SIZE-SPECIFIC DOSE ESTIMATES IN FETAL COMPUTED TOMOGRAPHY

2021 Fiscal Year Final Research Report

• Project/Area Number: 19K17152
• Research Category: Grant-in-Aid for Early-Career Scientists
• Allocation Type: Multi-year Fund
• Review Section: Basic Section 52040:Radiological sciences-related
• Research Institution: Fujita Health University
• Principal Investigator: Kobayashi Masanao 藤田医科大学, 保健学研究科, 准教授 (80720979)
• Project Period (FY): 2019-04-01 – 2022-03-31
• Keywords: CT / 被ばく / 放射線

Outline of Final Research Achievements

During fetal computed tomography (CT) imaging, because of differences in the pregnancy period and scanning conditions, different doses of radiation are absorbed by the fetus. We propose a correction coefficient for determining the fetal size-specific dose estimate (SSDE) from the CT dose index (CTDI) displayed on the console at tube voltages of 80,100,120,135 kVp. The CTDIs corresponding to pregnant women and fetuses were evaluated using a Monte Carlo (MC) simulation, and the ratio of these CTDIs was defined as the Fetus-factor. When the effective diameter of a fetus was approximately 10 cm, the Fetus-factor was 1.0. The estimated pregnant SSDE was multiplied by the Fetus-factor to estimate the fetal SSDE, which was compared with the fetal dose obtained by the MC simulation of the image of the fetal CT examination. The fetal dose could be estimated with an error of 31.5% in fetal examinations conducted using helical CT.

Free Research Field

radiation protection

Academic Significance and Societal Importance of the Research Achievements

胎児CT検査の実施には2人の個人を考慮しなければなりません．母体となる妊婦に対しては，本人に直接的な利益なく放射線を受けることになりますが被ばく線量を評価する方法は確立しています．一方，胎児に対しては，診断目的で放射線を受けることになりますが，その被ばく線量を評価する方法は確立していませ
ん．将来的な放射線障害を危惧する両親の不安を解消するためにも胎児の被ばく線量を評価する方法を新しく確立しました。