Quantification of radiation exposure through low-energy X-ray irradiation under contrast imaging and assessment of feasibility for novel radiotherapy approaches

2023 Fiscal Year Final Research Report

• Project/Area Number: 20K16727
• Research Category: Grant-in-Aid for Early-Career Scientists
• Allocation Type: Multi-year Fund
• Review Section: Basic Section 52040:Radiological sciences-related
• Research Institution: Hiroshima University
• Principal Investigator: Kawahara Daisuke 広島大学, 病院(医), 助教 (20630461)
• Project Period (FY): 2020-04-01 – 2024-03-31
• Keywords: 医学物理学 / 放射線治療 / 造影剤

Outline of Final Research Achievements

The aim of this study is to quantify the sensitization effect of low-energy X-rays caused by contrast agents, which have not been traditionally considered in radiation dose estimation, and to elucidate the radiation doses in low-energy X-rays under contrast enhancement. Furthermore, we aim to explore the feasibility of novel radiotherapy based on the dose enhancement effect when contrast agents are present in tumors.

We quantified the radiation dose increase due to contrast agent use in radiodiagnosis, finding a dose increase of over 20% even at low concentrations, and constructed dose increase coefficient models for various contrast agent concentrations. Additionally, we successfully proposed a novel treatment called LiPERT for increasing radiation doses when high concentrations of contrast agents are present. We are proceeding with efforts to generalize the findings of this study and promote their dissemination as part of treatment planning systems for high-precision radiotherapy.

Free Research Field

医学物理学

Academic Significance and Societal Importance of the Research Achievements

本研究はCT撮影における被ばく線量の概念を変えるもので、従来考慮されていなかった造影剤による低エネルギーX線の増感効果を定量化し、また被ばく線量増加係数としてモデル化したため一般化して従来の被ばく線量計算、測定と併用して使用が可能である。これにより、患者の被ばく線量をより正確に把握できリスクも明確になる。
また、増感効果を利用した新規治療法としてLiPERTを提案した。これは従来のような大型の放射線治療装置（リニアック）ではなく、多くの病院にあるCT装置を想定した新規治療法となる。従来の放射線治療法に比べて同等以上の治療効果も期待できることから新規放射線治療法として活用できる可能性をもっている。