X-ray CT (Computed Tomography) is very popular as a useful diagnostic method, so it is important to assess high exposure dose of CT in terms of justification and optimization. WAZA-ARI version 2 (WAZA-ARIv2, https://waza-ari.nirs.qst.go.jp/) is the web-based open system for X-ray CT dose calculation, which has been developed by National Institute of Radiological Sciences (NIRS), Oita University of Nursing and Health Sciences and the Japan Atomic Energy Agency (JAEA). The organ doses of various CT exposures were calculated using Monte Carlo simulation and voxel phantoms. In WAZA-ARIv2, can provide organ doses taking into consideration of the body type of patient using Japanese voxel phantoms developed by JAEA. And it can also provide exposure doses of children using child voxel phantoms developed by the University of Florida. In this system selectable CT scanners are 31 models. The number of CT models in WAZA-ARIv2 system is still increasing. Furthermore, we added the database function of storing the calculation results in each facility in order to check the exposure level of the CT examination in the facility in the stored distribution data in Japan. In January 2015, WAZA-ARIv2 system started, and currently over one thousand users are registered. In order to acquire more data on the actual situation of medical exposure in Japan, we plan to expand the number of users and to improve functions of WAZA-ARIv2 system. In this presentation, we will report the development and progress of WAZA-ARIv2 system.World Congress on Medical Physics and Biomedical Engineering 2018 (WC2018
