title: A fully automated method for CT-on-rails-guided online adaptive planning for prostate cancer intensity modulated radiation therapy.
abstract: OBJECTIVE
  This study was designed to validate a fully automated adaptive planning (AAP) method which integrates automated recontouring and automated replanning to account for interfractional anatomical changes in prostate cancer patients receiving adaptive intensity modulated radiation therapy (IMRT) based on daily repeated computed tomography (CT)-on-rails images.
  
  
  METHODS
  Nine prostate cancer patients treated at our institution were randomly selected. For the AAP method, contours on each repeat CT image were automatically generated by mapping the contours from the simulation CT image using deformable image registration. An in-house automated planning tool incorporated into the Pinnacle treatment planning system was used to generate the original and the adapted IMRT plans. The cumulative dose-volume histograms (DVHs) of the target and critical structures were calculated based on the manual contours for all plans and compared with those of plans generated by the conventional method, that is, shifting the isocenters by aligning the images based on the center of the volume (COV) of prostate (prostate COV-aligned).
  
  
  RESULTS
  The target coverage from our AAP method for every patient was acceptable, while 1 of the 9 patients showed target underdosing from prostate COV-aligned plans. The normalized volume receiving at least 70 Gy (V70), and the mean dose of the rectum and bladder were reduced by 8.9%, 6.4 Gy and 4.3%, 5.3 Gy, respectively, for the AAP method compared with the values obtained from prostate COV-aligned plans.
  
  
  CONCLUSIONS
  The AAP method, which is fully automated, is effective for online replanning to compensate for target dose deficits and critical organ overdosing caused by interfractional anatomical changes in prostate cancer.
authors.affiliation: Department of Radiation Physics, University of Texas MD Anderson Cancer Center, Houston, Texas, USA.
authors.forename: Xiaoqiang
authors.initials: X
authors.lastname: Li
authors.forename: Enzhuo M
authors.initials: EM
authors.lastname: Quan
authors.forename: Yupeng
authors.initials: Y
authors.lastname: Li
authors.forename: Xiaoning
authors.initials: X
authors.lastname: Pan
authors.forename: Yin
authors.initials: Y
authors.lastname: Zhou
authors.forename: Xiaochun
authors.initials: X
authors.lastname: Wang
authors.forename: Weiliang
authors.initials: W
authors.lastname: Du
authors.forename: Rajat J
authors.initials: RJ
authors.lastname: Kudchadker
authors.forename: Jennifer L
authors.initials: JL
authors.lastname: Johnson
authors.forename: Deborah A
authors.initials: DA
authors.lastname: Kuban
authors.forename: Andrew K
authors.initials: AK
authors.lastname: Lee
authors.forename: Xiaodong
authors.initials: X
authors.lastname: Zhang
mesh_terms: D000465:Algorithms; D019583:Dose Fractionation, Radiation; D005270:Femur Head / Q000000981:diagnostic imaging / Q000528:radiation effects; D006801:Humans; D008297:Male; D059351:Organ Sparing Treatments / Q000379:methods; D058958:Organs at Risk / Q000000981:diagnostic imaging / Q000528:radiation effects; D011471:Prostatic Neoplasms / Q000000981:diagnostic imaging / Q000532:radiotherapy*; D011832:Radiation Injuries / Q000517:prevention & control; D011859:Radiography; D011880:Radiotherapy Planning, Computer-Assisted / Q000379:methods*; D050397:Radiotherapy, Intensity-Modulated / Q000379:methods*; D012007:Rectum / Q000000981:diagnostic imaging / Q000528:radiation effects; D001743:Urinary Bladder / Q000000981:diagnostic imaging / Q000528:radiation effects