Spectral CT using a fine grid structure and varying x-ray incidence angle.
Spectral CT using a fine grid structure and varying x-ray incidence angle.
复制标题
能谱 CT 使用精细网格结构和变化的 X 射线入射角。
DOI：
10.1002/mp.14853
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发表时间：
2021
期刊：
影响因子：
3.8
通讯作者：
Noël,PeterB
中科院分区：
文献类型：
--
作者：
Stayman,JWebster;Tivnan,Matthew;Wang,Wenying;Shapira,Nadav;Gang,GraceJ;Noël,PeterB
目的光谱计算机断层扫描（CT）用于诊断和治疗评估的兴趣越来越大。具有不同光谱灵敏度的数据采集提供了区分多种材料、定量密度估计和减少由于能量依赖而产生的伪影的能力。我们介绍了一种新的光谱CT概念，其中包括用于x射线光束预过滤的细间距网格结构。方法：我们建立了网格设计的物理模型，并说明了基本的工作原理，其中入射x射线的小角度导致光束的显著过滤和光谱整形。我们用钨片制作了一个原型网格。我们在模拟学生和物理测量中比较了该滤波器诱导的x射线光谱随入射角的变化。网格还集成到CT测试台上，在那里我们扫描了具有临床相关浓度（5、10、20和50 mgI/mL）的碘化幻影，以展示进行光谱CT采集和材料分解的能力。结果x射线谱仪测量结果显示，在小角度变化的情况下，光谱形状多样、可控，与模拟研究结果一致。确定了诱导光谱特性发生显著变化的临界角。对相隔2°的两个角度的投影数据进行重建，物质分解为碘和水图像，与已知的碘浓度吻合良好。这项工作证明了基于网格的方法能够实现光谱CT数据采集和准确的材料分解。正在进行的和未来的研究将调查这种新概念的潜力，作为标准能量积分CT的相对简单的升级。
PurposeInterest in spectral computed tomography (CT) for diagnostics and therapy evaluation has been growing. Data acquisitions with distinct spectral sensitivities provide the ability to discriminate multiple materials, quantitative density estimates, and reduced artifacts due to energy dependencies. We introduce a novel spectral CT concept that includes a fine‐pitch grid structure for prefiltration of the x‐ray beam.MethodsWe develop physical models for grid designs and illustrate the basic operating principles wherein small angulations of the incident x rays results significant filtration and spectral shaping of the beam. We fabricate a prototype grid with tungsten lamellae. We compare x‐ray spectra induced by this filter as a function of incidence angle in both simulation students and in physical measurements. The grid is also integrated onto a CT test bench where we scanned an iodinated phantom with clinically relevant concentrations (5, 10, 20, and 50 mgI/mL) to demonstrate the ability to perform spectral CT acquisitions and material decomposition.ResultsX‐ray spectrometer measurements reveal diverse and controllable spectral shaping with small angle changes that are in agreement with simulation studies. Critical angles where the characteristics of the induced spectrum changes dramatically are identified. Reconstructions of projection data for two angulations separated by 2° was reconstructed and material decomposition into iodine and water images shows good agreement with the known iodine concentrations.ConclusionsThis work demonstrates the feasibility of the grid‐based approach to enable spectral CT data acquisitions and accurate material decompositions. On‐going and future studies will investigate the potential of this novel concept as a relatively simple upgrade to standard energy‐integrating CT.