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Comparison of Vendor-Dependent Versus Commercially-Available, Independent LINAC Quality Assurance (QA) for Daily QA

C Stambaugh*, C Melhus, Tufts Medical Center, Boston, MA

Presentations

(Sunday, 7/12/2020)   [Eastern Time (GMT-4)]

Room: AAPM ePoster Library

Purpose:
To investigate and compare time efficiency, data collected, and results of vendor-based versus independent-QA platforms for daily LINAC QA.

Methods:
Time needed to perform daily QA (DQA) on a single LINAC was collected for three months. TG-142-compliant DQA included dosimetry checks (4 photon, 4 electron beams); imaging checks (planar kV & MV, kV CBCT); and mechanical & safety checks using a commercially-available, web-based, independent QA platform (SunCHECK Machine). Additionally, a set of 5 (rotating through 10) vendor-specific machine checks were performed (Machine Performance Check). Data were collected to identify the time required to complete vendor-specific, independent, and total DQA. Independent-QA was further analyzed to determine time spent on dosimetry checks. Output collected from both methods was compared using a Wilcoxon rank sum test for 6MV, 6MeV and 10FFF, and center shift was compared for 6MV.

Results:
Total time for DQA averaged 32 minutes (21-62 min, s=7 min), vendor-specific tests averaged 11 minutes (7-45 min, s=7 min) and included geometry checks on isocenter, collimator, gantry and couch; output & uniformity for 2-3 photon and 2-3 electron energies; and center shift for photon energies. Independent-QA averaged 21 minutes (13-39 min, s=5 min). Six minutes (4-12 min, s=1 min) was spent on dosimetry checks, which included output, symmetry, flatness, energy, field size and center shift for 4 photon and 4 electron energies. The remainder was spent on imaging and mechanical/safety checks. Differences in measured output did not reach significance for any beam (p=0.288, 6MV; 0.704, 6MeV; 0.197, 10FFF), while center shift results showed a significant difference (p<0.001)

Conclusion:
This work indicates that vendor-dependent and an independent-QA platform obtain similar output results, but beam center-shifts are dependent on the platform. Additionally, the independent QA platform can obtain dosimetry results more efficiently and can provide a more user-friendly interface for complete DQA data collection.

Download ePoster [PDF]

Keywords

Quality Assurance, Linear Accelerator, Dosimetry

Taxonomy

TH- External Beam- Photons: Quality Assurance - Linear accelerator

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