Coil embolization is the treatment of choice for cerebral artery aneurysms at our institution. The duration of a fluoroscopic study and frequency of radiation exposure are varied, and the safety measures against radiation injury have not yet been established. Guidelines about radiation injury prevention with IVR have been published. However, there is not yet a detailed report for the head region. We also report our measures to try to reduce the amount of radiation exposure during the embolization procedure in our institution.

The goal of this study is to develop a more appropriate shielding calculation method for computed tomography (CT) in comparison with the Japanese conventional (JC) method and the National Council on Radiation Protection and Measurements (NCRP)-dose length product (DLP) method. Scattered dose distributions were measured in a CT room with 18 scanners (16 scanners in the case of the JC method) for one week during routine clinical use. The radiation doses were calculated for the same period using the JC and NCRP-DLP methods. The mean (NCRP-DLP-calculated dose)/(measured dose) ratios in each direction ranged from 1.7 ± 0.6 to 55 ± 24 (mean ± standard deviation). The NCRP-DLP method underestimated the dose at 3.4% in fewer shielding directions without the gantry and a subject, and the minimum (NCRP-DLP-calculated dose)/(measured dose) ratio was 0.6. The reduction factors were 0.036 ± 0.014 and 0.24 ± 0.061 for the gantry and couch directions, respectively. The (JC-calculated dose)/(measured dose) ratios ranged from 11 ± 8.7 to 404 ± 340. The air kerma scatter factor κ is expected to be twice as high as that calculated with the NCRP-DLP method and the reduction factors are expected to be 0.1 and 0.4 for the gantry and couch directions, respectively. We, therefore, propose a more appropriate method, the Japanese-DLP method, which resolves the issues of possible underestimation of the scattered radiation and overestimation of the reduction factors in the gantry and couch directions.

We analyzed the abdominal image quality demanded by Image Gently 2014, and we were able to adapt the results to the Japanese population and present them as our own Image Gently Japan recommendations. If the results of the present study become a foundation for scanning parameters for Japanese patients, we believe that they will eventually lead to a reduction in medical radiation exposure for this patient population.

In this study, scaled scan band was developed to provide size-specific dose estimation (SSDE) values based on head circumference of patients undergoing computed tomography (CT) scans. The scan band was tested in 40 consecutive head CT examinations. The accuracy of the specialized scan band method was determined by comparing SSDEband with SSDE293,forehead, SSDEmean and SSDEcenter. SSDE293,forehead was used as the control value. The results of the linear fit of SSDEband, SSDEmean and SSDEcenter against SSDE293, forehead, were R2 = 0.958, R2 = 0.984 and R2 = 0.936, respectively. There was no significant difference between SSDEband, SSDEmean and SSDEcenter for SSDE293,forehead. Use of the proposed scan band method makes it possible to accurately determine the required radiation dose before a CT examination is performed.

We aimed to develop a software for facilitating absorbed dose per pixel (pixel dose) calculation using a size-specific dose estimate (SSDE). We calculated the pixel dose at nine equal points inserted into the radiophotoluminescence glass dosimeter (RPLD) and compared the pixel dose with the measured doses using RPLD. With this method, the relative errors of average pixel dose was -0.1% for adults and 2.86, 3.36 and 1.17% for those aged 10, 5 and 1 years without tube current modulation, respectively. In contrast, the relative error of SSDE was 17.37% for adults and 20.38, 20.73 and 19.20% for those aged 10, 5 and 1 years, respectively. In other words, the pixel dose was almost equal to the measured doses. Therefore, our software can be useful for determining arbitrary point.