title: Dosimetric effects of roll rotational setup errors on lung stereotactic ablative radiotherapy using volumetric modulated arc therapy.
abstract: OBJECTIVE
  To evaluate the dosimetric effects of roll-rotational setup errors of stereotactic ablative radiotherapy (SABR) for lung cancer using volumetric modulated arc therapy (VMAT).
  
  
  METHODS
  A total of 23 lung SABR cases were evaluated retrospectively. Each of the planning CT images was intentionally rotated by ±1°, ±2° and ±3°. After that, to simulate the translational couch correction, rotated CT images were moved along the x, y and z axis to match the centroid of the target volume in the rotated CT images with that in the original CT images. The differences in D95% and V100% of the target volume, D0.35cc of spinal cord, D0.35cc and D5cc of oesophagus and V20Gy of lung between the original and the rotated CT images were calculated.
  
  
  RESULTS
  The average differences in D95% and V100% of target volume, D0.35cc of spinal cord, D0.35cc and D5cc of oesophagus and V20Gy of lung were -0.3% ± 0.4% and -0.7% ± 2.4%, 1.6 ± 27.9 cGy, -1.6 ± 37.6 cGy, 15.9 ± 25.3 cGy and 0.0% ± 0.1%, respectively. The dosimetric changes in organs at risk (OARs) near the target volume were sometimes considerable due to roll-rotational setup errors, despite the translational correction, and those were patient specific.
  
  
  CONCLUSIONS
  In the case of coplanar VMAT for lung SABR, dosimetric changes to the target volume due to roll-rotational setup errors could be compensated by translational correction, whereas those to the OARs could not in some cases.
  
  
  CONCLUSIONS
  Roll-rotational setup errors would increase the dose to OARs despite the translational correction.
authors.affiliation: 1 Program in Biomedical Radiation Sciences, Department of Transdisciplinary Studies, Seoul National University Graduate School of Convergence Science and Technology, Seoul, Korea.|2 Biomedical Research Institute, Seoul National University College of Medicine, Seoul, Korea.
authors.forename: Jaegi
authors.initials: J
authors.lastname: Lee
authors.affiliation: 2 Biomedical Research Institute, Seoul National University College of Medicine, Seoul, Korea.|3 Department of Radiation Oncology, Seoul National University Hospital, Seoul, Korea.|4 Institute of Radiation Medicine, Seoul National University Medical Research Center, Seoul, Korea.|5 Center for Convergence Research on Robotics, Advanced Institutes of Convergence Technology, Suwon, Korea.
authors.forename: Jung-In
authors.initials: JI
authors.lastname: Kim
authors.affiliation: 1 Program in Biomedical Radiation Sciences, Department of Transdisciplinary Studies, Seoul National University Graduate School of Convergence Science and Technology, Seoul, Korea.|3 Department of Radiation Oncology, Seoul National University Hospital, Seoul, Korea.
authors.forename: Sung-Joon
authors.initials: SJ
authors.lastname: Ye
authors.affiliation: 3 Department of Radiation Oncology, Seoul National University Hospital, Seoul, Korea.|4 Institute of Radiation Medicine, Seoul National University Medical Research Center, Seoul, Korea.|6 Department of Radiation Oncology, Seoul National University College of Medicine, Seoul, Korea.
authors.forename: Hak Jae
authors.initials: HJ
authors.lastname: Kim
authors.affiliation: 1 Program in Biomedical Radiation Sciences, Department of Transdisciplinary Studies, Seoul National University Graduate School of Convergence Science and Technology, Seoul, Korea.|2 Biomedical Research Institute, Seoul National University College of Medicine, Seoul, Korea.
authors.forename: Joel
authors.initials: J
authors.lastname: Carlson
authors.affiliation: 2 Biomedical Research Institute, Seoul National University College of Medicine, Seoul, Korea.|3 Department of Radiation Oncology, Seoul National University Hospital, Seoul, Korea.|4 Institute of Radiation Medicine, Seoul National University Medical Research Center, Seoul, Korea.|5 Center for Convergence Research on Robotics, Advanced Institutes of Convergence Technology, Suwon, Korea.
authors.forename: Jong Min
authors.initials: JM
authors.lastname: Park
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D019583:Dose Fractionation, Radiation; D005260:Female; D006801:Humans; D008175:Lung Neoplasms / Q000000981:diagnostic imaging / Q000532:radiotherapy*; D008297:Male; D008875:Middle Aged; D011874:Radiometry / Q000379:methods*; D011879:Radiotherapy Dosage; D011880:Radiotherapy Planning, Computer-Assisted; D050397:Radiotherapy, Intensity-Modulated; D012189:Retrospective Studies; D012399:Rotation; D014057:Tomography, X-Ray Computed