title: Intensity-modulated radiotherapy increases dose to the brachial plexus compared with conventional radiotherapy for head and neck cancer.
abstract: OBJECTIVE
  The preferential use of intensity-modulated radiotherapy (IMRT) over conventional radiotherapy (CRT) in the treatment of head and neck cancer has raised concerns regarding dose to non-target tissue. The purpose of this study was to compare dose-volume characteristics with the brachial plexus between treatment plans generated by IMRT and CRT using several common treatment scenarios.
  
  
  METHODS
  The brachial plexus was delineated on radiation treatment planning CT scans from 10 patients undergoing IMRT for locally advanced head and neck cancer using a Radiation Therapy Oncology Group-endorsed atlas. No brachial plexus constraint was used. For each patient, a conventional three-field shrinking-field plan was generated and the dose-volume histogram (DVH) for the brachial plexus was compared with that of the IMRT plan.
  
  
  RESULTS
  The mean irradiated volumes of the brachial plexus using the IMRT vs the CRT plan, respectively, were as follows: V50 (18±5 ml) vs (11±6 ml), p = 0.01; V60 (6±4 ml) vs (3±3 ml), p = 0.02; V66 (3±1 ml) vs (1±1 ml), p = 0.04, V70 (0±1 ml) vs (0±1 ml), p = 0.68. The maximum point dose to the brachial plexus was 68.9 Gy (range 62.3-78.7 Gy) and 66.1 Gy (range 60.2-75.6 Gy) for the IMRT and CRT plans, respectively (p = 0.01).
  
  
  CONCLUSIONS
  Dose to the brachial plexus is significantly increased among patients undergoing IMRT compared with CRT for head and neck cancer. Preliminary studies on brachial plexus-sparing IMRT are in progress.
authors.affiliation: Department of Radiation Oncology, University of California Davis Cancer Center, Sacramento, USA. allen.chen@ucdmc.ucdavis.edu
authors.forename: A M
authors.initials: AM
authors.lastname: Chen
authors.forename: W H
authors.initials: WH
authors.lastname: Hall
authors.forename: B-Q
authors.initials: BQ
authors.lastname: Li
authors.forename: M
authors.initials: M
authors.lastname: Guiou
authors.forename: C
authors.initials: C
authors.lastname: Wright
authors.forename: M
authors.initials: M
authors.lastname: Mathai
authors.forename: A
authors.initials: A
authors.lastname: Dublin
authors.forename: J A
authors.initials: JA
authors.lastname: Purdy
mesh_terms: D001917:Brachial Plexus / Q000528:radiation effects*; D006258:Head and Neck Neoplasms / Q000532:radiotherapy*; D006801:Humans; D008297:Male; D008875:Middle Aged; D011879:Radiotherapy Dosage; D020266:Radiotherapy, Conformal / Q000379:methods; D050397:Radiotherapy, Intensity-Modulated / Q000379:methods*; D018709:Statistics, Nonparametric; D014057:Tomography, X-Ray Computed