Medical linear accelerators are one of the most widespread methods for cancer treatment. Despite their advantages, unwanted photoneutrons are produced by high energy linacs. This photoneutrons are as undesired doses to patients and a significant problem for radiation protection of the staffs and patients. Photoneutrons radiological risk must be evaluated because of their high LET and range.in o...

Varian introduced (in 2010) the option of removing the flattening filter (FF) in their C-Arm linacs for intensity-modulated treatments. This mode, called flattening filter-free (FFF), offers the advantage of a greater dose rate. Varian's "Portal Dosimetry" is an electronic portal imager device (EPID)-based tool for IMRT verification. This tool lacks the capability of verifying flattening filter...

Introduction: During intensity modulated radiation therapy (IMRT) technique, theoretically, presence of flattening filter (FF) across the beamline of clinical linear accelerator (linac) is not essential to obtain uniform lateral profiles due to intensity modulation of photon beams by multileaf collimators (MLCs). The aim of this study was to investigate the dosimetrical propert...

Introduction: This study investigates basic dosimetric properties of unflattened 6 MV photon beam shaped by multileaf collimator and compares them with those of flattened beams.Materials and Methods: Monte Carlo simulation model using BEAM code was developed for a 6MV photon beam based on Varian Clinic 600 unique performance linac operated with and without a flattening filter in beam line. Dosi...

Background: During intensity modulated radiation therapy (IMRT) technique, theoretically, presence of flattening filter (FF) across the beamline of clinical linear accelerator (linac) is not essential to obtain uniform lateral profiles due to intensity modulation of photon beams by multileaf collimators (MLCs). The aim of this study was to investigate the dosimetrical properties of 18 MV photon...