Photon-counting computed tomography (PCCT) is an emerging technology based on new energy-resolving X-ray detectors (photon-counting detectors (PCDs)) that provide promising image performance compared to the conventional energy-integrating CT (EICT). It has the potential to provide higher resolution and contrast, lower radiation dose, and fewer artifacts, which has led to significant research interest. This study proposes a method to further improve the image performance of the PCCT using an X-ray spectrum filtration technique. We conducted a feasibility study via simulations using aluminum (Al), beryllium (Be), sodium (Na), nickel (Ni), tin (Sn), neodymium (Nd), and tantalum (Ta) incorporating varying thicknesses using a PCD simulation toolkit (PcTK). The PCCT system used in this simulation was modeled to have a cadmium telluride-based PCD with four multi-energy thresholds of E = 40, 60, 80, 100 keV, assuming that the object received the same number of photons. Using the PCCT images obtained with the highest threshold (i.e., E₄ = 100 keV), the image quality was evaluated quantitatively in terms of the signal difference-to-noise ratio (SDNR) and structural similarity (SSIM). Among the filtrations selected in this simulation, a filtration of 2.0 mmAl (inherent) and 1.5 mmSn (added) showed the best image quality. The SDNR and SSIM values measured in the PCCT image obtained with an added filtration of 1.5 mmSn were 3.73 and 0.81, approximately 1.9 and 1.8 times higher than those with no added filtration, respectively. Consequently, the X-ray spectrum filtration technique in PCCT is useful to further improve image performance.

中文翻译：

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使用 X 射线光谱过滤提高光子计数计算机断层扫描图像性能的可行性

光子计数计算机断层扫描 (PCCT) 是一种基于新型能量分辨 X 射线探测器（光子计数探测器 (PCD)）的新兴技术，与传统的能量积分 CT (EICT) 相比，它提供了有前景的图像性能。它有可能提供更高的分辨率和对比度、更低的辐射剂量和更少的伪影，这引起了人们的巨大研究兴趣。本研究提出了一种使用 X 射线光谱过滤技术进一步提高 PCCT 图像性能的方法。我们通过 PCD 模拟，使用不同厚度的铝 (Al)、铍 (Be)、钠 (Na)、镍 (Ni)、锡 (Sn)、钕 (Nd) 和钽 (Ta) 进行了可行性研究工具包（PcTK）。该模拟中使用的 PCCT 系统被建模为具有基于碲化镉的 PCD，其具有四个多能量阈值 E = 40、60、80、100 keV，假设物体接收到相同数量的光子。使用最高阈值（即E ₄ = 100 keV）获得的PCCT图像，从信号差噪比（SDNR）和结构相似性（SSIM）方面定量评估图像质量。在本模拟中选择的过滤器中，2.0 mmAl（固有）和 1.5 mmSn（添加）过滤器显示出最佳的图像质量。添加 1.5 mmSn 过滤的 PCCT 图像中测得的 SDNR 和 SSIM 值分别为 3.73 和 0.81，分别比未添加过滤的图像高约 1.9 和 1.8 倍。因此，PCCT 中的 X 射线能谱过滤技术有助于进一步提高图像性能。