Dosimetric comparison of coplanar intensity-modulated radiotherapy, noncoplanar intensity-modulated radiotherapy, and volumetric arc therapy planning technique in hippocampal-sparing whole-brain radiotherapy

The aim of this study was to compare the dosimetric parameters of Co-planar Intensity modulated radiotherapy (C-IMRT), non-coplanar (NC-IMRT), and volumetric arc therapy (VMAT) planning technique in hippocampal sparing (HS) whole brain radiotherapy (WBRT). Fifteen patients of brain metastasis (BM) treated with hippocampal sparing whole-brain palliative radiation were selected for this study. C-IMRT, NC-IMRT and VMAT plans were generated for the comparison. Generated plans were evaluated based on planning target volume (PTV) coverage, conformity index (CI), homogeneity index (HI), beam-on time (BOT) and dose delivered to organs at risk (OARs) for the prescribed dose (PD) of 30 Gy in 10 fractions. Statistically significant difference was found in PTVD95%, PTVmax, HI, BOT, MU, Dmax of the brainstem, Dmean of eyes, Dmax of lenses and Dmax, Dmean and D2% of the bilateral hippocampus. However, a non-significant difference was observed in CI, D100% of both the hippocampus, Dmax of the optic chiasm, optic nerves, and Dmax of eyes in all the three planning techniques. Considering the superior plan quality, both NC-IMRT and VMAT are better than the C-IMRT planning technique. Based on beam-on time and delivery efficiency VMAT is found to be superior to both the C-IMRT and NC-IMRT technique. Doses to OARs are very well within the limits in all the three planning techniques.