Development of disposable dosimeter for in-vivo measurement of organ at risk during radiation therapy

• Project/Area Number: 19K08223
• 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: Kanazawa University
• Principal Investigator: Hayashi Hiroaki 金沢大学, 保健学系, 准教授 (30422794)
• Co-Investigator(Kenkyū-buntansha): 金澤 裕樹 徳島大学, 大学院医歯薬学研究部(医学域), 助教 (80714013) ; 生島 仁史 徳島大学, 大学院医歯薬学研究部(医学域), 教授 (90202861)
• Project Period (FY): 2019-04-01 – 2022-03-31
• Project Status: Completed (Fiscal Year 2021)
• Budget Amount: ¥4,290,000 (Direct Cost: ¥3,300,000、Indirect Cost: ¥990,000); Fiscal Year 2021: ¥520,000 (Direct Cost: ¥400,000、Indirect Cost: ¥120,000); Fiscal Year 2020: ¥780,000 (Direct Cost: ¥600,000、Indirect Cost: ¥180,000); Fiscal Year 2019: ¥2,990,000 (Direct Cost: ¥2,300,000、Indirect Cost: ¥690,000)
• Keywords: 医学物理学 / 放射線線量計 / 子宮頸癌治療 / 密封小線源治療 / 放射線治療 / 精度検証 / インビボ測定 / 直腸線量 / OSL線量計 / 子宮頸がん治療 / 被曝線量 / リスク臓器 / 放射線計測

Outline of Research at the Start

本研究の目的は，放射線治療の中でも副作用が多くリスク臓器として管理が難しい直腸線量に着目し，カテーテルに光刺激ルミネッセンス(ＯＳＬ)シートを装着した安価な使い捨て(ディスポーザブル)型の直腸線量計を開発することである．本研究では，方法論を実証するため密封小線源を用いた子宮癌の治療に着目する．放射線治療における臓器の線量管理は，現状では治療前に撮られたコンピュータ断層撮影像(CT画像)を前提とした計算値が使用されており，実測される例はほとんどない．本研究によって，直腸線量を実測できることが立証されれば，放射線治療のトレンドの一つの解決策を提示することができ，学問や社会への貢献度が高い．

Outline of Final Research Achievements

Radiation therapy using 192Ir is used for the treatment of cervical cancer. Since the rectum, which is one of the radiation-sensitive organs, is an organ at risk in this treatment, it is required to control the dose precisely. In this study, we aimed to develop a new rectum dosimeter using an optically stimulated luminescence (OSL) dosimeter and actually measuring the dose during clinical treatment to obtain knowledge about the development of a novel radiation dosimeter and the accuracy of delivered doses during clinical treatment. The hand-made rectum dosimeter was very small and inexpensive, therefore it is suitable for disposable use and is hygienic. For the results obtained in clinical studies, although we experienced a few cases in which differences between the planned and the measured doses become 10% or more, we could analyze the causes.

Academic Significance and Societal Importance of the Research Achievements

放射線治療時の投与線量は数％の誤差範囲内で決定できていると言われているが，この値は人体模型などを用いて測定した静的な条件下での評価であり，一般的には患者さんに起因する誤差を含んでいない．本研究で行った実測では，患者さんの状態や治療計画に用いるX線画像の質によって，実際の投与線量と計画線量の間に10％を超える差異が生じる可能性があることを明らかにした．この事実は，放射線治療の安全性や危険性を示すものではなく，あくまでも実臨床において，患者さんに起因する誤差要因が入り込む可能性を明示し，またこのような差異を開発した放射線線量計によって検出することができたことは学術的に大変重要である．

