Table 4.

Comparison of the dosimetric parameters of PTV for the VMAT and proton plans. The values are averaged over four analyzed cases. (Note: PTV coverage was identical in the VMAT and proton plans for a given prostate case.)

PTV (volume: 86.4 cc)	VMAT	Proton
Minimum Dose	73.4 Gy	76.0 CGE
Maximum Dose	84.0 Gy	82.8 CGE
Mean Dose	81.1 Gy	80.7 CGE
${\mathrm{D}}_{95\mathrm{\%}}$	79.4 Gy	79.3 CGE
${\mathrm{V}}_{95\mathrm{\%}}(\mathrm{\%})$	100	100
${\mathrm{V}}_{103\mathrm{\%}}(\mathrm{\%})$	26.6	14.1
${\mathrm{V}}_{105\mathrm{\%}}(\mathrm{\%})$	1.6	0
${\mathrm{V}}_{107\mathrm{\%}}(\mathrm{\%})$	0	0
HI	0.04	0.03

$\text{PVT}=\text{planning target volume}$; ${\mathrm{V}}_{\mathrm{x}\mathrm{\%}}=$ relative volume of the PTV receiving x% of the prescription dose; ${\mathrm{D}}_{95\%}=\text{dose at}95\%\text{of the PTV}$; $\text{HI}=\text{homogeneity index}$.