title: Validation of Varian's SmartAdapt® deformable image registration algorithm for clinical application.
abstract: BACKGROUND
  Re-contouring of structures on consecutive planning computed tomography (CT) images for patients that exhibit anatomical changes is elaborate and may negatively impact the turn-around time if this is required for many patients. This study was therefore initiated to validate the accuracy and usefulness of automatic contour propagation for head and neck cancer patients using SmartAdapt® which is the deformable image registration (DIR) application in Varian's Eclipse™ treatment planning system.
  
  
  METHODS
  CT images of eight head and neck cancer patients with multiple planning CTs were registered using SmartAdapt®. The contoured structures of target volumes and OARs of the primary planning CT were deformed accordingly and subsequently compared with a reference structure set being either: 1) a structure set independently contoured by the treating Radiation Oncologist (RO), or 2) the DIR-generated structure set after being reviewed and modified by the RO.
  
  
  RESULTS
  Application of DIR offered a considerable time saving for ROs in delineation of structures on CTs that were acquired mid-treatment. Quantitative analysis showed that 84% of the volume of the DIR-generated structures overlapped with the independently re-contoured structures, while 94% of the volume overlapped with the DIR-generated structures after review by the RO. This apparent intra-observer variation was further investigated resulting in the identification of several causes. Qualitative analysis showed that 92% of the DIR-generated structures either need no or only minor modification during RO reviews.
  
  
  CONCLUSIONS
  SmartAdapt is a powerful tool with sufficient accuracy that saves considerable time in re-contouring structures on re-CTs. However, careful review of the DIR-generated structures is mandatory, in particular in areas where tumour regression plays a role.
authors.affiliation: Department of Radiation Oncology, Wellington Blood and Cancer Centre, Wellington Hospital, Private Bag 7902, 6242, Wellington, New Zealand. Ihab.Ramadaan@ccdhb.org.nz.|Current address: Liz Plummer Cancer Care Centre, Cairns, Australia. Ihab.Ramadaan@ccdhb.org.nz.
authors.forename: Ihab S
authors.initials: IS
authors.lastname: Ramadaan
authors.affiliation: Department of Radiation Oncology, Wellington Blood and Cancer Centre, Wellington Hospital, Private Bag 7902, 6242, Wellington, New Zealand. Karsten.Peick@ccdhb.org.nz.
authors.forename: Karsten
authors.initials: K
authors.lastname: Peick
authors.affiliation: Department of Radiation Oncology, Wellington Blood and Cancer Centre, Wellington Hospital, Private Bag 7902, 6242, Wellington, New Zealand. David.Hamilton@ccdhb.org.nz.
authors.forename: David A
authors.initials: DA
authors.lastname: Hamilton
authors.affiliation: Department of Radiation Oncology, Wellington Blood and Cancer Centre, Wellington Hospital, Private Bag 7902, 6242, Wellington, New Zealand. Jamie.Evans@ccdhb.org.nz.
authors.forename: Jamie
authors.initials: J
authors.lastname: Evans
authors.affiliation: Department of Radiation Oncology, Wellington Blood and Cancer Centre, Wellington Hospital, Private Bag 7902, 6242, Wellington, New Zealand. Douglas.Iupati@ccdhb.org.nz.
authors.forename: Douglas
authors.initials: D
authors.lastname: Iupati
authors.affiliation: Department of Radiation Oncology, Wellington Blood and Cancer Centre, Wellington Hospital, Private Bag 7902, 6242, Wellington, New Zealand. Anna.Nicholson@ccdhb.org.nz.
authors.forename: Anna
authors.initials: A
authors.lastname: Nicholson
authors.affiliation: Department of Radiation Oncology, Wellington Blood and Cancer Centre, Wellington Hospital, Private Bag 7902, 6242, Wellington, New Zealand. Lynne.Greig@ccdhb.org.nz.
authors.forename: Lynne
authors.initials: L
authors.lastname: Greig
authors.affiliation: Department of Radiation Oncology, Wellington Blood and Cancer Centre, Wellington Hospital, Private Bag 7902, 6242, Wellington, New Zealand. Rob.Louwe@ccdhb.org.nz.
authors.forename: Robert J W
authors.initials: RJ
authors.lastname: Louwe
mesh_terms: D000465:Algorithms; D001284:Atrophy; D003287:Contrast Media; D006258:Head and Neck Neoplasms / Q000000981:diagnostic imaging / Q000532:radiotherapy*; D006801:Humans; D007091:Image Processing, Computer-Assisted / Q000379:methods*; D009038:Motion; D015588:Observer Variation; D056888:Patient Positioning; D010865:Pilot Projects; D011857:Radiographic Image Interpretation, Computer-Assisted / Q000379:methods*; D011880:Radiotherapy Planning, Computer-Assisted / Q000379:methods*; D061106:Radiotherapy Setup Errors / Q000517:prevention & control; D012189:Retrospective Studies; D012984:Software; D013997:Time Factors; D014057:Tomography, X-Ray Computed; D047368:Tumor Burden
chemical_list: D003287:Contrast Media