title: Validation of an improved 'diffeomorphic demons' algorithm for deformable image registration in image-guided radiation therapy.
abstract: Deformable image registration (DIR) was widely used in radiation therapy, such as in automatic contour generation, dose accumulation, tumor growth or regression analysis. To achieve higher registration accuracy and faster convergence, an improved 'diffeomorphic demons' registration algorithm was proposed and validated. Based on Brox et al.'s gradient constancy assumption and Malis's efficient second-order minimization (ESM) algorithm, a grey value gradient similarity term and a transformation error term were added into the demons energy function, and a formula was derived to calculate the update of transformation field. The limited Broyden-Fletcher-Goldfarb-Shanno (L-BFGS) algorithm was used to optimize the energy function so that the iteration number could be determined automatically. The proposed algorithm was validated using mathematically deformed images and physically deformed phantom images. Compared with the original 'diffeomorphic demons' algorithm, the registration method proposed achieve a higher precision and a faster convergence speed. Due to the influence of different scanning conditions in fractionated radiation, the density range of the treatment image and the planning image may be different. In such a case, the improved demons algorithm can achieve faster and more accurate radiotherapy.
authors.affiliation: Radiotherapy Center, Affiliated Tumor Hospital of Guangzhou Medical University, Guangzhou 510095, China.
authors.forename: Lu
authors.initials: L
authors.lastname: Zhou
authors.forename: Linghong
authors.initials: L
authors.lastname: Zhou
authors.forename: Shuxu
authors.initials: S
authors.lastname: Zhang
authors.forename: Xin
authors.initials: X
authors.lastname: Zhen
authors.forename: Hui
authors.initials: H
authors.lastname: Yu
authors.forename: Guoqian
authors.initials: G
authors.lastname: Zhang
authors.forename: Ruihao
authors.initials: R
authors.lastname: Wang
mesh_terms: D000465:Algorithms; D003287:Contrast Media / Q000737:chemistry; D006801:Humans; D007091:Image Processing, Computer-Assisted / Q000379:methods*; D008962:Models, Theoretical; D009369:Neoplasms / Q000473:pathology; D016011:Normal Distribution; D019047:Phantoms, Imaging; D011878:Radiotherapy; D011880:Radiotherapy Planning, Computer-Assisted; D012044:Regression Analysis; D012984:Software; D014057:Tomography, X-Ray Computed
chemical_list: D003287:Contrast Media
keywords: Demons algorithm; L-BFGS algorithm; deformable registration; efficient second-order minimization; gradient constancy assumption