Purpose: This research compares commercial Patient-Specific QA Devices (PSQA) devices to EBT-XD (Ashland, Wilmington, DE) film dosimetry for pre-treatment evaluation of stereotactic body radiation therapy (SBRT) and stereotactic radiosurgery (SRS) treatment plans.
Methods: Forty IMRT/VMAT SBRT and SRS plans were created using Eclipse 15.6 treatment planning system. Plans were delivered with a Varian Edge LINAC with 6, 6FFF, 10 and 10FFF MV photon beam energies. Fluences were measured using EBT-XD film in a 15cm solid water phantom and an A1SL ion chamber, SNC ArcCHECK (Sun Nuclear, Melbourne, FL), MatriXX Resolution (IBA Dosimetry, Schwarzenbruck, Germany), Varian DMI EPID (Varian, Palo Alto, CA), SNC SRS Check (Sun Nuclear, Melbourne, FL), and IBA myQA SRS (IBA Dosimetry, Schwarzenbruck, Germany). EBT-XD film was scanned using an Epson 10000XL flatbed scanner and analyzed using RIT Classic v6.1. A 10% threshold dose was applied to the analysis of all plan measurements. Results were analyzed for each device with percentage difference and distance to agreement values of 3%/3mm, 2%/2mm, 2%/1mm, and 1%/1mm.
Results: EBT-XD film measurements produced an average gamma analysis passing rates of 97.98%, 91.37%, 75.42%, and 62.07% for 3%/3mm, 2%/2mm, 2%/1mm, and 1%/1mm gamma criteria, respectively. Corresponding results for PSQA devices were: MatriXX 96.28%, 89.08%, 75.65%, and 64.03% ; ArcCHECK 95.15%, 88.39%, 77.37%, and 67.50%; Varian DMI EPID 99.3%, 95.93%, 78.22%, and 71.57%; SRS Check 99.06%, 96.76%, 93.29%, and 84.61%; and myQA SRS 99.71%, 97.91%, 92.55%, and 84.31%.
Conclusion: All detectors have greater than 95% passing rates at 3%/3mm gamma criteria. However, passing rates decrease rapidly for film, ArcCHECK, and the Matrixx as criteria became more strict. In contrast, SNC SRS Check and IBA myQA SRS passing rates do not decline as rapidly and maintain greater than 90% passing rate at 2%/1mm and greater than 80% at 1%/1mm.
Stereotactic Radiosurgery, Quality Assurance, Film