Purpose: To compare each smoothing algorithm filters those effect on analyzing acquired scanned beam data from annual quality assurance.
Methods: There are 6 embedded smoothing algorithms in myQA Accept® beam scanning software incorporated with IBA Blue water tank® system. The algorithms are 1) Least square, 2) Median, 3) Arithmetic mean, 4) Geometric mean, 5) Envelope, and 6) Bezier. Maximum 2 smoothing runs were obtained each per AAPM TG-106 recommendation. Two photon energy profiles and percent depth doses (PDDs, 6 MV and 18 MV) and three electron profiles and PDDs (6 MeV, 9 MeV and 12 MeV) of Varian C-Series obtained from IBA Blue water tank with CC04 ion chamber. Profiles of 30 x 30 cm² field only, and PDDs of 4x4 cm², 10x10 cm², 30x30 cm² were used for comparison for photons. Only 15x15 cm² electron cone was used for electron profiles and PDDs.
Results: All six smoothing filters well within tolerances which was set by our institution for both profiles and PDDs. Specifically for photon PDDs, most of filters within 0.5% deviation from the baseline (tolerance, 2%) except showed up to 1.5% differences for the largest scanned field size (30 x 30 cm²). For electrons, PDDs were within 0.1 cm from the baseline for all depths. Variations of flatness and symmetry are within 0.3% among filters applied for both photons and electrons regardless of number of filtering run.
Conclusion: Although uncertainties related during the measurement such as selection of detector, scanning speed, water rippling, etc. may affect the outcome, all filtering algorithms satisfied the process of the raw scanned data within tolerance, and variations relatively insignificant each other. However, consistent selection of filtering method will guarantee solid estimation of collected data for repetitive QA results.