Target Coverage (TC):	TC describes the fraction of the target volume (VT) receiving at least the prescription dose (VT,presc) and is defined as $\mathit{\text{TC}}=\frac{V_{T,\mathit{\text{presc}}}}{V_T}$. For perfect coverage, TC equals 1.0.
Homogeneity Index (HI):	HI quantifies dose homogeneity in the target volumes, as recommended by the International Commission on Radiation Units and Measurements (11). The HI is defined as the greatest dose delivered to 2% of the target volume (D2%) minus the dose delivered to 98% of the target volume (D98%) divided by the median dose (Dmedian) of the target volume: $\mathit{\text{HI}}=\frac{D_{2\%}-D_{98\%}}{D_{\mathit{\text{median}}}}$ Smaller values of HI correspond to more homogenous irradiation of the target volume. A value of 0 corresponds to absolute homogeneity of dose within the target.
V90:	V90 quantifies volume of the whole brain PTV receiving 90% of the prescription dose.
V95:	V95 quantifies volume of the whole brain PTV receiving 95% of the prescription dose.
Mean Normalized Tissue Dose (NTDmean):
	NTDmean is defined as the total dose that would have the same biological effect as the actual treatment schedule, if it were given in 2 Gy fractions. This parameter allows us to compare the effects on normal tissue for two dose-volume histograms. An α/β ratio of 2 Gy was assumed for the hippocampus.