Measured neutron spectrum produced by a Varian 2100 accelerator operated at 18 MV with the flattening filter in place (FF) and with it removed (FFF).
Properties of neutron fields produced by a Varian 2100 accelerator operated with the flattening filter present (FF) and flattening filter-free (FFF).
Spot-checking validation of the Monte Carlo model with the flattening filter removed. Calculated and measured fluences generated by a closed field at different locations in the patient plane. Distances are in the in-plane direction; is in the direction toward the gantry, is away from the gantry.
(A–C) Sources of neutrons from an accelerator operated with the flattening filter (FF) and flattening filter-free (FFF). Absolute neutron contribution (abs.; neutrons per source electrons) as well as percent neutron contribution (%) are shown. “Closed field” refers to jaws and MLC closed, “clinical field” refers to jaws set to and MLC set to , “open field” refers to jaws set to and MLC retracted.
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