Program Information
Characterization of Vidar DosimetryPro Advantage RED Scanner with Application to SBRT and SRS QA
M Dumas*, N Wen , Henry Ford Health System, Detroit, MI
Presentations
SU-F-T-578 (Sunday, July 31, 2016) 3:00 PM - 6:00 PM Room: Exhibit Hall
Purpose: To use Gafchromic EBT3 film to quantify key dosimetric characteristics of the Vidar DosimetryPro Advantage RED film scanner for use in SBRT/SRS QA, by analyzing scanner uniformity and dose sensitivity.
Method: Gafchromic EBT3 film was used in this study. Films were irradiated using 6MV FFF and 10MV FFF beams from a Varian Edge linear accelerator, with setup of 100cm SAD at depth 5 cm. Nine doses were delivered per film, with calibration dose ranges of 1-10 Gy and 3-24 Gy for 6MV FFF, and 3-27 Gy for 10MV FFF. Films were scanned with the long side of the film parallel to the detector array. Dose calibration curves were fitted to a 3rd degree polynomial. The derivative of a calibration curve was taken to determine the scanner’s sensitivity per dose delivered (OD/Gy). Scanner non-uniformity was calculated in 2 dimensions by taking the mean of standard deviation in each row and column. Absolute dose SRS/SBRT Gamma analyses were performed with passing criteria of 3% and 1mm DTA. For comparison, Gamma analyses were also performed using an Epson Expression 10000 XL.
Results: Uniformity for the Vidar scanner was 0.37% +/- 0.03% in the perpendicular to scan direction and 0.67% +/- 0.05% in the parallel to scan direction, with an overall uniformity of 0.52% +/- 0.03%. Epson red channel uniformity was 0.85% +/- 0.05% and 0.88% +/- 0.08% for the green channel. The Vidar average dose sensitivity from 1-10 Gy was 0.112 OD/Gy and 0.061 OD/Gy for 3-24 Gy. SBRT/SRS Gamma pass rates were 97.8 +/- 1.4 for Vidar and 97.5 +/- 1.4 for Epson.
Conclusion: The Vidar scanner has 41% less non-uniformity compared to Epson XL10000 green channel. The dose sensitivity is 2-3 time greater for the Vidar scanner compared to the Epson in the SRS/SBRT dose range of 5-24 Gy.
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