title: 3D-2D Deformable Image Registration Using Feature-Based Nonuniform Meshes.
abstract: By using prior information of planning CT images and feature-based nonuniform meshes, this paper demonstrates that volumetric images can be efficiently registered with a very small portion of 2D projection images of a Cone-Beam Computed Tomography (CBCT) scan. After a density field is computed based on the extracted feature edges from planning CT images, nonuniform tetrahedral meshes will be automatically generated to better characterize the image features according to the density field; that is, finer meshes are generated for features. The displacement vector fields (DVFs) are specified at the mesh vertices to drive the deformation of original CT images. Digitally reconstructed radiographs (DRRs) of the deformed anatomy are generated and compared with corresponding 2D projections. DVFs are optimized to minimize the objective function including differences between DRRs and projections and the regularity. To further accelerate the above 3D-2D registration, a procedure to obtain good initial deformations by deforming the volume surface to match 2D body boundary on projections has been developed. This complete method is evaluated quantitatively by using several digital phantoms and data from head and neck cancer patients. The feature-based nonuniform meshing method leads to better results than either uniform orthogonal grid or uniform tetrahedral meshes.
authors.affiliation: University of Texas at Dallas, Richardson, TX 75080, USA; University of Texas Southwestern Medical Center, Dallas, TX 75235, USA.
authors.forename: Zichun
authors.identifier: 0000-0001-6489-6502
authors.initials: Z
authors.lastname: Zhong
authors.affiliation: University of Texas at Dallas, Richardson, TX 75080, USA.
authors.forename: Xiaohu
authors.initials: X
authors.lastname: Guo
authors.affiliation: University of Texas at Dallas, Richardson, TX 75080, USA.
authors.forename: Yiqi
authors.initials: Y
authors.lastname: Cai
authors.affiliation: University of New Mexico, Albuquerque, NM 87131, USA.
authors.forename: Yin
authors.initials: Y
authors.lastname: Yang
authors.affiliation: University of Texas Southwestern Medical Center, Dallas, TX 75235, USA.
authors.forename: Jing
authors.initials: J
authors.lastname: Wang
authors.affiliation: University of Texas Southwestern Medical Center, Dallas, TX 75235, USA.
authors.forename: Xun
authors.initials: X
authors.lastname: Jia
authors.affiliation: University of Texas Southwestern Medical Center, Dallas, TX 75235, USA.
authors.forename: Weihua
authors.identifier: 0000-0001-5985-4244
authors.initials: W
authors.lastname: Mao
mesh_terms: D006801:Humans; D021621:Imaging, Three-Dimensional / Q000379:methods*; D008962:Models, Theoretical; D014057:Tomography, X-Ray Computed