@misc{oai:repo.qst.go.jp:00075983,
 author = {Koba, Yusuke and Chang, Weishan and Yoshitake, Takayashu and Koba, Yusuke and Chang, Weishan},
 month = {May},
 note = {Introduction
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. 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.

Methods
The 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.

Results
The 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.

Conclusions
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. 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 Applications},
 title = {Construction of X-ray source model of various recent CT scanners and comparison of exposure dose using voxel phantom and Monte Carlo simulation},
 year = {2019}
}