title: Submandibular gland sparing in intensity-modulated radiotherapy for N0-stage nasopharyngeal carcinoma.
abstract: OBJECTIVE
  This study evaluated and quantified the feasibility of submandibular gland (SMG) sparing in intensity-modulated radiotherapy (IMRT) for N0-stage nasopharyngeal carcinoma (NPC).
  
  
  METHODS
  Ten patients with N0-stage NPC were enrolled in the study. Four IMRT plans were produced for each, with different limiting conditions. In plan A, SMG sparing was ignored; in plans B, C and D, the mean dose to SMGs was restricted to 39 Gy. In addition, at least 95% of planning target volume (PTV)-IIa (PTV of clinical target volume involving level IIa lymph node) in plan C and 90% of PTV-IIa in plan D were required to have a 60 Gy covering.
  
  
  RESULTS
  The average mean dose to SMGs was 54.6 ± 3.6 Gy in plan A and was lower 39.3 ± 0.3, 49.3 ± 1.9 and 46.7 ± 2.8 Gy in plans B, C and D, respectively. The volume of PTV-IIa covered by 60 Gy was 98.9%, 81.6%, 95.2% and 90.8% in plans A, B, C and D, respectively, and showed a parallel association between dose reduction to SMGs and the covering deficit of PTV-IIa.
  
  
  CONCLUSIONS
  Reducing the mean dose received by SMG to 39 Gy or less in IMRT for N0-stage NPC is feasible.
authors.affiliation: Department of Radiation Oncology, Cancer Hospital of Shantou University Medical College, Shantou, China.
authors.forename: L
authors.initials: L
authors.lastname: Huang
authors.forename: W
authors.initials: W
authors.lastname: Zhang
authors.forename: T
authors.initials: T
authors.lastname: Zhuang
authors.forename: F
authors.initials: F
authors.lastname: Wu
authors.forename: D
authors.initials: D
authors.lastname: Li
authors.forename: M
authors.initials: M
authors.lastname: Zheng
authors.forename: B
authors.initials: B
authors.lastname: Lin
authors.forename: M
authors.initials: M
authors.lastname: Zhuang
authors.forename: Z
authors.initials: Z
authors.lastname: Chen
mesh_terms: D000328:Adult; D000368:Aged; D002277:Carcinoma; D005240:Feasibility Studies; D005260:Female; D006801:Humans; D008198:Lymph Nodes; D008297:Male; D000077274:Nasopharyngeal Carcinoma; D009303:Nasopharyngeal Neoplasms / Q000473:pathology / Q000532:radiotherapy*; D009367:Neoplasm Staging; D011874:Radiometry; D011879:Radiotherapy Dosage; D011880:Radiotherapy Planning, Computer-Assisted; D050397:Radiotherapy, Intensity-Modulated / Q000379:methods*; D013363:Submandibular Gland / Q000528:radiation effects; D014987:Xerostomia / Q000517:prevention & control