title: Double-arc volumetric modulated therapy improves dose distribution compared to static gantry IMRT and 3D conformal radiotherapy for adjuvant therapy of gastric cancer.
abstract: BACKGROUND
  The objective of this study was to compare the dose distributions of RapidArc (RA), static gantry intensity-modulated radiotherapy (IMRT), and three-dimensional conformal radiotherapy (3DCRT) as adjuvant radiotherapy modalities for the treatment of gastric cancer.
  
  
  METHODS
  Fifteen patients with gastric cancer that underwent limited lymphadenectomy of perigastric lymph nodes were included in this study. Dosimetric values for a total dose of 45 Gy (1.8 Gy/day) were calculated for the RapidArc, IMRT, and 3DCRT modalities. The following parameters were compared: D99%, D1%, V95%, V107%, and conformity and homogeneity index values (CI and HI, respectively) for the planned target volume (PTV). Dose volume histogram (DVH) and dose distribution of the organs at risk (OAR), as the maximal dose to the spinal cord, V30 and V40 of the small bowel, and V20, V30 of liver and kidney were also assessed respectively.
  
  
  RESULTS
  RA, IMRT, and 3DCRT all achieved desirable PTV coverage. However, RA and IMRT significantly decreased D1% and V107%, and provided better CI and HI values compared with 3DCRT (P <0.05). Moreover, RA also achieved a significantly lower maximum dose for the spinal cord, liver V30, and kidney V20 compared to IMRT and 3DCRT; while the mean dose for these three organ types did not differ for the RA, IMRT, and 3DCRT plans.
  
  
  CONCLUSIONS
  Both RA and IMRT achieved favorable PTV coverage compared to 3DCRT. In addition, RA achieved better dosimetry than IMRT and 3DCRT, and provided better protection for the spinal cord, liver, and kidneys.
authors.affiliation: Cancer Center of Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, No. 13 Hangkong Road, Wuhan, Hubei, 430022, China. taowzhang@163.com.
authors.forename: Tao
authors.initials: T
authors.lastname: Zhang
authors.affiliation: Cancer Center of Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, No. 13 Hangkong Road, Wuhan, Hubei, 430022, China. lzw1091981@163.com.
authors.forename: Zhi-Wen
authors.initials: ZW
authors.lastname: Liang
authors.affiliation: Cancer Center of Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, No. 13 Hangkong Road, Wuhan, Hubei, 430022, China. great_mh@sina.com.
authors.forename: Jun
authors.initials: J
authors.lastname: Han
authors.affiliation: Cancer Center of Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, No. 13 Hangkong Road, Wuhan, Hubei, 430022, China. jianpingcbi@163.com.
authors.forename: Jian-Ping
authors.initials: JP
authors.lastname: Bi
authors.affiliation: Cancer Center of Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, No. 13 Hangkong Road, Wuhan, Hubei, 430022, China. evonnevertake@163.com.
authors.forename: Zhi-Yong
authors.initials: ZY
authors.lastname: Yang
authors.affiliation: Cancer Center of Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, No. 13 Hangkong Road, Wuhan, Hubei, 430022, China. wudajianzhu2004@163.com.
authors.forename: Hong
authors.initials: H
authors.lastname: Ma
mesh_terms: D006801:Humans; D021621:Imaging, Three-Dimensional / Q000379:methods*; D009367:Neoplasm Staging; D058958:Organs at Risk / Q000528:radiation effects; D056888:Patient Positioning; D011379:Prognosis; D011874:Radiometry / Q000379:methods; D011879:Radiotherapy Dosage; D011880:Radiotherapy Planning, Computer-Assisted / Q000379:methods*; D018714:Radiotherapy, Adjuvant; D020266:Radiotherapy, Conformal / Q000379:methods*; D050397:Radiotherapy, Intensity-Modulated / Q000379:methods*; D012189:Retrospective Studies; D013274:Stomach Neoplasms / Q000532:radiotherapy*