Table 2.

Ionization ratio ($\mathrm{J}={\mathrm{D}}_{20}/{\mathrm{D}}_{10}$) for various field sizes.

Field Size	6 MV	6MVFFF	% Diff	10 MV	10MVFFF	% Diff
$3\times 3\hspace{0.17em}{\text{cm}}^2$	0.5397	0.5431	0.62	0.5805	0.5748	$-0.98$
$10\times 10\hspace{0.17em}{\text{cm}}^2$	0.5734	0.5699	$-0.61$	0.6131	0.6011	$-1.95$
$20\times 20\hspace{0.17em}{\text{cm}}^2$	0.6049	0.5953	$-1.58$	0.6373	0.6194	$-2.81$
$30\times 30\hspace{0.17em}{\text{cm}}^2$	0.623	0.6047	$-2.93$	0.6499	0.6246	$-3.89$
$40\times 40\hspace{0.17em}{\text{cm}}^2$	0.6316	0.6076	$-3.80$	0.6602	0.6315	$-4.34$