title: Optimal adaptive IMRT strategy to spare the parotid glands in oropharyngeal cancer.
abstract: In oropharyngeal cancer adaptive radiation therapy (ART), this study aimed to quantify the dosimetric benefit of numerous replanning strategies, defined by various numbers and timings of replannings, with regard to parotid gland (PG) sparing.
  
  
  
  Thirteen oropharyngeal cancer patients had one planning and then six weekly CT scans during the seven weeks of IMRT. Weekly doses were recalculated without replanning or with replanning to spare the PG. Sixty-three ART scenarios were simulated by considering all the combinations of numbers and timings of replanning. The PG cumulated doses corresponding to "standard" IMRT and ART scenarios were estimated and compared, either by calculating the average of weekly doses or using deformable image registration (DIR).
  
  
  
  Considering average weekly doses, the mean PG overdose using standard IMRT, compared to the planned dose, was 4.1Gy. The mean dosimetric benefit of 6 replannings was 3.3Gy. Replanning at weeks 1, 1-5, 1-2-5, 1-2-4-5 and 1-2-4-5-6 produced the lowest PG mean doses, 94% of the maximum benefit being obtained with 3 replannings. The percentage of patients who had a benefit superior to 5Gy for the contralateral PG was 31% for the three-replannings strategy. The same conclusions were found using DIR.
  
  
  
  Early replannings proved the most beneficial for PG sparing, three replannings (weeks 1-2-5), representing an attractive combination for ART in oropharyngeal cancer.
authors.affiliation: National Key Laboratory for Electronic Measurement Technology, North University of China, Taiyuan, People's Republic of China; Université de Rennes 1, LTSI, France; INSERM, U1099, Rennes, France; Centre de Recherche en Information médicale sino-français (CRIBs), Rennes, France.
authors.forename: Pengcheng
authors.initials: P
authors.lastname: Zhang
authors.affiliation: Université de Rennes 1, LTSI, France; INSERM, U1099, Rennes, France; Centre de Recherche en Information médicale sino-français (CRIBs), Rennes, France.
authors.forename: Antoine
authors.initials: A
authors.lastname: Simon
authors.affiliation: Université de Rennes 1, LTSI, France; INSERM, U1099, Rennes, France. Electronic address: bastien.rig@gmail.com.
authors.forename: Bastien
authors.initials: B
authors.lastname: Rigaud
authors.affiliation: Université de Rennes 1, LTSI, France; INSERM, U1099, Rennes, France; Centre Eugene Marquis, Radiotherapy Department, Rennes, France.
authors.forename: Joël
authors.initials: J
authors.lastname: Castelli
authors.affiliation: Université de Rennes 1, LTSI, France; INSERM, U1099, Rennes, France.
authors.forename: Juan David
authors.initials: JD
authors.lastname: Ospina Arango
authors.affiliation: Université de Rennes 1, LTSI, France; INSERM, U1099, Rennes, France.
authors.forename: Mohamed
authors.initials: M
authors.lastname: Nassef
authors.affiliation: Centre Eugene Marquis, Radiotherapy Department, Rennes, France.
authors.forename: Olivier
authors.initials: O
authors.lastname: Henry
authors.affiliation: Department of Radiation Oncology, Shandong Cancer Hospital, Jinan, People's Republic of China; Laboratory of Image Science and Technology, Southeast University, Nanjing, People's Republic of China.
authors.forename: Jian
authors.initials: J
authors.lastname: Zhu
authors.affiliation: Université de Rennes 1, LTSI, France; INSERM, U1099, Rennes, France; Centre de Recherche en Information médicale sino-français (CRIBs), Rennes, France.
authors.forename: Pascal
authors.initials: P
authors.lastname: Haigron
authors.affiliation: Department of Radiation Oncology, Shandong Cancer Hospital, Jinan, People's Republic of China; Laboratory of Image Science and Technology, Southeast University, Nanjing, People's Republic of China.
authors.forename: Baosheng
authors.initials: B
authors.lastname: Li
authors.affiliation: Centre de Recherche en Information médicale sino-français (CRIBs), Rennes, France; Laboratory of Image Science and Technology, Southeast University, Nanjing, People's Republic of China.
authors.forename: Huazhong
authors.initials: H
authors.lastname: Shu
authors.affiliation: Université de Rennes 1, LTSI, France; INSERM, U1099, Rennes, France; Centre de Recherche en Information médicale sino-français (CRIBs), Rennes, France; Centre Eugene Marquis, Radiotherapy Department, Rennes, France. Electronic address: r.de-crevoisier@rennes.unicancer.fr.
authors.forename: Renaud
authors.initials: R
authors.lastname: De Crevoisier
mesh_terms: D000368:Aged; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009959:Oropharyngeal Neoplasms / Q000532:radiotherapy*; D010306:Parotid Gland / Q000528:radiation effects*; D011879:Radiotherapy Dosage; D011880:Radiotherapy Planning, Computer-Assisted / Q000379:methods; D050397:Radiotherapy, Intensity-Modulated / Q000379:methods*
keywords: Head and neck; Oropharyngeal; Radiotherapy; Replanning