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

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)).