A comparative dosimetric study of cervical cancer patients with para-aortic lymph node metastasis treated with volumetric modulated arc therapy vs. 9-field intensity-modulated radiation therapy

Yaqin Wu, Biqing Zhu, Jingjing Han, Hanzi Xu, Zhen Gong, Yongqin Yang, Jian Huang, Emei Lu


Background: To compare the dosimetric characteristics between volumetric modulated arc therapy (VMAT) and 9-field intensity-modulated radiation therapy (9F-IMRT) for cervical cancer patients with para- aortic lymph node (PALN) metastasis.
Methods: We selected 20 patients who had received extended-field radiotherapy for cervical cancer with PALN metastasis. IMRT and VMAT plans were compared in terms of target, organs at risk (OARs), homogeneity index (HI), conformity index (CI), the number of monitor units (MUs) and treatment time (s).
Results: The CI and HI of VMAT plans were superior to those of IMRT plans (P<0.05). As for OARs, the mean maximum doses (Dmean) to the kidneys in the VMAT plans were all lower than those in IMRT plans (P<0.001). V40, V50 of the rectum, and V40 of the bladder in VMAT plans involved fewer doses than IMRT plans (P<0.001). Compared with IMRT plans, VMAT reduced the average number of MUs by 51% and the average treatment time by 31%.
Conclusions: Both VMAT and IMRT plans can satisfy clinical dosimetric demands and protect OARs. VMAT has the best performance on CI and HI and can better protect the OARs. VMAT plans have fewer MUs and improve treatment efficiency.