title: Elastic image mapping for 4-D dose estimation in thoracic radiotherapy.
abstract: OBJECTIVE
  Demonstrate the path integration of a four-dimensional (4-D) dose distribution onto the 3-D anatomy.
  
  
  METHODS
  A computer-generated 4-D thoracic phantom with a lung tumour was constructed. Eight respiratory phases were generated. A radiotherapy treatment plan was applied to all the phases resulting in a 4-D dose distribution. An elastic image registration algorithm was used to find the vector displacement between all the image elements and the end expiration phase. The path-integrated tissue dose distribution and each component dose distribution were compared with the planned dose distribution.
  
  
  RESULTS
  Numerical path integration was performed to calculate the tissue dose distribution. Loss of tumour coverage was the predominant effect observed with tumour motion in this study. The loss was asymmetric and dependent on the tumour trajectory.
  
  
  CONCLUSIONS
  The elastic image registration allowed an accurate path integration through a 4-D data set to produce an accurate 3-D tissue dose estimate.
authors.affiliation: Department of Radiation Oncology, The University of Texas M.D. Anderson Cancer Center, Houston, TX, USA. tguerrero@mdanderson.org
authors.forename: Thomas
authors.initials: T
authors.lastname: Guerrero
authors.forename: Geoffrey
authors.initials: G
authors.lastname: Zhang
authors.forename: William
authors.initials: W
authors.lastname: Segars
authors.forename: Tzeng-Chi
authors.initials: TC
authors.lastname: Huang
authors.forename: Stephen
authors.initials: S
authors.lastname: Bilton
authors.forename: Geoffrey
authors.initials: G
authors.lastname: Ibbott
authors.forename: Lei
authors.initials: L
authors.lastname: Dong
authors.forename: Kenneth
authors.initials: K
authors.lastname: Forster
authors.forename: Kang Ping
authors.initials: KP
authors.lastname: Lin
mesh_terms: D016477:Artifacts; D001822:Body Burden; D003198:Computer Simulation; D004548:Elasticity; D006801:Humans; D008168:Lung / Q000000981:diagnostic imaging / Q000503:physiopathology*; D008175:Lung Neoplasms / Q000000981:diagnostic imaging / Q000503:physiopathology / Q000532:radiotherapy*; D008954:Models, Biological; D009038:Motion; D009928:Organ Specificity; D011857:Radiographic Image Interpretation, Computer-Assisted / Q000379:methods*; D013902:Radiography, Thoracic / Q000379:methods; D011874:Radiometry / Q000379:methods*; D011879:Radiotherapy Dosage; D011880:Radiotherapy Planning, Computer-Assisted / Q000379:methods*; D012062:Relative Biological Effectiveness; D013909:Thorax / Q000503:physiopathology / Q000528:radiation effects