Measuring breathing induced oesophageal motion and its dosimetric impact

Stereotactic body radiation therapy allows for a precise and accurate dose delivery. Organ motion during treatment bears the risk of undetected high healthy tissue exposure. An organ very susceptible to is oesophagus. Its low contrast on CT oblong shape renders estimation difficult. We tackle this issue by modern algorithms measure oesophageal voxel-wise estimate related dosimetric impact. Oesophageal was measured using deformable image registration 4DCT 11 internal 5 public datasets. Current clinical practice contouring 3DCT compared timely resolved contours. The impact estimated analysing trajectory each voxel in 4D distribution. Finally an model built, allowing easier patient-wise comparisons. Motion analysis showed mean absolute maximal amplitudes 4.55 +/- 1.81 mm left-right, 5.29 2.67 anterior-posterior 10.78 5.30 superior-inferior. between cohorts differed significantly. In around 50 % cases passing criteria violated. Contours created did not cover 14 respiratory cycle 3D contour 38 smaller than union all revealed that limited lower part organ. Our results higher most reported values literature heterogeneous across patients. Therefore, individual information should be considered planning.