Construction of X-ray source model of various recent CT scanners and comparison of exposure dose using voxel phantom and Monte Carlo simulation

IntroductionX-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. The organ doses of various CT exposures were calculated using Monte Carlo simulation and voxel phantoms. The selectable CT scanners in WAZA-ARIv2 are still not enough despite the continuing addition of CT scanners because the CT developers deliver a steady stream of new products. In this study, in order to construct X-ray source model of recent CT scanners, the measurements of radiation quality and distribution were carried out, and exposure dose by its source models were compared.MethodsThe measurements of radiation quality and dose distribution of newer CT scanners made by Canon, GE and Philips using Piranha model 657 (RTI Electronics AB) were carried out. Assuming that the bowtie filter is made of aluminum, the shape of the filter was estimated from the results of the radiation quality and dose distribution. The organ doses in CT exposure were calculated using Monte Carlo code, PHITS and Japanese adult voxel phantoms developed by JAEA.ResultsThe constructed sources model well reproduced the measurement results. Each CT scanner was equipped with one or more bow-tie filters, and the estimated filter shape of each CT scanner showed a characteristic shape for each manufacturer. Assuming a scan of the thoracoabdominal range, the effective dose per value of CTDI free air correlated with the effective energy of the source model.ConclusionsIn order to construct X-ray source model of recent CT scanners, the measurements of radiation quality and distribution were carried out, and exposure dose by its source models were compared. The effective dose per value of CTDI free air correlated with the effective energy of the source model.3rd International Conference on Dosimetry and its Application

Development and progress of the web-based CT exposure dose calculator WAZA-ARIv2

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