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Effects of hippocampal-sparing intensity-modulated radiotherapy on dose distribution of target volume and organs at risk in locally advanced nasopharyngeal carcinoma
Department of Radiation Oncology,Third Affiliated Hospital of Soochow University,First Peoples' of Changzhou,Changzhou 213003,China (Gu WD,Li QL,Mo JCH,Pei HL);Department of Radiation Oncology,Second Affiliated Hospital of Soochow University,Suzhou 215004,China (Tian Y)
Objective To investigate the effects of hippocampal-sparing intensity-modulated radiotherapy (IMRT) on dose distribution of target volume and organs at risk (OARs) in locally advanced nasopharyngeal carcinoma. Methods A retrospective dosimetric analysis was performed among 11 patients with locally advanced nasopharyngeal carcinoma. The MONACOv5.10 Treatment Planning System was used to design three treatment plans:routine volumetric modulated arc therapy (VMAT),hippocampal-sparing VMAT,and nine fixed-fields IMRT.The D98%,D50%,D2%,Dmean,conformity index (CI),and homogeneity index (HI) of planning target volume (PTV) and PTVnx as well as dose distribution of the hippocampus and OARs were evaluated. Using single factor analysis of variance,two group comparative was LSD or paired t-test. Results For the above three plans,the D2% values of PTVnx were ,7513,and 7462 cGy,respectively (P=0.016);the D98% values of PTV were 5837,5812,and 5914 cGy,respectively (P=0.029);the average D2% values of PTV were 7399,7380,and 7333 cGy,respectively (P=0.047);the HI values of PTV were 0.239,0.241,and 0.220,respectively (P=0.016);the V10 values of the brain stem were 97.2%,88.1%,and 90.3%,respectively (P=0.001);the V20 values of the brain stem were 74.2%,62.3%,and 67.1%,respectively (P=0.032);the V30 values of the brain stem were 50.9%,35.8%,and 45.5%,respectively (P=0.020);the V40 values of brain stem were 24.4%,14.4%,and 23.3%,respectively (P=0.018);the Dmean values of hippocampus were 1518,899,and 896 cGy,respectively (P=0.000);the D40% values of hippocampus were 1379,642,and 639 cGy,respectively (P=0.000);the V10 values of the hippocampus were 54.1%,25.1%,and 3.8%,respectively (P=0.000);the V20 values of the hippocampus were 26.2%,12.6%,and 12.0%,respectively (P=0.001). Conclusions Hippocampal-sparing VMAT and nine fixed-fields IMRT can significantly reduce the dose to the hippocampus without affecting dose distribution of target volume and OARs. VMAT may be superior to IMRT because VMAT can simultaneously reduce the dose to the brain stem.
Gu Wendong,Li Qilin,Tian Ye et al. Effects of hippocampal-sparing intensity-modulated radiotherapy on dose distribution of target volume and organs at risk in locally advanced nasopharyngeal carcinoma[J]. Chinese Journal of Radiation Oncology, 2017, 26(1): 6-11.
Gu Wendong,Li Qilin,Tian Ye et al. Effects of hippocampal-sparing intensity-modulated radiotherapy on dose distribution of target volume and organs at risk in locally advanced nasopharyngeal carcinoma[J]. Chinese Journal of Radiation Oncology, 2017, 26(1): 6-11.
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2017, Vol. 26 
