论文标题
使用具有飞行焦点（SMFF）的光谱调制器的多能混合CBCT光谱成像
Multi-Energy Blended CBCT Spectral Imaging Using a Spectral Modulator with Flying Focal Spot (SMFFS)
论文作者
论文摘要
常规的锥形束CT（CBCT）可以通过散射和横梁硬化的伪影很容易被损害，散射和光谱效应的纠缠引入了额外的复杂性。在这项工作中，我们提出了首次尝试使用Flove Pocal（SMFF）技术开发固定光谱调制器，作为一种有希望的低成本方法，以准确解决X射线散射问题并在统一框架中实现光谱成像。为了应对相互交织的散射 - 光谱挑战，我们提出了一种基于散射相似性的假设，提出了一种新型的散射式耦合材料分解（SDMD）方法。具有不同焦点偏转的纯水缸幻影的蒙特卡洛模拟表明，焦点偏转范围内的范围偏转范围约为2 mm。使用腹部CT数据集的数值模拟表明，具有SDMD方法的SMFF可以实现更好的材料分解和CT数量的精度，而伪像更少。使用γ多能CT Phantom进行拟人化的胸部幻影，在桌面CBCT系统上进行物理实验，以证明使用SMFFS进行CBCT光谱成像的可行性。对于胸部幻影，对于SMFFS CB扫描，在70 keV的虚拟单色图像（VMI）的选定区域（ROI）中的根平方误（RMSE）为11.8 HU，对于顺序80/140 kVp（DKV）CB扫描和不带分散的校正，序列的80/140 kvp（dkv）secential 80.5和437.6 HU。同样，对于SMFF CB扫描，选定区域之间的不均匀性为14.1 HU，使用和没有传统的散射校正方法的DKV CB扫描为59.4和184.0 HU。我们的初步结果表明，SMFF可以同时进行CBCT进行光谱成像，并有效地改善其定量成像性能。
Conventional cone-beam CT (CBCT) can be easily compromised by scatter and beam hardening artifacts, and the entanglement of scatter and spectral effects introduces additional complexity. In this work, we present the first attempt to develop a stationary spectral modulator with flying focal spot (SMFFS) technology as a promising, low-cost approach to accurately solving the X-ray scattering problem and physically enabling spectral imaging in a unified framework. To deal with the intertwined scatter-spectral challenge, we propose a novel scatter-decoupled material decomposition (SDMD) method for SMFFS based on a hypothesis of scatter similarity. Monte Carlo simulations of a pure-water cylinder phantom with different focal spot deflections show that focal spot deflections within a range of ~2 mm share quite similar scatter distributions overall. Numerical simulations using a clinical abdominal CT dataset demonstrate that SMFFS with SDMD method can achieve better material decomposition and CT number accuracy with less artifacts. Physics experiments on a tabletop CBCT system using a Gammex multi-energy CT phantom an anthropomorphic chest phantom, are carried out to demonstrate the feasibility of CBCT spectral imaging with SMFFS. For the chest phantom, the root mean square error (RMSE) in selected regions of interest (ROIs) of virtual monochromatic image (VMI) at 70 keV is 11.8 HU for SMFFS CB scan, and 14.5 and 437.6 HU for sequential 80/140 kVp (DKV) CB scan with and without scatter correction, respectively. Also, the non-uniformity among selected regions is 14.1 HU for SMFFS CB scan, and 59.4 and 184.0 HU for the DKV CB scan with and without a traditional scatter correction method, respectively. Our preliminary results show that SMFFS can enable spectral imaging with simultaneous scatter correction for CBCT and effectively improve its quantitative imaging performance.
