Localised 3D disparity regularisation for improving contour propagation in Adaptive Radiotherapy

Identifying target volumes is a key component in image-guided adaptive radiotherapy. Furthermore, propagating contours from treatment planning images to images acquired during treatment is a difficult image registration problem due to organ motion. Among many deformable image registration techniques, block matching has been studied extensively in prostate and bladder cancer. Here, we propose a two-pass, three-dimensional disparity regularisation that accounts for anatomical constraints by distance and neighbouring motion vectors' orientation. This approach improves the Dice similarity score of the delineation/contour propagation and results in a non- iterative and non-pyramidal method with reduced computational time.