Introduction: Several linacs with integrated kV imaging have been developed for delivery of image-guided Stereotactic Body Radiation Therapy (SBRT). High geometric accuracy and coincidence of kilovoltage (kV) imaging systems and MV beam delivery are essential for successful image guidance. A geometric QA tool is available of evaluating and characterizing geometric accuracy of kV and MV cone beam imaging systems. Materials and Methods: This geometric QA tool has been adapted as a routine QA tool for three different types of SBRT-dedicated linacs. They are a Varian Trilogy (Varian Medical Systems, Palo Alto, California, USA), Elekta Synergy (Elekta, Stockholm, Sweden), and Brainlab Vero (Brainlab AG, Feldkirchen, Germany). Both the Trilogy and Synergy linacs are equipped with a retractable kV x-ray tube and a flat panel detector. The Vero utilizes a rotating, rigid ring structure integrating a MV x-ray head mounted on orthogonal gimbals, an electronic portal imaging device (EPID), two kV xray tubes, and fixed two flat panel detectors. Two QA phantoms were built to suit different field sizes. Projection images of a QA phantom were acquired by MV and kV imaging systems at a series of gantry angles. In-house software was used to analyze projection images and calculate eight geometric parameters for each projection. Results: Over 4,300 individual projections have been acquired and analyzed. The Trilogy was calibrated 4 times over a six month period while the Synergy and the Vero were calibrated twice and once, respectively. Quantitative geometric parameters of both MV and kV imaging systems were successfully evaluated. Isocenter consistency of the imaging systems was evaluated. Additionally, the gimbal-based x-ray source positioning of the Vero was examined. Conclusion: Geometric accuracies of both MV and integrated kV imaging systems were quantitatively evaluated by this QA tool.