Assessment of Monitor Units and Gamma Pass Rate for 6 MV and Flattening Filter Free (FFF) Beams in Volumetric Modulated Arc Therapy (VMAT)

Background: In linear accelerators, the treatment field’s uniform intensity is achieved by including a flattening filter in beam. However, to produce more conformal dose distributions, contemporary radiotherapy practice now frequently uses fluence and aperture modifying techniques, such as volumetric modulated arc therapy. these circumstances, beam manufacturing process no longer required. It therefore necessary compare monitor units of 6 MV free plans how it influences gamma pass rates determine which best for treating cervical cancer with pelvic lymph node metastasis. Methods: VMAT fifteen patients pathological metastasis were included this study. Each patient had two using conventional one (FFF). The made arcs, then recalculated give planned distribution detectors Delta4 phantom. irradiated on phantom an Elekta accelerator (6 MV). Results: mean unit was 506.3 MU standard deviation 48.6 while that FFF 701.5 87.6. total (MUs) significantly greater than (p = 6.1 × 10-5). Conclusion: Flattening (FFF) require numbers comparison filtered beams external radiation nodes involvement.