Spatial resolution measurement for iterative reconstruction by use of image-averaging techniques in computed tomography.
Spatial resolution measurement for iterative reconstruction by use of image-averaging techniques in computed tomography.
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DOI：
10.1007/s12194-014-0273-2
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发表时间：
2014-07-01
影响因子：
1.6
通讯作者：
Nakaya, Yoshihiro
中科院分区：
文献类型：
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作者：
Urikura, Atsushi;Ichikawa, Katsuhiro;Nakaya, Yoshihiro
我们研究的目的是研究使用条形模型和图像平均技术相结合的空间分辨率测量方法的有效性，并评估具有中等对比度（50 HU）物体的迭代重建（IR）图像的空间分辨率特性。我们使用通过红外技术自适应迭代剂量减少 3D (AIDR 3D) 重建的条形模型的计算机断层扫描 (CT) 图像，该技术安装在多探测器 CT 系统 Aquilion ONE（日本大田原东芝医疗系统）中。条形图像的对比度设置为50 HU，这被认为是临床上需要较高空间分辨率的中间对比度。我们采用图像平均技术来消除图像噪声的影响，并获得了噪声足够低的条形模型的平均图像。从图像中测量调制传递函数（MTF）。也采用传统的拉丝法进行比较；在此方法中，AIDR 3D 显示的 MTF 值与滤波反投影的值相当。对于中等对比度条件，结果表明AIDR 3D的MTF随着IR处理强度的增加而降低。此外，AIDR 3D 的 MTF 随着剂量减少而降低。所使用的图像平均技术对于正确评估红外图像中中等对比度物体的空间分辨率是有效的。通过我们的方法获得的结果表明，AIDR 3D 的分辨率保留对于中等对比度的物体来说是不够的。
The purpose of our study was to investigate the validity of a spatial resolution measuring method that uses a combination of a bar-pattern phantom and an image-averaging technique, and to evaluate the spatial resolution property of iterative reconstruction (IR) images with middle-contrast (50 HU) objects. We used computed tomography (CT) images of the bar-pattern phantom reconstructed by the IR technology Adaptive Iterative Dose Reduction 3D (AIDR 3D), which was installed in the multidetector CT system Aquilion ONE (Toshiba Medical Systems, Otawara, Japan). The contrast of the bar-pattern image was set to 50 HU, which is considered to be a middle contrast that requires higher spatial resolution clinically. We employed an image-averaging technique to eliminate the influence of image noise, and we obtained averaged images of the bar-pattern phantom with sufficiently low noise. Modulation transfer functions (MTFs) were measured from the images. The conventional wire method was also used for comparison; in this method, AIDR 3D showed MTF values equivalent to those of filtered back projection. For the middle-contrast condition, the results showed that the MTF of AIDR 3D decreased with the strength of IR processing. Further, the MTF of AIDR 3D decreased with dose reduction. The image-averaging technique used was effective for correct evaluation of the spatial resolution for middle-contrast objects in IR images. The results obtained by our method clarified that the resolution preservation of AIDR 3D was not sufficient for middle-contrast objects.