Research Products

• [Journal Article] A disposable OSL dosimeter for in‐vivo measurement of rectum dose during brachytherapy (2021)
  • Author(s): Hayashi Hiroaki、Kimoto Natsumi、Maeda Tatsuya、Tomita Emi、Asahara Takashi、Goto Sota、Kanazawa Yuki、Shitakubo Yasufumi、Sakuragawa Kanako、Ikushima Hitoshi、Okazaki Tohru、Hashizume Takuya
  • Journal Title: Medical Physics Volume: - Issue: 8 Pages: 4621-4635
  • DOI: 10.1002/mp.14857
  • Peer Reviewed
• [Journal Article] Direct radiation dose measurement of rectum during High-Dose-Rate 192Ir brachytherapy for cervical cancer treatment (2019)
  • Author(s): Takashi Asahara, Hiroaki Hayashi, Emi Tomita, Kanako Sakuragawa, Hiroshi Saegusa, Yasufumi Shitakubo, Hitoshi Ikushima, Yuki Kanazawa, Yoshiki Mihara, Yoshinori Miyahara, Tohru Okazaki, Takuya Hashizume and Vergil LE Cruz
  • Journal Title: Progress in Nuclear Science and Technology Volume: 6 Issue: 0 Pages: 39-42
  • DOI: 10.15669/pnst.6.39
  • ISSN: 2185-4823
  • Year and Date: 2019-01-31
  • Peer Reviewed
• [Journal Article] Energy and angular dependence of the small-type OSL dosimeter in nuclear medicine regions using Monte Carlo simulation (2019)
  • Author(s): Vergil Lorenzo E. Cruz, Tohru Okazaki, Hiroaki Hayashi, Yoshiki Mihara, Takashi Asahara, Natsumi Kimoto, Hiroki Okino, Yuki Kanazawa, Takuya Hashizume, Ikuo Kobayashi
  • Journal Title: Progress in Nuclear Science and Technology Volume: 6 Issue: 0 Pages: 34-38
  • DOI: 10.15669/pnst.6.34
  • ISSN: 2185-4823
  • Year and Date: 2019-01-31
  • Peer Reviewed
• [Journal Article] Applicability of a practical calibration for the small-type OSL dosimeter for measuring doses from direct X-rays and penetrating X-rays affected by scattered radiation (2019)
  • Author(s): Tohru Okazaki, Hiroaki Hayashi, Yoshiki Mihara, Takashi Asahara, Natsumi Kimoto, Yuki Kanazawa, Kosaku Higashino, Kazuta Yamashita, Sumi Yokoyama, Kazuki Takegami, Takuya Hashizume, Vergil LE Cruz and Ikuo Kobayashi
  • Journal Title: Progress in Nuclear Science and Technology Volume: 6 Issue: 0 Pages: 22-25
  • DOI: 10.15669/pnst.6.22
  • ISSN: 2185-4823
  • Year and Date: 2019-01-31
  • Peer Reviewed
• [Presentation] OSL 線量計を用いた 直腸線量計 の開発とHDR RALSによる子宮頸癌治療におけるin vivo線量測定 (2022)
  • Author(s): 林 裕晃
  • Organizer: 医学物理士会主催の医学物理士セミナー
  • Invited
• [Presentation] ディスポ型自作直腸線量計を用いた子宮頸がん治療における線量の実測 (2021)
  • Author(s): 林 裕晃，前田達哉，淺原 孝，後藤聡汰，竹上和希，李 青海，安藤未来, 金澤裕樹, 生島仁史, 岡崎 徹, 橋詰拓弥
  • Organizer: 第3回日本放射線安全管理学会・日本保健物理学会合同大会
• [Presentation] Dose calibration factor of an OSL dosimeter during CT examination to measure exposure dose of patients taking into consideration proper X-ray quality (2020)
  • Author(s): Kazuki Takegami, Hiroaki Hayashi, Takashi Asahara, Sota Goto, Emi Tomita, Natsumi Kimoto, Yuki Kanazawa, Shohei Kudomi
  • Organizer: ECR2020
  • Int'l Joint Research
• [Presentation] Development of a Clinically Applicable Rectum Dosimeter for Brachytherapy using an Optically Stimulated Luminescence Dosimeter (2019)
  • Author(s): Emi Tomita, Hiroaki Hayashi, Takashi Asahara, Natsumi Kimoto, Sota Goto, Yuki Kanazawa, Yasufumi Shitakubo, Kanako Sakuragawa, Hitoshi Ikushima, Tohru Okazaki, Takuya Hashizume
  • Organizer: 19th International Conference on Solid State Dosimetry (SSD19)
  • Int'l Joint Research
• [Presentation] Novel Disk-Shaped OSL Dosimeter Having Smaller Angular Dependence (2019)
  • Author(s): Sota GOTO, Hiroaki HAYASHI, Emi TOMITA, Takashi ASAHARA, Natsumi KIMOTO, Yuki KANAZAWA, Hidetoshi YAMAGUCHI, Morihito SHIMIZU
  • Organizer: 19th International Conference on Solid State Dosimetry (SSD19)
  • Int'l Joint Research
• [Presentation] Precise dose calibration method of OSL dosimeter with help of X-ray spectra toward exposure dose evaluation of eye lens (2019)
  • Author(s): Takashi Asahara, Hiroaki Hayashi, Sota Goto, Emi Tomita, Natsumi Kimoto, Takumi Asakawa, Kazuki Takegami, Yuki Kanazawa, Tohru Okazaki, Takuya Hashizume
  • Organizer: 19th International Conference on Solid State Dosimetry (SSD19)
  • Int'l Joint Research
• [Remarks] 金沢大学医薬保健研究域保健学系 林研究室HP
  • URL: http://hayashi.w3.kanazawa-u.ac.jp/index.html
• [Remarks] 金沢大学医薬保健研究域保健学系(林研究室)内の研究成果紹介ページ
  • URL: http://hayashi.w3.kanazawa-u.ac.jp/index_02.html