Development of positioning system by dose distribution

• Project/Area Number: 15K19200
• Research Category: Grant-in-Aid for Young Scientists (B)
• Allocation Type: Multi-year Fund
• Research Field: Medical Physics and Radiological Technology
• Research Institution: Gunma University
• Principal Investigator: Kawashima Motohiro 群馬大学, 大学院医学系研究科, 助教 (50638989)
• Project Period (FY): 2015-04-01 – 2019-03-31
• Project Status: Completed (Fiscal Year 2018)
• Budget Amount: ¥3,380,000 (Direct Cost: ¥2,600,000、Indirect Cost: ¥780,000); Fiscal Year 2017: ¥1,300,000 (Direct Cost: ¥1,000,000、Indirect Cost: ¥300,000); Fiscal Year 2016: ¥1,430,000 (Direct Cost: ¥1,100,000、Indirect Cost: ¥330,000); Fiscal Year 2015: ¥650,000 (Direct Cost: ¥500,000、Indirect Cost: ¥150,000)
• Keywords: 放射線治療 / 水等価深 / IGRT / 計算精度 / 線量分布 / 画像誘導放射線治療 / 線量分布変形 / 水透過厚 / CT画像 / 水透過深 / 線量計算 / 位置決め / 計算誤差 / 計算速度

Outline of Final Research Achievements

We confirmed influence of the calculation grid size, it was found that the effect of the calculation grid size on the dose distribution for rotating radiation is small. In the case of rotating irradiation, it is required to shorten the time because it becomes irradiation of a large number of fields. However, it was found that the effect would not be much if the calculation grid was 3 mm.

We created software to convert the dose distribution by water equivalent depth. It was confirmed that the dose distribution calculated by this software and the treatment planning device did not significantly difference. The dose distribution is converted by CT images for each treatment of actual clinical data. We are collecting data to decide the optimal margin for coverage of target and normal organ dose.

Academic Significance and Societal Importance of the Research Achievements

放射線治療では標的を照射するために日々の臓器の動きや変化、また、体形の変化などを考慮してマージンを設けて計画的照射体積を決定している。但し、マージンを設ける事で照射体積は大きくなり、正常臓器も照射する事となる。
標的の動きを考慮してマージンを設ける事で、標的をしっかりと照射する事はできる。しかし、標的がずれ込んだ部分に正常臓器が入ってくることとなる。そこで、本研究の目的として、標的の変形のみのマージンで照射体積が済むように、線量分布で位置決めをはかる手法を確立する。
それによって、照射体積の縮小をはかり正常臓器の線量を低減する事により、より高精度な治療を可能とする。

Research Products

• [Journal Article] Dose Distribution Optimization in Combined Intracavitary and Interstitial Brachytherapy for Cervical Cancer (2018)
  • Author(s): 尾崎 大輔、宮澤 真、幅野 陽二、川嶋 基敬、星野 佳彦、須藤 高行
  • Journal Title: Japanese Journal of Radiological Technology Volume: 74 Issue: 4 Pages: 354-361
  • DOI: 10.6009/jjrt.2018_JSRT_74.4.354
  • NAID: 130006712087
  • ISSN: 0369-4305, 1881-4883
  • Peer Reviewed
• [Journal Article] The impact of the grid size on tomotherapy for prostate cancer (2017)
  • Author(s): Kawashima Motohiro、Kawamura Hidemasa、Onishi Masahiro、Takakusagi Yosuke、Okonogi Noriyuki、Okazaki Atsushi、Sekihara Tetsuo、Ando Yoshitaka、Nakano Takashi
  • Journal Title: Journal of Medical Physics Volume: 42 Issue: 3 Pages: 144-144
  • DOI: 10.4103/jmp.jmp_123_16
  • Peer Reviewed
• [Journal Article] A Clinical outcomes using carbon-ion radiotherapy and dose-volume histogram comparison between carbon-ion radiotherapy and photon therapy for T2b-4N0M0 non-small cell lung cancer-A pilot study. (2017)
  • Author(s): Shirai K, Kawashima M, Saitoh JI, Abe T, Fukata K, Shigeta Y, Irie D, Shiba S, Okano N, Ohno T, Nakano T.
  • Journal Title: PLoS One. Volume: 12 Issue: 4 Pages: e0175589-e0175589
  • DOI: 10.1371/journal.pone.0175589
  • Peer Reviewed / Open Access / Int'l Joint Research / Acknowledgement Compliant
• [Presentation] 治療時のMVCTを用いた線量分布の検証 (2016)
  • Author(s): 川嶋 基敬
  • Organizer: 日本医学物理学会
  • Place of Presentation: 沖縄コンベンションセンター
  • Year and Date: 2016-09-08
• [Presentation] The influence of grid size on dose distribution for TomoTherapy (2015)
  • Author(s): 川嶋 基敬
  • Organizer: 日本放射線腫瘍学会第28回学術大会
  • Place of Presentation: 群馬県前橋市ベイシア文化ホール
  • Year and Date: 2015-11-19