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

摘要

Purpose: To investigate using 3D γ analysis for IMRT and VMAT QA. Methods: We explored and studied 3D γ-analysis by comparing TPS computed and EPID back-projection reconstructed doses in patient's CT images. Two 3D γ quantities, γ PTV and γ 10, were proposed and studied for evaluating the QA results, and compared to 2D γ (MapCheck composite: γ MC). Results: It was found that when 3(global)3 mm criteria was used, all IMRT and 90 of VMAT plans passed QA with a γ pass rate 90. A significant statistical correlation was observed between 3D and 2D γ-analysis results for IMRT QA if γ 10 and γ MC are concerned, but no significant relation is found between γ PTV and γ MC. Conclusions: 3D γ analysis based on EPID dose back-projection may provide a feasible tool for IMRT and VMAT pretreatment plan QA.