title: Influence of intravenous contrast medium on dose calculation using CT in treatment planning for oesophageal cancer.
abstract: OBJECTIVE
  To evaluate the effect of intravenous contrast on dose calculation in radiation treatment planning for oesophageal cancer.
  
  
  METHODS
  A total of 22 intravein-contrasted patients with oesophageal cancer were included. The Hounsfield unit (HU) value of the enhanced blood stream in thoracic great vessels and heart was overridden with 45 HU to simulate the non-contrast CT image, and 145 HU, 245 HU, 345 HU, and 445 HU to model the different contrast-enhanced scenarios. 1000 HU and -1000 HU were used to evaluate two non-physiologic extreme scenarios. Variation in dose distribution of the different scenarios was calculated to quantify the effect of contrast enhancement.
  
  
  RESULTS
  In the contrast-enhanced scenarios, the mean variation in dose for planning target volume (PTV) was less than 1.0%, and those for the total lung and spinal cord were less than 0.5%. When the HU value of the blood stream exceeded 245 the average variation exceeded 1.0% for the heart V40. In the non-physiologic extreme scenarios, the dose variationof PTV was less than 1.0%, while the dose calculations of the organs at risk were greater than 2.0%.
  
  
  CONCLUSIONS
  The use of contrast agent does not significantly influence dose calculation of PTV, lung and spinal cord. However, it does have influence on dose accuracy for heart.
authors.affiliation: Department of Radiation Oncology, Cancer Hospital and Institute, Tianjin Medical University, Tianjin, China. pubmed@sohu.com
authors.forename: Hong-Sheng
authors.initials: HS
authors.lastname: Li
authors.forename: Jin-Hu
authors.initials: JH
authors.lastname: Chen
authors.forename: Wei
authors.initials: W
authors.lastname: Zhang
authors.forename: Dong-Ping
authors.initials: DP
authors.lastname: Shang
authors.forename: Bao-Sheng
authors.initials: BS
authors.lastname: Li
authors.forename: Tao
authors.initials: T
authors.lastname: Sun
authors.forename: Xiu-Tong
authors.initials: XT
authors.lastname: Lin
authors.forename: Yong
authors.initials: Y
authors.lastname: Yin
mesh_terms: D000368:Aged; D002294:Carcinoma, Squamous Cell / Q000000981:diagnostic imaging* / Q000532:radiotherapy; D003287:Contrast Media; D004938:Esophageal Neoplasms / Q000000981:diagnostic imaging* / Q000532:radiotherapy; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008175:Lung Neoplasms / Q000000981:diagnostic imaging* / Q000532:radiotherapy; D008297:Male; D008875:Middle Aged; D009367:Neoplasm Staging; D011379:Prognosis; D011879:Radiotherapy Dosage; D011880:Radiotherapy Planning, Computer-Assisted; D014057:Tomography, X-Ray Computed
chemical_list: D003287:Contrast Media