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SU‐F‐T‐521: Flattening‐Filter‐Free Beam Parameters Comparison From Different Linac Machine Types
Author(s) -
Hussain A
Publication year - 2016
Publication title -
medical physics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.473
H-Index - 180
eISSN - 2473-4209
pISSN - 0094-2405
DOI - 10.1118/1.4956706
Subject(s) - truebeam , linear particle accelerator , flatness (cosmology) , physics , dosimetry , optics , beam (structure) , series (stratigraphy) , calibration , nuclear medicine , medicine , paleontology , cosmology , quantum mechanics , biology
Purpose: Novel linac machines, TrueBeam (TB) and Elekta Versa have updated head designing and software control system, include flattening‐filter‐free (FFF) photon and electron beams. Later on FFF beams were also introduced on C‐Series machines. In this work FFF beams for same energy 6MV but from different machine versions were studied with reference to beam data parameters. Methods: The 6MV‐FFF percent depth doses, profile symmetry and flatness, dose rate tables, and multi‐leaf collimator (MLC) transmission factors were measured during commissioning process of both C‐series and Truebeam machines. The scanning and dosimetric data for 6MV‐FFF beam from Truebeam and C‐Series linacs was compared. A correlation of 6MV‐FFF beam from Elekta Versa with that of Varian linacs was also found. Results: The scanning files were plotted for both qualitative and quantitative analysis. The dosimetric leaf gap (DLG) for C‐Series 6MV‐FFF beam is 1.1 mm. Published values for Truebeam dosimetric leaf gap is 1.16 mm. 6MV MLC transmission factor varies between 1.3 % and 1.4 % in two separate measurements and measured DLG values vary between 1.32 mm and 1.33 mm on C‐Series machine. MLC transmission factor from C‐Series machine varies between 1.5 % and 1.6 %. Some of the measured data values from C‐Series FFF beam are compared with Truebeam representative data. 6MV‐FFF beam parameter values like dmax, OP factors, beam symmetry and flatness and additional parameters for C‐Series and Truebeam liancs will be presented and compared in graphical form and tabular data form if selected. Conclusion: The 6MV flattening filter (FF) beam data from C‐Series & Truebeam and 6MV‐FFF beam data from Truebeam has already presented. This particular analysis to compare 6MV‐FFF beam from C‐Series and Truebeam provides opportunity to better elaborate FFF mode on novel machines. It was found that C‐Series and Truebeam 6MV‐FFF dosimetric and beam data was quite similar.