ESTRO 2021 Abstract Book

S1408

ESTRO 2021

Conclusion Based on the results from this study, an ideal detector would consist of a BRT with a thin energy detector for dE-E filtering. TOF detectors need significant technical development before reaching an acceptable noise level for clinical usage. PO-1683 Spatial Characterization of errors in pseudo-CT generation for MRI-only radiotherapy H. Chourak 1 , A. Barateau 1 , C. Cadin 1 , C. Lafond 1 , J. Nunes 1 , R. De Crevoiser 1 , J. Dowling 2 , P. Greer 3 , O. Acosta 1 1 Univ Rennes, CLCC Eugène Marquis, INSERM, LTSI - UMR 1099, Rennes, France; 2 CSIRO, Australian e-Health Research Centre, Herston, Australia; 3 Calvary Mater, Department of Radiation Oncology, Newcastle, Australia Purpose or Objective Several approaches have been proposed to generate pseudo-CT (pCT) from MR images for radiotherapy dose calculation. The aim of this work was to propose a population voxel-based workflow allowing the assessment of local errors in the generation of pCTs and dose distribution for clinical implementation of MRI only based planning. Materials and Methods Figure 1 depicts the proposed voxel-wise analysis workflow in which CT, pCT, and corresponding planning 3D dose distributions were aligned in a single coordinate system. First, MRI were non-rigidly registered to a template via a customized method exploiting organ delineations. CTs, pCTs and planning doses were propagated using the deformation fields. Voxel-based evaluation was performed on images and doses. Mean