title: Hepatic arterial phase and portal venous phase computed tomography for dose calculation of stereotactic body radiation therapy plans in liver cancer: a dosimetric comparison study.
abstract: OBJECTIVE
  To investigate the effect of computed tomography (CT) using hepatic arterial phase (HAP) and portal venous phase (PVP) contrast on dose calculation of stereotactic body radiation therapy (SBRT) for liver cancer.
  
  
  METHODS
  Twenty-one patients with liver cancer were studied. HAP, PVP and non-enhanced CTs were performed on subjects scanned in identical positions under active breathing control (ABC). SBRT plans were generated using seven-field three-dimensional conformal radiotherapy (7 F-3D-CRT), seven-field intensity-modulated radiotherapy (7 F-IMRT) and single-arc volumetric modulated arc therapy (VMAT) based on the PVP CT. Plans were copied to the HAP and non-enhanced CTs. Radiation doses calculated from the three phases of CTs were compared with respect to the planning target volume (PTV) and the organs at risk (OAR) using the Friedman test and the Wilcoxon signed ranks test.
  
  
  RESULTS
  SBRT plans calculated from either PVP or HAP CT, including 3D-CRT, IMRT and VMAT plans, demonstrated significantly lower (p <0.05) minimum absorbed doses covering 98%, 95%, 50% and 2% of PTV (D98%, D95%, D50% and D2%) than those calculated from non-enhanced CT. The mean differences between PVP or HAP CT and non-enhanced CT were less than 2% and 1% respectively. All mean dose differences between the three phases of CTs for OARs were less than 2%.
  
  
  CONCLUSIONS
  Our data indicate that though the differences in dose calculation between contrast phases are not clinically relevant, dose underestimation (IE, delivery of higher-than-intended doses) resulting from CT using PVP contrast is larger than that resulting from CT using HAP contrast when compared against doses based upon non-contrast CT in SBRT treatment of liver cancer using VMAT, IMRT or 3D-CRT.
authors.forename: Jianghong
authors.initials: J
authors.lastname: Xiao
authors.forename: Yan
authors.initials: Y
authors.lastname: Li
authors.forename: Qingfeng
authors.initials: Q
authors.lastname: Jiang
authors.forename: Lan
authors.initials: L
authors.lastname: Sun
authors.forename: Fraser
authors.initials: F
authors.lastname: Henderson
authors.forename: Yongsheng
authors.initials: Y
authors.lastname: Wang
authors.forename: Xiaoqin
authors.initials: X
authors.lastname: Jiang
authors.forename: Guangjun
authors.initials: G
authors.lastname: Li
authors.affiliation: Department of Radiation Oncology, Cancer Center, West China Hospital, Sichuan University, Chengdu, Sichuan 610041, PR China. nychenyy@gmail.com.
authors.forename: Nianyong
authors.initials: N
authors.lastname: Chen
mesh_terms: D000328:Adult; D000368:Aged; D003287:Contrast Media / Q000737:chemistry; D005260:Female; D006499:Hepatic Artery / Q000473:pathology* / Q000528:radiation effects; D006801:Humans; D021621:Imaging, Three-Dimensional; D008113:Liver Neoplasms / Q000532:radiotherapy*; D008297:Male; D008875:Middle Aged; D058958:Organs at Risk; D011169:Portal Vein / Q000473:pathology* / Q000528:radiation effects; D011829:Radiation Dosage; D011874:Radiometry / Q000379:methods; D016634:Radiosurgery / Q000379:methods*; D011880:Radiotherapy Planning, Computer-Assisted / Q000379:methods; D020266:Radiotherapy, Conformal / Q000379:methods; D050397:Radiotherapy, Intensity-Modulated / Q000379:methods*; D014057:Tomography, X-Ray Computed
chemical_list: D003287:Contrast Media