Lung Deformation Estimation with Non-rigid Registration for Radiotherapy Treatment

A main challenge in radiotherapy is to precisely take into account organs deformation and motion in order to adapt the treatment to each patient. This is particularly important in lung cancer where breathing leads to large displacements. In this work, breath holding techniques (with Active Breath Control device) were used to reduce movements during treatment. We study thorax and lung deformation between different CT scans acquired at same and different breathing stages. We developed non-rigid registration tools to evaluate for each patient the reproducibility of ABC and to extract motion information for subsequent dosimetric and modeling studies. First results show that ABC has a good reproducibility, that vector fields can be used to detect pathological situations and that deformations due to breathing can be estimated.