Basic dosimetric verification in water of the anisotropic analytical algorithm for Varian, Elekta and Siemens linacs

Since early 2007 a new version of the Anisotropic Analytical Algorithm (AAA) for photon dose calculations was released by Varian Medical Systems for clinical usage on Elekta linacs and also, with some restrictions, for Siemens linacs. Basic validation studies were performed and reported for three beams: 4,6 and 15 MV for an Elekta Synergy, 6 and 15 MV for a Siemens Primus and, as a reference, for 6 and 15 MV from a Varian Clinac 2100C/D. Generally AAA calculations reproduced well measured data and small deviations were observed for open and wedged fields. PDD curves showed in average differences between calculation and measurement smaller than 1% or 1.2 mm for Elekta beams, 1% or 1.8 mm for Siemens beams and 1% or 1 mm for Varian beams. Profiles in the flattened region matched measurements with deviations smaller than 1% for Elekta and Varian beams, 2% for Siemens. Percentage differences in Output Factors were observed as small as 1% in average.