Spectral distortion correction for a photon-counting CT system

2022 Fiscal Year Final Research Report

• Project/Area Number: 20K20232
• Research Category: Grant-in-Aid for Early-Career Scientists
• Allocation Type: Multi-year Fund
• Review Section: Basic Section 90130:Medical systems-related
• Research Institution: National Astronomical Observatory of Japan
• Principal Investigator: Murata Kazumi 国立天文台, ハワイ観測所, 特任研究員 (90770040)
• Project Period (FY): 2020-04-01 – 2023-03-31
• Keywords: フォトンカウンティングCT / スペクトル歪み補正 / 圧縮センシング / 媒質分離

Outline of Final Research Achievements

In this study, we conducted research on the spectral distortion, which is the biggest challenge in spectral CT, a next-generation X-ray CT technology. The greatest advantage of spectral CT is the ability to acquire spectral information and perform material decomposition, which leads new application fields. However, the accuracy of material decomposition is significantly degraded when the spectrum is distorted, particularly due to a phenomenon called pulse pile-up effect. We developed a technique to accurately correct the distortion by applying methods such as "total variation regularization" and "low-rank approximation by tensor decomposition."

Free Research Field

天文学，画像工学

Academic Significance and Societal Importance of the Research Achievements

スペクトルCTの最大の利点は、スペクトルを取得し、媒質分離を行うことである. 媒質分離を行うことで、被写体の断層画像を媒質ごとに取得でき、複数の造影剤を同時に使用可能にするなど、従来のCTでは不可能であった幅広い応用が期待されている. しかし、特にパルス・パイルアップ効果と呼ばれる現象によりスペクトルが歪められてしまうと、媒質分離の精度は著しく劣化してしまう. そのため、高精度で歪みを補正する技術を開発することで，X線CTの応用可能性を大きく広げることになる.