title: Prospective study evaluating the use of IV contrast on IMRT treatment planning for lung cancer.
abstract: OBJECTIVE
  To investigate the impact of exclusively using intravenous (IV) contrast x-ray computed tomography (CT) scans on lung cancer intensity-modulated radiation therapy (IMRT) treatment planning.
  
  
  METHODS
  Eight patients with lung cancer (one small cell, seven nonsmall cell) scheduled to receive IMRT consented to acquisition of simulation CT scans with and without IV contrast. Clinical treatment plans optimized on the noncontrast scans were recomputed on contrast scans and dose coverage was compared, along with the γ passing rates.
  
  
  RESULTS
  IV contrast enhanced scans provided better target and critical structure conspicuity than the noncontrast scans. Using noncontrast scan as a reference, the median absolute/relative differences in mean, maximum, and minimum doses to the planning target volume (PTV) were -4.5 cGy/-0.09%, 41.1 cGy/0.62%, and -19.7 cGy/-0.50%, respectively. Regarding organs-at-risk (OARs), the median absolute/relative differences of maximum dose to heart was -13.3 cGy/-0.32%, to esophagus was -63.4 cGy/-0.89%, and to spinal cord was -16.3 cGy/-0.46%. The median heart region of interest CT Hounsfield Unit (HU) number difference between noncontrast and contrast scans was 136.4 HU (range, 94.2-161.8 HU). Subjectively, the regions with absolute dose differences greater than 3% of the prescription dose were small and typically located at the patient periphery and/or at the beam edges. The median γ passing rate was 0.9981 (range, 0.9654-0.9999) using 3% absolute dose difference/3 mm distance-to-agreement criteria. Overall, all evaluated cases were found to be clinically equivalent.
  
  
  CONCLUSIONS
  PTV and OARs dose differences between noncontrast and contrast scans appear to be minimal for lung cancer patients undergoing IMRT. Using IV contrast scans as the primary simulation dataset could increase treatment planning efficiency and accuracy by avoiding unnecessary scans, manually region overriding, and planning errors caused by nonperfect image registrations.
authors.affiliation: Department of Radiation Oncology, Washington University School of Medicine, Saint Louis, Missouri 63110.
authors.forename: Hua
authors.initials: H
authors.lastname: Li
authors.affiliation: Department of Radiation Oncology, Washington University School of Medicine, Saint Louis, Missouri 63110.
authors.forename: Beth
authors.initials: B
authors.lastname: Bottani
authors.affiliation: Department of Radiation Oncology, Washington University School of Medicine, Saint Louis, Missouri 63110.
authors.forename: Todd
authors.initials: T
authors.lastname: DeWees
authors.affiliation: Department of Radiation Oncology, University of California Los Angeles, Los Angeles, California 90095.
authors.forename: Daniel A
authors.initials: DA
authors.lastname: Low
authors.affiliation: Department of Radiation Oncology, Washington University School of Medicine, Saint Louis, Missouri 63110.
authors.forename: Jeff M
authors.initials: JM
authors.lastname: Michalski
authors.affiliation: Department of Radiation Oncology, Washington University School of Medicine, Saint Louis, Missouri 63110.
authors.forename: Sasa
authors.initials: S
authors.lastname: Mutic
authors.affiliation: Department of Radiation Oncology, Washington University School of Medicine, Saint Louis, Missouri 63110.
authors.forename: Jeffrey D
authors.initials: JD
authors.lastname: Bradley
authors.affiliation: Department of Radiation Oncology, Washington University School of Medicine, Saint Louis, Missouri 63110.
authors.forename: Clifford G
authors.initials: CG
authors.lastname: Robinson
mesh_terms: D003287:Contrast Media / Q000008:administration & dosage*; D004947:Esophagus / Q000528:radiation effects; D056973:Four-Dimensional Computed Tomography / Q000379:methods; D006321:Heart / Q000528:radiation effects; D006801:Humans; D007262:Infusions, Intravenous; D008175:Lung Neoplasms / Q000532:radiotherapy*; D058958:Organs at Risk; D011446:Prospective Studies; D011874:Radiometry / Q000379:methods; D011879:Radiotherapy Dosage; D011880:Radiotherapy Planning, Computer-Assisted / Q000379:methods*; D050397:Radiotherapy, Intensity-Modulated / Q000379:methods*; D012119:Respiration; D013116:Spinal Cord / Q000528:radiation effects; D014057:Tomography, X-Ray Computed / Q000379:methods*
chemical_list: D003287:Contrast Media