventional photon-based radiotherapy due to the reduced risk of long-term side-effects and second tumors. However, there are few data on the actual toxicity after PT in this setting. In particular, randomized studies and literature reviews addressing this topic are lacking. Therefore, we performed a systematic review on toxicity and outcome after PT in pediatric