title: A broadly adaptive array of dose-constraint templates for planning of intensity-modulated radiation therapy for advanced T-stage nasopharyngeal carcinoma.
abstract: OBJECTIVE
  To develop and validate adaptive dose-constraint templates in intensity-modulated radiotherapy (IMRT) planning for advanced T-stage nasopharyngeal carcinoma (NPC).
  
  
  METHODS
  Dose-volume histograms of clinically approved plans for 20 patients with advanced T-stage NPC were analyzed, and the pattern of distribution in relation to the degree of overlap between targets and organs at risk (OARs) was explored. An adaptive dose constraint template (ADCT) was developed based on the degree of overlap. Another set of 10 patients with advanced T-stage NPC was selected for validation. Results of the manual arm optimization protocol and the ADCT optimization protocol were compared with respect to dose optimization time, conformity indices, multiple-dose end points, tumor control probability, and normal tissue complication probability.
  
  
  RESULTS
  For the ADCT protocol, average time required to achieve an acceptable plan was 9 minutes, with one optimization compared with 94 minutes with more than two optimizations of the manual arm protocol. Target coverage was similar between the manual arm and ADCT plans. A more desirable dose distribution in the region of overlap between planning target volume and OARs was achieved in the ADCT plan. Dose end points of OARs were similar between the manual arm and ADCT plans.
  
  
  CONCLUSIONS
  With the developed ADCT, IMRT treatment planning becomes more efficient and less dependent on the planner's experience on dose optimization. The developed ADCT is applicable to a wide range of advanced T-stage NPC treatment and has the potential to be applied in a broader context to IMRT planning for other cancer sites.
authors.affiliation: Department of Clinical Oncology, Prince of Wales Hospital, Hong Kong, SAR, China.
authors.forename: Ricky Ming-Chun
authors.initials: RM
authors.lastname: Chau
authors.forename: Sing-Fai
authors.initials: SF
authors.lastname: Leung
authors.forename: Michael Koon-Ming
authors.initials: MK
authors.lastname: Kam
authors.forename: Kin-Yin
authors.initials: KY
authors.lastname: Cheung
authors.forename: Wing-Hon
authors.initials: WH
authors.lastname: Kwan
authors.forename: Kwok-Hung
authors.initials: KH
authors.lastname: Yu
authors.forename: Kwok-Wing
authors.initials: KW
authors.lastname: Chiu
authors.forename: Michael Lok-Man
authors.initials: ML
authors.lastname: Cheung
authors.forename: Anthony Tak-Cheung
authors.initials: AT
authors.lastname: Chan
mesh_terms: D001933:Brain Stem / Q000528:radiation effects; D006801:Humans; D009303:Nasopharyngeal Neoplasms / Q000000981:diagnostic imaging / Q000473:pathology / Q000532:radiotherapy*; D009367:Neoplasm Staging; D009897:Optic Chiasm / Q000528:radiation effects; D009900:Optic Nerve / Q000528:radiation effects; D011832:Radiation Injuries / Q000517:prevention & control; D011859:Radiography; D011879:Radiotherapy Dosage; D011880:Radiotherapy Planning, Computer-Assisted / Q000379:methods / Q000592:standards; D050397:Radiotherapy, Intensity-Modulated / Q000379:methods* / Q000592:standards; D013116:Spinal Cord / Q000528:radiation effects; D013997:Time Factors; D047368:Tumor Burden