Table 1.

Measured scatter factors for Elekta Precise 6‐MV photons: collimator $(S_c)$, water phantom $({\mathrm{S}}_{\mathrm{c},\mathrm{p}})$, and $\text{iViewGT}\text{EPID}({\mathrm{S}}_{\text{EPID}})$. ${\mathrm{S}}_{\text{EPID}}$ was calculated using the integrated central axis pixel values for the respective field‐size images.

Fieid size $({\text{cm}}^2)$	$S_c$	$S_{c,p}$	$S_{\text{EPID}}$
$2\times 2$	0.8947	0.8859	0.8449
$5\times 5$	0.9704	0.9511	0.9316
$10\times 10$	1.0000	1.0000	1.0000
$20\times 20$	1.0307	1.0489	1.0706
$25\times 25$	1.0373	1.0598	1.0896