磁场对平行MR-lincs小场剂量计的影响
1Department of Medical Physics, School of Medicine and Public Health, University of Wisconsin-Madison, Madison, Wisconsin, USA.
Medical physics
|August 14, 2025
概括
在MR指导放射治疗 (MRgRT) 中,磁场对在水中的剂量测量影响最小,高达1.0 T. 然而,更高的磁场在肺幻影瘤中显著改变了输出因子和剂量分布,需要仔细规划治疗.
科学领域:
- 医学物理 医学物理
- 辐射瘤学 辐射瘤学
- 磁共振成像技术 磁共振成像技术
背景情况:
- 磁共振导向辐射疗法 (MRgRT) 的日益广泛使用,需要了解小型模块化治疗场的剂量计.
- 关于磁场对平行MR-linacs小场剂量计的影响的数据有限.
研究的目的:
- 为了研究磁场对平行MR-linacs小场剂量学的影响.
- 用蒙特卡洛模拟来量化水和肺幽灵中的剂量干扰.
主要方法:
- 一个TOPAS蒙特卡洛模型的6 MV FFF光束被开发和验证.
- 模拟评估了磁场效应 (高达3.0 T) 对水幻影中的百分比深度剂量,束形状和输出因子.
- 模拟瘤的肺幻体中的剂量分布被分析为弧交付.
主要成果:
- 到1.0 T的平行磁场对水中剂量测量 (PDD,配置文件) 产生了微不足道的影响.
- 小田地 (<2x2cm2) 的产量因子在1.5T和3.0T时显著增加 (高达9%).
- 与0T相比,肺幻影中的剂量分布呈现出3-8%的差异,瘤覆盖范围更加均,在更高的领域减少半阴影.
结论:
- 直至1.0 T的平行磁场对水中小场剂量测量的影响最小.
- 肺瘤周围的输出因子和剂量差异显著增加,需要在治疗计划中考虑更高的磁场 (≥1.5 T).
- 在较高磁场的电子聚焦效应影响剂量分配,特别是对于较小的瘤.
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