title: The effect of intravenous contrast on intensity-modulated radiation therapy dose calculations for head and neck cancer.
abstract: OBJECTIVE
  The objective of this study was to determine if the use of intravenous contrast results in clinically important errors in intensity-modulated radiation therapy (IMRT) dose calculations for head and neck radiotherapy treatment planning.
  
  
  METHODS
  Nonionic, iodinated intravenous contrast (Iohexol) was administered during the treatment planning computed tomography (CT) scan of 5 patients with head and neck cancer of varying disease sites. The potential effect of intravenous contrast was studied by changing the density of the contrast-enhanced vessels. An inverse IMRT plan was generated from an unmanipulated "normal contrast" planning scan. We then applied the same planning parameters to a "no contrast" planning scan. The effect of intravenous contrast was quantified by calculating the percent change of dose in a variety of target and normal structures. To evaluate a worst-case scenario situation, this comparison was repeated by assigning the vessels the maximum density in our planning system ("maximum contrast" density plan).
  
  
  RESULTS
  Dose differences between a planning set of images using intravenous contrast and a set of images without contrast were less than 0.2% for all relevant target volumes and critical structures. A worst-case scenario in which normal contrast was overridden with "maximum contrast" led to small dose differences, generally less than 0.5%.
  
  
  CONCLUSIONS
  Planning head and neck IMRT from CT scans that contain intravenous contrast does not result in clinically important errors in dose delivery.
authors.affiliation: Department of Radiation Oncology, University of Florida College of Medicine, Gainesville, Florida 32610-0385, USA.
authors.forename: Stanley L
authors.initials: SL
authors.lastname: Liauw
authors.forename: Robert J
authors.initials: RJ
authors.lastname: Amdur
authors.forename: William M
authors.initials: WM
authors.lastname: Mendenhall
authors.forename: Jatinder
authors.initials: J
authors.lastname: Palta
authors.forename: Siyong
authors.initials: S
authors.lastname: Kim
mesh_terms: D003287:Contrast Media / Q000008:administration & dosage*; D006258:Head and Neck Neoplasms / Q000000981:diagnostic imaging* / Q000532:radiotherapy*; D006801:Humans; D007262:Infusions, Intravenous; D011879:Radiotherapy Dosage; D014057:Tomography, X-Ray Computed
chemical_list: D003287:Contrast Media