dosimetric characteristics of percentage depth dose
beam profiles
dose rate on the central axis
and total scattering factor
were estimated by using BEAMnrc and DOSXYZnrc Monte Carlo code
for 6 MV photon beams from a SIEMENS linac with and without flattening filter.The results showed that the percentage depth dose of flattening filter free(FFF) beam were lower than flattening filter(FF) beam;the dose rate on central axis was higher than FF beam
and the ratio of FFF/FF decreased with field size and depth increasing.Besides
the width of penumbra for FFF beam was slightly smaller than that of with FF case.And the variation of total scatter factor showed the flattening filter free mode had smaller depth dependence than flattening filter mode.Our study shows that the beams without flattening can be advantageous in clinical applications.