前立腺MR誘導型適応放射線治療の治療計画における密度のオーバーライドの用量測定の影響
Carson Matthews1, Sotirios Stathakis2, Krystal Kirby2
1Department of Physics and Astronomy, Louisiana State University, Baton Rouge, LA 70820, USA.
まとめ
この研究では,Elekta Unityシステムでの磁気共鳴 (MR) 誘導型適応放射線療法 (MRgART) 計画における大量密度オーバーライド (BDOs) が,主に直腸などの領域で,小量の測定不確実性を導入しているが,重要な QUANTEC 投与量メトリックには大きな影響を与えないことが判明した.
科学分野:
- 医学物理 医学物理学
- 放射線腫瘍学 放射線腫瘍学
- 放射線療法の技術について
背景:
- MR誘導型線形加速器 (MR-LINACs) を使った適応放射線療法 (ART) は,日々の治療適応を可能にします.
- 大量密度オーバーライド (BDOs) は,適応計画において電子密度 (ED) を近似し,CTと比較して潜在的にドシメトリックの不確実性を引き起こします.
- 正確な用量計算は,安全で効果的なMR誘導適応放射線療法 (MRgART) に不可欠です.
研究 の 目的:
- 前立腺のBDOベースの治療計画とCTベースの治療計画とのドシメトリックの違いを評価し,定量化するためにMRgART.
- モナコの治療計画システム (TPS) 内の用量体積ヒストグラム (DVH) メトリックに対するBDOの影響を評価する.
主な方法:
- 21人の前立腺VMAT患者さんの遡及的分析.
- 組織的なCT-to-ED表を使用してCT番号をEDに変換する.
- ベースラインと QUANTEC DVH メトリクスを用いて,BDO-オーバーライドされたプランと,レファレンスCTベースのプランの投与量分布の比較.
主要な成果:
- ベースラインのDVH指標 (例えば,直腸のD50%) で最大9%までの局所的な用量差異が,BDOsのために観察されました.
- QUANTECのDVH指標や前立腺への平均用量において,有意な違い (>1%) は見つかりませんでした.
- 前立腺に対する平均平均用量差は0.6%であり,他のコントールされた体積は平均用量差1.0%を超えるものではありません.
結論:
- BDOは,Elekta Unity/Monacoのワークフロー内でMRgARTに対して臨床的に有効である.
- BDOからの局所的な用量測定の不一致は,重要な QUANTEC DVH メトリックに有意な影響を与えない.
- システム固有の違いがあるため,異なるTPSプラットフォームでのさらなる評価が推奨されています.
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