Standardization of high precision high dose rate interstitial brachytherapy for oral cancer

2021 Fiscal Year Final Research Report

• Project/Area Number: 19K10289
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Review Section: Basic Section 57060:Surgical dentistry-related
• Research Institution: Hiroshima University
• Principal Investigator: Kakimoto Naoya 広島大学, 医系科学研究科(歯), 教授 (50324794)
• Co-Investigator(Kenkyū-buntansha): Verdonschot RG 広島大学, 医系科学研究科(歯), 助教 (30756094) ; 中元 崇 広島大学, 医系科学研究科(歯), 准教授 (60403630) ; 小西 勝 広島大学, 病院(歯), 講師 (60537447)
• Project Period (FY): 2019-04-01 – 2022-03-31
• Keywords: 口腔癌 / 高線量率組織内照射 / 高精度 / 規格化

Outline of Final Research Achievements

The purpose of this study was to quantify and standardize applicators’ position and dose distribution in high-dose-rate interstitial brachytherapy (HDR-ISBT) for oral cancer patients. Seven patients and 53 flexible tubes that were treated by HDR-ISBT were examined. Prescribed doses were GTV=CTV=PTV=100%, and dose distribution maps were prepared so that V200% was less than 20% of GTV volume. The displacement of the flexible tube position by cross-sectional image comparison based on anatomical landmarks was 1.8 ± 1.3 mm, and the displacement based on the flexible tubes’ comparison was 2.1 ± 1.9 mm, respectively. There was no statistically significant difference between them. Since the flexible tubes are displaced during treatment, to know the amount of change can be used as a reference for treatment planning of HDR-ISBT for oral cancer patients.

Free Research Field

歯科放射線学

Academic Significance and Societal Importance of the Research Achievements

口腔癌に対する高線量率組織内照射において、アプリケーター位置および線量分布の数値化を行い、定量的に検討した結果、フレキシブルチューブの位置は1日目と3日目で1.8㎜または2.1㎜の変位量があることが示された。これらの変位量は線量に換算すると6～8%の誤差を生じるため、事前にこれらの誤差を勘案した線量分布図の作成が必要となる。また、より正確な線量処方を行うためには適応放射線治療（Adoptive radiotherapy）を行う必要があると思われれた。