Challenge to tumor pathology by particle beams – biological washout study using in-beam PET

2023 Fiscal Year Final Research Report

• Project/Area Number: 21K07608
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Review Section: Basic Section 52040:Radiological sciences-related
• Research Institution: National Institutes for Quantum Science and Technology (2022-2023); Tokyo Women's Medical University (2021)
• Principal Investigator: Chie Toramatsu 国立研究開発法人量子科学技術研究開発機構, 量子医科学研究所 先進核医学基盤研究部, 主幹研究員 (90421825)
• Project Period (FY): 2021-04-01 – 2024-03-31
• Keywords: 粒子線治療 / PET / 核医学 / 動態解析 / バイオマーカ

Outline of Final Research Achievements

During particle beam therapy, positron-emitting nuclides generated in the body by the nuclear fragmentation reaction of the treatment beam are mainly metabolized by the bloodstream, and the rate at which they are washed out is considered to indicate the hemodynamics of the tumor. Since the response of tumor tissue to radiation therapy is reflected in changes in blood perfusion, oxygen status, and hemodynamics, we hypothesized that the washout rate itself would be a biomarker of tumor hemodynamics, and verified this through animal experiments. As a result of conducting heavy ion beam irradiation experiments on rat tumor models, it was found that the distribution of biological washout rate could be determined depending on the vascular dynamics within the tumor. It has been suggested that PET monitoring of heavy ion radiotherapy makes it possible to determine the pathological state of tumors and treatment effects.

Free Research Field

医学物理学

Academic Significance and Societal Importance of the Research Achievements

放射線治療における腫瘍組織の反応は、血液灌流や酸素状態つまり、血行動態の変化として反映されるため、治療効果の判定にはMRIやCTによる血管造影や腫瘍内の血行動態の診断が行われる 。一方、PETは粒子線治療の飛程検証法として注目されてきた。粒子線が引き起こす原子核破砕反応により、体内で発生する陽電子放出核種を可視化する原理である。
本研究成果により、生成陽電子放出核種の代謝速度は腫瘍の血行動態を示していることが示された。飛程検証のPET撮像により副次的に腫瘍血行状態も分かるようになれば、治療期間中の腫瘍病理状態をその場で検査することができ、造影剤などを用いる検査を省略できるようになるであろう。