Program Information
TrueBeam 5 Years Annual QA Data
R Li1 , T Xue1*, K Xue2 , X Song1 , N Deb1 , (1) St Luke's University Health Network, Bethlehem, PA, (2) University Of Pennsylvania, Philadelphia, PA,
Presentations
SU-I-GPD-T-473 (Sunday, July 30, 2017) 3:00 PM - 6:00 PM Room: Exhibit Hall
Purpose: In our facility, we have been using TrueBeam in clinic since the commissioning in 2011, which was over 5 years ago. This is to review the beam data measured during the annual QAs from the past 5 years and to compare with the commissioning data.
Methods: We used Sun Nuclear Dosimetry 3D Scanner with nominal 100 cm SSD setup to collect beam data during commissioning and annual QA. The Scanner can automatically and reproducibly set detectors position at water surface, level and align tank. This data was post processed using Sun Nuclear Dosimetry software, including normalization, interpolation, and smoothing. Photon beam (6 MV,10 MV, 6 MVFFF, 10 MVFFF) PDDs at various field sizes obtained during annual QA from 2012 – 2016 are compared with the commissioning data of 2011. Annual QA Inline and crossline beam profiles of field size 20 x20 cm² at depth of 10 cm were also compared with the commissioning data.
Results: PDDs: the PDDs measured during the past 5 years’ annual QAs with field sizes of 4x4, 6x6, 10x10, 15x15, 20x20 cm² (30x30 and 40x40 cm² for 6 MV and 10 MV only) are very close to the commissioning data. The maximal variation of PDDs at depths of 5, 10, 15, 20, and 30 cm is 1.7 % for 6 MV and 6 MVFFF, and less than 1 % for 10 MV and 10 MVFFF. The mean maximal variation is 0.6 %, with standard deviation of 0.4 % for all beams, field sizes and depths. Profiles: Inline and crossline beam profiles obtained during annual QA are almost identical to the commissioning data. The maximal variation from commissioning data is less than 1%, except 1.6% in 2016 of 10 MV crossline profile Symmetry.
Conclusion: Overall, we observed strong agreement. The TrueBeam beam parameters are very stable.
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