title: Intensity-modulated radiotherapy for gliomas:dosimetric effects of changes in gross tumor volume on organs at risk and healthy brain tissue.
abstract: OBJECTIVE
  The aim of this study was to explore the effects of changes in the gross tumor volume (GTV) on dose distribution in organs at risk (OARs) and healthy brain tissue in patients with gliomas.
  
  
  METHODS
  Eleven patients suffering from gliomas with intensity-modulated radiotherapy (IMRT) plans treated with a simultaneous integrated boost technique planned before therapy (initial plans) were prospectively enrolled. At the end of radiotherapy, patients underwent repeat computed tomography and magnetic resonance imaging, and IMRT was replanned. The GTV and dosimetric parameters between the initial and replanned IMRT were compared using the Wilcoxon two-related-sample test, and correlations between the initial GTV and the replanned target volumes were assessed using the bivariate correlation test.
  
  
  RESULTS
  The volume of the residual tumor did not change significantly (P>0.05), the volume of the surgical cavity decreased significantly (P<0.05), and the GTV and target volumes decreased significantly at the end of IMRT (all P<0.05). The near-maximum dose to OARs and volumes of healthy brain tissue receiving total doses of 10-50 Gy were lower in the replanned IMRT than in the initial IMRT (all P<0.05). The GTV in the initial plan was significantly positively correlated with the changes in the GTV and planning target volume 1 that occurred during IMRT (all P<0.05).
  
  
  CONCLUSIONS
  The reduction in the GTV in patients with gliomas resulted from shrinkage of the surgical cavity during IMRT, leading to decreased doses to the OARs and healthy brain tissue. Such changes appeared to be most meaningful in patients with large initial GTV values.
authors.affiliation: Department of Oncology, The Institute of Skull Base Surgery and Neurooncology at Hunan, Central South University, Xiangya Hospital, Changsha, Hunan, People's Republic of China.
authors.forename: Zhen
authors.initials: Z
authors.lastname: Yang
authors.affiliation: Department of Oncology, The Institute of Skull Base Surgery and Neurooncology at Hunan, Central South University, Xiangya Hospital, Changsha, Hunan, People's Republic of China.
authors.forename: Zijian
authors.initials: Z
authors.lastname: Zhang
authors.affiliation: Department of Oncology, The Institute of Skull Base Surgery and Neurooncology at Hunan, Central South University, Xiangya Hospital, Changsha, Hunan, People's Republic of China.
authors.forename: Xia
authors.initials: X
authors.lastname: Wang
authors.affiliation: Department of Oncology, The Institute of Skull Base Surgery and Neurooncology at Hunan, Central South University, Xiangya Hospital, Changsha, Hunan, People's Republic of China.
authors.forename: Yongmei
authors.initials: Y
authors.lastname: Hu
authors.affiliation: Department of Oncology, The Institute of Skull Base Surgery and Neurooncology at Hunan, Central South University, Xiangya Hospital, Changsha, Hunan, People's Republic of China.
authors.forename: Zhiping
authors.initials: Z
authors.lastname: Lyu
authors.affiliation: Department of Neurosurgery, The Institute of Skull Base Surgery and Neurooncology at Hunan, Central South University, Xiangya Hospital, Changsha, Hunan, People's Republic of China.
authors.forename: Lei
authors.initials: L
authors.lastname: Huo
authors.affiliation: Department of Oncology, The Institute of Skull Base Surgery and Neurooncology at Hunan, Central South University, Xiangya Hospital, Changsha, Hunan, People's Republic of China.
authors.forename: Rui
authors.initials: R
authors.lastname: Wei
authors.affiliation: Department of Oncology, The Institute of Skull Base Surgery and Neurooncology at Hunan, Central South University, Xiangya Hospital, Changsha, Hunan, People's Republic of China.
authors.forename: Jun
authors.initials: J
authors.lastname: Fu
authors.affiliation: Department of Oncology, The Institute of Skull Base Surgery and Neurooncology at Hunan, Central South University, Xiangya Hospital, Changsha, Hunan, People's Republic of China.
authors.forename: Jidong
authors.initials: J
authors.lastname: Hong
keywords: dose distribution; glioma; gross tumor volume; intensity-modulated radiotherapy; tumor bed