Comparison of IMRT and VMAT radiotherapy planning for Graves’ ophthalmopathy based on dosimetric parameters analysis

S.-C. Wang, J. Wu, X.-Q. Xie, X.-L. Liu, Y. Luo, F. Wang, Z.-P. Li, B.-L. Qu, J.-B. Kang, D.-B. Wu, W.-M. Li, R.-Y. Wang

Department of Radiation Oncology, Cancer Center, West China Hospital, West China Medical School, Sichuan University, Chengdu, P.R. China. wangfeng5024@126.com

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• Pharmacology

OBJECTIVE: To compare volumetric modulated arc therapy (VMAT) and intensity-modulated radiation therapy (IMRT) for the treatment of Graves’ ophthalmopathy (GO) based on the dosimetric data.

PATIENTS AND METHODS: 19 patients diagnosed with GO were recruited in this study. For each patient, a dual-partial-arc VMAT plans and a 7-fixed-field IMRT plans were replanned. Dosimetric parameters of the targets and organs at risk (OARs) originated from the two kinds of plans were compared and analyzed.

RESULTS: Homogeneity index (HI) was superior in IMRT plans compared with VMAT (p=0.0014) but there was no significant statistical difference in conformity index (CI) between them (p=0.0673). IMRT plans revealed advantage in the OARs protection especially for the left and right lenses, optic nerves and eyeballs (p<0.05).

CONCLUSIONS: VMAT and IMRT are both feasible techniques in radiotherapy in GO from the perspective of dosimetric parameters. Homogeneity and OAR protection were slightly superior in IMRT plans compared with VMAT plans.

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