title: [Two-step image registration based on control volumes].
abstract: OBJECTIVE
  To increase the accuracy of beam targeting and improve the dose distributions in radiotherapy using a robust image registration algorithm based on control volumes.
  
  
  METHODS
  Control volume mapping and thin-plate spline deformable transformation were combined. The use of the control volumes increased the accuracy for the deformable registration. A bi-directional mapping method was also employed to correctly match the control volumes.
  
  
  RESULTS
  The clinical images were simulated using the proposed two-step image registration algorithm. The simulation results indicated that the registration algorithm was robust and universal, even in cases of obvious deformation.
  
  
  CONCLUSIONS
  The algorithm provides a more convenient and robust resolution as compared to manual landmark-based methods and single-step deformable transformations, and may help in automatic image registration in radiation therapy.
authors: School of Biomedical Engineering, Southern Medical University, Guangzhou 510515, China. gwlu@fimmu.com
authors: Guang-wen
authors: GW
authors: Lu
authors: Yao-qin
authors: YQ
authors: Xie
mesh_terms: D000465:Algorithms; D006801:Humans; D007091:Image Processing, Computer-Assisted; D011880:Radiotherapy Planning, Computer-Assisted / Q000379:methods*; D020266:Radiotherapy, Conformal / Q000379:methods