Improved Demons Three-Dimensional Registration Algorithm and the Application in Image-Guided Radiotherapy

Deformable image registration (DIR) between the planning CT and the daily cone beam CT (CBCT) has become an effective way for accurate radiotherapy. Demons DIR had been successfully applied to implemented monomodality images such as CT/CT, but failed in CT/CBCT DIR due to the bad image quality and intensity uncertainty of CBCT. In this paper, a DIR method based on CBCT intensity correction was proposed. The performance of the proposed method was evaluated on clinical images and the computational time decreased by a half of that with traditional Demons. The results showed that intensity correction based CT/CBCT DIR method was robust and efficient against severe CBCT artifacts and intensity uncertainty, and the registration accuracy and efficiency was improved comparing to traditional Demons.