Intensity-modulated radiotherapy for gliomas: dosimetric effects of changes in gross tumor volume on organs at risk and healthy brain tissue
Received 13 November 2015
Accepted for publication 7 February 2016
Published 15 June 2016 Volume 2016:9 Pages 3545—3554
Checked for plagiarism Yes
Review by Single-blind
Peer reviewers approved by Dr Manfred Beleut
Peer reviewer comments 2
Editor who approved publication: Dr Jianmin Xu
Zhen Yang,1 Zijian Zhang,1 Xia Wang,1 Yongmei Hu,1 Zhiping Lyu,1 Lei Huo,2 Rui Wei,1 Jun Fu,1 Jidong Hong1
1Department of Oncology, 2Department of Neurosurgery, The Institute of Skull Base Surgery and Neurooncology at Hunan, Central South University, Xiangya Hospital, Changsha, Hunan, People’s Republic of China
Aim: 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).
Conclusion: 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.
Keywords: intensity-modulated radiotherapy, dose distribution, glioma, gross tumor volume, tumor bed
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