2020 Fiscal Year Final Research Report
Establishment of coronary artery calcium scoring in low-dose CT using model-based iterative reconstruction
| Project/Area Number |
16K10279
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Multi-year Fund |
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| Section | 一般 |
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| Research Field |
Radiation science
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| Research Institution | Hiroshima University |
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Principal Investigator |
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| Co-Investigator(Kenkyū-buntansha) |
粟井 和夫 広島大学, 医系科学研究科(医), 教授 (30294573)
檜垣 徹 広島大学, 医系科学研究科(医), 共同研究講座准教授 (80611334)
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| Project Period (FY) |
2016-04-01 – 2021-03-31
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| Keywords | 冠動脈石灰化 / 逐次近似再構成法 / CT |
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| Outline of Final Research Achievements |
We investigated the accuracy of volume measurement for coronary artery calcium using various image reconstruction methods. A phantom containing simulated calcification with various size and density were scanned with 320 slice CT and high-resolution CT. Images were generated with thin-slice thickness (0.5mm) and reconstructed with filtered back projection (FBP), hybrid iterative reconstruction (hybrid IR), and model-based IR (MBIR). MBIR had the highest accuracy of calcium volume measurement. For calcium of 3 mm or more, it was considered possible to reduce the radiation dose by 67-84% by using MBIR. However, the accurate assessments of small calcifications (1-2 mm or less) or calcifications in low density (200 HU or less) were difficult even with the use of MBIR. Also, the error rate became larger with a lower radiation dose. Therefore, it was difficult to reduce radiation exposure in clinical practice, and we could not establish a calcium score using low-dose CT.
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| Free Research Field |
放射線診断学
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| Academic Significance and Societal Importance of the Research Achievements |
冠動脈石灰化スコアは通常3mm厚の画像を用いて定量評価を行うため、それ以下の小さな石灰化は背景組織と平均化され検出困難となる。今回は、0.5mm厚の薄い画像を作成し、小さな石灰化を正確に定量できるかを検討したが、1-2mm程度の石灰化や200HU以下の石灰化は、逐次近似画像再構成法を用いても真値との間に大きな誤差が生じた。また線量低減によりその差はさらに増大した。今後、薄い厚さの画像を用いて石灰化の有無を確認することは重要ではあるが、現状のCT装置の空間分解能では被ばく低減にはリスクがあると考えられる。低線量撮影を実現するには、新たな画像再構成法やCT装置のさらなる発展が必要と考えられた。
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