Collimators for Gamma Dual Energy CT Arch-Detector: A Simulation Study
Collimators for Gamma Dual Energy CT Arch-Detector: A Simulation Study
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DOI：
10.3938/jkps.76.79
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发表时间：
2020-01
影响因子：
0.6
通讯作者：
Eva Pratiwi;Seungbin Bae;Hakjee Lee;Muhammad Nasir Ullah;Boram Lee;Kisung Lee;J. Yeom
中科院分区：
文献类型：
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作者：
Eva Pratiwi;Seungbin Bae;Hakjee Lee;Muhammad Nasir Ullah;Boram Lee;Kisung Lee;J. Yeom
CT扫描系统的图像分辨率受准直器材料、准直器设计、探测器阻止本领、散射光子抑制和/或校正技术等因素的影响。散射光子是背景噪声的主要来源之一，其可以极大地降低CT系统的图像质量。图像质量又影响系统的辨别和识别性能，特别是在用于材料分解的双能量CT系统的情况下。因此，对于材料识别，以最小的噪声采集原始数据是非常重要的。在这项模拟研究中，两种类型的准直器的性能进行了评估，提出了一个更好的准直器设计的背景噪声压缩。两个准直器均由钨制成，具有相似的30 mm长度，但具有不同的孔形状（扇形和平行）。在这两种情况下，结果表明，在空间分辨率方面有明显的改善。在网格结构的比较中，在大多数情况下，风扇网格的性能略好于平行网格。扇形准直器和平行准直器对122 keV γ辐射源的峰谷比分别平均提高了16%和23%。对于60 keV伽马源，改进分别为0.14（14%）和0.17（17%）。因此，从结果中可以得出结论，与平行栅格准直器相比，扇形栅格准直器可以提供上级性能。
The image resolution of computed tomography (CT) scan system can be affected by numbers of factors such as collimator material, collimator design, stopping power of detector and scatter photons rejection and/or correction technique. The scatter photons are one of the major sources of background noise that can immensely degrade the image quality of the CT system. The image quality, in turn, affects the discrimination and identification performance of the system especially in the case of dual-energy CT systems for material decomposition. Therefore, for material identification, acquisition of raw data with minimal noise is of immense importance. In this simulation study, the performance of two types of collimators was evaluated to come up with a better collimator design for background noise compression. Both collimators were made of tungsten with similar length of 30 mm but with different hole shapes (fan and parallel). In both cases, results suggest that there is a clear improvement in terms of spatial resolution. In a comparison of grids structure, fan grid performed slightly better than parallel for most of the cases. The peak-to-valley (PV) ratio for 122 keV gamma radiation source improved on average ∼0.16 (16%) and ∼0.23 (23%) for fan collimator and parallel collimator respectively. For 60 keV gamma source, the improvements were ∼0.14 (14%) and ∼0.17 (17%) respectively. Thus, from the results, it can be concluded that fan grid collimator can provide superior performance compared to parallel grid collimator.