Quality evaluation of image‐based iterative reconstruction for CT: Comparison with hybrid iterative reconstruction
Quality evaluation of image‐based iterative reconstruction for CT: Comparison with hybrid iterative reconstruction
复制标题
基于图像的 CT 迭代重建质量评估：与混合迭代重建的比较
DOI：
10.1002/acm2.12597
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发表时间：
2019
影响因子：
2.1
通讯作者：
Kobayashi Satoshi
中科院分区：
文献类型：
--
作者：
Kawashima Hiroki;Ichikawa Katsuhiro;Matsubara Kosuke;Nagata Hiroji;Takata Tadanori;Kobayashi Satoshi
本研究的目的是评估一种商用的基于图像的迭代重建(IIR)系统对软组织(60HU)和增强血管(270HU)两种对比度的物理图像质量，并与滤波反投影(FBP)和迭代重建(IR)的结果进行比较。使用192层CT扫描仪进行数据采集。对FBP图像进行IIR图像处理。在4个剂量水平(2.5、5、10和20mGy四个剂量水平)下，测量了直径为25 cm的水模中杆状物体的基于任务的面内传递函数(TTF)和切片灵敏度分布(SSP任务)。从仅含水的部分测量噪声功率谱(NPS)。系统性能(SP)函数被计算为FBP、IR和IIR的TTF2/NPS以进行比较。此外，使用杆状物体、条形体模和临床腹部病例的图像进行图像减影，以观察IIR的降噪性能。结果表明，IIR基本保持了FBP的TTF和SSPtask值，而60HU对比度和270HU对比度的IIR在10和20mGy时表现出增强的TTF。2.5、5、10mGyIIR半量照射的SP与5、10、20mGyFBP照射的SP相似。IR在中高频时表现为SP增强。减影图像在条形图像和腹部图像中显示微弱的残留边缘信号。总而言之，IIR在整个频率范围内一致地改善了基于任务的FBP的图像质量，而IR则改善了中到高频下的图像质量。当允许轻微的信号减少时，从SP估计的IIR的剂量减少潜力约为50%。
The purpose of this study is to evaluate the physical image quality of a commercially available image‐based iterative reconstruction (IIR) system for two object contrasts to resemble a soft tissue (60 HU) and an enhanced vessel (270 HU), and compare the results with those of filtered back projection (FBP) and iterative reconstruction (IR). A 192‐slice computed tomography (CT) scanner was used for data acquisitions. IIR images were processed from the FBP images. Task‐based in‐plane transfer function (TTF) and slice sensitivity profile (SSPtask) were measured from rod objects inside of a 25‐cm diameter water phantom at four dose levels (2.5, 5, 10, and 20 mGy). Noise power spectrum (NPS) was measured from the water‐only part. System performance (SP) function was calculated as TTF2/NPS over FBP, IR, and IIR for comparison. In addition, an image subtraction was performed using images of rod objects, a bar‐pattern phantom, and a clinical abdomen case to observe the noise reduction performance of IIR. As a results, IIR mostly preserved TTF and SSPtaskof FBP, whereas IR exhibited enhanced TTF at 10 and 20 mGy for 60 HU contrast and at all doses for 270 HU contrast. SP of IIR at 2.5, 5, 10 mGy (half doses) were similar to those of FBP at 5, 10, 20 mGy, respectively. IR exhibited enhanced SP at medium to high frequencies. The subtracted images showed weak remained edge signals in the bar‐pattern and abdominal images. In conclusion, IIR uniformly improved the task‐based image quality of FBP over the entire frequency range, whereas IR improved the characteristics over medium to high frequencies. The dose reduction potential of IIR estimated from SP is approximately 50%, when allowing the slight signal reductions.