在0.35 T MRgRT上实时电影MRI成像扭曲的特征与同心电影成像QA幻影
Shanti Marasini1, Mike Cole2, Austen Curcuru1
1Departments of Radiation Oncology, Washington University School of Medicine, St. Louis, MO,United States of America.
Physics in medicine and biology
|February 26, 2024
概括
实时MRI指导放射治疗 (MRgRT) 影像成像显示在0.35 T MR-Linac上的门架旋转期间显著的几何扭曲和同心位移. 这项质量保证幻影研究凸显了MR引导弧形治疗中需要提高空间精度的需要.
科学领域:
- 医学物理 医学物理
- 放射治疗技术 放射治疗技术
- 图像分析 图像分析
背景情况:
- 实时MRI指导放射疗法 (MRgRT) 使用2D-cine成像用于治疗期间精确的目标跟踪和运动评估.
- 在MR-Linac系统中,格兰特旋转可以诱导B0外共振,导致图像工件和同心位移,从而损害了MR导向弧线疗法.
- 现有的MRI幻影通常是为高分辨率成像而设计的,这对于对高率至关重要的低分辨率电影成像的评估构成了挑战.
研究的目的:
- 为了评估空间准确性,特别是几何扭曲和同心位移,在0.35 T MR-Linac.在实时门架旋转期间.
- 评估一个同心的电影成像质量保证 (QA) 幻影及其实时电影MRI分析软件的性能.
- 为了研究道旋转对MR指导放射治疗中的图像质量和空间完整性的影响.
主要方法:
- 一个同心的Cine成像QA幻影,采用矿物油和中央对齐结构,使用2D平衡稳定状态自由前行 (bSSFP) cine成像进行扫描.
- 在0.55 T,1.5 T MRI系统和0.35 T ViewRay MRIdian MR-Linac上进行了扫描,MR-Linac门架既静止又旋转 (300°→0°和0°→300°).
- 图像分析软件量化了每个电影的几何扭曲和同心位置,在MR-Linac上测试了B0补偿.
主要成果:
- 静止门架MRI和MR-Linac上的几何扭曲在1mm以内.
- 在0.35 T MR-Linac上,分别在顺时针和反时针旋转时观察到大量的几何扭曲 (2 mm 和 2.2 mm).
- 图像成像等心位移在轮过程中≤1.5mm,在B0补偿下减少1±0.2mm;静态系统的平均移动为0.1mm.
结论:
- 电影成像QA幻影有效地检测到MRI和MR-Linacs上的实时电影成像扭曲.
- 在0.35 T MR-Linac上,在门架旋转过程中发生了显著的几何扭曲,影响了空间准确性.
- 需要进一步的研究,以减轻动态门架旋转期间的图像扭曲,以改进MR引导弧线治疗.
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