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在用于放射治疗的光子计数CBCT中对散射诱导的光谱污染进行实验性表征和减轻

Ryan Sabounchi¹, Uttam Pyakurel¹, Abhinya Shukla^1,2

¹Department of Radiation Oncology, University of Colorado School of Medicine, Aurora, Colorado, USA.

Medical physics

|March 15, 2026

概括

放射治疗的光谱圆束计算机断层扫描 (CBCT) 中的光子计数探测器 (PCD) 受到X射线散射的影响,这会偏向能量光谱并降低CT数量,特别是在较低的能量下. 一个2D反散射网格 (ASG) 有效地减轻了散射,提高了pcCBCT的数据保真度.

科学领域:

医学物理医学物理
放射治疗技术放射治疗技术
影像科学影像科学

背景情况:

光子计数探测器 (PCD) 在放射治疗中为光谱圆束计算断层扫描 (CBCT) 提供了潜在的可能性,提高了可视化和精度.
反映X射线衰减的定量原始数据对于基于PCD的光谱成像和材料分解至关重要.

研究的目的:

在CBCT中实验性地描述PCD计数和能量光谱上的散射效应.
研究一种基于硬件的方法,以减轻光子计数CBCT (pcCBCT) 中的散射污染.

主要方法:

将PCD (CdTe传感器) 集成到模拟CBCT几何的X射线系统中.
量化散射污染,散射与初级比率 (SPR) 和使用幻影和光束停止方法的光谱偏差.
使用二维反散射网格 (ASG) 评估散射缓解,并评估其对CT数值准确性的影响.

主要成果:

散射使低能计数 (25-50 keV) 增加了高达 96% ,并将光谱的平均能量降低了 8 keV .
在较低的能量 (在25-60 keV范围内高达4) 时,SPR显著更高.
二维ASG将SPR减少了90-94%,CT数量损失从>390 HU降至<34 HU.

结论:

散射显著偏向CBCT中较低能量的能量光谱,降低CT数量并挑战定量低能光谱成像.
分散诱导的脉冲堆积对计数低估的影响很小 (<3%).
2D ASG有效地减少了整个能源频谱的散射污染,提高了pcCBCT的原始数据准确性.

关键词:

在CBCT中,CBCT是CBCT.IGRTT 在线观看光子计数计数的光子计数

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