title: [A preliminary study on image guided hypofractionated radiotherapy for pulmonary tumor].
abstract: BACKGROUND
  Image guided radiotherapy (IGRT) is a new precise radiotherapy applied in clinic. The aim of this study is to evaluate the impact of using active breath control (ABC) and stereotactic body frame on reducing the positioning error and increasing treatment precision during radiotherapy for pulmonary cancer.
  
  
  METHODS
  Seven patients with pulmonary recurrences or metastasis after prior treatment were enrolled. A total number of 13 tumor targets received irradiation, with a fraction dose of 7Gy treated every other day to a total of 7 fractions. X-ray beam volume CT was done at every fraction for correction of positioning error at 3 dimensions.
  
  
  RESULTS
  The errors between pre-treatment positioning and treatment planning at left-right, anterior-posterior and cephalic-caudal directions were 0.30cm±0.14cm, 0.22cm±0.15cm and 0.28cm ±0.21cm, respectively. The positioning error was reduced after correction by volume CT and after treatment but the errors between pre-correction, post-correction and post-treatment had no statistical significance at all 3 directions. Eight targets had complete response, 4 targets had partial response, and 1 had no change.
  
  
  CONCLUSIONS
  Image guided hypofractionation radiotherapy with ABC and stereotactic body frame has the advantage of increasing radiation dose and reducing overall treatment time and radiation toxicity.
authors.affiliation: Department of Radiation Oncology, Cancer Center, West China Hospital, Sichuan University, Chengdu, Sichuan 610041, P.R.China.
authors.forename: Feng
authors.initials: F
authors.lastname: Xu
authors.forename: Sen
authors.initials: S
authors.lastname: Bai
authors.forename: Hong
authors.initials: H
authors.lastname: Zhang
authors.forename: Renming
authors.initials: R
authors.lastname: Zhong
authors.forename: Xiaoqin
authors.initials: X
authors.lastname: Jiang
authors.forename: Yali
authors.initials: Y
authors.lastname: Shen
authors.forename: Qingfeng
authors.initials: Q
authors.lastname: Xu
authors.forename: Xiaoyu
authors.initials: X
authors.lastname: Li