title: Volumetric change of selected organs at risk during IMRT for oropharyngeal cancer.
abstract: OBJECTIVE
  To assess volumetric changes of selected organs at risk (OAR) during intensity-modulated radiotherapy (IMRT) for oropharyngeal carcinoma.
  
  
  METHODS
  Twenty-six consecutive patients that were treated with definitive IMRT ± chemotherapy between November 2007 and November 2008 were selected for the present study. As part of an internal quality assurances program, a repeat kilovolt (KV) computed tomography was planned weekly during the 7-week treatment course. On each available scan, a single observer contoured the parotid submandibular, and thyroid glands (PG/SMG/TG), larynx (L), and constrictor, masticatory, and sternocleidomastoid muscles (CM/MM/SCM) as appropriate. The volume at each scan was compared with the one at planning CT in a pair-wise fashion. p values <0.05 after correction for multiple testing were considered significant.
  
  
  RESULTS
  A total of 159 scans was obtained during treatment for a total of 185 scans, including the baseline imaging. All OARs showed statistically significant changes over baseline by week 5. At week 7, the PG showed the largest absolute change with an average reduction of ∼10 mL followed by both the SCM and MM (∼-5 mL). The largest (∼-30%) relative change was observed for the salivary glands. L and CM showed a ∼15% increase in volume during treatment.
  
  
  CONCLUSIONS
  All selected OAR undergo significant volumetric changes during a course of IMRT for oropharyngeal squamous cell carcinoma.
authors.affiliation: Department of Radiation Oncology and Molecular Radiation Sciences, Johns Hopkins University, Baltimore, MD 21231-2410, USA.
authors.forename: Francesco
authors.initials: F
authors.lastname: Ricchetti
authors.forename: Binbin
authors.initials: B
authors.lastname: Wu
authors.forename: Todd
authors.initials: T
authors.lastname: McNutt
authors.forename: John
authors.initials: J
authors.lastname: Wong
authors.forename: Arlene
authors.initials: A
authors.lastname: Forastiere
authors.forename: Shanthi
authors.initials: S
authors.lastname: Marur
authors.forename: Heather
authors.initials: H
authors.lastname: Starmer
authors.forename: Giuseppe
authors.initials: G
authors.lastname: Sanguineti
mesh_terms: D000328:Adult; D000368:Aged; D002294:Carcinoma, Squamous Cell / Q000000981:diagnostic imaging / Q000188:drug therapy / Q000532:radiotherapy* / Q000601:surgery; D005260:Female; D006801:Humans; D007830:Larynx / Q000033:anatomy & histology / Q000000981:diagnostic imaging / Q000528:radiation effects; D008297:Male; D008410:Masticatory Muscles / Q000033:anatomy & histology / Q000000981:diagnostic imaging / Q000528:radiation effects; D008875:Middle Aged; D009334:Neck Muscles / Q000033:anatomy & histology / Q000000981:diagnostic imaging / Q000528:radiation effects; D009929:Organ Size / Q000528:radiation effects; D058958:Organs at Risk / Q000033:anatomy & histology / Q000000981:diagnostic imaging / Q000528:radiation effects*; D009959:Oropharyngeal Neoplasms / Q000000981:diagnostic imaging / Q000188:drug therapy / Q000532:radiotherapy* / Q000601:surgery; D050397:Radiotherapy, Intensity-Modulated; D013363:Submandibular Gland / Q000033:anatomy & histology / Q000000981:diagnostic imaging / Q000528:radiation effects; D013961:Thyroid Gland / Q000033:anatomy & histology / Q000000981:diagnostic imaging / Q000528:radiation effects; D013997:Time Factors; D014057:Tomography, X-Ray Computed