title: Comparison of treatment techniques for reduction in the submandibular gland dose: A retrospective study.
abstract: BACKGROUND
  Recent studies have suggested reducing the dose submandibular glands receive when patients undergo head and neck radiotherapy can play a crucial role in preventing xerostomia. However, they are traditionally not spared due to concern that target coverage may be compromised. We investigated the possibility of sparing the contralateral submandibular gland (cSM) by utilising modern planning techniques.
  
  
  METHODS
  10 head and neck patients previously treated with conformal therapy at our centre were retrospectively planned using intensity modulated radiation therapy (IMRT), and volumetric modulated arc therapy (VMAT). Each patient was prescribed 70 Gy in 35 fractions to the primary volume, with 56 Gy delivered to the elective nodal areas. The primary objective was to spare the cSM gland using appropriate dose constraints.
  
  
  RESULTS
  Mean dose to the cSM gland was reduced to an acceptable dose level (39 Gy) for all patients replanned using an IMRT or VMAT technique, without compromising planned target volume (PTV) coverage or other critical structures. VMAT was able to reduce the mean dose to 31.5 ± 5.5 Gy compared to 34.5 ± 4.8 Gy of IMRT and offered improved plan conformity.
  
  
  CONCLUSIONS
  Sparing the cSM gland is possible using IMRT and VMAT planning, whilst preserving coverage on the elective PTV. This has produced a change in protocol in our department, more focus placed on sparing the SM glands. VMAT is a viable alternative method of delivering treatment and will be utilised when required.
authors.affiliation: Ballarat Austin Radiation Oncology Centre, Ballarat, Victoria, Australia.
authors.forename: Christopher
authors.initials: C
authors.lastname: Hoyne
authors.affiliation: Adelaide Radiotherapy Centre, Adelaide, South Australia, Australia.
authors.forename: Marcus
authors.initials: M
authors.lastname: Dreosti
authors.affiliation: Princess Alexandra Hospital, Woolloongabba, Queensland, Australia.
authors.forename: John
authors.initials: J
authors.lastname: Shakeshaft
authors.affiliation: South West Radiation Oncology Service, Bunbury, Western Australia, Australia.
authors.forename: Siddartha
authors.initials: S
authors.lastname: Baxi
mesh_terms: D006258:Head and Neck Neoplasms / Q000532:radiotherapy; D006801:Humans; D058958:Organs at Risk / Q000528:radiation effects*; D011829:Radiation Dosage; D011879:Radiotherapy Dosage; D011880:Radiotherapy Planning, Computer-Assisted; D050397:Radiotherapy, Intensity-Modulated / Q000009:adverse effects*; D012189:Retrospective Studies; D013363:Submandibular Gland / Q000528:radiation effects*; D014987:Xerostomia / Q000209:etiology / Q000517:prevention & control
keywords: IMRT; VMAT; radiotherapy; submandibular; xerostomia