A Monte Carlo simulation study of an improved K-edge log-subtraction X-ray imaging using a photon counting CdTe detector
A Monte Carlo simulation study of an improved K-edge log-subtraction X-ray imaging using a photon counting CdTe detector
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DOI：
10.1016/j.nima.2016.06.024
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发表时间：
2016-09
影响因子：
1.4
通讯作者：
Youngjin Lee;Amy Candy Lee;Hee-Joung Kim
中科院分区：
文献类型：
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作者：
Youngjin Lee;Amy Candy Lee;Hee-Joung Kim
近年来，基于CdTe的光子计数探测器(PCD)在X射线成像系统中的应用得到了很大的发展。开发PCD的动机是更高的图像质量。特别是，使用PCD的K边缘减影(KES)成像技术能够改善图像质量，并有助于通过使用造影剂来提高目标材料的对比度分辨率。基于上述技术，我们提出了一种改进的K边缘对数减影(KELS)成像技术。基于PCDS的KELS成像技术可以通过采用不同的能量窗减去能量宽度来实现。在这项研究中，通过蒙特卡罗模拟，研究了KELS成像技术和能量窗减影能量宽度对对比度、标准差和CNR的影响。我们模拟了基于不同碘造影剂组成的CdTe和聚甲基丙烯酸甲酯(PMMA)体模的PCD X射线成像系统。为了获得KELS图像，在不同的能量范围内采集了使用碘对比剂K边吸收能量(33.2keV)上下的体模的图像。结果表明，随着能量窗减去能量宽度的增加，对比度和标准差减小。此外，使用KELS成像技术的CNR高于使用全能量范围获取的图像的CNR。其中，直径为1、2、3 mm的碘造影剂的全能量范围图像与KELS图像的CNR最大差值分别为11.33、8.73、8.29倍。此外，对于直径为1 mm、2 mm和3 mm的碘造影剂，分别在5、4和3keV处可以获得最佳的减影能量窗宽度。总之，我们成功地建立了一种改进的KELS成像技术，并优化了能量窗的减影能量宽度，根据我们的结果，我们建议使用该技术来获得高质量的图像。
Recently, significant effort has been spent on the development of photons counting detector (PCD) based on a CdTe for applications in X-ray imaging system. The motivation of developing PCDs is higher image quality. Especially, the K-edge subtraction (KES) imaging technique using a PCD is able to improve image quality and useful for increasing the contrast resolution of a target material by utilizing contrast agent. Based on above-mentioned technique, we presented an idea for an improved K-edge log-subtraction (KELS) imaging technique. The KELS imaging technique based on the PCDs can be realized by using different subtraction energy width of the energy window. In this study, the effects of the KELS imaging technique and subtraction energy width of the energy window was investigated with respect to the contrast, standard deviation, and CNR with a Monte Carlo simulation. We simulated the PCD X-ray imaging system based on a CdTe and polymethylmethacrylate (PMMA) phantom which consists of the various iodine contrast agents. To acquired KELS images, images of the phantom using above and below the iodine contrast agent K-edge absorption energy (33.2 keV) have been acquired at different energy range. According to the results, the contrast and standard deviation were decreased, when subtraction energy width of the energy window is increased. Also, the CNR using a KELS imaging technique is higher than that of the images acquired by using whole energy range. Especially, the maximum differences of CNR between whole energy range and KELS images using a 1, 2, and 3 mm diameter iodine contrast agent were acquired 11.33, 8.73, and 8.29 times, respectively. Additionally, the optimum subtraction energy width of the energy window can be acquired at 5, 4, and 3 keV for the 1, 2, and 3 mm diameter iodine contrast agent, respectively. In conclusion, we successfully established an improved KELS imaging technique and optimized subtraction energy width of the energy window, and based on our results, we recommend using this technique for high image quality.