title: Feasibility of a novel deformable image registration technique to facilitate classification, targeting, and monitoring of tumor and normal tissue.
abstract: OBJECTIVE
  To investigate the feasibility of a biomechanical-based deformable image registration technique for the integration of multimodality imaging, image guided treatment, and response monitoring.
  
  
  METHODS
  A multiorgan deformable image registration technique based on finite element modeling (FEM) and surface projection alignment of selected regions of interest with biomechanical material and interface models has been developed. FEM also provides an inherent method for direct tracking specified regions through treatment and follow-up.
  
  
  RESULTS
  The technique was demonstrated on 5 liver cancer patients. Differences of up to 1 cm of motion were seen between the diaphragm and the tumor center of mass after deformable image registration of exhale and inhale CT scans. Spatial differences of 5 mm or more were observed for up to 86% of the surface of the defined tumor after deformable image registration of the computed tomography (CT) and magnetic resonance images. Up to 6.8 mm of motion was observed for the tumor after deformable image registration of the CT and cone-beam CT scan after rigid registration of the liver. Deformable registration of the CT to the follow-up CT allowed a more accurate assessment of tumor response.
  
  
  CONCLUSIONS
  This biomechanical-based deformable image registration technique incorporates classification, targeting, and monitoring of tumor and normal tissue using one methodology.
authors.affiliation: Radiation Medicine Program, Princess Margaret Hospital, University of Toronto, Toronto, ON, Canada. kristy.brock@rmp.uhn.on.ca
authors.forename: Kristy K
authors.initials: KK
authors.lastname: Brock
authors.forename: Laura A
authors.initials: LA
authors.lastname: Dawson
authors.forename: Michael B
authors.initials: MB
authors.lastname: Sharpe
authors.forename: Douglas J
authors.initials: DJ
authors.lastname: Moseley
authors.forename: David A
authors.initials: DA
authors.lastname: Jaffray
mesh_terms: D001696:Biomechanical Phenomena; D003964:Diaphragm; D005240:Feasibility Studies; D020342:Finite Element Analysis; D006801:Humans; D008099:Liver / Q000000981:diagnostic imaging; D008113:Liver Neoplasms / Q000000981:diagnostic imaging* / Q000532:radiotherapy*; D009068:Movement; D011860:Radiography, Abdominal; D011873:Radiology Information Systems; D011880:Radiotherapy Planning, Computer-Assisted / Q000379:methods*; D011881:Radiotherapy, Computer-Assisted / Q000379:methods*; D012119:Respiration; D014057:Tomography, X-Ray Computed / Q000379:methods*