Development of real time monitoring system of radiotherapy accuracy by Cherenkov emission

• Project/Area Number: 18K15613
• Research Category: Grant-in-Aid for Early-Career Scientists
• Allocation Type: Multi-year Fund
• Review Section: Basic Section 52040:Radiological sciences-related
• Research Institution: National Cancer Center Japan
• Principal Investigator: Okamoto Hiroyuki 国立研究開発法人国立がん研究センター, 中央病院, 医学物理士 (90595729)
• Project Period (FY): 2018-04-01 – 2022-03-31
• Project Status: Completed (Fiscal Year 2021)
• Budget Amount: ¥4,030,000 (Direct Cost: ¥3,100,000、Indirect Cost: ¥930,000); Fiscal Year 2021: ¥260,000 (Direct Cost: ¥200,000、Indirect Cost: ¥60,000); Fiscal Year 2020: ¥130,000 (Direct Cost: ¥100,000、Indirect Cost: ¥30,000); Fiscal Year 2019: ¥1,690,000 (Direct Cost: ¥1,300,000、Indirect Cost: ¥390,000); Fiscal Year 2018: ¥1,950,000 (Direct Cost: ¥1,500,000、Indirect Cost: ¥450,000)
• Keywords: 放射線治療 / 品質管理 / チェレンコフ光 / フィルム / ノイズ / シンチレータ / 小線源治療

Outline of Final Research Achievements

In this study, we developed a real tie monitoring system to evaluate radiotherapy accuracy using Cherenkov emission generated by irradiation. The Cherenkov emission detector is a C-dose camera (OptiDose, Inc.), which equips a scintillator built into the camera to detect scattered radiation and images with a high signal-to-noise ratio as a trigger signal can be obtained. By using this method, Cherenkov emission could be observed even in relatively bright treatment rooms. Comparison with conventional radiation detector, radiochromic film was also performed, and the intensity distribution was almost similar to that of the film. The linearity with the irradiation MU was confirmed, and it was demonstrated that it is possible to perform dosimetric assessment.

Academic Significance and Societal Importance of the Research Achievements

従来では放射線照射中の体表面の線量を計測する場合には皮膚表面に放射線に感度を持つフィルムや熱ルミネッセンス線量計，ガラス線量計などを貼付する必要があるが，照射中のチェレンコフ光を観測することにより非侵襲的に表面線量を評価することが可能となった．この方法が確立すれば，患者の負担，線量計読み出しのための後処理作業を減らすことができる．品質管理ツールにおいては，従来フィルムで照射位置を評価していたが，チェレンコフ光を用いることで照射位置のみならず線量情報，放射線のエネルギーも評価できる．またすべて画像処理で結果を解析するため，フィルムなどの消耗品も減らすことができる．

Research Products

• [Journal Article] Technical note: Analysis of brachytherapy source movement by high-speed camera (2022)
  • Author(s): Hiroyuki Okamoto, Kotaro Iijima, Takahito Chiba, et al.,
  • Journal Title: Medical Physics Volume: 1 Issue: 7 Pages: 1-8
  • DOI: 10.1002/mp.15601
  • Peer Reviewed
• [Journal Article] Dummy-run for standardizing plan quality of intensity-modulated radiotherapy for postoperative uterine cervical cancer: Japan Clinical Oncology Group study (JCOG1402). (2019)
  • Author(s): Okamoto H, Murakami N, Isohashi F, Kasamatsu T, Hasumi Y, Iijima K, Nishioka S, Nakamura S, Nakamura M, Nishio T, Igaki H, Nakayama Y, Itami J, Ishikura S, Nishimura Y, Toita T.
  • Journal Title: Radiat Oncol. Volume: 14 Issue: 1 Pages: 133-133
  • DOI: 10.1186/s13014-019-1340-y
  • Peer Reviewed / Open Access
• [Journal Article] Monte Carlo modeling of a 60Co MRI-guided radiotherapy system on Geant4 and experimental verification of dose calculation under a magnetic field of 0.35 T. (2019)
  • Author(s): Okamoto H, Nishioka S, Iijima K, Nakamura S, Sakasai T, Miura Y, Takemori M, Nakayama H, Morishita Y, Shimizu M, Abe Y, Igaki H, Nakayama Y, and Itami J.
  • Journal Title: Journal of Radiation Research Volume: 60(1) Issue: 1 Pages: 116-123
  • DOI: 10.1093/jrr/rry087
  • Peer Reviewed / Open Access / Int'l Joint Research
• [Presentation] ハイスピードカメラを用いた線源駆動情報からのTransit doseの評価 (2021)
  • Author(s): 岡本裕之，飯島康太郎，中村哲志，他
  • Organizer: 小線源治療部会 第23回学術大会
• [Presentation] チェレンコフ光を用いた新たな品質管理への期待 (2019)
  • Author(s): 岡本裕之
  • Organizer: 第５６回 臨床医学物理研究会