ESTRO 2023 - Abstract Book

S503

Sunday 14 May 2023

ESTRO 2023

Figure 1: Clinical and GAN dose distributions. Single slices for three examples Q1-Q3 is shown, defined by the quartiles from the CT+PTV+OAR model body contour L1-loss. Abbreviations: CT: computed tomography; PTV: planning target volume; OAR: organ-at-risk; Conclusion Expectedly, by applying dose prediction with only the CT-scan, the GAN has difficulty to determine what exactly should be the PTV for each patient. Further, GAN-predicted dose distributions were found most accurate when using all available information, but only by a small margin. This suggests that the need for OAR contours for dose prediction can potentially be circumvented. In addition, CT HUs may be replaced by the body contour. Future work should focus on investigating whether produced plans are deliverable using treatment planning software. OC-0617 A multi-institutional retrospective deformable dose accumulation analysis for MR-guided RT M. Murr 1 , U. Bernchou 2 , E. Bubula-Rehm 3 , M. Ruschin 4 , P. Sadeghi 5 , P. Voet 3 , J.D. Winter 5 , J. Yang 6 , E. Younus 4 , C. Zachiu 7 , Y. Zhao 8 , H. Zhong 9 , D. Thorwarth 10 1 University Hospital Tuebingen, Section for Biomedical Physics, Department of Radiation Oncology, Tuebingen, Germany; 2 Institute of Clinical Research, University of Southern Denmark, Laboratory of Radiation Physics, Odense, Denmark; 3 Elekta AB, Research, Stockholm, Sweden; 4 Odette Cancer Centre, Sunnybrook Health Sciences Centre, University of Toronto, Department of Radiation Oncology, Toronto, Canada; 5 University of Toronto, Medical Physics, Princess Margaret Cancer Centre, Department of Radiation Oncology, Toronto, Canada; 6 University of Texas, MD Anderson Cancer Center, Department of Radiation Physics,, Houston, USA; 7 University Medical Centre Utrecht, Department of Radiotherapy, Utrecht, The Netherlands; 8 University of Texas, MD Anderson Cancer Center, Department of Radiation Physics, Houston, USA; 9 Medical College of Wisconsin, Department of Radiation Oncology, Milwaukee, WI, USA; 10 University Hospital Tuebingen, University of Tuebingen, Section for Biomedical Physics, Department of Radiation Oncology, Tuebingen, Germany Purpose or Objective Online MR-guided radiotherapy (MRgRT) enables optimal plan adaptation with respect to the patient’s daily anatomy, allowing for improved target coverage and organ at risk (OAR) sparing. Deformable dose accumulation (DDA) promises precise evaluation of organ-specific accumulated doses. However, various DDA algorithms and implementations are available, making QA, inter-institutional comparison and recommendations for clinical use of DDA challenging. The aim of