title: Clinical implementation of an online adaptive plan-of-the-day protocol for nonrigid motion management in locally advanced cervical cancer IMRT.
abstract: OBJECTIVE
  To evaluate the clinical implementation of an online adaptive plan-of-the-day protocol for nonrigid target motion management in locally advanced cervical cancer intensity modulated radiation therapy (IMRT).
  
  
  METHODS
  Each of the 64 patients had four markers implanted in the vaginal fornix to verify the position of the cervix during treatment. Full and empty bladder computed tomography (CT) scans were acquired prior to treatment to build a bladder volume-dependent cervix-uterus motion model for establishment of the plan library. In the first phase of clinical implementation, the library consisted of one IMRT plan based on a single model-predicted internal target volume (mpITV), covering the target for the whole pretreatment observed bladder volume range, and a 3D conformal radiation therapy (3DCRT) motion-robust backup plan based on the same mpITV. The planning target volume (PTV) combined the ITV and nodal clinical target volume (CTV), expanded with a 1-cm margin. In the second phase, for patients showing >2.5-cm bladder-induced cervix-uterus motion during planning, two IMRT plans were constructed, based on mpITVs for empty-to-half-full and half-full-to-full bladder. In both phases, a daily cone beam CT (CBCT) scan was acquired to first position the patient based on bony anatomy and nodal targets and then select the appropriate plan. Daily post-treatment CBCT was used to verify plan selection.
  
  
  RESULTS
  Twenty-four and 40 patients were included in the first and second phase, respectively. In the second phase, 11 patients had two IMRT plans. Overall, an IMRT plan was used in 82.4% of fractions. The main reasons for selecting the motion-robust backup plan were uterus outside the PTV (27.5%) and markers outside their margin (21.3%). In patients with two IMRT plans, the half-full-to-full bladder plan was selected on average in 45% of the first 12 fractions, which was reduced to 35% in the last treatment fractions.
  
  
  CONCLUSIONS
  The implemented online adaptive plan-of-the-day protocol for locally advanced cervical cancer enables (almost) daily tissue-sparing IMRT.
authors.affiliation: Department of Radiation Oncology, Erasmus Medical Center-Cancer Institute, Rotterdam, The Netherlands. Electronic address: s.heijkoop@erasmusmc.nl.
authors.forename: Sabrina T
authors.initials: ST
authors.lastname: Heijkoop
authors.affiliation: Department of Radiation Oncology, Erasmus Medical Center-Cancer Institute, Rotterdam, The Netherlands.
authors.forename: Thomas R
authors.initials: TR
authors.lastname: Langerak
authors.affiliation: Department of Radiation Oncology, Erasmus Medical Center-Cancer Institute, Rotterdam, The Netherlands.
authors.forename: Sandra
authors.initials: S
authors.lastname: Quint
authors.affiliation: Department of Radiation Oncology, Erasmus Medical Center-Cancer Institute, Rotterdam, The Netherlands.
authors.forename: Luiza
authors.initials: L
authors.lastname: Bondar
authors.affiliation: Department of Radiation Oncology, Erasmus Medical Center-Cancer Institute, Rotterdam, The Netherlands.
authors.forename: Jan Willem M
authors.initials: JW
authors.lastname: Mens
authors.affiliation: Department of Radiation Oncology, Erasmus Medical Center-Cancer Institute, Rotterdam, The Netherlands.
authors.forename: Ben J M
authors.initials: BJ
authors.lastname: Heijmen
authors.affiliation: Department of Radiation Oncology, Erasmus Medical Center-Cancer Institute, Rotterdam, The Netherlands.
authors.forename: Mischa S
authors.initials: MS
authors.lastname: Hoogeman
mesh_terms: D002584:Cervix Uteri / Q000000981:diagnostic imaging; D054893:Cone-Beam Computed Tomography; D005260:Female; D057918:Fiducial Markers; D006801:Humans; D009068:Movement; D059351:Organ Sparing Treatments / Q000379:methods; D058958:Organs at Risk / Q000000981:diagnostic imaging; D056888:Patient Positioning; D016684:Prone Position; D011873:Radiology Information Systems; D011880:Radiotherapy Planning, Computer-Assisted / Q000379:methods*; D020266:Radiotherapy, Conformal / Q000379:methods / Q000706:statistics & numerical data; D061089:Radiotherapy, Image-Guided / Q000379:methods; D050397:Radiotherapy, Intensity-Modulated / Q000379:methods* / Q000706:statistics & numerical data; D013997:Time Factors; D001743:Urinary Bladder / Q000000981:diagnostic imaging*; D002583:Uterine Cervical Neoplasms / Q000000981:diagnostic imaging* / Q000473:pathology / Q000532:radiotherapy*; D014599:Uterus