Recent theoretical studies and clinical investigations have indicated that volumetric modulated arc therapy (VMAT) can produce equal or better treatment plans than intensity modulated radiation therapy (IMRT), while achieving a significant reduction in treatment time. Built upon the concept of aperture-based multi-level beam source sampling optimization, VMAT has overcome many engineering constraints and become a clinically viable radiation treatment modality. At this point in time, however, there are only two commercial VMAT treatment planning systems (TPS) on the market, which severely limit the dissemination of this novel technology. To address this issue, we recently have successfully developed our own version of VMAT TPS. In this paper, we present our preliminary test results.