On using 3D γ-analysis for IMRT and VMAT pretreatment plan QA

Purpose: To investigate using 3D c analysis for IMRT and VMAT QA. Methods: We explored and studied 3D c-analysis by comparing TPS computed and EPID backprojection reconstructed doses in patient's CT images. Two 3D c quantities, cPTV and c10, were proposed and studied for evaluating the QA results, and compared to 2D c (MapCheck composite: cMC). Results: It was found that when 3%(global)= 3 mm criteria was used, all IMRT and 90% of VMAT plans passed QA with a c pass rate -90%. A significant statistical correlation was observed between 3D and 2D c-analysis results for IMRT QA if c10 and cMC are concerned, but no significant relation is found between cPTV and cMC. Conclusions: 3D c analysis based on EPID dose back-projection may provide a feasible tool for IMRT and VMAT pretreatment plan QA. (C) 2012 American Association of Physicists in Medicine. [http:/dx.doi.org10.11181.4711755]