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Dosimetric Comparison of Volumetric Arc Therapy and Intensity Modulated Radiotherapy for Glioblastoma Treatment
I Kaptan1*, G Ugurluer2 , B Ispir1 , Y Akdeniz1 , M Serin2 , (1) Acibadem Adana Hospital, Adana, ,(2) Acibadem University Faculty of Medicine, Adana,
Presentations
SU-I-GPD-J-16 (Sunday, July 30, 2017) 3:00 PM - 6:00 PM Room: Exhibit Hall
Purpose: To compare volumetric arc therapy (VMAT) and intensity modulated radiotherapy (IMRT) for glioblastoma patients' treatments.
Methods: Ten glioblastoma patients were selected. Tomography images were imported to treatment planning system (Eclipse Helios v13.6). Target volumes (PTV) and organs at risk (OAR) were contoured. IMRT and VMAT treatment plans were regenerated for comparison. Anisotropic Analytical Algorithm (AAA) was used. The evaluation of plans was performed using dose-volume histograms (DVH).
Results: Minimum PTV doses (D%98) were 5913.30 ± 64.22 and 5928.90±90.38 cGy (p>0,05); maximum PTV doses were (D%2) 6165.10±40.15 and 6116.30±49.05 cGy (p>0.05); conformity index was 1.28 and 1.44 (p>0.05); homogenity index was 1.12 and 1.08 (p>0.05) for VMAT and IMRT techniques, respectively. Maximum and mean brainstem doses were 929.4 and 1069.1 cGy vs. 311.3 and 305.9 cGy; maximum and mean chiasm doses were 922.9 and 953.7 cGy vs. 607.8 and 559.7 cGy; maximum and mean ipsilateral optic nerve doses were 447.7 and 669.4 cGy vs. 347.3 and 486 cGy; maximum and mean ipsilateral eye doses were 595.4 and 740.0 cGy vs. 296 and 379.1 cGy; maximum and mean ipsilateral lens doses were 339 and 350.9 cGy vs. 273.5 and 317.1 cGy; maximum and mean contralateral lens doses were 308.4 and 309.9 cGy vs. 249.1 and 281.7 cGy, for VMAT and IMRT techniques, respectively. Statistically, there was no difference between techniques. But ipsilateral eye, lens and optic nerve doses in VMAT plans were lower. Monitor units (MU) were 410.4 and 466.8 for VMAT and IMRT techniques, respectively and difference was statistically significant.
Conclusion: The coverage of PTV and protection of organs at risk were comparable between two techniques. However, total MU and ipsilateral organ doses were decreased in VMAT plans.
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