Verification of CT scan exposure since DRLs2015

2018 Fiscal Year Final Research Report

• Project/Area Number: 16K19845
• Research Category: Grant-in-Aid for Young Scientists (B)
• Allocation Type: Multi-year Fund
• Research Field: Radiation science
• Research Institution: Iwate Medical University
• Principal Investigator: Tamura Akio (赤羽明生) 岩手医科大学, 医学部, 助教 (90714444)
• Research Collaborator: Ota Yoshitaka
• Project Period (FY): 2016-04-01 – 2019-03-31
• Keywords: X線CT / 医療被ばく / DRL / ノイズ低減

Outline of Final Research Achievements

In Iwate Prefecture, 33% of all facilities have introduced iterative reconstruction into CT scanner. The DLP75 percentile at each site for a standard body type was 1254mGy・cm for an adult head, 601 mGy・cm for an adult chest, 948 mGy・cm for an adult abdomen, and 1580 mGy・cm the coronary artery. For a child’s head the percentiles were 286 mGy・cm for children younger than 12 months, 708 mGy・cm for children aged 1~5 years, and 706 mGy・cm for children aged 6~10 years. In a comparison of DRLs2015 and the results of this survey, the values in Iwate Prefecture were slightly high for the coronary artery and the chest. Phantom experiment demonstrated the feasibility of dose-reduction imaging using image-based noise reduction software as a means of achieving low-dose imaging not reliant on CT scanner and reconstruction methods.

Free Research Field

放射線医学

Academic Significance and Societal Importance of the Research Achievements

各施設のCTで低管電圧、逐次近似応用再構成法の適用が少なく、これが施設間でDLP値に差が生じた理由と考えられた。逐次近似応用再構成法の採用にはCT撮影装置の更新が必要であるため、多額の費用が生じる。撮影装置、再構成方法に依存しない低線量撮影方法の実現手法ととして、イメージベースのノイズ低減ソフトウェアによる線量低減撮影の実行可能性が示されたことは患者のみならず医療者側にとっても有益な知見と考えられる。