Deformable Registration Method Using Edge Preserving Scale Space withApplication in Adaptive Radiation Therapy
基于边缘保护尺度空间的形变配准方法及在自适应放疗中的应用

Registration of planning CT with daily cone beam CT (CBCT) images is an important component for adaptive radiation therapy in CBCT based image guided radiation therapy (IGRT) system. The edge preserving scale space which is derived from the anisotropic diffusion model can provide abundant spatial information for mutual information based registration. For improving the registration efficiency in system, a multi-scale deformable registration framework is proposed by combining edge preserving scale space with the multi-level free form deformation (FFD) grids. Different scales use different FFD grid, where the deformation fields are gained by a coarse to fine manner. Furthermore, considering clinical application, we design an optimal method for estimation of the parameters in anisotropic diffusion model for automated registration. The experiment results demonstrate that the proposed method can register the daily CBCT with the planning CT accurately and has a promising efficiency when used in CBCT based IGRT system. After gaining the deformation field, tumor target, organ at risk (OR) and iso-dose are contoured automatically, and then 'DVH (Dose volume histograms) analysis' are also studied. Finally, radiation planning is transferred from planning CT to daily CBCT images adaptively.