ESTRO 2021 Abstract Book

S557

ESTRO 2021

Daily setup of the patient is performed relying on bony anatomy. In orthogonal X-ray imaging or in-room CT, the position of the fiducials can be visualised. The aim is to assure that the fiducials are inside a margin of 3 – 5 mm compared to planning CT. During the 6-week treatment, anatomical changes may influence the dose distribution of PTx. Therefore, to evaluate possible changes in dose distributions and possibly re-optimize the treatment plan based on these changes, a 4D control-CT is performed weekly starting from the second week of treatment. Referenz: Schneider, S. „Inter- and Intrafraction motion management for MR guided Proton Therapy of Pancreatic Carcinoma “, 2020